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Computer-Aided Clinical Decision System: Differential Diagnosis and Treatment of Essential Hypertension by a Novel Noninvasive Hemodynamic Analyzer
Abstract
The objective of this paper was to compute cardiac output (CO) noninvasively and other hemodynamic parameters by a new computer-aided decision system: a Noninvasive Hemodynamic Analyzer (NHA), and use the obtained data to demonstrate hemodynamic instability of two hypertensive patients. The NHA is composed of several instruments, including an electronic blood pressure instrument (with pulse curve detection), oxymeter (SpO2), hemoglobinometer and a core-body thermometer. Their data inputs are the dynamic characteristics of the patient’s condition. The static characteristics including, date of birth, sex, height, weight and test date are entered manually or via computer. These inputs are analyzed by a high performance multi-function data acquisition computer. In a recently published retrospective study of 203 ICU patients thermodilution cardiac output data were compared with NHA computed CO values. Statistical evaluation, concerning bias, precision and accuracy showed clinically acceptable ranges according to a literature survey. The hemodynamic pattern of two essential hypertensive patients were computed by the NHA and diagnostic and therapeutic directions were demonstrated. The NHA computer-aided clinical decision system provides reliable guidance for hemodynamic evaluation and leads to a scientifically based differential diagnosis of hypertensive patients as a promising screening method. Since the NHA system can function separately from direct patient measurement, it can be ideally applied to telemedicine applications.
... By using models in combination with bedside monitoring of the cardiovascular and respiratory system, which is already done in patients receiving mechanical ventilation, models can be used for individual patients. While there are various model-based clinical decision support systems that use patient specific characteristics, 7,19,27 to our knowledge this is the first model aimed at the decisions regarding volume management at the ICU. ...
... By using models in combination with bedside monitoring of the cardiovascular and respiratory system, which is already done in patients receiving mechanical ventilation, models can be used for individual patients. While there are various model-based clinical decision support systems that use patient specific characteristics, 7,19,27 to our knowledge this is the first model aimed at the decisions regarding volume management at the ICU. ...
Fluid therapy is commonly used to improve cardiac output in hemodynamically instable patients in the intensive care unit. However, to predict whether patients will benefit from this intervention (i. e. are volume responsive), is difficult. Dynamic indices, that rely on heart-lung interactions, have shown to be good predictors of fluid responsiveness under strict clinical conditions, but clinical use is still limited. This is due to the lack of understanding of the complex underlying physiology since multiple quantities are involved. We present a physiologically based mathematical model of the interaction between the respiratory and cardiovascular systems incorporating dynamic indices and fluid responsiveness. Our model is based on existing models of the cardiovascular system, its control, and the respiratory system during mechanical ventilation. The model of the cardiovascular system is expanded by including non-linear cardiac elastances to improve simulation of the Frank-Starling mechanism. An original model including five mechanisms for interaction between mechanical ventilation and the circulation is also presented. This model allows for the simulation of these complex relationships and may predict the effect of volume infusion in specific patients in the future. The presented model must be seen as a first step to a bedside clinical decision support system, and can be used as an educational model. © 2013 Biomedical Engineering Society.
... This clinical trial did not include hemodynamic data except the average vital sign changes were presented with the corresponding anthropological information which was utilized in this retrospective study. The computerized clinical decision system (NHA) is able to utilize this databank independently of the EGG results and by computing myocardial hemodynamic parameters allow it to reach the same conclusions as the clinical trial ( Lagerman, 2004a,b, Kabal and Lagerman, 2005). Considering that the results of this study could not be compared to any available actual counterparts of the obtained myocardial hemodynamic parameters, but only to our calculated ideal values, the real purpose of this research was to find applicability of the NHA to evaluate and differentiate among the reported clinical conditions with scientific objectivity during treadmill stress testing. ...
Objective: By applying a clinical decision system, the Noninvasive Hemodynamic Analyzer (NHA), demonstrates its capability to compute
the Myocardial Hemodynamic status of exercising patients. Design: Retrospective study to use the average vital signs and anthropological data of a large clinical trial of Exercise Treadmill
Test. The NHA system computes Stroke Volume and various hemodynamic parameters. With the assistance of the NHA computer-aided
clinical decision system; the Epicardial and Endocardial Blood Pressure/Blood Flow relationships, as well as components or
determinants of Myocardial Oxygen Supply during exercise treadmill test were calculated. Patients: Four groups of the clinical study (1) Healthy, (2) Hypertensive, (3) Angina Pectoris, and (4) Post-Myocardial Infarction
and Angina Pectoris were used in this study which comprised the average data of several hundred patients. Each group had three
subgroups according to the Exercise Treadmill Test, upright and two exercise periods. Validity: We previously conducted a comparative study of Stroke Volume computed by the NHA with the Thermodilution technique which
proved to be clinically acceptable concerning Bias, Accuracy, and Precision. In this particular study, the statistical evaluation
was not available because the average values did not allow for such computation. Instead, we have chosen to compute the Myocardial
Hemodynamic Parameters parallel with their Ideal values. Altogether 18 hemodynamic parameters were included and the normal
values were expressed in ± 20%. Conclusion: The NHA clinical decision system can differentiate among the reported clinical conditions of the “Seattle Heart Watch” report.
We were able to comparatively evaluate physiological and pathophysiological principles, such as, coronary flow reserve, endocardial
autoregulation, and remodeling. Further medical trials will reveal the practical clinical importance and applicability of
our NHA system.
To correlate the values in the basic blood pressure groups presented in the JNC 7th with the computed values of the Noninvasive Hemodynamic Analyzer (NHA) and to demonstrate the pathophysiological alterations by three proportional hypertensive models.
Hemodynamic values of each of the blood pressure groups presented in the JNC 7th are tabulated for men between 20 and 50 years of age with particular interest in Pulse Pressure.
Idealized patients were used in the three groups of the proportional hypertensive models.
Previous studies demonstrated that the Bias, Precision, and Accuracy of Cardiac Output measurement, compared to Thermodilution technique, resulted in statistically acceptable clinical values.
This research has successfully demonstrated, with the use of the NHA, the leading role of Pulse Pressure in normal and hypertensive patients. We are convinced that this technique can be used as an economical and time-saving alternative screening tool in clinical medicine.
The efficacy and safety of the pulmonary artery catheter are under scrutiny because of its association with increased morbidity and mortality in observational studies. In response, the National Heart, Lung, and Blood Institute (NHLBI) and the US Food and Drug Administration (FDA) conducted the Pulmonary Artery Catheterization and Clinical Outcomes workshop in Alexandria, Va, on August 25 and 26, 1997, to develop recommendations regarding actions to improve pulmonary artery catheter utility and safety.
The NHLBI and FDA planning task force selected a workshop chairperson, subcommittee chairs, and participants. Approximately 85 participants were selected for their collective expertise in critical care, pulmonary medicine, cardiovascular medicine and surgery, pediatrics, nursing, biostatistics, and medical economics. The meeting was open to industry representatives and other government and lay observers. This workshop was funded by the NHLBI and the FDA's Division of Devices.
Published reports relating to the efficacy and safety of the pulmonary artery catheter, especially consensus documents developed by professional societies.
The planning task force disseminated materials, held teleconferences, and developed draft position papers prior to the workshop. These were modified during the workshop and thereafter in the course of several teleconferences, and presented to the entire group for final modifications and approval.
A need exists for collaborative education of physicians and nurses in performing, obtaining, and interpreting information from the use of pulmonary artery catheters. This effort should be led by professional societies, in collaboration with federal agencies, with the purpose of developing and disseminating standardized educational programs. Areas given high priority for clinical trials were pulmonary artery catheter use in persistent/refractory congestive heart failure, acute respiratory distress syndrome, severe sepsis and septic shock, and low-risk coronary artery bypass graft surgery. JAMA. 2000;283:2568-2572
"The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" provides a new guideline for hypertension prevention and management. The following are the key messages(1) In persons older than 50 years, systolic blood pressure (BP) of more than 140 mm Hg is a much more important cardiovascular disease (CVD) risk factor than diastolic BP; (2) The risk of CVD, beginning at 115/75 mm Hg, doubles with each increment of 20/10 mm Hg; individuals who are normotensive at 55 years of age have a 90% lifetime risk for developing hypertension; (3) Individuals with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 mm Hg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD; (4) Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, calcium channel blockers); (5) Most patients with hypertension will require 2 or more antihypertensive medications to achieve goal BP (<140/90 mm Hg, or <130/80 mm Hg for patients with diabetes or chronic kidney disease); (6) If BP is more than 20/10 mm Hg above goal BP, consideration should be given to initiating therapy with 2 agents, 1 of which usually should be a thiazide-type diuretic; and (7) The most effective therapy prescribed by the most careful clinician will control hypertension only if patients are motivated. Motivation improves when patients have positive experiences with and trust in the clinician. Empathy builds trust and is a potent motivator. Finally, in presenting these guidelines, the committee recognizes that the responsible physician's judgment remains paramount.
Due to rapid advances in invasive and non-invasive imaging technology in
clinical medicine, it is now possible to obtain images of target organs for use in
computational analysis modelling. Our ultimate goal is to build a system that
can assist clinicians in diagnosis, treatment planning, and follow-up of patients
with cardiovascular diseases, and as patients differ in terms of anatomical
configuration and disease condition, a wide variety of patient data must be
accumulated, not only for statistical analysis but also to improve the processing
system. Therefore, a comprehensive database that includes patient data, medical
images, computational models, and computed results must be constructed that is
within the scope of our current projects. This is part of a long-term research
program in the field of computational medicine, which will inevitably become
part of mainstream medical development in the near future. The introduction of
computational mechanical assistance to medical diagnosis and treatment will
enhance the objectiveness of medical decisions.
Keywords: computational study, cardiovascular system, clinical application,
medical image, blood flow-vascular wall interactions, atherosclerosis.
1 Introduction
In the past decades, a great advance was achieved in the computer technology
and it enabled us to analyze various phenomena that were not possible to study
by numerical means before. Complex biological subjects are nothing
exceptional. One of the most successful fields among those conducted by
computational methods was the study of the blood flow. Many investigators
including us started from fairly simple objects to quite complicated system and
This study was coordinated by the International Society on Hypertension in Blacks (ISHIB) by Kermit G. Payne (project coordinator), Christopher T. Fitzpatrick (associate project coordinator), and Carrie T. Hamilton (assistant project coordinator). The data coordinating center included Mizpah Johnson (assistant project manager), Kathy Lane (programmer), John M. Flack, MD, MPH (director), and Carla Yunis, MD, MPH (project manager). Central laboratory was SmithKline Beecham, Van Nuys, Calif. Senior collaborators from Bayer Pharmaceuticals were Tim M. Shannon, Joe Carafano, Deborah Deakin, Steven Ripa, Lawrence Schwartz, and Kenneth Pomerantz. The ISHIB investigators and sites are as follows (asterisk indicates principal investigator): DeAnna Cheek, MD,* Vernette Brown, RN (Medical University of South Carolina, Charleston); Mandeep Dhadley, MD,* Johnnie Bloom, LPN (Roxbury Heart Center, Roxbury, Mass); Keith C. Ferdinand, MD,* Daphne Ferdinand, RN (Heartbeats Life Center, New Orleans, La); Charles K. Francis, MD,* Leroy Herbert, MD, Velvie Pogue, MD, Hope Bannister (Harlem Hospital Center, New York, NY); Henry Gift, MD,* Louis Gottlieb, MD, Ahang Zafari, MD (St Mary's Family Health Center, Waterbury, Conn); Ami Patel, MD,* C. Andrew Brown, Ardell Hinton (Veterans Affairs Medical Center, Jackson, Miss); Emanuel O. Quaye, MD,* Tim Briscoe, PharmD (Morehouse School of Medicine, Atlanta, Ga); Malcolm Taylor, MD,* Gwen Taylor (Jackson Cardiology Associates, Jackson, Miss); Harry Ward, MD,* Bella Forster, RN (King Drew Medical Center, Los Angeles, Calif); and Matthew R. Weir, MD,* Wallace Johnson, MD, Elijah Saunders, MD, B. J. Shaneman, LPN (University of Maryland, Baltimore).
Interest in two-wavelength classic, that is, nonpulse, oximetry began early in the 20th century. Noninvasive in vivo measurements of oxygen saturation showed promise, but the methods were beset by several problems. The pulse oximetry technique, by focusing on the pulsatile arterial component, neatly circumvented many of the problems of the classic nonpulse arterial approach. Today's pulse oximeter owes a good measure of its success to the technologic advances in light emission and detection and the ready availability of microcomputers and their software. Many clinicians have recognized how valuable the assessment of the patient's oxygenation in real time can be. This appreciation has propelled the use of pulse oximeters into many clinical fields, as well as nonclinical fields such as sports training and aviation. Understanding how and what pulse oximetry measures, how pulse oximetry data compare with data derived from laboratory analysis, and how the pulse oximeter responds to dyshemoglobins, dyes, and other interfering conditions must be understood for the correct application and interpretation of this revolutionary monitor.
Interest in two-wavelength classic, that is, nonpulse, oximetry began early in the 20th century. Noninvasive in vivo measurements of oxygen saturation showed promise, but the methods were beset by several problems. The pulse oximetry technique, by focusing on the pulsatile arterial component, neatly circumvented many of the problems of the classic nonpulse arterial approach. Today's pulse oximeter owes a good measure of its success to the technologic advances in light emission and detection and the ready availability of microcomputers and their software. Many clinicians have recognized how valuable the assessment of the patient's oxygenation in real time can be. This appreciation has propelled the use of pulse oximeters into many clinical fields, as well as nonclinical fields such as sports training and aviation. Understanding how and what pulse oximetry measures, how pulse oximetry data compare with data derived from laboratory analysis, and how the pulse oximeter responds to dyshemoglobins, dyes, and other interfering conditions must be understood for the correct application and interpretation of this revolutionary monitor.
Characteristics such as age and race are often cited as determinants of the response of blood pressure to specific antihypertensive agents, but this clinically important issue has not been examined in sufficiently large trials, involving all standard treatments, to determine the effect of such factors.
In a randomized, double-blind study at 15 clinics, we assigned 1292 men with diastolic blood pressures of 95 to 109 mm Hg, after a placebo washout period, to receive placebo or one of six drugs: hydrochlorothiazide (12.5 to 50 mg per day), atenolol (25 to 100 mg per day), captopril (25 to 100 mg per day), clonidine (0.2 to 0.6 mg per day), a sustained-release preparation of diltiazem (120 to 360 mg per day), or prazosin (4 to 20 mg per day). The drug doses were titrated to a goal of less than 90 mm Hg for maximal diastolic pressure, and the patients continued to receive therapy for at least one year.
The mean (+/- SD) age of the randomized patients was 59 +/- 10 years, and 48 percent were black. The average blood pressure at base line was 152 +/- 14/99 +/- 3 mm Hg. Diltiazem therapy had the highest rate of success: 59 percent of the treated patients had reached the blood-pressure goal at the end of the titration phase and had a diastolic blood pressure of less than 95 mm Hg at one year. Atenolol was successful by this definition in 51 percent of the patients, clonidine in 50 percent, hydrochlorothiazide in 46 percent, captopril in 42 percent, and prazosin in 42 percent; all these agents were superior to placebo (success rate, 25 percent). Diltiazem ranked first for younger blacks (< 60 years) and older blacks (> or = 60 years), among whom the success rate was 64 percent, captopril for younger whites (success rate, 55 percent), and atenolol for older whites (68 percent). Drug intolerance was more frequent with clonidine (14 percent) and prazosin (12 percent) than with the other drugs.
Among men, race and age have an important effect on the response to single-drug therapy for hypertension. In addition to cost and quality of life, these factors should be considered in the initial choice of a drug.
Hypertension is more prevalent, appears at an earlier age, is more likely to be associated with end-organ complications, and is less likely to be treated with traditional therapies in African Americans compared to Americans of European descent. Epidemiological associations have been made between the excess burden of hypertension in this population group and some biological, psychosocial, and socioeconomic factors. These associations might be used as a starting point that guides research to identify the cause(s) for the higher proportion of African Americans with hypertension. At present, such associations can help in the design of risk factor intervention strategies.
At least 43 million (24%) adults in the general population of the United States have hypertension. The prevalence of hypertension increases with age and is higher among African-Americans compared to other ethnic groups. During the past several decades, the prevalence of hypertension in the general population of the United States has declined and the proportion of hypertensives who are aware of their high blood pressure, as well as the portion who are being treated and controlled has improved. Hypertension is the most important modifiable risk factor for coronary heart disease, stroke, congestive heart failure, and end-stage renal disease. To achieve the final goal of eliminating all blood pressure-related disease in the community, detection and treatment of hypertension must be complemented by equally energetic approaches directed at primary prevention of hypertension. A small downward shift in the entire distribution of blood pressure in the general population will not only reduce the incidence of hypertension, but substantially diminish the burden of blood pressure in the general population.
Hypertension is a prevalent disease among African Americans, and successful treatment rates are low. Since calcium channel blockers are well-tolerated and efficacious in African Americans, we undertook this study to compare the efficacy, safety, and tolerability of 3 commonly prescribed calcium channel blockers: amlodipine besylate (Norvasc), nifedipine coat core (CC) (Adalat CC), and nifedipine gastrointestinal therapeutic system (GITS) (Procardia XL).
One hundred ninety-two hypertensive patients across 10 study centers were randomly assigned to double-blind monotherapy with amlodipine besylate (5 mg/d), nifedipine CC (30 mg/d), or nifedipine GITS (30 mg/d) for 8 weeks. Patients not achieving therapeutic response after 4 weeks had their dose doubled for the next 4 weeks. The primary end point was a comparison of the average reduction (week 8 minus baseline) in 24-hour ambulatory diastolic blood pressure (DBP). Secondary end points included a comparison of average 24-hour ambulatory systolic blood pressure (SBP), office SBP or DBP reduction, responder rates, safety, and tolerability.
One hundred sixty-three patients were evaluable for efficacy after 8 weeks. There was no significant difference in the average 24-hour ambulatory DBP (-8.5, -9.0, and -6.1 mm Hg, respectively) or SBP (-14.3, -15.7, and -11.8 mm Hg, respectively) reduction. Average office SBP and DBP were reduced to a comparable degree (19-22 mm Hg [P =.50] and 12-14 mm Hg [P =.51], respectively). Responder rates (DBP <90 or reduced by > or = 10 mm Hg) were similar (P = .38). Discontinuation rates and adverse event frequency were distributed similarly across the 3 treatment groups.
The efficacy, safety, and tolerability of the 3 dihydropyridine calcium channel blockers are equivalent in African Americans with stages 1 and 2 hypertension.
Impedance cardiography (IC) is an inexpensive, reliable and noninvasive technique for determining stroke volume (SV) and cardiac output (CO). It relies on the measurement of phasic changes in transthoracic electrical resistivity, related to ejection of blood into the ascending aorta with each heart beat. Because of its non-invasive nature, IC is becoming increasingly used in clinical settings, as well as in many areas of physiological research. This paper discusses IC in terms of its theoretical basis, the components of the impedance signal and how impedance data is mathematically processed. One of the major controversies surrounding IC concerns how well it compares with conventional methods of determining SV and CO, such as thermodilution. A literature review of such comparative studies demonstrated that the controversy is far from settled, but that IC is generally agreed to be capable of accurately monitoring trends in cardiovascular dynamics. The question of accuracy of IC in terms of absolute values of SV and CO remains to be determined. The methodological limitations, accuracy, reliability and reproducibility of IC are examined, as are some of the methods developed to improve these aspects of the technique. The application and utility of IC in aerospace medicine research is also addressed.
Although invasive monitoring has not been effective in late stages after organ failure has occurred, early postoperative monitoring revealed differences in survivor and nonsurvivor patterns and provided goals for improving outcome. We searched for the earliest divergence of survivor and nonsurvivor circulatory changes as an approach to earlier preventive therapy. The aim was to describe the intraoperative time course of circulatory dysfunction in survivors and nonsurvivors among high-risk elective surgery patients using both the thermodilution pulmonary artery catheter (PAC) and multicomponent noninvasive monitoring.
Prospective intraoperative description of circulatory dysfunction.
University-run county hospital.
Two hundred nine consecutively monitored high-risk elective surgery patients.
We evaluated the data of high-risk elective surgery patients using both PAC and multicomponent noninvasive monitoring. The latter consisted of the following: a) an improved bioimpedance method for estimating cardiac output; b) the standard pulse oximetry to screen for pulmonary problems; c) transcutaneous oxygen and carbon dioxide tension sensors to evaluate tissue perfusion; and d) routine noninvasive blood pressure and heart rate. The current noninvasive impedance cardiac output estimations closely approximated those of the thermodilution method; r2 = .74, p < .001; the precision and bias was -0.124 +/- 0.75 L/min/m2. Outcome measures included intraoperative description of circulatory patterns of high-risk surgical patients who survived compared with nonsurvivors. Hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oxygen, high transcutaneous carbon dioxide tensions, low oxygen delivery, and low oxygen consumption developed intraoperatively gradually over time; the abnormalities were more pronounced in the nonsurvivors than in the survivors.
The survivors had slightly higher mean arterial pressure, cardiac index, and mixed venous oxygen saturation, as well as significantly higher oxygen delivery, oxygen consumption, transcutaneous oxygen tension, and transcutaneous oxygen tension/FIO2 ratios, than did the nonsurvivors. The data suggest that blood flow, oxygen delivery, and tissue oxygenation of the nonsurvivors became inadequate toward the end of the operation. Noninvasive monitoring provides similar information to that of the PAC; both approaches revealed low-flow and poor tissue perfusion that were worse in the nonsurvivors. The continuous on-line real-time displays of hemodynamic trends facilitate early recognition of acute circulatory dysfunction.
Elevated blood pressure is known to be a risk factor for death from coronary heart disease (CHD). However, it is unclear whether the risk of death from CHD in relation to blood pressure varies among populations.
In six populations in different parts of the world, we examined systolic and diastolic blood pressures and hypertension in relation to long-term mortality from CHD, both with and without adjustment for variability in blood pressure within individual subjects. Blood pressure was measured at base-line in 12,031 men (age range, 40 to 59 years) who were free of CHD. During 25 years of follow-up, 1291 men died from CHD.
At systolic and diastolic blood pressures of about 140 and 85 mm Hg, respectively, 25-year rates of mortality from CHD (standardized for age) varied by a factor of more than three among the populations. Rates in the United States and northern Europe were high (approximately 70 deaths per 10,000 person-years), but rates in Japan and Mediterranean southern Europe were low (approximately 20 deaths per 10,000 person-years). However, the relative increase in 25-year mortality from CHD for a given increase in blood pressure was similar among the populations. The overall unadjusted relative risk of death due to CHD was 1.17 (95 percent confidence interval, 1.14 to 1.20) per 10 mm Hg increase in systolic pressure and 1.13 (95 percent confidence interval, 1.10 to 1.15) per 5 mm Hg increase in diastolic pressure, and it was 1.28 for each of these increments after adjustment for within-subject variability in blood pressure.
Among the six populations we studied, the relative increase in long-term mortality due to CHD for a given increase in blood pressure is similar, whereas the absolute risk at the same level of blood pressure varies substantially. If the absolute risk of CHD is used as an indication for antihypertensive therapy, these findings will have major implications for treatment in different parts of the world.
To evaluate the effect of early optimization in the survival of severely injured patients.
It is unclear whether supranormal ("optimal") hemodynamic values should serve as endpoints of resuscitation or simply as markers of the physiologic reserve of critically injured patients. The failure of optimization to produce improved survival in some randomized controlled trials may be associated with delays in starting the attempt to reach optimal goals. There are limited controlled data on trauma patients.
Seventy-five consecutive severely injured patients with shock resulting from bleeding and without major intracranial or spinal cord trauma were randomized to resuscitation, starting immediately after admission, to either normal values of systolic blood pressure, urine output, base deficit, hemoglobin, and cardiac index (control group, 35 patients) or optimal values (cardiac index >4.5 L/min/m2, ratio of transcutaneous oxygen tension to fractional inspired oxygen >200, oxygen delivery index >600 mL/min/m2, and oxygen consumption index >170 mL/min/m2; optimal group, 40 patients). Initial cardiac output monitoring was done noninvasively by bioimpedance and, subsequently, invasively by thermodilution. Crystalloids, colloids, blood, inotropes, and vasopressors were used by predetermined algorithms.
Optimal values were reached intentionally by 70% of the optimal patients and spontaneously by 40% of the control patients. There was no difference in rates of death (15% optimal vs. 11% control), organ failure, sepsis, or the length of intensive care unit or hospital stay between the two groups. Patients from both groups who achieved optimal values had better outcomes than patients who did not. The death rate was 0% among patients who achieved optimal values compared with 30% among patients who did not. Age younger than 40 years was the only independent predictive factor of the ability to reach optimal values.
Severely injured patients who can achieve optimal hemodynamic values are more likely to survive than those who cannot, regardless of the resuscitation technique. In this study, attempts at early optimization did not improve the outcome of the examined subgroup of severely injured patients.
African Americans outrank other ethnic groups in the United States in prevalence, early onset, and severity of hypertension. Furthermore, African Americans suffer the highest rates of mortality from cardiovascular, cerebrovascular, and end-stage renal disease. The recently concluded Heart Outcomes Prevention Evaluation (HOPE) study reports that the angiotensin-converting enzyme (ACE) inhibitor ramipril significantly reduced morbidity and mortality in a broad range of patients at high risk for cardiovascular events. These results strengthen the case for increasing the use of ACE inhibitor therapy. In accord with the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) guidelines, antihypertensive monotherapy for African Americans is based on the known ability of diuretics and calcium channel blockers to produce greater reductions in blood pressure in this population than those attainable with beta blockers and ACE inhibitors. The national guidelines also suggest ACE inhibitors for all hypertensive patients with left ventricular dysfunction or nephropathy, which implies that African Americans must cross a clinical threshold to become candidates for these agents. The rationale for delaying ACE inhibitor therapy is due in part to a perceived unique pathobiology in hypertensive African Americans: an excess prevalence of salt sensitivity, hypervolemia, and low plasma renin activity (PRA). At first glance, it would seem intuitive to avoid agents that further depress the renin-angiotensin system (RAS) and choose agents that reduce plasma volume. However, most hypertensive African Americans are not hypovolemic. Furthermore, dietary sodium restriction and diuretic therapy raise PRA and improve the response to ACE inhibitors. The overall aim of this article is to explain the rationale for expanded use of drugs that block the RAS in African Americans and low-renin populations.
Measuring cardiac output is of paramount importance in the management of critically ill patients in the intensive care unit and of 'high risk' surgical patients in the operating room. Alternatives to thermodilution are now available and are gaining acceptance among practitioners who have been trained almost exclusively in the use of the pulmonary artery catheter. The present review focuses on the principles, advantages and limitations of oesophageal Doppler, Fick principle applied to carbon dioxide, and pulse contour analysis. No single method stands out or renders the others obsolete. By making cardiac output easily measurable, however, these techniques should all contribute to improvement in haemodynamic management.
Even small elevations above optimal blood pressure values (<120/80 mm Hg) increase the likelihood of developing hypertension (blood pressure >or=140/90 mm Hg) and incurring target organ damage. Until recently, the main emphasis in hypertension treatment had been lowering diastolic blood pressure; however, in the past decade, the important contributions of systolic hypertension, increased pulse pressure, and a blunted reduction in nocturnal blood pressure have been described. Primary hypertension arises from complex, interrelated pathologies. Among the contributors are genetic, environmental, metabolic, vascular, and endothelial factors. Signs of target organ damage herald a poorer prognosis and may present in the heart, blood vessels, kidneys, brain, or eyes. Later consequences include cardiac, cerebrovascular, vascular, and renal morbidities and death. The goal in treating hypertension is to prevent cardiovascular and renal complications. Thus, hypertensive patients with high-normal blood pressure values may benefit from intensive lifestyle interventions to further reduce blood pressure. This is particularly true in patients with additional cardiovascular risk factors. Because of the complex nature of hypertension, it is not surprising that single antihypertensive agents normalize blood pressure for less than a majority of hypertensive patients. Using combination antihypertensive therapy consisting of agents from two or more different antihypertensive drug classes not only increases the likelihood of achieving the target blood pressure goal, but also offers the potential for greater protection against target organ damage by targeting separate pathologic mechanisms.
High blood pressure is the most common chronic medical problem prompting visits to primary health care providers, yet it is estimated that only 34% of the 50 million American adults with hypertension have their blood pressure controlled to a level of <140/90 mm Hg. Thus, about two thirds of Americans with hypertension are at increased risk for cardiovascular events. The medical, economic, and human costs of untreated and inadequately controlled high blood pressure are enormous. Adequate management of hypertension can be hampered by inadequacies in the diagnosis, treatment, and/or control of high blood pressure. Health care providers face many obstacles to achieving blood pressure control among their patients, including a limited ability to adequately lower blood pressure with monotherapy and a typical reluctance to increase therapy (either in dose or number of medications) to achieve blood pressure goals. Patients also face important challenges in adhering to multidrug regimens and accepting the need for therapeutic lifestyle changes. Nonetheless, the achievement of blood pressure goals is possible, and, most importantly, lowering blood pressure significantly reduces cardiovascular morbidity and mortality, as proved in clinical trials. The medical and human costs of treating preventable conditions such as stroke, heart failure, and end-stage renal disease can be reduced by antihypertensive treatment. The recurrent and chronic morbidities associated with hypertension are costly to treat. Pharmacotherapy for hypertension therefore offers a substantial potential for cost savings. Pharmacoeconomic analyses regarding antihypertensive drug therapies, their costs, and the relevant reductions in health care expenditures are a useful framework for optimizing current strategies for hypertension management.
To compare the accuracy and reliability of cardiac output (CO) measurement by a Noninvasive Hemodynamic Analyzer (NHA) to the thermodilution cardiac output (COTD) technique in ICU patients of cardiac condition.
ICU retrospective data collected in a 700-bed university-affiliated regional medical center. The data results from 203 patients who required invasive hemodynamic monitoring for clinical and/or surgical management.
The ranges of the two CO measurements were: CO(TD) = 2.06 to 8.8 l/min and CO(NHA) = 2.06 to 8.46 l/min, respectively. The Mean and SD of CO(NHA) = 4.819 l/min +/- 1.053 was near to CO(TD) = 4.902 l/min +/- 1.421. Variance was better for CO(NHA) = 1.110 l/min compared to CO(TD) = 1.421 l/min. Median of CO(NHA) showed 4.813 l/min and CO(TD) = 4.660 l/min. Bias was 0.083 l/min with 95% Confidence Interval (Precision): -0.26 to 0.040, and 95% Limits of Agreement was between -1.661 to 1.827 l/min.
The results of this retrospective study indicate that the CO(NHA) technique may be a promising screening method. Additional studies are needed to explore its diagnostic trending capability. This noninvasive CO technique has been proven to be clinically accurate and may be applicable for telemedicine applications.
TheSeventhReportoftheJointNationalCommitteeonPrevention, Detection,Evaluation,andTreatmentofHighBloodPressure:The JNC 7 Report
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AACN Procedure Manual for Critical Care Deficient oxygen transport: An alternative mechanism for the development of hypertension?
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