The Influence of Prone Positioning on the Accuracy of Calibrated and Uncalibrated Pulse Contour-Derived Cardiac Index Measurements
ABSTRACT BACKGROUND:Patients with lung failure who undergo prone positioning often receive extended hemodynamic monitoring. We investigated the influence of modified prone positioning (135°) on the accuracy of pulse contour-derived calibrated cardiac index (CIPC) and uncalibrated cardiac index (CIVIG) in this patient population with transpulmonary thermodilution (TPTD) as reference technique.METHODS:We studied 16 critically ill and mechanically ventilated patients (11 men, 5 women, aged 20-71 years) with acute lung injury or acute respiratory distress syndrome. Patients were monitored by TPTD with an integrated calibrated pulse contour technique (PiCCO®) and by uncalibrated pulse contour analysis (FloTrac/Vigileo™). Before prone positioning, cardiac index (given in L·min-1·m-2) was measured by TPTD (CITPTD) and CIPC was calibrated. After positioning, CIPC and CIVIG were read from the monitor and CITPTD was measured. After 8 to 10 hours, prone positioning was completed and measurements were performed analogously. Bland-Altman analysis based on a random-effects model was used to calculate limits of agreement (LOA) and percentage errors. Polar plots were used for trend analysis.RESULTS:Supine CITPTD was 3.3 ± 0.9 (mean ± SD) and CIVIG was 3.1 ± 0.8. After proning, CIPC was 3.5 ± 0.8, CIVIG 3.3 ± 0.8, and CITPTD 3.6 ± 0.8. Before repositioning, CITPTD was 3.5 ± 0.7 and CIVIG 3.3 ± 1.0. After repositioning, CITPTD was 3.1 ± 0.7, CIPC 3.3 ± 0.7, and CIVIG 2.9 ± 0.6. Mean bias pooled for proning and repositioning was -0.1 (LOA -0.7 to 0.6) for CIPC (percentage error 19%) and 0.3 (LOA -1.3 to 1.9) for CIVIG (percentage error 48%). Changes in CI were too small for trending analysis.CONCLUSION:Although calibrated CI measurements are only marginally influenced by prone positioning, according to the criteria of Critchley and Critchley, uncalibrated CI values show a degree of error, too high to be considered clinically acceptable.
SourceAvailable from: Koichi SuehiroJournal of Cardiothoracic and Vascular Anesthesia 10/2014; 28(5). DOI:10.1053/j.jvca.2014.02.020 · 1.48 Impact Factor
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ABSTRACT: Haemodynamic monitoring with transpulmonary thermodilution (TPTD) is less invasive than a pulmonary artery catheter, and is increasingly used in the Intensive Care Unit and the Operating Room. Optimal treatment of the critically ill patient demands adequate, precise and continuous monitoring of clinical parameters. Little is known about staff knowledge of the basic principles and practical implementation of TPTD measurements at the bedside. The aims of this review are to: 1) present the results of a survey on the knowledge of TPTD measurement among 252 nurses and doctors; and 2) to focus on specific situations and common pitfalls in order to improve patient management in daily practice. Web-based survey on knowledge of PiCCO technology (Pulsion Medical Systems, Feldkirchen, Germany), followed by PubMed and Medline search with review of the relevant literature regarding the use of TPTD in specific situations. In total, 252 persons participated in the survey: 196 nurses (78%) and 56 medical doctors (22%) of whom 17 were residents in training. Knowledge on the use of TPTD appears to be suboptimal, with an average score of 58.3%. Doctors performed better than nurses (62.7% vs 57.0%, P = 0.012). About 190 out of 252 (75.4%) scored at least 50% but only 45 respondents (17.9%) obtained a score of 70% or more. Having five years of PiCCO experience was present in 15.8% of the participants and this was correlated to passing the test, defined as obtaining a test result of ≥ 50% (P = 0.07) or obtaining a test result of ≥ 70% (P = 0.05). There were no other parameters significantly predictive for obtaining a result above 50% or above 70% such as gender or doctor versus nurse or Belgian versus Dutch residency, or years of ICU experience. High quality education of nursing and medical staff is necessary to perform the technique correctly and to analyse and interpret the information that can be obtained. Visual inspection of thermodilution curves is important as this can point towards specific pathology. Interpretation of the parameters that can be obtained with TPTD in specific conditions is discussed. Finally, a practical approach is given in ten easy steps for nurses and doctors. TPTD has gained its place in the haemodynamic monitoring field, but, as with any technique, its virtue is only fully appreciated with correct use and interpretation.11/2014; DOI:10.5603/AIT.a2014.0068
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ABSTRACT: OBJECTIVES: The aims of this study were to compare cardiac output (CO) measured by the new fourth-generation FloTracTM/VigileoTM system (Version 4.00) (COFVS) with that measured by a pulmonary artery catheter (COREF), and to investigate the ability of COFVS to track CO changes induced by increased peripheral resistance. DESIGN: Prospective study. SETTING: University Hospital. PARTICIPANTS: Twenty-three patients undergoing cardiac surgery. INTERVENTIONS: Phenylephrine (100 microg) was administered. MEASUREMENTS AND MAIN RESULTS: Hemodynamic variables, including COREF and COFVS, were measured before and after phenylephrine administration. Bland-Altman analysis was used to assess the discrepancy between COREF and COFVS. Four-quadrant plot and polar-plot analyses were utilized to evaluate the trending ability of COFVS against COREF after phenylephrine boluses. One hundred thirty-six hemodynamic interventions were performed. The bias shown by the Bland-Altman analysis was-0.66 L/min, and the percentage error was 55.4%. The bias was significantly correlated with the systemic vascular resistance index (SVRI) before phenylephrine administration (p<0.001, r2 = 0.420). The concordance rate determined by four-quadrant plot analysis and the angular concordance rate calculated using polar-plot analysis were 87.0% and 83.0%, respectively. Additionally, this trending ability was not affected by SVRI state. CONCLUSIONS: The trending ability of the new fourth-generation FloTracTM/VigileoTM system after increased vasomotor tone was greatly improved compared with previous versions; however, the discrepancy of the new system in CO measurement was not clinically acceptable, as in previous versions. For clinical application in critically ill patients, this vasomotor tone-dependent disagreement must be decreased.Journal of Cardiothoracic and Vascular Anesthesia 11/2014; DOI:10.1053/j.jvca.2014.07.022 · 1.48 Impact Factor