ArticleLiterature Review

Central venous pressure: A useful but not so simple measurement

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Abstract

To review the clinical use of central venous pressure measurements. The Medline database, biographies of selected articles, and the author's personal database. Four basic principles must be considered. Pressure measurements with fluid-filled systems are made relative to an arbitrary reference point. The pressure that is important for preload of the heart is the transmural pressure, whereas the pressure relative to atmosphere still affects other vascular beds outside the thorax. The central venous pressure is dependent upon the interaction of cardiac function and return function. There is a plateau to the cardiac function curve, and once it is reached, further volume loading will not increase cardiac output. If careful attention is paid to proper measurement techniques, central venous pressure can be very useful clinically. However, the physiologic or pathophysiological significance of the central venous pressure should be considered only with a corresponding measurement of cardiac output or at least a surrogate measure of cardiac output.

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... Für die Messung des intravasalen Druckes wird dieser in Beziehung zum atmosphärischen Druck gesetzt. Beatmung, PEEP, Nullabgleich und Wahl des Referenzniveaus sind bei dieser Form der Druckmessung maßgebliche Einflussfaktoren und können sich relevant auf die Messung des ZVD auswirken [16,17]. ...
... Dieser Zustand ist sowohl bei beatmeten als auch bei spontan atmenden Patienten annähernd endexspiratorisch erreicht. Bei Verwendung eines PEEP ("positive endexpiratory pressure") ist allerdings der intrathorakale Druck niemals 0, sodass die Messungen immer bis zu einem gewissen Grad beeinflusst bleiben [17]. Ein weiterer Faktor, der in diesem Zusammenhang eine Rolle spielt, ist die Lungen-Compliance, die einen relevanten Einfluss auf den intrathorakalen Druck und damit auch auf die Messung des ZVD hat. ...
... Zur Bestimmung der kardialen Vorlast ist die c-Kurve (. Abb. 1) am besten geeignet, da sie zeitlich dem atrialen Druck kurz vor der Ventrikelsystole entspricht [17]. Aber auch die anderen Abschnitte und die Form der Kurve können wichtige Informationen liefern, insbesondere wenn auf die Hämodynamik der Leber geschlos-sen werden soll. ...
Article
Central venous pressure (CVP) is deemed to be an important parameter of anesthesia management in liver surgery. To reduce blood loss during liver resections, a low target value of CVP is often propagated. Although current meta-analyses have shown a connection between low CVP and a reduction in blood loss, the underlying studies show methodological weaknesses and advantages with respect to morbidity and mortality can hardly be proven. The measurement of the CVP itself is associated with numerous limitations and influencing factors and the measures to reduce the CVP have been insufficiently investigated with respect to hepatic hemodynamics. The definition of a generally valid target area for the CVP must be called into question. The primary objective is to maintain adequate oxygen supply and euvolemia. The CVP should be regarded as a mosaic stone of hemodynamic management.
... Alguns autores afirmam que a PVC não deveria ser rotineiramente verificada por não ser um bom preditor de volume intravascular, e deveria ser usada em circunstâncias selecionadas, como pacientes que se submeteram a transplante cardíaco, sofreram um infarto do ventrículo direito, ou nos quadros de embolia pulmonar aguda, como marcador da função ventricular direita, em vez de indicador de estado do volume sanguíneo 7,9 . Dessa forma, a análise dos resultados da PVC fica condicionada aos demais parâmetros de monitoração e ao quadro clínico do paciente, bem como sua função cardíaca 10 . ...
... Determinar a via de acesso é o ponto de partida para mensuração da PVC. O cateter pode ser instalado via jugulares internas, subclávias, femorais, cateteres centrais de inserção periférica o Peripherally Inserted Central Catheter (PICC), por punção ou dissecção 2,[9][10][11][12] . A escolha do local de inserção deve considerar os riscos e benefícios de cada local. ...
... Para tal, deve--se saber que 1mmHg = 1,36cmH 2 O. A conversão de cmH 2 O para mmHg é realizada dividindo o valor obtido em cmH 2 O por 1,36 e a conversão para cmH 2 O é feita multiplicando o valor obtido em mmHg por1,36 4,10 . ...
Article
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Objetivo: identificar se existe diferença nos valores da pressão venosa central com a cabeceira do leito do paciente elevada. Método: estudo longitudinal, analítico e de abordagem quantitativa, realizado em quatro unidades de terapia intensiva de um hospital de grande porte do noroeste paulista, de agosto a novembro de 2013. A pressão venosa central foi mensurada em 156 pacientes, em quatro angulações diferentes, totalizando 624 medidas. Os dados são apresentados em números absolutos e percentuais, as variáveis analisadas pelo Teste de Mann-Whitney e Wilcoxon e associação entre as medidas pela análise do coeficiente de correlação de Pearson (r). Conclusão: a mensuração pode ser realizada com acurácia a 0° e 30°, pois apresentaram correlação positiva entre as medidas, porém a 0° e 45° a correlação é fraca, demonstrando pouca associação entre as variáveis.
... Unfortunately, the CVP is affected by multiple and at times opposite hemodynamic events, and its clinical interpretation is complex. 26,27 The CVP as a surrogate for RA pressure is the downstream pressure for VR (MCFP -CVP; see the VR equation), and a low CVP increases the VR and consequently the RVEDV. On the other hand, a fluid bolus also increases the RVEDV, generally with a concomitant increase of the CVP, which in this case is just a consequence of higher MCFP. ...
... The CVP alone (as a single measurement or trend) has little discriminating power because many factors other than blood volume can affect it, as discussed earlier. 15,26 In the presence of hypotension, perturbing the existing steady state with a known intervention such as a fluid bolus will create a new steady state along an imaginary Starling curve that will be steep under conditions of hypovolemia and then flatten with further fluid boluses as preload is optimized. 13 The increase in CO or arterial pressure that follows a fluid challenge has been termed ''fluid responsiveness'', 40,41 Importantly, fluid responsiveness is not synonymous with hypovolemia; for example, hypotension that occurs with the application of positive end-expiratory pressure (PEEP) is related to a low Vs relative to that level of PEEP and is not necessarily related to hypovolemia per se. ...
Article
Purpose: Understanding cardiovascular physiology should help clinicians to understand the purpose of fluid and drug management during the perioperative period. The purpose of this narrative review is to describe the pivotal role of the venous circulation in goal-directed hemodynamic and fluid therapy. Source: We selected relevant literature that examines the appropriateness of fluid therapy and pharmacologic interventions during the perioperative period. Principal findings: The interaction between the stressed and unstressed intravascular volume (Vs and Vu, respectively) regulates the venous return, which is the main determinant of cardiac output. The lack of hemodynamic response to an intravascular fluid challenge likely results from an unpredictable distribution of infused fluid between the Vs and Vu. Other factors affecting hemodynamic responses include the pharmacodynamics of common vasoactive drugs, which further highlight the complexity of the regulation of venous return during infusion of exogenous catecholamines. The response to even a highly selective agent can result in different hemodynamic effects. Low doses of α-adrenergic agonists constrict veins and may often shift blood from the Vu to the Vs, subsequently increasing the venous return and cardiac output, whereas higher drug doses constrict arteries and usually decrease cardiac output. Conclusions: The physiologic basis of goal-directed hemodynamic therapy is complex and not necessarily reflected in the information received from hemodynamic monitors. Understanding the physiologic basis of such therapy is a logical step towards its optimal use.
... However, the radial artery is susceptible to vasospasm and hematoma formation after multiple cannulation attempts. In a prospective randomized study by Levin et al. comparing ultrasound-guided radial artery cannulation versus the traditional palpation technique, two-dimensional ultrasoundguided catheterization was superior to palpation for first insertion attempt and overall total number of attempts (15). ...
... When the tip of the pulmonary artery catheter (PAC) is in the superior vena cava and right atrium, the waveform corresponds to the central venous pressure tracing. Entrance to the right ventricle leads to a sudden increase in the systolic pressure (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) with the same diastolic pressure as on the right atrium (0-8 mmHg). As the PAC is advanced more deeply, the pulmonary artery is entered. ...
... variation in RAP could predict fluid responsiveness in spontaneously breathing patients although several requirements, such as a sufficient inspiratory effort and absence of forced expiration, must be met, otherwise no adequate prediction can be made. [22][23][24] This is similar for SVV and PPV for which mechanical ventilation without spontaneous breathing activity is required with tidal volumes > 8 ml/kg. Stroke volume variation and PPV were calculated using the modified Modelflow â which is an uncalibrated pulse contour analysis method. ...
... Others have used variation in the components of the central venous pressure waveform, such as the difference between the awave and x-descent, variation of the base of the a-or c-wave, or by analyzing the y-descent. 11,23,24 However, the components of the central venous pressure waveform are frequently not easy to discern and small errors in measurements can interfere with the index. We showed that variations in beat-to-beat mean CVP can be used instead. ...
Article
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Background: Ventilator-induced dynamic hemodynamic parameters such as stroke volume variation (SVV) and pulse pressure variation (PPV) have been shown to predict fluid responsiveness in contrast to static hemodynamic parameters such as central venous pressure (CVP). We hypothesized that the ventilator-induced central venous pressure variation (CVPV) could predict fluid responsiveness. Methods: Twenty-two elective cardiac surgery patients were studied post-operatively on the intensive care unit during mechanical ventilation with tidal volumes of 6-8 ml/kg without spontaneous breathing efforts or cardiac arrhythmia. Before and after administration of 500mL hydroxyethyl starch, SVV and PPV were measured using pulse contour analysis by modified Modelflow(®) , while CVP was obtained from a central venous catheter positioned in the superior vena cava. CVPV was calculated as 100 × (CVPmax -CVPmin )/[(CVPmax + CVPmin) /2]. Results: Nineteen patients (86%) were fluid responders defined as an increase in cardiac output of ≥ 15% after fluid administration. CVPV decreased upon fluid loading in responders, but not in non-responders. Baseline CVP values showed no correlation with a change in cardiac output in contrast to baseline SVV (r = 0.60, P = 0.003), PPV (r = 0.58, P = 0.005), and CVPV (r = 0.63, P = 0.002). Baseline values of SVV > 9% and PPV > 8% could predict fluid responsiveness with a sensitivity of 89% and 95%, respectively, both with a specificity of 100%. Baseline CVPV could identify all fluid responders and non-responders correctly at a cut-off value of 12%. There was no difference between the area under the receiver operating characteristic curves of SVV, PPV, and CVPV. Conclusion: The use of ventilator-induced CVPV could predict fluid responsiveness similar to SVV and PPV in post-operative cardiac surgery patients.
... Variability in current practices related to crystalloid or colloid "fluid bolus, " "fluid challenge, " or assessment of "preload responsiveness" including methods for the assessment of "hemodynamic improvement, " in addition to longer term outcomes, preclude comparisons for substantive conclusions (121,178,204,(212)(213)(214)(215)(216). Recent studies have focused on data for objective characterization of some of these terms, but no consensus has been established (137,204,213,(217)(218)(219). Continued research is required, specifically focused on veterinary patients (i.e., for each species and in diverse clinical situations) before they can be effectively translated into clinical practice. ...
Article
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Although the utility and benefits of anesthesia and analgesia are irrefutable, their practice is not void of risks. Almost all drugs that produce anesthesia endanger cardiovascular stability by producing dose-dependent impairment of cardiac function, vascular reactivity, and compensatory autoregulatory responses. Whereas anesthesia-related depression of cardiac performance and arterial vasodilation are well recognized adverse effects contributing to anesthetic risk, far less emphasis has been placed on effects impacting venous physiology and venous return. The venous circulation, containing about 65–70% of the total blood volume, is a pivotal contributor to stroke volume and cardiac output. Vasodilation, particularly venodilation, is the primary cause of relative hypovolemia produced by anesthetic drugs and is often associated with increased venous compliance, decreased venous return, and reduced response to vasoactive substances. Depending on factors such as patient status and monitoring, a state of relative hypovolemia may remain clinically undetected, with impending consequences owing to impaired oxygen delivery and tissue perfusion. Concurrent processes related to comorbidities, hypothermia, inflammation, trauma, sepsis, or other causes of hemodynamic or metabolic compromise, may further exacerbate the condition. Despite scientific and technological advances, clinical monitoring and treatment of relative hypovolemia still pose relevant challenges to the anesthesiologist. This short perspective seeks to define relative hypovolemia, describe the venous system’s role in supporting normal cardiovascular function, characterize effects of anesthetic drugs on venous physiology, and address current considerations and challenges for monitoring and treatment of relative hypovolemia, with focus on insights for future therapies.
... 25 Based on evidence, CVP remains an important variable in the monitoring of patients in perioperative and critical care settings. 26 The aim of the study was primarily to assess the variability in CVP transducer alignment in the ICU. Secondary, we assessed whether patient characteristics had any influence on the deviation in CVP transducer alignment. ...
Article
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Background: The phlebostatic axis is the most commonly used anatomical external reference point for central venous pressure measurements. Deviation in the central venous pressure transducer alignment from the phlebostatic axis causes inadequate pressure readings, which may affect treatment decisions for critically ill patients in intensive care units. Aim: The primary aim of the study was to assess the variability in central venous pressure transducer levelling in the intensive care unit. We also assessed whether patient characteristics impacted on central venous pressure transducer alignment deviation. Methods: A sample of 61 critical care nurses was recruited and asked to place a transducer at the appropriate level for central venous pressure measurement. The measurements were performed in the intensive care unit on critically ill patients in supine and Fowler's positions. The variability among the participants using eyeball levelling and a laser levelling device was calculated in both sessions and adjusted for patient characteristics. Results: A significant variation was found among critical care nurses in the horizontal levelling of the pressure transducer placement when measuring central venous pressure in the intensive care unit. Using a laser levelling device did not reduce the deviation from the phlebostatic axis. Patient characteristics had little impact on the deviation in the measurements. Conclusion: The anatomical external landmark for the phlebostatic axis varied between critical care nurses, as the variation in the central venous pressure transducer placement was not reduced with a laser levelling device. Standardisation of a zero-level for vascular pressures should be considered to reduce the variability in vascular pressure readings in the intensive care unit to improve patient treatment decisions. Further studies are needed to evaluate critical care nurses' knowledge and use of central venous pressure monitoring and whether assistive tools and/or routines can improve the accuracy in vascular pressure measurements in intensive care units.
... CVP continues to be used for volume assessment. Provided principles of physiology and of measurement are borne in mind, CVP can provide a useful guide to assessment of cardiac preload, volume status, and the cause of a change in cardiac output and blood pressure [5]. Specific lower and higher CVP values have been shown to have positive and negative predictive value, respectively, for fluid responsiveness [6]. ...
Article
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Introduction: Early assessment of volume status is paramount in critically ill patients. Central venous pressure (CVP) measurement and ultrasound assessment of the inferior vena cava (IVC) are both used for volume assessment in the emergency centre. Recent data is conflicting over whether there is a correlation between CVP and ultrasound assessment of the IVC. Methods: This was a retrospective review of an audit previously performed in the Emergency Unit of Ngwelezane Hospital in Kwazulu-Natal. The audit involved measuring inferior vena cava collapsibility index (IVC-CI) within 5 min of CVP measurement. In this retrospective study, audit data were analysed to determine if an association exists. Results: Twenty-four patients were included. The median age of participants was 36 (IQR 42) years (95% CI 33-56). The median time to ultrasound was 18.6 (52.5) h (95% CI 7.5-36.2). The mean CVP was 13.7 ± 7.7 cm H2O and mean IVC-CI was 39.4 ± 17.8%. Based on a Pearson correlation test, there was a weak negative correlation between CVP and IVC-CI, which was not statistically significant (r = -0.05, n = 24, p = 0.81, 95% CI -0.5 to 0.4) for all participants. However, among females there was a moderate negative correlation between CVP and IVC-CI, which was not statistically significant (r = -0.43, n = 7, p = 0.34, 95% CI -0.9 to 0.5), while among males there was a weak positive correlation, which was not statistically significant (r = 0.16, n = 17, p = 0.53, 95% CI -0.3 to 0.6). Discussion: There is no significant correlation between CVP and IVC-CI. Further validation research is required to support our preliminary findings of no significant correlation between CVP measurement and ultrasound assessment of the IVC. CVP and IVC ultrasound should be used as clinical adjuncts, and not as stand-alone measures of volume assessment.
... A definitive review to demonstrate the clinical use of CVP to assess preload in patients was published in 2006. 66 The author explains that the CVP measured value reaches a plateau where cardiac output is optimal and an increase of fluid volume will cause no change in this value. Cardiac output will also not increase. ...
Thesis
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Abstract The HI-MAP scan is a focussed ultrasound examination designed to assess the hydration status of patients by looking at the heart, inferior vena cava, abdomen, aorta and chest. In the Emergency Centre (EC) this non-invasive tool can assist in early accurate diagnosis of critically ill patients. Aim The aim of this study is to demonstrate the use of the HI-MAP scan in a regional EC in KZN to assist in assessment of hydration status of critically ill patients. Methods This is a cross sectional retrospective descriptive study of HI-MAP scans performed on haemodynamically unstable patients who were admitted to the EC at Ngwelezane Hospital from January 2010 until October 2011. Diagnosis before and after ultrasound, times and specific ultrasound findings were documented and analysed. Results A total of 133 patients were included. When provisional compared to final diagnosis after ultrasound, 87 patients had the same and 46 had different diagnosis confirmed by HI-MAP. A third of the patients had a different diagnosis after the HI-MAP scan was performed. In fluid overloaded patients 95% had either poor contractility or Inferior vena cava collapsibility index (IVC-CI) of less than 25%. In hypovolaemic patients 96% had either hyperdynamic cardiac contractility or IVC-CI of less than 50%. Conclusion HI-MAP scan is a good non-invasive tool for volume assessment. Cardiac contractility and IVC-CI are the two most sensitive components of this scan to predict hydration status in critical patients.
... No es recomendable el monitoreo de la presión venosa central o de la presión de oclusión de la arteria pulmonar como única variable para guiar la reanimación o el estado de volumen de la paciente (48) , ya que se considera un parámetro dinámico que debe ser interpretado en relación al resto de los signos vitales y, en caso de tenerlos, parámetros de flujo (56) . Las intervenciones deben ir dirigidas a mantener una presión venosa central entre 6 a 10 mmHg (57) , observando que la ausencia de respuesta clínica en la paciente requiere modificar el plan de manejo. ...
Article
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SUMMARY Maternal death has a preventive character and therefore avoidable, this is a problem of human rights, gender equality and social justice. One of the main strategies to reduce the presence of obstetric hemorrhage and its complications is the management and identification of risk factors for the development of this complication. A consensus of experts is proposed for the management of this important cause of death in the perioperative period, with the aim of unifying the clinical decision-making at the three levels of obstetric hemorrhage in the perioperative period, based on the recommendations supported by real evidence and available. The consensus is presented as a list of recommendations for each question of the selected topic. A PubMed and Cochrane Library search was conducted with clinical practice guidelines, systematic reviews, randomized clinical trials, meta-analyzes and clinical reports. Results were expressed in evidence level recommendation grade according to the characteristics of the design and type of study. The adequate management of the patient presenting obstetric hemorrhage is a priority, the decision making is adapted to the clinical context of the patient.
... Most of the intensive care units with training programs and community hospitals are not always staffed by senior physicians or intensivists; thus, obtaining a central venous access at internal jugular or sub-clavian site is associated with frequent complications if not performed by experienced hands. The main reason for avoiding femoral access has been the infection and misconception that this site cannot be relied for central venous pressure monitoring 3,4 . Literature is clear about the femoral site infection but if appropriate care is provided with bundle during insertion and maintenance thereafter, its rate of infection is similar to internal jugular site 5,6 . ...
Article
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Objective: To find the correlation between thoracic and femoral central venous pressure (CVP) and changes in femoral CVP, if any, incurred by intra-abdominal pressure. Study Design: Cross sectional observational study. Place and Duration of Study: Coronary care unit of National Institute of Cardiovascular Diseases Karachi, from Jul 2017 to Sep 2017. Material and Methods: We randomly selected 90 patients who had a thoracic central catheter and another femoral catheter in place. A central venous pressure (CVP) pressure was recorded at both sites simultaneously with the same electronic transducer after zero calibration. An intra-abdominal pressure was also noted. Results: Ninety patients participated in our study where mean age was 58.90 ± 11.34 years. The mean thoracic CVP was 11.22 ± 3.53 mmHg while mean femoral CVP was 11.38 ± 3.53 mmHg, with a mean pressure difference of -0.16 mmHg between the two. We also calculated intra-abdominal pressure with mean of 6.20 ± 2.47 mmHg. The reliability of the two methods was determined by intra class coefficient model where we got a higher value of 0.97 with significant p-value of <0.001. We analyzed the limits of agreement between the two approaches by Bland and Altman plot, where the mean difference between thoracic and femoral CVP was -0.16 mmHg (95 % CI - 0.34 - 0.02). Conclusion: Central venous pressure can be reliably and accurately measured through femoral site.
... No es recomendable el monitoreo de la presión venosa central o de la presión de oclusión de la arteria pulmonar como única variable para guiar la reanimación o el estado de volumen de la paciente (48) , ya que se considera un parámetro dinámico que debe ser interpretado en relación al resto de los signos vitales y, en caso de tenerlos, parámetros de fl ujo (56) . Las intervenciones deben ir dirigidas a mantener una presión venosa central entre 6 a 10 mmHg (57) , observando que la ausencia de respuesta clínica en la paciente requiere modifi car el plan de manejo. ...
Article
Full-text available
Maternal death has a preventive character and therefore avoidable, this is a problem of human rights, gender equality and social justice. One of the main strategies to reduce the presence of obstetric hemorrhage and its complications is the management and identification of risk factors for the development of this complication. A consensus of experts is proposed for the management of this important cause of death in the perioperative period, with the aim of unifying the clinical decision-making at the three levels of obstetric hemorrhage in the perioperative period, based on the recommendations supported by real evidence and available. The consensus is presented as a list of recommendations for each question of the selected topic. A PubMed and Cochrane Library search was conducted with clinical practice guidelines, systematic reviews, randomized clinical trials, meta-analyzes and clinical reports. Results were expressed in evidence level recommendation grade according to the characteristics of the design and type of study. The adequate management of the patient presenting obstetric hemorrhage is a priority, the decision making is adapted to the clinical context of the patient. © 2018, Colegio Mexicano de Anestesiologia A.C. All Rights Reserved.
... Central venous pressure (CVP) is the pressure in the thoracic vena cava near the right atrium. CVP is an important factor in critical care medicine because it can be used to estimate a patient's fluid volume status, assess cardiac function, and gauge how well the right ventricle of the heart is functioning (1). Due to the emphasis on early fluid resuscitation, excessive fluid resuscitation is more common in clinical practice (2). ...
Article
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Background: The Frank-Starling curve is the basis of hemodynamics. Changes in cardiac output (CO) caused by central venous pressure (CVP) are the most important concerns in the treatment of critically ill patients. Objectives: To explore the use of CVP and its relevant mechanisms with respect to CO in the clinic. Methods: A total of 134 patients with circulatory shock were retrospectively included and analyzed. Hemodynamic data were recorded and analyzed at PICCO initiation and 24 h after PICCO. Data regarding 28-day mortality and renal function were also collected. Results: The patients were divided into a CVP↑+ CO↑ group (n = 23), a CVP↑+ CO↓ group (n = 29), a CVP↓+ CO↑ group (n = 44), and a CVP↓+ CO↓ group (n = 38) based on values at PICCO initiation and 24 h after PICCO. Post- hoc tests showed that the CVP↓+ CO↑ group had a higher 28-day survival than the other groups [log-rank (Mantel-Cox) = 8.758, 95%, CI, 20.112–23.499, P = 0.033]. In terms of hemodynamic characteristics, the CVP↓+ CO↑ group had a lower cardiac function index (CFI) (4.1 ± 1.4/min) and higher extravascular lung water index (EVLWI) (11.0 ± 4.7 ml/kg) at PICCO initiation. This group used more cardiotonic drugs (77.3%, P < 0.001) and had a negative fluid balance (−780.4 ± 1720.6 ml/24 h, P = 0.018) 24 h after PICCO than the other three groups. Cardiotonic drug use and dehydration treatment were associated with increased CFI (from 4.1 ± 1.4 /min to 4.5 ± 1.3/min, P = 0.07) and reduced ELVWI (from 11.0 ± 4.7 ml/kg to 9.0 ± 3.5 ml/kg, P = 0.029). Renal function tests showed that SCr and BUN levels in the CVP↓+ CO↑ group were significantly improved (SCr from 197.1 ± 128.9 mmol/L to 154.4 ± 90.8 mmol/L; BUN from 14.3 μmol/L ± 7.3 to 11.6 ± 7.0 μmol/L, P < 0.05). Conclusions: Lower CVP was associated with increased CO, which may improve the 28-day prognosis in patients with circulatory shock. Notably, higher CO derived from lower CVP may also contribute to renal function improvement.
... CVP is frequently used for the assessment of cardiac preload and volume status [24]. Previously, many studies have documented a positive correlation between IAP and CVP [14,15,25]. ...
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Objective Many studies have indicated that intra-abdominal pressure (IAP) is positively correlated with central venous pressure (CVP) in severe cases. However, although elevated IAP is common in patients with severe acute pancreatitis (SAP), its relationship with CVP remains unclear. Our study aimed to investigate the association of IAP with CVP in early-phase SAP patients. Methods In total, 116 SAP patients were included in this retrospective study. On the first day of hospitalization , blood samples were collected for biochemical examination and cytokine concentration monitoring. Additionally, a urinary catheter and right subclavian vein catheter were inserted for IAP and CVP measurement, respectively. Other routine clinical data were also recorded. Results Within 24 hours after hospitalization, CVP fluctuated and increased with increasing IAP up to 15.7 mmHg (P = 0.054) but decreased with increasing IAP when the IAP was > 15.7 PLOS ONE |
... 10 Com efeito, um aumento da PVC mesmo na sequência de repleção volémica pode nada ter a ver com esta, refletindo apenas uma alteração da pressão nas vias aéreas de um paciente ventilado, ou ainda disfunção cardíaca direita. 7 Por outro lado, esse aumento não nos informa quanto ao efeito da pré-carga no débito cardíaco, podendo corresponder por exemplo à fase de plateau da curva de Frank-Starling. Também nestas condições haveria lugar a elevação da PVC, sem contudo corresponder a otimização do estado cardiovascular e aliás com franco potencial deletério. ...
Article
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http://revistas.rcaap.pt/anestesiologia/article/view/7114 Introduction: Central venous pressure (CVP) monitoring has been in use for decades to guide fluid therapy in unstable patients. However, a growing number of studies and meta-analysis have questioned its use. We sought to ascertain the validity of the physiologic principles leading to its adoption into clinical practice. Materials and Methods: We performed a non-systematic literature review to evaluate the real physiologic meaning of CVP. A PubMed search was made for the expressions " central venous pressure " and " fluid herapy " , and some of the most relevant references from the obtained articles were also included in our analysis. Results: Different articles and meta-analysis demonstrate that CVP is not a reliable marker of preload nor does it predict the response to a fluid challenge. The physio-logic principles underlying its use do not take into account dynamic cardiovascular changes occurring in the organism as a whole. Discussion and Conclusion: The accumulated evidence shows not only that we must not rely on CVP as a guide for fluid therapy, but also that its use draws on physiologic principles that are not totally correct, focusing on only part of the global picture. However, we realize CVP monitoring is still recommended by some international guidelines, a situation that is bound to change when more valid, accessible and widespread alternatives to this method are available. Technologies relying on dynamic preload indices are one such example.
... A change in either can alter it. Furthermore, a certain number of extrinsic factors can alter the precision in evaluating CVP [1][2][3]. Among those factors there are the mechanisms that increase thoracic pressure, for example, cough, effort and positive pressure ventilation [4]. ...
Article
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Central venous pressure (CVP) is primarily measured to assess intravascular volume status and heart preload. In clinical practice, the measuring device most commonly used in emergency departments and intensive care units, is an electronic transducer that interconnects a central venous catheter (CVC) with a monitoring system. Non-invasive ventilation (NIV) consists in a breathing support that supplies a positive pressure in airways through a mask or a cask though not using an endotracheal prosthesis. In emergency settings, non-invasive ultrasonography evaluation of CVP, and hence of intravascular volume status entail the measurement by a subxiphoid approach of inferior vena cava diameter and its variations in relation to respiratory activity. In the literature, there are many studies analyzing the ability to estimate CVP through ultrasonography, rating inspiratory and expiratory vena cava diameters and their ratio, defined as inferior vena cava collapsibility index (IVC-CI). At the same time, the effects of invasive mechanical ventilation on blood volume and the correlation during ventilation between hemodynamic invasive measurement of CVP and inferior vena cava diameters have already been demonstrated. Nevertheless, there are no available data regarding the hemodynamic effects of NIV and the potential correlations during this kind of ventilation between invasive and non-invasive CVP measurements. Therefore, this study aims to understand whether there exists or not an interrelationship between the values of CVP assessed invasively through a CVC and non-invasively through the IVC-CI in patients with severe respiratory distress, and above all to evaluate if these means of assessment can be influenced using NIV.
... connected to a differential pressure transducer which was filled with a 0.9% saline solution. CVP measurements were zeroed at mid-thoracic position at the level of the fifth rib [27], and the value was taken during either end-inspiration or end-expiration, at the base of "c" wave [28]. Transmural CVP was calculated as the difference between CVP and Pes [29]. ...
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Purpose The COVID-19-related shortage of ICU beds magnified the need of tools to properly titrate the ventilator assistance. We investigated whether bedside-available indices such as the ultrasonographic changes in diaphragm thickening ratio (TR) and the tidal swing in central venous pressure (ΔCVP) are reliable estimates of inspiratory effort, assessed as the tidal swing in esophageal pressure (ΔPes). Methods Prospective, observational clinical investigation in the intensive care unit of a tertiary care Hospital. Fourteen critically-ill patients were enrolled (age 64 ± 7 years, BMI 29 ± 4 kg/m²), after 6 [3; 9] days from onset of assisted ventilation. A three-level pressure support trial was performed, at 10 (PS10), 5 (PS5) and 0 cmH2O (PS0). In each step, the esophageal and central venous pressure tidal swing were recorded, as well as diaphragm ultrasound. Results The reduction of pressure support was associated with an increased respiratory rate and a reduced tidal volume, while minute ventilation was unchanged. ΔPes significantly increased with reducing support (5 [3; 8] vs. 8 [14; 13] vs. 12 [6; 16] cmH2O, p < 0.0001), as did the diaphragm TR (9.2 ± 6.1 vs. 17.6 ± 7.2 vs. 28.0 ± 10.0%, p < 0.0001) and the ΔCVP (4 [3; 7] vs. 8 [5; 9] vs. 10 [7; 11] cmH2O, p < 0.0001). ΔCVP was significantly associated with ΔPes (R² = 0.810, p < 0.001), as was diaphragm TR, albeit with a lower coefficient of determination (R² = 0.399, p < 0.001). Conclusions In patients with COVID-19-associated respiratory failure undergoing assisted mechanical ventilation, ΔCVP is a better estimate of inspiratory effort than diaphragm ultrasound.
... Electrolyte disturbances often accompany patients, especially those who are hospitalized in highly specialized departments. It is important to conduct research that shows the correlation between the correct level of sodium and potassium and the impact on the functioning of the body in the course of specific diseases [13]. ...
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Introduction: Delirium is a common complication of patients hospitalized in Intensive care units (ICU). The risk of delirium is estimated at approximately 80% in intensive care units. In the case of cardiac surgery ICU, the risk of delirium increases due to the type of procedures performed with the use of extracorporeal circulation. The aim of this study was to provide an official translation and evaluation of Nursing Delirium Screening Scale (NuDESC) into Polish. The NuDESC scale is a scale used by nurses around the world to detect delirium at an early stage in treatment. Methods: The method used in the study was the NuDESC tool, which was translated into Polish. The study was conducted by Cardiac ICU nurses during day shift (at 8 a.m.), night shift (at 8 p.m.) and in other situations where the patients showed delirium-like symptoms. Results: Statistically significant differences were observed between the first and second day in the studied group of patients in the case of illusions/hallucinations. Delirium occurred more frequently during the night, but statistical significance was demonstrated for both daytime and nighttime shifts. It was not demonstrated in relation to the NuDESC scale in the case of insomnia disorders. The diagnosis of delirium and disorientation was the most common diagnosis observed in patients on the first day of their stay in the ICU, followed by problems with communication. Delirium occurred on the first day, mainly at night. On the second day, delirium was much less frequent during the night; the biggest problem was disorientation and problems with communication. Conclusion: This study contributed to the development of the Polish version of the scale (NuDESC PL) which is now used as the Polish screening tool for delirium detection. The availability of an easy-to-use nurse-based delirium instrument is a prerequisite for widespread implementation.
... Ini tidak mengherankan, mengingat ketersediaan pengukuran CVP untuk setiap pasien yang memiliki akses vena sentral. CVP bahkan dapat dilakukan pengukuran pada sebagian besar orang dengan memeriksa distensi vena jugularis (Magder, 2006). Penelitian yang dilakukan oleh Fougères et al., (2010), mengenai perubahan hemodinamik akibat perubahan PEEP menunjukkan bahwa terdapat penurunan curah jantung dengan adanya peningkatan afterload ventrikel kanan. ...
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The purpose of this literature review is to discuss PEEP (Positive End Ekspiratory Pressure) and CVP (Central Venous Pressure) in patients who have ventilators. Adequate interpretation is needed by nurses who make direct observations about the patient's actual volume status without the influence of expiratory end pressure due to the administration of PEEP to patients who are attached to a ventilator. Study of this literature through a search of scientific publications using the database Pubmed, Google Scholar, Science Direct. Pubmed. Criteria for inclusion of this research article on PEEP and CVP in patients who are ventilators with publications between 2010-2017. This study shows that the effect of changing CVP values greatly influences hemodynamics and fluid status in the patient's body and determines the next interventions that will be given to patients so that changes in CVP values with PEEP in patients who are fitted with mechanical ventilators are needed in order to determine a meaningful CVP value. Based on this description, it is recommended that research studies related to changes in the conversion of CVP values with PEEP.
... e fluctuation of CVP can be enhanced through transmural pressure change in forced expiration, cardiac rhythm disorders, and respiratory variation [20]. CVP measurement in a clinical setting is not an easy task and may be affected by the zeroing and levelling of the transducer and any minor movement of patients and their respiration [21,22]. In the present study, TIPP measurements were correlated with those of CICCP, with only small discrepancies in intubated patients with ventilation support, especially those in a calm state. ...
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Background: A conventional centrally inserted central catheter (CICC) is frequently used to measure central venous pressure (CVP) to monitor the cardiocirculatory status of patients. The tip of the totally implanted port (TIP) is inserted at the same location in the superior vena cava as that of a CICC, and the TIP has been implanted in many patients with cancer. Measurements of CVP using CICC (CICCP) and TIP (TIPP) may be closely related. Material and Methods. Ten patients with TIPs in an intensive care unit were prospectively studied, and 121 records of 4536 paired CICCP and TIPP measurements were collected. A bench test in a static or dynamic setting was performed, and 598 paired measurements taken using CICC and TIP were recorded. Results: The measurement of TIPP was highly correlated with that of CICCP in patients with cancer, especially those in a calm state. Patients with a calm state and ≥3 consecutive identical TIPP were recorded (≥30 seconds), and 90% of the mean difference between CICCP and TIPP was ≤2 mmHg. The pressure measurements recorded using CICC and TIP were identical in both the static and dynamic bench tests. Conclusions: TIP may be an alternative to CICC for measuring CVP.
... which might partly explain this result [10]. Next, the CVP is the intramural pressure rather than the transmural pressure of the RV, while the actual pressure that determines RV preload is the CVP relative to the pressure surrounding the heart [19][20][21][22]. We cannot exclude conditions where the transmural pressure Fig. 2 Haemodynamic and echocardiographic parameters in four groups. ...
Article
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Introduction: Right ventricle (RV) dilation in combination with elevated central venous pressure (CVP), which is a state of RV congestion, is seen as a sign of RV failure (RVF). On the other hand, RV systolic function is usually assessed by tricuspid annular plane systolic excursion (TAPSE) and fractional area change (FAC). This study aimed to investigate the prevalence and prognostic value of RVF and RV systolic dysfunction (RVSD) in septic patients. Methods: Mechanically ventilated sepsis and septic shock patients were included. We collected haemodynamic and echocardiographic parameters as well as prognostic information including mechanical ventilation duration, length of ICU stay and 30-day mortality. RVF was defined as a right and left ventricular end-diastolic area ratio ≥ 0.6 in combination with CVP ≥ 8 mmHg. RVSD was defined as TAPSE < 16 mm or FAC < 35%. Results: A total of 215 patients were enrolled in this study, and the patients were divided into 4 groups: patients with normal RV function (normal, n = 101), patients with RVF but without RVSD (RVF only, n = 38), patients with RVSD but without RVF (RVSD only, n = 44), and patients with combined RVF-RVSD (RVF/RVSD, n = 32). The RVF/RVSD group and RVSD only group had a lower cardiac index than the RVF only group and normal groups (p < 0.05). At 30 days after ICU admission, 50.0% of patients had died in the RVF/RVSD group, which was much higher than the mortality in the RVF only group (13.2%) and normal group (13.9%) (p < 0.05). In a Cox regression analysis, the presence of RVF/RVSD was independently associated with 30-day mortality (HR 3.004, 95% CI:1.370-6.587, p = 0.006). In contrast, neither the presence of RVF only nor the presence of RVSD only was associated with 30-day mortality (HR 0.951, 95% CI:0.305-2.960, p = 0.931; HR 1.912, 95% CI:0.853-4.287, p = 0.116, respectively). Conclusion: The presence of combined RVF-RVSD was associated with 30-day mortality in mechanically ventilated septic patients. Additional studies are needed to confirm and expand this finding.
... CVP is a variable indicative of cardiovascular function, having the dual role of distending the diastolic right ventricle and opposing venous return [5]. As such, CVP is a useful guide for assessing cardiac preload and vascular volume status, as well as being an indicator that can assist in better understanding the reasons for changes in cardiac output, given the interaction that exists between cardiac function and venous return [6]. Its measurement remains widely used in intensive care units and emergency centers mainly for guiding fluid administration in patients with haemodynamic instability [7]. ...
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Objectives Acquiring central venous pressure (CVP), an important clinical parameter, requires an invasive procedure, which poses risk to patients. The aim of the study was to develop a non-invasive methodology for determining mean-CVP from ultrasound assessment of the jugular venous pulse. Methods In thirty-four adult patients (age = 60 ± 12 years; 10 males), CVP was measured using a central venous catheter, with internal jugular vein (IJV) cross-sectional area (CSA) variation along the cardiac beat acquired using ultrasound. The resultant CVP and IJV-CSA signals were synchronized with electrocardiogram (ECG) signals acquired from the patients. Autocorrelation signals were derived from the IJV-CSA signals using algorithms in R (open-source statistical software). The correlation r-values for successive lag intervals were extracted and used to build a linear regression model in which mean-CVP was the response variable and the lagging autocorrelation r-values and mean IJV-CSA, were the predictor variables. The optimum model was identified using the minimum AIC value and validated using 10-fold cross-validation. Results While the CVP and IJV-CSA signals were poorly correlated (mean r = -0.018, SD = 0.357) due to the IJV-CSA signal lagging behind the CVP signal, their autocorrelation counterparts were highly positively correlated (mean r = 0.725, SD = 0.215). Using the lagging autocorrelation r-values as predictors, mean-CVP was predicted with reasonable accuracy (r² = 0.612), with a mean-absolute-error of 1.455 cmH2O, which rose to 2.436 cmH2O when cross-validation was performed. Conclusions Mean-CVP can be estimated non-invasively by using the lagged autocorrelation r-values of the IJV-CSA signal. This new methodology may have considerable potential as a clinical monitoring and diagnostic tool.
... In this study, we classified the patients into two groups: patients with CVP values greater than or equal to (≧) 12 mmHg when starting PMX-DHP were placed in the high CVP group, while the remaining patients whose CVP values were less than (<) 12 mmHg were placed in the low CVP group. CVP was measured using the standard method when starting PMX-DHP and expressed as mmHg, as described previously [16,17]. This classification is also based on the SSCG recommendations, which suggest that in mechanical ventilation patients, a higher target CVP of 12 mmHg should be achieved [2]. ...
Article
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Background Direct hemoperfusion with polymyxin B-immobilized fiber column (PMX-DHP) could improve the hemodynamic status of septic shock patients. As PMX-DHP is an invasive and costly procedure, it is desirable to estimate the therapeutic effect before performing the therapy. However, it is still unclear when this therapy should be started and what type of sepsis it should be employed for. In this study, we retrospectively examined the clinical effect of patients treated with PMX-DHP by using central venous pressure (CVP). Methods Seventy patients who received PMX-DHP for septic shock during the study period were recruited and divided into a low CVP group (n = 33, CVP < 12 mmHg) and a high CVP group (n = 37, CVP≧12 mmHg). The primary endpoint was vasopressor dependency index at 24 hours after starting PMX-DHP, and the secondary endpoint was the 28-day survival rate. Additionally, we performed a multivariate linear regression analysis on the difference in the vasopressor dependency index. ResultsThe vasopressor dependency index significantly improved at 24 h in the low CVP group (0.33 to 0.16 mmHg−1; p < 0.01) but not in the high CVP group (0.43 to 0.34 mmHg−1; p = 0.41), and there was a significant difference between the two groups in the index at 24 h (p = 0.02). The 28-day survival rate was higher in the low CVP group (79 vs. 43 %; p < 0.01). Multivariate linear regression analysis showed that CVP (p = 0.04) was independently associated with the difference in the vasopressor dependency index. Conclusions Our study indicates that the clinical effect of PMX-DHP for septic shock patients with higher CVP (≧12 mmHg) might be limited and that the initial CVP when performing PMX-DHP could function as an independent prognostic marker for the hemodynamic improvement.
... Une méthode consiste à retenir la pression à la base de l'onde c (identifiée en traçant une ligne verticale à la fin du QRS), cette pression étant considérée par certains comme la plus proche de la PTDVD. 22 Figure 5). ...
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CONTEXTE : L'hypovolémie aggrave le pronostic neurologique des patientsneurochirurgicaux et le bénéfice de l'hypervolémie est remis en question. Les indices permettant de détecter la précharge dépendance et de réserver le remplissage vasculaire (RV) aux patients susceptibles d'en bénéficier, ont été peu étudiés en réanimation neurochirurgicale. L'objectif de ce travail était de comparer la pression veineuse centrale (PVC), le Temps d'éjection corrigé en Doppler transoesophagien (TEc), les variations respiratoires de la pression artérielle pulsée ([delta]PP) et un indice de variabilité respiratoire de la courbe de pléthysmographie de l'oxymètre de pouls (PVI, Masimo corp), pour prédire la réponse au RV en réanimation neurochirurgicale.METHODES : Chez 13 patients ventilés pour une pathologie neurochirurgicale(hémorragie méningée (n=4), traumatisme crânien (n=8) ou accident vasculairecérébral hémorragique (n=1)), nous avons mesuré la PVC, le TEc, [delta]PP et PVI avant et après RV (Voluven® 7mL/kg). Une augmentation de ?10% du volume déjection systolique indexé (Doppler oesophagien) définissait la réponse au RV.RESULTATS : 17 épreuves de RV ont été analysées. [delta]PP avant RV était plus élevé chez les répondeurs (12±7 vs 3±2 %, p=0.003). [delta]PP#gt#6% prédisait la réponse au RV (Sensibilité 80%, Spécificité 100%, Aire sous la courbe ROC (AUCROC)=0.936, p#lt#0.0001). [delta]PP et PVI n'étaient pas corrélés avant RV (rs=0,346 p=0.189). PVI (AUCROC=0.651 p=0,332), PVC (AUCROC=0.571 p=0,643) et TEc (AUCROC=0.564, p=0,680) ne prédisaient pas la réponse au RV. L'AUCROC de [delta]PP était significativement supérieure à celle de PVC et TEC (p=0.022 et p=0.038, respectivement) mais pas à celle de PVI (p=0.086).CONCLUSION : [delta]PP prédit la réponse au RV chez nos patients de réanimationneurochirurgicale, contrairement à TEc, PVC et PVI
Article
Mean systemic filling pressure (P ms ) defines the pressure measured in the venous-arterial system when the cardiac output is nil. Its estimation has been proposed in patients with beating hearts by building the venous return curve, using different pairs of right atrial pressure/cardiac output during mechanical ventilation. We raised the hypothesis according to which the P ms is altered by tidal ventilation and positive end-expiratory pressure (PEEP), which would challenge this extrapolation method based on cardiopulmonary interactions. We conducted a two-center, noninterventional, observational, and prospective study, using an arterial and a venous catheter to measure the pressure in the circulatory system at the time of death in critically ill, mechanically ventilated patients with a PEEP. Arterial (P art ) and venous pressures (P ra ) were recorded in five conditions: at end expiration and end inspiration with and without PEEP and finally once the ventilator was disconnected. P art and P ra did not differ in any experimental conditions. Tidal ventilation increased P ra and P art by 2.4 and 1.9 mmHg, respectively, whereas PEEP increased both values by 1.2 and 1 mmHg, respectively. After disconnection of the ventilator, P ra and P art were 10.0 ± 4.2 and 9.9 ± 4.2 mmHg, respectively. P ms increases during mechanical ventilation, with an effect of tidal ventilation and PEEP. This calls into question the validity of its evaluation in heart-beating patients using cardiopulmonary interactions during mechanical ventilation. NEW & NOTEWORTHY The physiology of the mean systemic filling pressure (P ms ) is not well understood in human beings. This study is the first report of a tidal ventilation- and positive end-expiratory pressure-related increase in P ms in critically ill patients. The results challenge the utility and the value estimating P ms in heart-beating patients by reconstruction of the venous return curve using varying inflation pressures.
Chapter
The primary focus of monitoring anesthetized patients is the assessment of depth of anesthesia, cardiovascular and pulmonary consequences of the anesthetized state, and temperature. Animals that are too deeply anesthetized may suffer adverse cardiopulmonary consequences and death. Anesthetic depth is determined by: the amount of anesthetic drug(s) in the brain, the magnitude of surgical (or environmental) stimulation, and underlying conditions that have synergistic CNS depressant effects (i.e., hypothermia, hypotension). Lacrimation in horses is a sign of a light level of anesthesia. The Bispectral Index is a processed electroencephalogram that quantifies the degree of anesthetic induced cortical depression. Heart rate is an important determinant of cardiac output. Arterial blood pressure is arterial hydrostatic pressure compared with atmospheric pressure. Direct measurement of arterial blood pressure, via an arterial catheter, is more continuous and less variable than using indirect methods. Central venous pressure (CVP) is the luminal pressure of the intrathoracic vena cava.
Chapter
Hemodynamic monitoring and tissue oxygenation assessment are regarded as essential tools for the management of the critically ill patient and require a physician who is properly trained to employ the techniques and interpret the data accurately. The information obtained from bedside monitoring should be interpreted in the context of other relevant investigations and clinical findings. Therefore, integrating hemodynamic variables with the clinical presentation increases the accuracy of assessment. These techniques are only useful when they have the capacity to provide additional information, the information is interpreted correctly, the interpretation of this additional information results in a change of therapy, and this change in therapy alters outcome.
Article
Materials and methods: Thirteen pigs were anesthetized and allocated to either the modified cardiac output group (m-CO group, n = 10) or the control group (control group, n = 3). In the m-CO group, CO was sequentially modulated from high CO (high CO) to two grades of low CO (low CO-1 and low CO-2) with dobutamine and propranolol with lidocaine, respectively, in the absence of any apparent change in basal fluid volume status. Thermodilutional CO and IDVG were measured at each CO condition. The IDVG was measured according to a one-compartment model with 2 g glucose. The same parameters were measured in the control group using the same time schedule as for the m-CO group but without inotropes and at a stable CO state. Thereafter, 250 ml of 10% dextran were infused over 15 min to compare the effects of a preload-dependent increase in CO on IDVG measurements to the effects of the pharmacological modification of CO. Data were expressed as the mean ± SD. Statistical analysis was performed with repeated measures ANOVA followed by Dunnett's test. Pearson's correlation test was also used. A P value of <0.05 was considered to indicate statistical significance. Results: In the m-CO group, where CO increased to 147.2 ± 26.7% of the baseline CO value in the high CO state and decreased to 65.9 ± 11.0 and 37.3 ± 14.4% of the baseline CO value in the low CO-1 state and the low CO-2 state, respectively, the IDVG did not change as CO was modified. IDVG significantly increased in response to volume loading of dextran in the control group. There was no correlation between the IDVG and CO in the m-CO group when there was no fluid gain or loss (r = 0.097, n = 40, P = 0.554), but the IDVG was well correlated with CO in the control group with volume loading (r = 0.764, n = 18, P = 0.0002). Conclusion: This study suggests that the IDVG is dependent on the central extracellular fluid volume and not on cardiac output.
Article
Background: Several techniques exist for measuring central venous pressure (CVP) but little information is available about the accuracy of each method. The aim of this study was to compare different methods of CVP measurements in mechanically ventilated patients. Methods: CVP was measured in mechanically ventilated patients without spontaneous breathing using four different techniques: 1) end expiratory CVP measurement at the base of the" c" wave (CVPMEASURED), chosen as the reference method; 2) CVP measurement from the monitor averaging CVP over the cardiac and respiratory cycles (CVPMONITOR); 3) CVP measurement after a transient withdrawing of mechanical ventilation (CVPNADIR); 4) CVP measurement corrected for the transmitted respiratory pressure induced by intrinsic PEEP (calculated CVP: CVPCALCULATED). Bias, precision, limits of agreement, and proportions of outliers (difference > 2 mm Hg) were determined. Results: Among 61 included patients, 103 CVP assessments were performed. CVPMONITOR bias [-0.87 (1.06) mm Hg] was significantly different from those of CVPCALCULATED [1.42 (1.07), P < 0.001 and CVPNADIR (1.04 (1.29), P < 0.001]. The limits of agreement of CVPMONITOR [-2.96 to 1.21 mm Hg] were not significantly different to those of CVPNADIR (-1.49 to 3.57 mm Hg, P = 0.39) and CVPCALCULATED (-0.68 to 3.53 mm Hg, P = 0.31). The proportion of outliers was not significantly different between CVPMONITOR (n = 5, 5%) and CVPNADIR (n = 9, 9%, P = 0.27) but was greater with CVPCALCULATED (n = 16, 15%, P = 0.01). Conclusions: In mechanically ventilated patients, CVPMONITOR is a reliable method for assessing CVPMEASURED Taking into account transmitted respiratory pressures, CVPCALCULATED had a higher proportion of outliers and precision than CVPNADIR.
Chapter
Stevin’s law and Pascal’s principle are two laws of the so-called statics of fluids. Stevin’s law states that the pressure at any point within a fluid at rest (of a certain density) depends only on the depth of that point: undersea, pressure increases according to this law. Pascal’s principle states that the variation in the pressure applied to an enclosed fluid is transmitted unchanged to each portion of the fluid and to the walls of its container: the Heimlich maneuver and hydraulic car lifts rely on it. There are many applications (and implications) of Stevin’s law and Pascal’s principle in the clinical practice of anesthesia: verify the inflation of a tracheal tube cuff, external cardiac massage, invasive pressure monitoring, zeroing and leveling of pressure transducers, measuring pulmonary artery occlusion pressure, and phleboclysis have all something to do with one or both of these laws.
Article
Right atrial pressure (Pra) is determined by the interaction of the function of the heart as a pump, called cardiac function, and the factors that determine the return of blood to heart, called return function. Thus, monitoring Pra or its surrogate, central venous pressure (CVP), can give important insights into mechanisms behind changes in hemodynamic status, responses to interventions, and the likelihood of diagnoses. Examination of the components of the Pra tracing, especially during the ventilator cycle, also can give information about right heart diastolic function, status of the tricuspid valve, volume responsiveness and the cardiac rhythm. Importantly, the pressure difference from the large venous reservoir to the heart is small and thus great care must be taken with technical factors that affect the measurement.
Chapter
This chapter contains clinical questions and answers for those involved in critical care and acute surgery, focusing on the unique problems and complications of respiratory and cardiovascular illnesses. It covers the kind of specialist daily care these patients would require and will be an ideal learning/review text for surgical residents and trainees who care for these patients and also those taking the surgical critical care examination. The questions are accompanied by vignettes and associated references used to support the answer. Each multiple‐choice question uses a different clinical scenario that will help in assessing the medical professionals and will also help them decide whether the patient requires critical care or surgical intervention.
Article
Objective: By analogy with the classical central venous pressure rules to assess a fluid challenge, we hypothesized that an increase in central venous pressure greater than or equal to 5 cm H2O (i.e., 4 mm Hg) during passive leg raising can predict preload unresponsiveness diagnosed by the absence of increase in velocity-time integral of the left ventricular outflow tract greater than or equal to 10% during the test (negative passive leg raising test). Design and settings: Velocity-time integral was measured by transthoracic echocardiography. Central venous pressure and velocity-time integral were measured before and during passive leg raising. Patients: Critically ill patients for whom the physician decided to test preload responsiveness by passive leg raising were prospectively included. Measurement and main results: Fifty-seven set of measurements were performed in 50 patients. Preload unresponsiveness (negative passive leg raising test) was observed in 32 cases. The changes in central venous pressure during passive leg raising did not differ between positive passive leg raising cases (positive passive leg raising test) and negative passive leg raising test cases (3 ± 2 vs 3 ± 2 mm Hg, respectively) and thus did not predict preload unresponsiveness (area under the receiver-operating characteristic curve of 0.59). An increase in central venous pressure greater than or equal to 4 mm Hg during passive leg raising was observed in 10 cases of positive passive leg raising test and in 11 cases of negative passive leg raising test. Taking an increase in central venous pressure greater than or equal to 3 or greater than or equal to 5 mm Hg rather than greater than or equal to 4 mm Hg during passive leg raising did not better allow one to identify negative passive leg raising test. Conclusions: Marked increase in central venous pressure during passive leg raising cannot identify negative passive leg raising test cases and thus preload unresponsiveness. Measurements of cardiac output (or its surrogates) during passive leg raising are, thus, mandatory to appropriately interpret this test.
Chapter
Central venous pressure (CVP) reflects the pressure in the major veins, namely, vena cava superior and inferior. From the physiological point of view, the central venous pressure is a product of the complex interplay between potential heart performance and venous return; therefore, the response of CVP to the similar hemodynamic interventions can be opposite in different ICU patients. Historically, CVP was often used for the assessment of hemodynamics, volume status, and fluid responsiveness. However, over the last decades, multiple studies have demonstrated the absence of correlation of both absolute values and changes in CVP with end-diastolic left ventricle volume and cardiac output. Not surprisingly, CVP is unable to predict changes in cardiac output in response to fluid challenge. Nowadays, a certain “renaissance” of CVP seems to be possible since new studies show that increased baseline values and/or fast increment of this parameter are associated with progression to acute kidney injury, multiple organ failure, splanchnic congestion, and death. Thus, the therapy aiming to decrease CVP may improve organ function and clinical outcome. Obviously, there are many questions to be addressed concerning CVP in critically ill patients before the decision on when and how to use this hemodynamic parameter.
Chapter
Stevin’s law and Pascal’s principle are two laws of the so-called statics of fluids. Stevin’s law states that the pressure at any point within a fluid at rest (of a certain density) depends only on the depth of that point: undersea, pressure increases according to this law. Pascal’s principle states that the variation in the pressure applied to an enclosed fluid is transmitted unchanged to each portion of the fluid and to the walls of its container; the Heimlich maneuver and hydraulic car lifts rely on it. There are many applications (and implications) of Stevin’s law and Pascal’s principle in the clinical practice of anesthesia and critical care; verify the inflation of a tracheal tube cuff, external cardiac massage, invasive pressure monitoring, zeroing and leveling of pressure transducers, measuring pulmonary artery occlusion pressure, and phleboclysis have all something to do with one or both of these laws.
Article
Introduction: Contrast-induced nephropathy (CIN) is a common complication resulting from the administration of contrast media. This study was designed to determine whether inferior vena cava (IVC) ultrasonography (IVCU)-guided hydration can reduce the risk of CIN in chronic heart failure patients undergoing coronary angiography or coronary angiography with percutaneous coronary intervention compared with standard hydration. Methods: This prospective clinical trial enrolled 207 chronic heart failure patients from February 2016 to November 2017, who were randomly assigned to either the IVCU-guided hydration group (n = 104) or the routine hydration group (n = 103). In the IVCU-guided group, the hydration infusion rate was set according to the IVC diameter determined by IVCU, while the control group received intravenous infusion of 0.9% saline at 0.5 mL/(kg·h). Serum Cr was measured before and 48-72 h after the procedure. All patients were followed up for 18 months. The incidence of nephropathy and major adverse cardiovascular or cerebrovascular events (MACCEs) was also compared between the 2 groups. Results: Statistically significant difference between the 2 groups regarding the occurrence of CIN was observed (12.5 vs. 29.1%, p = 0.004). The hydration volume of the IVCU-guided group was significantly higher than that of the routine group (p < 0.001). In addition, patients receiving IVCU-guided hydration had significantly lower risk of developing MACCEs than patients in the control group during the 18-month follow-up (14.4 vs. 27.2%, p = 0.027). Conclusion: Our findings support that IVCU-guided hydration is superior to standard hydration in prevention of CIN and may substantially reduce longtime composite major adverse events.
Article
Riassunto La mortalità perioperatoria è diminuita significativamente negli ultimi decenni in Francia. Oggi è stimata pari a circa il 3% in chirurgia non cardiaca. Questa riduzione è in gran parte dovuta al miglioramento della gestione anestesiologica e del monitoraggio emodinamico, reso obbligatorio dal decreto legge n. 94-1050 del 5 dicembre 1994 relativo alle condizioni tecniche di funzionamento degli istituti sanitari per quanto riguarda la pratica dell’anestesia. Tuttavia, il monitoraggio emodinamico in sala operatoria è ancora troppo spesso limitato al solo monitoraggio della frequenza cardiaca e della pressione arteriosa, senza alcuna valutazione della precarico-dipendenza e/o della gittata cardiaca. Tuttavia, una strategia individuale di ottimizzazione emodinamica permette di ridurre la morbimortalità postoperatoria, la durata della degenza ospedaliera e i costi relativi alle cure. Negli ultimi anni sono comparse nuove tecniche per il monitoraggio della pressione arteriosa, della precarico-dipendenza e della gittata cardiaca, più semplici da implementare e meno invasive per i pazienti. Oltre alla termodiluizione arteriosa polmonare o transpolmonare e al Doppler esofageo, le tecniche basate sull’analisi del profilo delle onde di polso o sulla bioimpedenziometria cardiotoracica sono in corso di validazione in chirurgia non cardiaca. La scelta del monitoraggio emodinamico deve dipendere dal rischio operatorio associato al paziente e all’intervento chirurgico. Questa scelta di un monitoraggio adeguato dovrebbe aumentare l’adozione in routine di efficaci strategie di ottimizzazione emodinamica intraoperatoria.
Article
Resumen La mortalidad perioperatoria ha disminuido significativamente en las últimas décadas en Francia. En la actualidad, se estima en alrededor del 3% en cirugía no cardíaca. Esta reducción se debe en gran parte a la mejora del tratamiento anestésico y de la monitorización hemodinámica, que es obligatoria según las leyes que rigen las condiciones técnicas de funcionamiento de los centros asistenciales en lo que respecta a la práctica de la anestesia. Sin embargo, la monitorización hemodinámica en el quirófano se limita todavía demasiado a menudo a la vigilancia de la frecuencia cardíaca y de la presión arterial, sin ninguna evaluación de la dependencia de la precarga y/o del gasto cardíaco. No obstante, una estrategia individual de optimización hemodinámica permite disminuir la morbimortalidad postoperatoria, la duración de la hospitalización y el coste asistencial. Han aparecido nuevas técnicas de monitorización de la presión arterial, de la dependencia de la precarga y del gasto cardíaco en los últimos años, más sencillas de aplicar y menos invasivas para los pacientes. Además de la termodilución arterial pulmonar o transpulmonar y del Doppler esofágico, las técnicas basadas en el análisis del contorno de la onda del pulso o en la bioimpedanciometría cardiotorácica están en fase de validación en cirugía no cardíaca. La elección de la monitorización hemodinámica debe depender del riesgo quirúrgico asociado al paciente y a la cirugía. Esta elección de una monitorización adaptada debería aumentar la adopción sistemática de estrategias eficaces de optimización hemodinámica peroperatoria.
Article
Background: Fluid resuscitation, which is critical to counter acute hemorrhagic shock, requires prompt and accurate intravascular volume estimation for optimal fluid administration. This study aimed to evaluate whether cardiac variation of internal jugular vein (IJV), evaluated by ultrasonography, could detect hypovolemic status and predict response to fluid resuscitation. Methods: Patients undergoing autologous blood transfusion for elective surgery who were prospectively enrolled at the study blood donation center between August 2014 and January 2015. Vertical B-mode ultrasonography movies of IJV were recorded at five timepoints during blood donation: before donation, during donation, end of donation, end of fluid replacement, and after hemostasis. Cardiac variation of the IJV area and circumference were objectively measured using an automated extraction program together with blood pressure and heart rate. Results: A total of 140 patients were screened, and data from 104 patients were included in the final analyses. Among the variables analyzed, only collapse index area (CIa) and collapse index circumference (CIc) could detect both intravascular volume loss and response to fluid administration. Conclusions: Cardiac variation of IJV may be a reliable indicator of intravascular volume loss and response to fluid administration in hemorrhagic shock.
Article
The purpose of this study was to evaluate the sensitivity of quantitative time-harmonic ultrasound elastography (THE) of the inferior vena cava (IVC) and abdominal aorta (AA) to changes in central volume status. THE of the IVC and AA was performed in 20 healthy volunteers before and after oral intake of 1 L of water and before or during passive leg raising to augment venous filling. Compound maps of shear wave speed (SWS) as surrogate measures of vessel wall stiffness were generated within the full field of view from multifrequency harmonic wave fields. SWS was measured in regions of the IVC and AA. Blood pressure, stroke volume, cardiac output and pulse wave velocity were recorded. Statistical significance of SWS changes was tested using one-way repeated-measures analysis of variance. SWS measured in the IVC increased from 1.71 ± 0.1 m/s before water intake to 1.82 ± 0.1 m/s during passive leg raising and, further, to 1.87 ± 0.1 m/s after hydration and to 1.95 ± 0.1 m/s with hydration plus passive leg raising (p < 0.001). SWS in the AA did not change significantly after hydration (2.14 ± 0.13 m/s vs. 2.15 ± 0.16 m/s; p = 0.792). SWS was significantly higher in the AA than in the IVC across all experiments (p < 0.001). Water drinking did not significantly influence blood pressure, pulse wave velocity and cardiac output (all p values >0.1), whereas stroke volume increased significantly (p = 0.031). Time-harmonic ultrasound elastography enables quantification of the wall stiffness of the large abdominal vessels and is sensitive to different volume and pressure states in the IVC.
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In this chapter, we outline important elements for the general supportive care for patients with sepsis in resource-limited settings. We discuss the use of corticosteroids, sedation, neuromuscular blocking agents, deep venous thrombosis (DVT) prophylaxis, gastric ulcer prevention, glucose control, enteral feeding, renal replacement therapy, and initial fluid resuscitation. Low-dose corticosteroids are recommended in septic patients with refractory shock, pending completion of current trials. Important issues around sedation include the availability of selected opiates and benzodiazepines, ways of administration, and availability of expertise and (human) resources essential for dosing and monitoring of sedation to care for mechanically ventilated patients with sepsis. Venous thromboembolism prophylaxis with proton-pump inhibitors and histamine-2 receptor antagonists is generally available for stress ulcer prophylaxis in resource-limited ICUs and can be delivered feasibly and safely. Critical illness-associated hyperglycemia is common, and short-acting insulin is widely available and inexpensive. However, stringent blood glucose control is not recommended, since this is dangerous in settings where continuous intravenous insulin with frequent monitoring is not feasible. Enteral feeding can be with hospital-prepared foods where commercial feeds are not available or expensive. Risk of aspiration pneumonia starts early in comatose non-intubated patients. Although not as effective as hemodialysis or hemofiltration methods, peritoneal dialysis is a feasible and cost-effective alternative for renal replacement therapy in very resource-limited settings. Initial fluid resuscitation in severe sepsis or septic shock should be more conservative in resource-limited settings where positive-pressure mechanical ventilation is not readily available.
Article
Venous return, i.e., the blood flowing back to the heart, is driven by the pressure difference between mean systemic filling pressure and right atrial pressure (RAP). Besides cardiac function, it is the major determinant of cardiac output. Mean systemic filling pressure is a function of the vascular volume. The concept of venous return has a central role for heart lung interactions and the explanation of shock states. Mechanical ventilation during anaesthesia and critical illness may severely affect venous return by different mechanisms. In the first part of the following article, we will discuss the development of the concept of venous return, its specific components mean systemic and mean circulatory filling pressure (MCFP), RAP and resistance to venous return (RVR). We show how these pressures relate to the volume state of the circulation. Various interpretations and critiques are elucidated. In the second part, we focus on the impact of positive pressure ventilation on venous return and its components, including latest results from latest research.
Article
An essential contributor to the hemodynamic responses observed during pregnancy, the venous system is affected by hormones, blood volume, flow rates, and an enlarging uterus. The venous system is a dynamic reservoir for blood volume, within which a virtual point of conversion between unstressed volume (Vu) and stressed volume (Vs) exists. The physiologic importance of the venous system during pregnancy is best understood when the basic concepts, functional characteristics, and alterations in pregnancy are reviewed.
Article
PurposeA proper reference level is important for measuring intracardiac pressures, especially for parameters with small normal values such as central venous pressure (CVP). Although several external zero reference levels (eZRLs) have been proposed for non-obese patients, none has been reported for severely obese patients. The aim of this study was to investigate an appropriate eZRL for CVP measurements of severely obese patients. Methods Chest computed tomography images of 65 patients with body mass index (BMI) ≥ 35 kg/m2 were retrospectively reviewed. The anteroposterior thoracic diameter and height of the mid-right atrium (RA) were measured. Four reported eZRLs for CVP measurements (midthoracic level, two-thirds and four-fifths of the thoracic diameter above table level, and 5 cm below the anterior thorax) were examined for error when predicting the midpoint of the RA. ResultsThe median BMI was 36.9 kg/m2 [interquartile range (IQR), 36.0–39.2]. There was a significant difference in the calculated errors for the midpoint of the RA among the four eZRLs (Kruskal–Wallis test, P < 0.001). Two-thirds of the thoracic diameter above table level was the most accurate reference level for CVP measurement (Steel–Dwass post hoc analysis, P < 0.001). The Bland–Altman plot showed acceptable agreement for clinical use (mean difference, − 7 mm; 95% limit of agreement, − 23 to 9 mm). Conclusion The most accurate eZRL for CVP measurements of severely obese patients in the supine position was two-thirds of the thoracic diameter above table level. This result is consistent with that of a previous report of non-obese patients.
Chapter
There are many methods for measuring the adequacy of resuscitation in a patient in shock, but none is universally applicable and few appear to be without significant limitations. As in so many areas of medicine, the constellation of findings from multiple modalities and the patient’s trajectory must be interpreted and acted upon, occasionally with imperfect data. Further, given the disparate settings and situations in which resuscitations are performed, the methods of guiding resuscitation must be tailored to local capabilities. While under-resuscitation often has grave consequences, over-resuscitation also leads to worse outcomes. In this chapter, we attempt to present a concise review of available endpoints of resuscitation and caveats to their use, as well as the limitations to available modalities.
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The purpose of this study was to determine the role of changes in the parameters of venous return on the homeostatic adaption to the application of PEEP. We studied 13 dogs anesthetized with alpha-chloralose, intubated, and ventilated. We measured central venous pressure (CVP), arterial pressure (Pao) and cardiac output by thermal dilution. The cardiac output was transiently stopped by inflating a balloon in the right atrium, and the subsequent plateau in the CVP was used to obtain mean circulatory filling pressure (MCFP). Total blood volume was measured with Evans blue. To measure vascular capacitance and compliance, we rapidly infused 4 ml/kg or 8 ml/kg of blood and repeated the MCFP measurement. The same volume was withdrawn after the measurement. The volume and MCFP were used to construct pressure-volume (P-V) lines, and the unstressed volume was calculated by extrapolating the P-V to zero pressure. The P-V appeared linear in the range studied. PEEP produced a left shift of the curves and, thus, a decrease in unstressed volume. The shift with 20 cm H2O of PEEP was greater than with 10 cm H2O of PEEP. The rise in MCFP matched the rise in CVP so that the pressure gradient for venous return did not change. However, there was also an increase in the resistance to venous return, which resulted in a lower cardiac output than expected for the rise in MCFP. In conclusion, homeostatic adjustments to PEEP included a decrease in vascular capacitance, which is partially offset by a rise in the resistance to venous return.
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To test the hypothesis that passive leg raising (PLR) induces changes in arterial pulse pressure that can help to predict the response to rapid fluid loading (RFL) in patients with acute circulatory failure who are receiving mechanical ventilation. Prospective clinical study. Two medical ICUs in university hospitals. Thirty-nine patients with acute circulatory failure who were receiving mechanical ventilation and had a pulmonary artery catheter in place. PLR for > 4 min and a subsequent 300-mL RFL for > 20 min. Radial artery pulse pressure (PPrad), heart rate, right atrial pressure, pulmonary artery occlusion pressure (PAOP), and cardiac output were measured invasively in a population of 15 patients at each phase of the study procedure (i.e., before and during PLR, and then before and after RFL). PPrad, PAOP, and stroke volume (SV) significantly increased in patients performing PLR. These changes were rapidly reversible when the patients' legs were lowered. Changes in PPrad during PLR were significantly correlated with changes in SV during PLR (r = 0.77; p < 0.001). Changes in SV induced by PLR and by RFL were significantly correlated (r = 0.89; p < 0.001). Finally, PLR-induced changes in PPrad were significantly correlated to RFL-induced changes in SV (r = 0.84; p < 0.001). In a second population of 24 patients, we found the same relationship between PLR-induced changes in PPrad and RFL-induced changes in SV (r = 0.73; p < 0.001). The response to RFL could be predicted noninvasively by a simple observation of changes in pulse pressure during PLR in patients with acute circulatory failure who were receiving mechanical ventilation.
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To identify and critically review the published peer-reviewed, English-language studies investigating predictive factors of fluid responsiveness in ICU patients. Studies were collected by doing a search in MEDLINE (from 1966) and scanning the reference lists of the articles. Studies were selected according to the following criteria: volume expansion performed in critically ill patients, patients classified in two groups (responders and nonresponders) according to the effects of volume expansion on stroke volume or on cardiac output, and comparison of responder and nonresponder patients' characteristics before volume expansion. Twelve studies were analyzed in which the parameters tested were as follows: (1) static indicators of cardiac preload (right atrial pressure [RAP], pulmonary artery occlusion pressure [PAOP], right ventricular end-diastolic volume [RVEDV], and left ventricular end-diastolic area [LVEDA]); and (2) dynamic parameters (inspiratory decrease in RAP [Delta RAP], expiratory decrease in arterial systolic pressure [Delta down], respiratory changes in pulse pressure [Delta PP], and respiratory changes in aortic blood velocity [Delta Vpeak]). Before fluid infusion, RAP, PAOP, RVEDV, and LVEDA were not significantly lower in responders than in nonresponders in three of five studies, in seven of nine studies, in four of six studies, and in one of three studies, respectively. When a significant difference was found, no threshold value could discriminate responders and nonresponders. Before fluid infusion, Delta RAP, Delta down, Delta PP, and Delta Vpeak were significantly higher in responders, and a threshold value predicted fluid responsiveness with high positive (77 to 95%) and negative (81 to 100%) predictive values. Dynamic parameters should be used preferentially to static parameters to predict fluid responsiveness in ICU patients.
Chapter
Central hemodynamic pressures, including central venous pressure (CVP), right atrial pressure (Pra), and pulmonary capillary wedge pressure (Pcw), are very useful for determining the appropriate vascular volume for cardiac output, the management of pulmonary edema, and the diagnosis of cardiac pathophysiology. Besides the simple magnitude of the pressure, there is a lot of important clinical information available from the actual pattern of pressure variation which occurs during a respiratory cycle, as well as the waveform of the pressure fluctuations that occur during the cardiac cycle. In this chapter, the basic principles of measurement will first be reviewed and then the effects of changes in pleural pressure and abdominal pressure, as well as the fluctuations of the wave pattern in the cardiac cycle will be reviewed.
Article
We tested the hypothesis that the respiratory pattern of the right atrial pressure (Pra) can be used to predict the response to a fluid challenge. We used a case series in medical and postcardiovascular surgery intensive care units at a university teaching hospital. The sample included 33 patients with Swan-Ganz catheters (Spectramed Inc, Oxnard, CA) in place for clinical indications. The fluid challenge was prescribed by the treating physician and consisted of a rapid infusion of normal saline until Pre increased by ≥2 mm Hg. The volume infused to achieve this ranged from 100 to 950 mL. Right atrial pressure, pulmonary capillary wedge pressure (Pcw), and arterial pressure (Pa) were measured. Capillary wedge pressure had to fall by ≥2 mm Hg to indicate an adequate inspiratory effort. Patients were classified as having a positive respiratory response if Pre decreased by ≥1 mm Hg and negative respiratory response of Pre decreased by less than 1 mm Hg. An increase in cardiac output of ≥250 mL/min was considered a significant response to the fluid challenge. Cardiac output increased in only one of 14 patients with negative respiratory response but increased in 16 of 19 patients with positive respiratory response. The initial Pra, Pcw, cardiac output, and Pa did not predict the response to the fluid infusion. In conclusion, it is very unlikely that volume loading will increase the cardiac output in a patient who does not have an inspiratory fall in Pra, whereas volume loading will usually increase the cardiac output of patients who have an inspiratory fall in Pra.
Article
The use of the pulmonary artery (PA) catheter has become a central part of the management of critically ill patients in modern intensive care units. The PA catheter provides a remarkable amount of information that continues to increase with ongoing technological advances. In modern intensive care units, measurement of the pulmonary arterial wedge pressure (PAWP) is perhaps the most common and most important indication for inserting PA catheters in critically ill patients, The interpretation of the measured PAWP in such patients is also the most controversial aspect of the use of PA catheters, however. The most important use of PAWP is to estimate (not measure) two parameters: (1) the hydrostatic pressure gradient for pulmonary edema formation and (2) the left ventricular end-diastolic volume (LVEDV) or preload, PAWP does not directly measure either of these two parameters. When properly acquired, mean PAWP, taken at end-expiration, generally provides a reliable measure (a minimum estimate) of the pulmonary microvascular hydrostatic pressure, which is the major determinant of fluid flux from the pulmonary microvasculature, Similarly, when properly acquired, end-diastolic PAWP, taken at end-expiration, generally provides a reliable estimate of left ventricular end-diastolic pressure (LVEDP), but importantly this value may not reliably reflect LVEDV, or preload, if left ventricular (LV) compliance or juxtacardiac pressure are abnormal.
Article
Our objective was to determine if the magnitude of the Y descent in the central venous pressure tracing could be used to determine which patients have restrictive hemodynamics. To better understand the determinants of the Y descent, we also examined the effects of changes in blood volume, changes in pleural pressure, and respiratory maneuvers on its magnitude. Studies were performed in both humans and dogs. In six anesthetized dogs, we examined the effect on the Y descent in central venous pressure (CVP) of an infusion of normal saline, a decrease in pleural pressure produced by having animals perform a Mueller maneuver, and the combination of a Mueller maneuver and volume loading. Observations were made with the chest closed, chest open, and chest and pericardium open. The state of the chest did not effect the Y descent. The Y descent was only significantly increased when a Mueller maneuver was combined with volume loading. There was a significant inverse relationship between the magnitude of the decrease in esophageal pressure and the Y descent. There was also a linear relationship between the CVP and Y descent. For the human studies, we examined patients undergoing routine cardiac surgery. They were examined during spontaneous breathing before intubation, with positive pressure breathing and closed chest, with positive pressure breathing and open chest, with an open pericardium, with a closed chest and positive pressure breathing postsurgery, and with spontaneous breathing after extubation following surgery. The Y descent was greater in spontaneous breaths postsurgery compared to before surgery, and this was associated with an increase in CVP. However, the magnitude of CVP did not correlate with the magnitude of the Y descent. A restrictive pattern in cardiac filling was identified by a lack of respiratory variation in right atrial pressure during spontaneous breaths. All patients with large Y descents had a restrictive pattern, but many patients with restrictive filling patterns did not have a large Y descent. The magnitude of the Y descent is affected by the volume status, the magnitude and direction of the changes in pleural pressure, and the compliance of the pericardial compartment. A large Y descent indicates a restrictive cardiac state, but a small Y descent does not rule out a restrictive condition because of the many interacting variables.
Article
To assess volume replacement strategies on intensive care units (ICUs) in Germany. A postal survey questionnaire of 18 questions was sent to 451 ICUs in Germany. The questionnaire was sent to general, surgical, anesthesiology, neurosurgery, cardiac surgery, and medical ICUs of hospital with more than 200 beds. 286 questionnaires (64%) were returned and analysed. Hydroxyethylstarch (HES) solution is the solution most often used for volume replacement (total: 193 ICUs, exclusively HES: 93 ICUs), crystalloids are next (crystalloids exclusively: 61 ICUs), and human albumin is used rarely as a first choice. Clinical experience is a very important argument for administering volume. Diagnostic tools, e.g. measurement of central venous pressure or pulmonary capillary wedge pressure, also play an important role. Albumin/total protein and colloid osmotic pressure (COP) are measured often on ICUs (albumin measured routinely: 173 ICUs; COP measured routinely: 33 ICUs). Critical values for albumin/total protein are defined in most ICUs. Reduced plasma levels of albumin/total protein was the indication most often cited for administering human albumin. Only 149 ICUs (52%) have a financial budget for their unit. Costs still do not play a major role in the choice of volume replacement on 30 ICUs (10%). The kind of volume therapy differs widely among the different ICUs. This questionnaire supported the supposition that no standards exist for volume therapy in intensive care patients. New results concerning the abuse of albumin in the critically ill have not yet influenced strategies of volume replacement.
Article
This study describes observations designed to test the validity of the hepatojugular reflux as an indicator of actual or incipient heart failure. The central venous pressure (CVP) could be predicted from the height of the jugular venous pulsations in 44 of 48 comparisons. In the remaining comparisons, discrepancies ranged from 5 to 7 mm Hg. In patients with normal resting cardiac function, abdominal compression did not cause an increase in CVP of greater than 2 mm Hg (2.7 mm H2O). In 16 of 19 patients with impaired function, CVP increased by greater than or equal to 3 mm Hg. The increase in CVP was estimated from neck veins to within 2 mm Hg in all but 3 instances. CVP stabilized by 10 seconds and did not change over the subsequent 60 seconds. Abdominal compression caused no consistent change in cardiac output. Changes in venous pressure could not be attributed to changes in esophageal pressure or to compression of the heart by elevation of the diaphragm. Observations were consistent with the hypothesis that an increase in right-sided cardiac filling pressures resulting from abdominal compression carried out as described here, reflects both the volume of blood in the abdominal veins and the ability of the ventricles to respond to increased venous return, and constitutes a useful clinical test for detecting congestive cardiac failure. An increase of 3 cm in the height of neck vein distention is a reasonable upper limit of normal.
Article
Blood volumes measured by indicator dilution method in over 1500 instances of critically ill patients of various etiologies and at various times throughout their critical illness were compared with the values of concomitantly measured mean arterial pressure (MAP), CVP, pulmonary arterial wedge pressure (WP), Hct, and cardiac output. During resuscitation from hypovolemic shock, the patients' blood volumes and the monitored variables were significantly altered. However, there were poor correlations between the extent of blood volume changes and these variables during resuscitation as well as throughout the critical illness, irrespective of the etiologic type or stage of shock. With administration of a fluid load, blood volume and values of the commonly monitored variables improved appropriately, but the correlation coefficients, in general, were not good. The data suggest that the commonly monitored variables, in and of themselves, do not reflect adequately the blood volume status in critically ill patients.
Article
To determine whether the reduced exercise capacity of patients after heart transplantation is primarily a result of decreased cardiac or peripheral vascular factors, we examined the cardiac output (CO) and right atrial pressure (Pra) relation during graded cycle ergometry. We studied 12 male patients (51.2+/-15.3 years [mean+/-SD]) 35.3+/-12.5 weeks after heart transplantation and 6 young healthy men. Patients had a normal increase in CO with increasing oxygen uptake (VO2) (CO = 0.00597 VO2 + 4.4, r = 0.83). Mean (+/-SEM) heart rate increased from 97.0+/-5.0 beats/min at rest to 146.9+/-6.9 beats/min at peak effort compared with the increase of 67.2+/-1.9 beats/min to 187.2+/-2.5 beats/min in the normal group. Pra in patients increased from 1.6+/-1.0 mm Hg at rest to 8.9+/-1.6 mm Hg during mild exercise but did not increase further at the highest work rates, even though CO continued to increase. In the normal group there was an initial increase in Pra from rest to exercise transition but little further change in Pra with increasing CO. Aerobic capacity (peak VO2) did not increase when cardiac function was increased with dobutamine during exercise in two patients. The steep increase in CO relative to Pra during severe exercise in patients who undergo heart transplantation argues against the heart as the sole limiting factor during maximal effort.
Article
Purpose: A volume challenge is useful for determining whether cardiac output will respond to further volume loading by the Frank-Starling mechanism. To properly test this mechanism, there must be an increase in right atrial pressure (Pra) but this requires variable amounts of normal saline. The purpose of this study was to determine if 100 mL of 25% albumin would reliably provide a predictable increase in Pra and to compare this with a volume challenge with normal saline. As in a previous study, we also examined the potential for the pattern of respiratory variation of Pra to predict the response to a fluid challenge. Materials and methods: Twenty-eight stable patients following cardiopulmonary bypass surgery were studied in a randomized, nonblinded interventional study in an intensive care unit. All patients had pulmonary artery flotation catheter as part of their routine management and were breathing spontaneously. They were randomized to receive sufficient normal saline to increase Pra by 2 mm Hg (n = 15) or 100 mL of 25% albumin (n = 13). We also tested the ability of the respiratory variation in Pra to predict the response to a fluid challenge. They had to have an inspiratory fall in the pulmonary capillary wedge pressure of more than 2 mm Hg as an indication that they had an adequate inspiratory effort. They were classified as either having or not having an inspiratory fall in Pra. We predicted that patients without an inspiratory fall in Pra should not respond to volume loading. Results: In contrast to our prediction, the increase in Pra with albumin was less than the increase with normal saline. However, the cardiac output increased more with albumin, which suggests that there was an increase in cardiac function with the hypertonic, hyperosmolar albumin solution. In the saline group, a lack of inspiratory fall in Pra successfully predicted that cardiac output would fail to increase with an increase in Pra in 8 out of 10 patients given saline, and 5 of 6 patients given albumin. Conclusion: A hyperoncotic albumin solution appears to have an inotropic effect in patients following cardiopulmonary bypass procedures. We also again show that the pattern of respiratory variation in right atrial pressure is a useful guide to predict response to volume loading.
Article
Pulmonary artery occlusion pressure and central venous pressure have been considered to be reliable measures of left and right ventricular preload in patients requiring invasive hemodynamic monitoring. Studies in recent years have questioned the correlation between these estimates of ventricular filling pressures and ventricular end-diastolic volumes/cardiac performance variables in specific patient groups, but clinicians have continued to consider the relationship valid in the broader context. The objective of this study was to assess the relationship between pressure estimates of ventricular preload (pulmonary artery occlusion pressure, central venous pressure) and end-diastolic ventricular volumes/cardiac performance in healthy volunteers. Prospective, nonrandomized, nonblinded interventional study. Cardiac catheterization and echocardiography laboratories. Normal healthy volunteers (n = 12 group 1, n = 32 group 2). Pulmonary catheterization and radionuclide cineangiography (group 1) and volumetric echocardiography (group 2) during 3 L of normal saline infusion over 3 hrs. In group 1, the initial pulmonary artery occlusion pressure and central venous pressure did not correlate significantly with initial end-diastolic ventricular volume indexes or cardiac performance (cardiac index and stroke volume index). Changes in pulmonary artery occlusion pressure and central venous pressure following saline infusion also did not correlate with changes in end-diastolic ventricular volume indexes or cardiac performance. In contrast, initial end-diastolic ventricular volume indexes and changes in these ventricular volume indexes in response to 3 L of normal saline loading correlated well with initial stroke volume index and changes in stroke volume index, respectively. The relationship between left ventricular end-diastolic volume index and stroke volume index was confirmed in group 2 subjects using mathematically independent techniques to measure these variables. In addition, initial central venous pressure, right ventricular end-diastolic volume index, pulmonary artery occlusion pressure, and left ventricular end-diastolic volume index failed to correlate significantly with changes in cardiac performance in response to saline infusion in group 1 subjects. Normal healthy volunteers demonstrate a lack of correlation between initial central venous pressure/pulmonary artery occlusion pressure and both end-diastolic ventricular volume indexes and stroke volume index. Similar results are found with respect to changes in these variables following volume infusion. In contrast, initial end-diastolic ventricular volume indexes and changes in end-diastolic ventricular volume indexes in response to saline loading correlate strongly with initial and postsaline loading changes in cardiac performance as measured by stroke volume index. These data suggest that the lack of correlation of these variables in specific patient groups described in other studies represents a more universal phenomenon that includes normal subjects. Neither central venous pressure nor pulmonary artery occlusion pressure appears to be a useful predictor of ventricular preload with respect to optimizing cardiac performance.
Article
Central venous pressure is a very common clinical measurement, but it is frequently misunderstood and misused. As with all hemodynamic measurements, it is important to understand its basic principles. This analysis indicates that it is best to always consider the significance of central venous pressure in the context of the corresponding cardiac output. Even more important is the use of dynamic measures to interpret the meaning of the central venous pressure. This includes the hemodynamic response to fluid load, respiratory variations in central venous pressure, and even the change in central venous pressure with changes in the patient's overall status. The clinical application of central venous pressure measurement requires a good understanding of the concept of the interaction of the function of the heart with the function of the return of blood to the heart.
CVP and volume responsiveness of cardiac output
  • F Bafaqeeh
  • Magder
Bafaqeeh F, Magder S: CVP and volume responsiveness of cardiac output. Am J Respir Crit Care Med 2004; 169:A344
Cardiac vs. non-cardiac limits to exercise following heart transplantation
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Notarius CF, Levy RD, Tully A, et al: Cardiac vs. non-cardiac limits to exercise following heart transplantation. Am Heart J 1998; 135: 339 –348
Venous return In: Respiratory-Circulatory Interactions in Health and Disease
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Magder S, Scharf SM: Venous return. In: Respiratory-Circulatory Interactions in Health and Disease. Scharf SM, Pinsky MR, Magder S (Eds). New York, Marcel Dekker, 2001, pp 93–112