Reliability Of Cardiac Output Measurement Research Articles

Reliability of Cardiac Output Measurements Using LiDCOrapid and Calibration by Transesophageal Echocardiography With the Continuous Pulmonary Artery Thermodilution Method in Patients Undergoing Aortic Valve Replacement for Aortic Stenosis

This study investigated the accuracy of arterial waveform analysis estimations of cardiac output (COAW) and the efficacy of calibrations involving transesophageal echocardiography with continuous cardiac output values obtained using a pulmonary artery catheter. Prospective cohort study. University hospital operating room. Twelve patients undergoing aortic valve replacement for aortic stenosis. A pulmonary artery catheter was placed in each patient, and continuous cardiac output was determined using thermodilution principles. LiDCOrapid and transesophageal echocardiography were used to measure COAW and to perform the calibration, respectively. Simultaneous recording of continuous cardiac output and COAW values were performed every 20 minutes, after inducing anesthesia. COAW was calibrated using transesophageal echocardiography (COAW-cal) before and after initiating cardiopulmonary bypass (CPB); the COAW and COAW-cal were recorded concurrently using a LiDCOrapid monitor. For the pre-CPB dataset (34 data pairs), the mean bias and percentage error were, respectively, 0.10 L/min and 34% for COAW versus continuous cardiac output and -0.098 L/min and 27% for COAW-cal versus continuous cardiac output. Similarly, for the post-CPB (45 data pairs), the mean bias and percentage error were, respectively, 0.75 L/min and 34% for COAW and 0.059 L/min and 26% for COAW-cal. A 4-quadrant plot demonstrated an acceptable pre-CPB concordance rate of 93.3% for COAW and 93.8% for COAW-cal. COAW measurements, using LiDCOrapid, have acceptable trending ability pre-CPB. The determination of cardiac output variations, using transesophageal echocardiography, is useful for managing patients undergoing aortic valve replacement for aortic stenosis.

Cardiac Output Assessed by the Fourth-Generation Arterial Waveform Analysis System Is Unreliable in Liver Transplant Recipients

BackgroundLiver transplant recipients often have violent hemodynamic fluctuation during surgery that may be related to perioperative and postoperative morbidity. Because there are some considerations for the risk of the pulmonary arterial catheter (PAC), the conventional invasive device for cardiac output (CO) measurement, a reliable and minimally invasive alternative is required. We validated the reliability of CO measurements with the use of a minimally invasive FloTrac system with the latest fourth-generation algorithm in liver transplant recipients. MethodsForty liver transplant recipients without atrial fibrillation, valvular pathology, or intracardiac shunt were recruited in this prospective, observational study. CO values measured by use of PAC with continuous thermodilution method (COTh) and FloTrac devices (COFT) were collected simultaneously throughout the operation for reliability validation. ResultsFour hundred pairs of CO data points were collected in total. The linear regression analysis showed a high correlation coefficient (73%, P < .001). However, the percent error between COTh and COFT was 42.2%, which is worse than the established interchangeability criterion of 30%. The concordance rates were calculated at 89% and 59% by 4-quadrant plot and polar plot analysis, respectively. Neither met the preset validation criteria (>92% for the 4-quadrant plot and >90% for polar plot analyses). ConclusionsOur study demonstrates that the CO measurements in liver transplant recipients by the latest FloTrac system and the PAC do not meet the recognized interchangeability criterion. Although the result showed improvement in linear regression analysis, it failed to display a qualified trending ability.

FloTrac/Vigileo system monitoring in acute-care surgery: current and future trends

As acute critical-care surgery evolves, it is imperative to introduce reliable devices that can intraoperatively assess a patient's cardiovascular functions. Owing to the fact that traditional methods are usually invasive, non- or less-invasive innovations have attracted the attention of clinicians in recent decades. The FloTrac system monitors cardiovascular performance by analyzing peripheral arterial waveforms and a preset database, and it decreases the invasiveness by using a pulmonary arterial catheter. The reliability of cardiac output measurements was confirmed in many critically ill subjects in cardiac surgeries and intensive care units. Moreover, the FloTrac system is easy to set up, and interpreting the information is simple. The FloTrac system also provides a useful preload predictor, that is, stroke volume variation (SVV), for fluid management, which has been proven to enhance surgical safety in the treatment of critically ill patients. Goal-directed therapy guided by SVV and other hemodynamic variables was advocated for peri-operative fluid optimization. Although the evolution of each updated algorithm of the FloTrac system has demonstrated improved accuracy and limited shortcomings, the latest third-generation algorithm is still not equal to the gold standard reference. The accuracy of the latest third-generation algorithm is controversial in septic conditions, and its use is still unacceptable in liver transplantation. Due to vasoactive challenges, especially in the administration of norepinephrine, a conclusion could not be reached. Clinicians should recognize the appropriate uses and limitations when using the algorithm during acute critical surgeries.

Transpulmonary thermodilution cardiac output measurement is not affected by severe pulmonary oedema: a newborn animal study

BackgroundThe transpulmonary thermodilution (TPTD) technique is widely used in clinical practice for measuring cardiac output (CO). This study was designed to investigate the influence of various levels of pulmonary oedema on the reliability of CO measurements by the TPTD method. MethodsIn 11 newborn lambs pulmonary oedema was induced using a surfactant washout technique. Serial CO measurements using TPTD (COTPTD) were performed at various amounts of lung water. Simultaneously, CO was measured by an ultrasound flow probe around the main pulmonary artery (COMPA) and used as the standard reference. CO was divided by the body surface area to calculate cardiac index (CI). Data were analysed using correlational statistics and Bland–Altman analysis. ResultsOne lamb died prematurely. A total of 56 measurements in 10 lambs were analysed with a median CIMPA of 2.95 (IQR 1.04) litre min−1 m−2. Mean percentage increase in extravascular lung water (EVLW) between the start and the end of the study was 126.4% (sd 40.4). Comparison of the two CO methods showed a mean bias CI of −0.16 litre min−1 m−2 (limits of agreement ±0.73 litre min−1 m−2) and a percentage error of 23.8%. Intraclass correlation coefficients were 0.91 (95% CI 0.81–0.95) for absolute agreement and 0.92 (95% CI 0.87–0.95) for consistency. Acceptable agreement was confirmed by a tolerability-agreement ratio of 0.39. The within-subject correlation between the amount of EVLWI and the bias between the two methods was not significant (−0.02; P=0.91). ConclusionsCO measurements by the transpulmonary thermodilution technique over a wide range of CI values are not affected by the presence of high EVLWI. The slight underestimation of the CO is independent of the amount of pulmonary oedema.

Measurement of cardiac output using the transpulmonary thermodilution method in the presence of high extravascular lung water in a pediatric animal model

Cardiac output (CO) can be measured using the transpulmonary thermodilution (TPTD) technique. TPTD is considered to be the gold standard in pediatric patients. We studied the influence of high levels of EVLW on the reliability of CO measurement using the TPTD technique in a pediatric animal model.

Interrater reliability of cardiac output measurements by transcutaneous Doppler ultrasound: implications for noninvasive hemodynamic monitoring in the ED

Introduction Hemodynamic monitoring is an important aspect of caring for the critically ill patients boarding in the emergency department (ED). The purpose of this study is to investigate the interrater agreement of noninvasive cardiac output measurements using transcutaneous Doppler ultrasound technique. Methods This is a prospective observational cohort study performed in a 32-bed adult ED of an academic tertiary center with approximately 65 000 annual patient visits. Patients were enrolled after verbal consent over a 7-month period. The raters were ED personnel involved in patient care. Paired measurements of cardiac index (CI) and stroke volume index (SVI) were obtained from a transcutaneous Doppler ultrasound cardiac output monitor. Results A convenience sample of 107 (50 women and 57 men) patients with a median age of 49 (32, 62) years was enrolled. One hundred two paired measurements were performed in 91 patients in whom adequate Doppler ultrasound signals were obtainable. The raters included 35 emergency medicine attending physicians, 31 emergency medicine residents, 80 medical students, 47 nurses, and 11 emergency medical technicians. Cardiac index range was 0.6 to 5.3 L/min per square meter, and SVI range was 7.7 to 63.0 mL/m 2. The correlation of CI measurements between 2 raters was good ( r 2 = 0.87; 95% confidence interval, 0.86-1.00; P < .001). Likewise, SVI measurements between 2 raters also showed acceptable correlation ( r 2 = 0.84; 95% confidence interval, 0.81-0.96; P < .001). Interrater reliability was strong for CI ( κ = 0.83 with 92.2% agreement) and SVI measurements ( κ = 0.72 with 88.2% agreement). Most patients had an interrater difference below 10% in CI and SVI measurements. Conclusions Emergency department personnel, regardless of their role in patient care, are able to obtain reliable cardiac output measurements in ED patients over a wide range of CI and SVI. Transcutaneous Doppler ultrasound technique may be an alternative to traditional invasive hemodynamic monitoring of critically ill patients presenting to the ED.

LETTER TO THE EDITORS

LETTER TO THE EDITORS

Effects of injectate volume on thermodilution measurements of cardiac output in patients with low ventricular ejection fraction

To determine the effect of 5-mL injectate on cardiac output measurements in critically ill patients with low ventricular ejection fraction (< 35%). Thermodilution cardiac output measurements obtained with three 5-mL and three 10-mL (randomly ordered) iced injectates in 50 patients with low ejection fraction were averaged if the measurements were within 10% of the median. If the 3 measurements were not within those limits, additional measurements were obtained. Cardiac output measured with the 5-mL injectate (mean, 4.63 L/min) and cardiac output measured with the 10-mL injectate (mean, 4.52 L/min) were not significantly different (P = .64). Lower and upper limits of agreement were -1.7 L/min to +1.6 L/min. The bias (mean difference between 10- and 5-mL measurements) of all measurements was -0.09, and the precision was 1.43 L/min, with a 95% confidence limit (mean difference +/- 2 SD) of -1.7 to +1.6 L/min. An additional measurement was necessary in 77% of patients in the 5-mL group but in only 48% of the 10-mL group (P = .006). Cardiac outputs measured with 5- and 10-mL injectates do not differ significantly. The greater variability of measurements obtained with a 5-mL injectate suggests that more measurements, and thus more time, are needed to measure cardiac output accurately. Clinicians must weigh the benefit of minimizing fluid volume used against the potential decreased reliability of cardiac output measurements.