Reliability of cardiac output measurements using LiDCOrapid™ and FloTrac/Vigileo™ across broad ranges of cardiac output values

Knowing a patient’s cardiac output (CO) could contribute to a safe, optimized hemodynamic control during surgery. Precise CO measurements can serve as a guide for resuscitation therapy, catecholamine use, differential diagnosis, and intervention during a hemodynamic crisis. Despite its invasiveness and intermittent nature, the thermodilution technique via a pulmonary artery catheter (PAC) remains the clinical gold standard for CO measurements. LiDCOrapid? (LiDCO, London, UK) and FloTrac/Vigileo? (Edwards Lifesciences, Irvine, CA) are less invasive continuous CO monitors that use arterial waveform analysis. Their calculations are based on arterial waveform characteristics and do not require calibration. Here, we evaluated LiDCOrapid? and FloTrac/Vigileo? during off-pump coronary artery bypass graft (OPCAB) and living-donor liver transplantation (LDLT) surgery. This observational, single-center study included 21 patients (11 OPCAB and 10 LDLT). We performed simultaneous measurements of CO at fixed sampling points during surgery using both devices (LiDCOrapid? version 1.04-b222 and FloTrac/Vigileo? version 3.02). The thermodilution technique via a PAC was used to obtain the benchmark data. LiDCOrapid? and FloTrac/Vigileo? were used in an uncalibrated fashion. We analyzed the measured cardiac index using a Bland–Altman analysis (the method of variance estimates recovery), a polar plot method (half-moon method), a 4-quadrant plot and compared the widths of the limits of agreement (LOA) using an F test. One OPCAB patient was excluded because of the use of an intra-aortic balloon pumping during surgery, and 20 patients (10 OPCAB and 10 LDLT) were ultimately analyzed. We obtained 149 triplet measurements with a wide range of cardiac index. For the FloTrac/Vigileo?, the bias and percentage error were ?0.44 L/min/m² and 74.4 %. For the LiDCOrapid?, the bias and percentage error were ?0.38 L/min/m² and 53.5 %. The polar plot method showed an angular bias (FloTrac/Vigileo? vs. LiDCOrapid?: 6.6° vs. 5.8°, respectively) and radial limits of agreement (?63.9 to 77.1 vs. ?41.6 to 53.1). A 4-quadrant plot was used to obtain concordance rates (FloTrac/Vigileo? vs. PAC and LiDCOrapid? vs. PAC: 84.0 and 92.4 %, respectively). We could compare CO measurement devices across broad ranges of CO and SVR using LDLT and OPCAB surgical patients. An F test revealed no significant difference in the widths of the LoA for both devices when sample sizes capable of detecting a more than two-fold difference were used. We found that both devices tended to underestimate the calculated CIs when the CIs were relatively high. These proportional bias produced large percentage errors in the present study.     

Cardiac output monitoring in septic shock: evaluation of the third-generation Flotrac-Vigileo<Superscript>®</Superscript>

Continuous cardiac index (CI) monitoring is frequently used in critically ill patients. Few studies have compared the pulse contour-based device FloTrac/Vigileo^® to pulmonary artery thermodilution (PAC) in terms of accuracy for CI monitoring in septic shock. The aim of our study was to compare the third-generation FloTrac/Vigileo^® to PAC in septic shock. Eighteen patients with septic shock requiring monitoring by PAC were included in this study. We monitored CI using both FloTrac/Vigileo^® and continuous thermodilution (PAC-CI). Hemodynamic data were recorded every hour or every 2 min during fluid challenges. The primary endpoint was the global agreement of all CI-paired measurements determined using the Bland–Altman method adapted to replicated data. We tested the linearity of the bias by regression analysis, and compared the reactivity of the 2 techniques during fluid challenges. A receiver operating characteristic (ROC) curve analysis tested the ability of FloTrac/Vigileo^® to detect concordant and significative CI changes, using PAC-CI as the reference method. Overall, 1,201 paired CI measurements were recorded. The Bland–Altman analysis for global agreement of the 2 techniques showed a bias of ?0.1 ± 2.1 L min^?1 m^?2 and a percentage error of 64 %. The overall correlation coefficient between PAC-CI and FloTrac/Vigileo^® CI was 0.47 (p < 0.01), with r² = 0.22. The area under the curve of the ROC curve for detecting concordant and significant changes in CI was 0.72 (0.53; 0.87). In our study, third-generation Flowtrac-Vigileo^® appears to be too inaccurate to be recommended for CI monitoring in septic shock.     

Arterial pressure waveform derived cardiac output FloTrac/Vigileo system (third generation software): comparison of two monitoring sites with the thermodilution cardiac output

The present study was conducted to study the effect of monitoring site, radial or femoral, for arterial pressure waveform derived cardiac output using FloTrac/Vigileo system with third generation software version 3.02 during cardiac surgery. The cardiac output derived from the two sites was also compared to the pulmonary artery catheter (PAC) derived cardiac output to reevaluate the relation between them using the newer software. The effect of cardiopulmonary bypass (CPB) was also studied by doing the sub analysis before and after bypass. Forty patients undergoing coronary artery bypass surgery with cardiopulmonary bypass were enrolled in the study. Cardiac output derived from radial artery (RADCO), femoral artery (FEMCO) using FloTrac/Vigileo system with third generation software version 3.02 and cardiac output using pulmonary artery catheter (PACCO) at predefined nine time points were recorded. Three hundred and forty two cardiac output data triplets were analysed. The Bland–Altman analysis of RADCO and FEMCO revealed a mean bias of −0.28 with percentage error of 20%. The pre CPB precision of both RADCO and FEMCO was 1.25 times as that of PACCO. The post CPB precision of FEMCO was 1.2 times of PACCO while that of RADCO was 1.7 times of PACCO. The third generation of FloTrac/Vigileo system shows good correlation between the radial and femoral derived cardiac outputs in both pre and post bypass periods. The newer software correlates better to PAC derived cardiac output in the post bypass period for femoral artery than radial artery.     

Cross-comparisons of trending accuracies of continuous cardiac-output measurements: pulse contour analysis,bioreactance, and pulmonary-artery catheter

We compared the similarity of cardiac-output (CO) estimates between available bolus thermodilution pulmonary-artery catheters (PAC), arterial pulse-contour analysis (LiDCOplus^?, FloTrac^? and PiCCOplus^?), and bioreactance (NICOM^?). Repetitive simultaneous estimates of CO obtained from the above devices were compared in 21 cardiac-surgery patients during the first 2 h post-surgery. Mean and absolute values for CO across the devices were compared by ANOVA, Bland–Altman, Pearson moment, and linear-regression analyses. Twenty-one simultaneous CO measurements were made before and after therapeutic interventions. Mean PAC CO (5.7?±?1.5 L min) was similar to LiDCO^?, FloTrac^?, PiCCO^?, and NICOM^? CO (6.0?±?1.9, 5.9?±?1.0, 5.7?±?1.8, 5.3?±?1.0 L min, respectively). Mean CO bias between each paired method was ?0.10 (PAC–LiDCO), 0.18 (PAC–PiCCO), ?0.40 (PAC–FloTrac), ?0.71 (PAC–NICOM), 0.28 (LiDCO–PiCCO), 0.39 (LiDCO–FloTrac), ?0.97 (NICOM–LiDCO), 0.61 (PiCCO–FloTrac), ?1.0 (NICOM–FloTrac), ?0.73 (NICOM–PiCCO) L/min, with limits of agreement (1.96 SD, ±95% CI) of ±?2.01, ±2.35, ±2.27, ±2.70, ±1.97, ±2.17, ±3.51, ±2.87, ±2.40, and ±?3.14 L min, respectively, and the percentage error for each of the paired devices was 35, 41, 40, 47, 33, 36, 59, 50, 42, and 55%, respectively. From Pearson moment analysis, dynamic changes in CO, estimated by each device, showed good cross-correlations. Although all devices studied recorded similar mean CO values, which dynamically changed in similar directions, they have markedly different bias and precision values relative to each other. Thus, results from prior studies that have used one device to estimate CO cannot be used to validate others devices.     

The impact of systemic vascular resistance on the accuracy of the FloTrac/Vigileo™ system in the perioperative period of cardiac surgery: a prospective observational comparison study

FloTrac/Vigileo? system is based on arterial pressure waveform analysis arterial pressure-based CO (APCO). Therefore, systemic vascular resistance (SVR) can influence the accuracy of APCO. The purpose of this study is to evaluate the relationship between SVR and the accuracy of APCO. We managed 50 consecutive patients in the perioperative period of cardiac surgery with FloTrac/Vigileo? system (v. 3.02) and Swan–Ganz catheter/Vigilance? system pulmonary artery catheter-based CO (PAC-CO) simultaneously. Continuous hemodynamic measurement using both methods was performed every 20 s from the induction of anesthesia to PAC removal 4 h after extubation. A total of 11,092 (intraoperative), 38,455 (postoperative, pre-extubation), and 44,235 (postoperative, post-extubation) data pairs were finally analyzed. Bland–Altman analysis revealed that in the intraoperative [postoperative pre-extubation, post-extubation] period, the bias was 0.5 [0.1, 0.0] L/min and the limits of agreement ranged from ?2.4 to 3.3 [?2.2 to 2.4, ?2.4 to 2.3] L/min. The percentage error was 60.3 [54.5, 48.5] %. Regression analysis of the systemic vascular resistance index (SVRI) and the bias between APCO and PAC-CO showed that the bias was positively correlated to the SVRI. Subanalysis based on SVR with Lin’s concordance correlation coefficient revealed that relatively satisfactory concordance was found in the normal-SVR group (concordance correlation coefficient ρ _c = 0.51–0.56) regardless of vasoactive agent use. The accuracy of the FloTrac/Vigileo? System (v. 3.02) is relatively satisfactory in the condition with normal SVR regardless of vasoactive agent use. Positive correlation between the bias and SVR can be the clue to the more effective use of FloTrac/Vigileo? system.     

Continuous cardiac output measurement by un-calibrated pulse wave analysis and pulmonary artery catheter in patients with septic shock

Septic shock is a serious medical condition. With increased concerns about invasive techniques, a number of non-invasive and semi-invasive devices measuring cardiac output (CO) have become commercially available. The aim of the present study was to determine the accuracy, precision and trending abilities of the FloTrac and the continuous pulmonary artery catheter thermodilution technique determining CO in septic shock patients. Consecutive septic shock patients were included in two centres and CO was measured every 4 h up to 48 h by FloTrac (APCO) and by pulmonary artery catheter (PAC) using the continuous (CCO) and intermittent (ICO) technique. Forty-seven septic shock patients with 326 matched sets of APCO, CCO and ICO data were available for analysis. Bland and Altman analysis revealed a mean bias ±2 SD of 0.0 ± 2.14 L min^?1 for APCO–ICO (%error = 34.5 %) and 0.23 ± 2.55 L min^?1 for CCO–ICO (%error = 40.4 %). Trend analysis showed a concordance of 85 and 81 % for APCO and CCO, respectively. In contrast to CCO, APCO was influenced by systemic vascular resistance and by mean arterial pressure. In septic shock patients, APCO measurements assessed by FloTrac but also the established CCO measurements using the PAC did not meet the currently accepted statistical criteria indicating acceptable clinical performance.     

Comparison of an advanced minimally invasive cardiac output monitoring with a continuous invasive cardiac output monitoring during lung transplantation

The aim of this study was to compare a continuous non-calibrated left heart cardiac index (CI) measurement by arterial waveform analysis (FloTrac^®/Vigileo^®) with a continuous calibrated right heart CI measurement by pulmonary artery thermodilution (CCOmbo-PAC^®/Vigilance II^®) for hemodynamic monitoring during lung transplantation. CI was measured simultaneously by both techniques in 13 consecutive lung transplants (n = 4 single-lung transplants, n = 9 sequential double-lung transplants) at distinct time points perioperatively. Linear regression analysis and Bland–Altman analysis with percentage error calculation were used for statistical comparison of CI measurements by both techniques. In this study the FloTrac^® system underestimated the CI in comparison with the continuous pulmonary arterial thermodilution (p < 0.000). For all measurement pairs we calculated a bias of ?0.55 l/min/m² with limits of agreement between ?2.31 and 1.21 l/min/m² and a percentage error of 55 %. The overall correlations before clamping a branch oft the pulmonary artery (percentage error 41 %) and during the clamping periods of a branch oft the pulmonary artery (percentage error 66 %) failed to reached the required percentage error of less than 30 %. We found good agreement of both CI measurements techniques only during the measurement point “15 min after starting the second one-lung ventilation period” (percentage error 30 %). No agreement was found during all other measurement points. This pilot study shows for the first time that the CI of the FloTrac^® system is not comparable with the continuous pulmonary-artery thermodilution during lung transplantation including the time periods without clamping a branch of the pulmonary artery. Arterial waveform and continuous pulmonary artery thermodilution are, therefore, not interchangeable during these complex operations.     

Pulse-contour derived cardiac output measurements in morbid obesity: influence of actual,ideal and adjusted bodyweight

The non-invasive Nexfin cardiac output (CO) monitor shows a low level of agreement with the gold standard thermodilution method in morbidly obese patients. Here we investigate whether this disagreement is related to excessive bodyweight, and can be improved when bodyweight derivatives are used instead. We performed offline analyses of cardiac output recordings of patient data previously used and partly published in an earlier study by our group. In 30 morbidly obese patients (BMI?>?35 kg/m²) undergoing laparoscopic gastric bypass, cardiac output was simultaneously determined with PiCCO thermodilution and Nexfin pulse-contour method. We investigated if agreement of Nexfin-derived CO with thermodilution CO improved when ideal and adjusted—instead of actual- bodyweight were used as input to the Nexfin. Bodyweight correlated with the difference between Nexfin-derived and thermodilution-derived CO (r?=??0.56; p?=?0.001). Bland Altman analysis of agreement between Nexfin and thermodilution-derived CO revealed a bias of 0.4?±?1.6 with limits of agreement (LOA) from ?2.6 to 3.5 L min when actual bodyweight was used. Bias was ?0.6?±?1.4 and LOA ranged from ?3.4 to 2.3 L min when ideal bodyweight was used. With adjusted bodyweight, bias improved to 0.04?±?1.4 with LOA from ?2.8 to 2.9 L min. Our study shows that agreement of the Nexfin-derived with invasive CO measurements in morbidly obese patients is influenced by body weight, suggesting that Nexfin CO measurements in patients with a BMI above 35 kg/m² should be interpreted with caution. Using adjusted body weight in the Nexfin CO-trek algorithm reduced the bias.     

Evaluation of the use of the fourth version FloTrac system in cardiac output measurement before and after cardiopulmonary bypass

The FloTrac system is a system for cardiac output (CO) measurement that is less invasive than the pulmonary artery catheter (PAC). The purposes of this study were to (1) compare the level of agreement and trending abilities of CO values measured using the fourth version of the FloTrac system (CCO-FloTrac) and PAC-originated continuous thermodilution (CCO-PAC) and (2) analyze the inadequate CO-discriminating ability of the FloTrac system before and after cardiopulmonary bypass (CPB). Fifty patients were included. After exclusion, 32 patients undergoing cardiac surgery with CPB were analyzed. All patients were monitored with a PAC and radial artery catheter connected to the FloTrac system. CO was assessed at 10 timing points during the surgery. In the Bland–Altman analysis, the percentage errors (bias, the limits of agreement) of the CCO-FloTrac were 61.82% (0.16, ??2.15 to 2.47 L min) and 51.80% (0.48, ??1.97 to 2.94 L min) before and after CPB, respectively, compared with CCO-PAC. The concordance rates in the four-quadrant plot were 64.10 and 62.16% and the angular concordance rates (angular mean bias, the radial limits of agreement) in the polar-plot analysis were 30.00% (17.62°, ??70.69° to 105.93°) and 38.63% (??10.04°, ??96.73° to 76.30°) before and after CPB, respectively. The area under the receiver operating characteristic curve for CCO-FloTrac was 0.56, 0.52, 0.52, and 0.72 for all, ≥?±?5, ≥?±?10, and ≥?±?15% CO changes (ΔCO) of CCO-PAC before CPB, respectively, and 0.59, 0.55, 0.49, and 0.46 for all, ≥?±?5, ≥?±?10, and ≥?±?15% ΔCO of CCO-PAC after CPB, respectively. When CO <?4 L/min was considered inadequate, the Cohen κ coefficient was 0.355 and 0.373 before and after CPB, respectively. The accuracy, trending ability, and inadequate CO-discriminating ability of the fourth version of the FloTrac system in CO monitoring are not statistically acceptable in cardiac surgery.     

Comparison of cardiac output measures by transpulmonary thermodilution,pulse contour analysis,and pulmonary artery thermodilution during off-pump coronary artery bypass surgery: a subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre

Cardiac output measurement has a long history in haemodynamic management and many devices are now available with varying levels of accuracy. The purpose of the study was to compare the agreement and trending abilities of cardiac output, as measured by transpulmonary thermodilution and calibrated pulse contour analysis, using the VolumeView? system, continuous thermodilution via a pulmonary artery catheter, and uncalibrated pulse contour analysis, using FloTrac? with pulmonary artery bolus thermodilution. Twenty patients undergoing off-pump coronary artery bypass surgery using a pulmonary artery catheter and the VolumeView? and FloTrac? systems were included in this subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre. During surgery, cardiac output was assessed after the induction of anaesthesia, after sternotomy, during the harvesting of grafts, during revascularization of the anterior and posterior/lateral wall, after protamine infusion, and after sternal fixation. In total, 145 sets of measurements were evaluated using Bland–Altman with % error calculation, correlation, concordance, and polar plot analyses. The percentage error (bias, limits of agreement) was 12.6 % (?0.12, ?0.64 to 0.41 L/min), 26.7 % (?0.38, ?1.50 to 0.74 L/min), 29.3 % (?0.08, ?1.32 to 1.15 L/min), and 33.8 % (?0.05, ?1.47 to 1.37 L/min) for transpulmonary thermodilution, pulmonary artery continuous thermodilution, calibrated, and uncalibrated pulse contour analysis, respectively, compared with pulmonary artery bolus thermodilution. All pairs of measurements showed significant correlations (p < 0.001), whereas only transpulmonary thermodilution revealed trending ability (concordance rate of 95.1 %, angular bias of 1.33°, and radial limits of agreement of 28.71°) compared with pulmonary artery bolus thermodilution. Transpulmonary thermodilution using the VolumeView? system provides reliable data on cardiac output measurement and tracking the changes thereof when compared with pulmonary artery bolus thermodilution in patients with preserved cardiac function during off-pump coronary artery bypass surgery. Trial registration NCT01713192 (ClinicalTrials.gov).     

Cardiac index assessment using bioreactance in patients undergoing cytoreductive surgery in ovarian carcinoma

This clinical study compared the cardiac index (CI) assessed by the totally non-invasive method of bioreactance (CI_BR) (NICOM?, Cheetah Medical, Vancouver, USA) to transpulmonary thermodilution (CI_TD) during cytoreductive surgery in ovarian carcinoma. The hypothesis was that CI could be assessed by bioreactance in an accurate and precise manner including accurate trending ability when compared to transpulmonary thermodilution. In 15 patients CI_BR and CI_TD were assessed after induction of anesthesia, after opening of the peritoneum, hourly during the operative procedure, and 30 min after extubation. Trending ability was assessed between the described timepoints. In total 84 points of measurement were analyzed. Concordance correlation coefficient for repeated measures correlating the CI_BR and CI_TD was 0.32. Bias was 0.26 l/min/m² (limits of agreement ?1.39 and 1.92 l/min/m²). The percentage error was 50.7 %. Trending ability quantified by the mean of angles θ which are made by the ΔCI vector and the line of identity (y = x) showed a value for CI_BR of θ = 23.4°. CI assessment by bioreactance showed acceptable accuracy and trending ability. However, its precision was poor. Therefore, CI measurement can not be solely based on bioreactance in patients undergoing cytoreductive surgery in ovarian carcinoma.     

Continuous cardiac index monitoring: A prospective observational study of agreement between a pulmonary artery catheter and a calibrated minimally invasive technique

IntroductionContinuous cardiac index (CCI) monitoring can provide information to assist in hemodynamic support. However, pulmonary artery catheters (PAC) pose logistic challenges in acute care settings. We hypothesized that CCI measured with a calibrated minimally invasive technique (LiDCO/PulseCO, UK) would have good agreement with the PAC.MethodsWe performed a prospective observational study in post-operative cardiac surgery patients. All patients had a PAC with CCI monitoring capability. We connected the LiDCO apparatus to a radial artery line and performed a one-time calibration with a lithium dilution indicator. In order to test the least invasive method possible, we used a peripheral intravenous (IV) line for indicator delivery rather than the conventional central line technique. We recorded paired PAC/LiDCO-PulseCO CCI measurements every minute for 3 h. We blinded investigators and clinicians to minimally invasive data with an opaque shield over the monitor. We assessed agreement with Bland-Altman analysis.ResultsWe obtained 1485 paired measurements in 8 subjects. The mean CI was 2.9 L/min/m². By Bland-Altman plot, PAC and LiDCO measurements showed minimal bias (?0.01), but the 95% limits of agreement (±2SD) of ± 1.3 L/min/m² were relatively wide with respect to the mean.ConclusionsThis calibrated minimally invasive (i.e. radial arterial line and peripheral IV) technique demonstrated low bias compared with CCI measured by PAC. However, the relatively wide confidence limits indicate that differences in the two measurements could still be clinically significant.     

Utility of stroke volume variation measured using non-invasive bioreactance as a predictor of fluid responsiveness in the prone position

The aim of this prospective study was to evaluate the usefulness of stroke volume variation (SVV) derived from NICOM^® to predict fluid responsiveness in the prone position. Forty adult patients undergoing spinal surgery in the prone position were included in this study. We measured SVV from NICOM^® (SVV_NICOM) and FloTrac?/Vigileo? systems (SVV_Vigileo), and pulse pressure variation (PPV) using automatic (PPV_auto) and manual (PPV_manual) calculations at four time points including supine and prone positions, and before and after fluid loading of 6 ml kg^?1 colloid solution. Fluid responsiveness was defined as an increase in the cardiac index from Vigileo? of ≥12 %. There were 19 responders and 21 non-responders. Prone positioning induced a significant decrease in SVV_NICOM, SVV_Vigileo, PPV_auto, and PPV_manual. However, all of these parameters successfully predicted fluid responsiveness in the prone position with area under the receiver-operator characteristic curves for SVV_NICOM, SVV_Vigileo, PPV_auto, and PPV_manual of 0.78 [95 % confidence interval (CI) 0.62–0.90, P = 0.0001], 0.79 (95 % CI 0.63–0.90, P = 0.0001), 0.76 (95 % CI 0.6–0.88, P = 0.0006), and 0.84 (95 % CI 0.69–0.94, P < 0.0001), respectively. The optimal cut-off values were 12 % for SVV_NICOM, SVV_Vigileo, and PPV_auto, and 10 % for PPV_manual. SVV from NICOM^® successfully predicts fluid responsiveness during surgery in the prone position. This totally non-invasive technique for assessing individual functional intravenous volume status would be useful in a wide range of surgeries performed in the prone position.     

Accuracy and precision of transcardiopulmonary thermodilution in patients with cardiogenic shock

Hemodynamic monitoring plays a crucial role in the supportive treatment of critically ill patients. In this setting, the use of the pulmonary artery catheter (PAC) is a standard procedure. In this study we prospectively compare the accuracy and precision of pulmonary thermodilution (PTD) by PAC and transcardiopulmonary thermodilution (TC-PTD) in patients with cardiogenic shock following an acute cardiac event. In this prospective study 77 hemodynamic measurements were taken in 11 patients presenting cardiogenic shock (CS) treated at the medical intensive care unit of our university hospital. Hemodynamic parameters were measured simultaneously by PTD and by TC-PTD. Both techniques assessed showed a strong correlation in the obtained hemodynamic parameters. The mean bias of cardiac index between measured by PTD (CIpa) and by TC-PTD (CIpi) was 0.04 ± 0.35 L/min/m². During intra-aortic balloon pump (IABP) counterpulsation and therapeutic hypothermia (TH) in post-resuscitation care, mean bias between CIpa and CIpi was 0.04 ± 0.36 and 0.04 ± 0.34 L/min/m², respectively. Similarly, patients presenting mitral or tricuspid regurgitation showed interchangeable parameters. Preload parameters obtained by TC-PTD showed significant differences in patients with left ventricular ejection fraction (LVEF) <35 %, compared to patients with LVEF ≥35 %. In contrast, pulmonary arterial occlusion pressure showed no significant difference. Hemodynamic measurements by PTD and TC-PTD are interchangeable during therapy of CS, including patients IABP, TH, mitral or tricuspid regurgitation. Preload parameters measured by TC-PTD seem to be more accurate in these patients than pressure parameters of PTD to gather the acute hemodynamic situation.     

Transesophageal Doppler reliably tracks changes in cardiac output in comparison with intermittent pulmonary artery thermodilution in cardiac surgery patients

In this study a comparison of cardiac output (CO) measurements obtained with CardioQ transesophageal Doppler (TED) and pulmonary artery catheter (PAC) thermodilution (TD) technique was done in a systematic set-up, with induced changes in preload, afterload and heart rate. Twenty-five patients completed the study. Each patient were placed in the following successive positions: (1) supine, (2) head-down tilt, (3) head-up tilt, (4) supine, (5) supine with phenylephrine administration, (6) pace heart rate 80 beats per minute (bpm), (7) pace heart rate 110 bpm. The agreement of compared data was investigated by Bland–Altman plots, and to assess trending ability a four quadrants plot and a polar plot were constructed. Both methods showed an acceptable precision 6.4 % (PAC TD) and 12.8 % (TED). In comparison with PAC TD, the TED was associated with a mean bias in supine position of ?0.30 l min^?1 (95 % CI ?0.88; 0.27), wide limits of agreement, a percentage error of 69.5 %, and a trending ability with a concordance rate of 92 %, angular bias of 1.1° and a radial sector size of 40.0° corresponding to an acceptable trending ability. In comparison with PAC TD, the CardioQ TED showed a low mean bias, wide limits of agreement and a larger percentage error than should be expected from the precision of the two methods. However, an acceptable trending ability was found. Thus, the CardioQ TED should not replace CO measurements done by PAC TD, but could be a valuable tool in guiding therapy.     

Influence of different infracardial positions of central venous catheters in hemodynamic monitoring using the transpulmonal thermodilution method

Hemodynamic measurements are often conducted by the transpulmonary thermodilution (TPTD)-based PiCCO^®-system. This requires a central-venous (CVC) and a thermistor-tipped arterial catheter, usually placed in the femoral artery. In certain clinical situations, CVC devices have to be placed in the inferior vena cava. However, little is known about the influence of different CVC positions (i.e. ipsi- vs. contra-lateral to the arterial catheter) on the accuracy of the TPTD measurement results. In this prospective observational study surgical intensive care unit patients who had been inserted with CVCs either into the superior (CVC_VCS) or the inferior vena cava (CVC_inf) in addition to an arterial PiCCO^®-catheter, were enrolled. Patients were then divided into two groups: Group I was provided with a CVC in the contralateral (CVC_contra) and Group II in the ipsilateral (CVC_ipsi) inferior vena cava. Thermodilution via injection of ice-cold saline was then performed via CVC_sup and CVC_inf. Bland–Altman analysis for cardiac index (CI), extra-vascular lung water index (EVLWI) and global end-diastolic volume index (GEDVI) were employed. Additional correction formulas for femorally assed parameters were determined. In a total of 28 patients, bias (limits of agreement) for measurements of CI in CVC_contra was found to be +0.2 (?0.4; +0.9) and +0.3 (?0.4; +1.0) L/min/m² in CVC_ipsi. GEDVI showed a bias of +274.8 (?47.3; +596.9) mL/m² in CVC_contra and +274.7 (?100.7; +650.1) mL/m² in CVC_ipsi. The mean EVLWI were 9.4 ± 4.3 mL/kg for EVLWI_VCS and 10.7 ± 5.2 mL/kg for EVLWI_inf. The LoA yielded at ?3.4 and +6.1 mL/kg with a bias of +1.3 mL/kg. Percentage errors revealed clinically acceptable limits for CI and GEDVI, but not for EVLWI. Using TPTD via an infracardial central vein, measurements of CI showed high accuracy and precision while GEDVI measurements were precise with a lower accuracy, irrespective of the position of the infracardial CVC.     

Cardiac output measured by uncalibrated arterial pressure waveform analysis by recently released software version 3.02 versus thermodilution in septic shock

To evaluate the 3.02 software version of the FloTrac/Vigileo? system for estimation of cardiac output by uncalibrated arterial pressure waveform analysis, in septic shock. Nineteen consecutive patients in septic shock were studied. FloTrac/Vigileo? measurements (COfv) were compared with pulmonary artery catheter thermodilution-derived cardiac output (COtd). The mean cardiac output was 7.7 L min^?1 and measurements correlated at r = 0.53 (P < 0.001, n = 314). In Bland–Altman plot for repeated measurements, the bias was 1.7 L min^?1 and 95 % limits of agreement (LA) were ?3.0 to 6.5 L min^?1, with a %error of 53 %. The bias of COfv inversely related to systemic vascular resistance (SVR) (r = ?0.54, P < 0.001). Above a SVR of 700 dyn s cm^?5 (n = 74), bias was 0.3 L min^?1 and 95 % LA were ?1.6 to 2.2 L min^?1 (%error 32 %). Changes between consecutive measurements (n = 295) correlated at 0.67 (P < 0.001), with a bias of 0.1 % (95 % limits of agreement ?17.5 to 17.0 %). All changes >10 % in both COtd and COfv (n = 46) were in the same direction. Eighty-five percent of the measurements were within the 30°–330° of the polar axis. COfv with the latest software still underestimates COtd at low SVR in septic shock. The tracking capacities of the 3.02 software are moderate-good when clinically relevant changes are considered.     

RETRACTED ARTICLE: Noninvasive assessment of cardiac output using thoracic electrical bioimpedance in hemodynamically stable and unstable patients after cardiac surgery: a comparison with pulmonary artery thermodilution

Objective To compare noninvasive cardiac output (CO)measurement obtained with a new thoracic electrical bioimpedance (TEB) device, using a proprietary modification of the impedance equation, with invasive measurement obtained via pulmonary artery thermodilution.Design Prospective, observational study.Setting Surgical intensive care unit (ICU) of a university-affiliated community hospital.Patients and participants Seventy-four adult patients undergoing elective cardiac surgery with routine pulmonary artery catheter placement.Interventions None.Measurements and results Simultaneous paired CO and cardiac index (CI) measurements by TEB and thermodilution were obtained in mechanically ventilated patients upon admission to the ICU. For analysis of CI data the patients were subdivided into a hemodynamically stable group and a hemodynamically unstable group. The groups were analyzed using linear regression and tests of bias and precision. We found a significant correlation between thermodilution and TEB (r = 0.83; n< 0.001), accompanied by a bias of –0.01 l/min/m² and a precision of ±0.57 l/min/m² for all CI data pairs. Correlation, bias, and precision were not influenced by stratification of the data. The correlation coefficient, bias, and precision for CI were 0.86 (n< 0.001), 0.03 l/min/m², and ±0.47 l/min/m² in hemodynamically stable patients and 0.79 (n< 0.001), 0.06 l/min/m², and ±0.68 l/min/m² in hemodynamically unstable patients.Conclusions Our results demonstrate a close correlation and clinically acceptable agreement and precision between CO measurements obtained with impedance cardiography using a new algorithm to calculate CO from variations in TEB, and those obtained with the clinical standard of care, pulmonary artery thermodilution, in hemodynamically stable and unstable patients after cardiac surgery.     

Cardiac output measurement by arterial waveform analysis in cardiac surgery--a comparison of measurements derived from waveforms of the radial artery versus the ascending aorta

In cardiac surgery, perioperative haemodynamic management is often guided by cardiac output (CO) measurements. The Vigileo monitor offers uncalibrated CO measurement by arterial waveform analysis (CO(wave)). This validation study compared CO measurements derived from radial artery waveform analysis with those derived from the ascending aorta. CO measurements from the radial artery versus the ascending aorta showed a significant correlation before and after cardiopulmonary bypass (CPB). However, Bland-Altman analysis showed a mean bias of 0.1 l/min and 0.1 l/min, and limits of agreement (LOA) of +2.2 l/min and -1.9 l/min prior to CPB, and +2.5 l/min and -2.7 l/min after weaning from CPB. A comparison of these CO measurements showed a low mean bias, but wide LOA before and after CPB. Therefore measurements using uncalibrated CO(wave) have to be interpreted with caution in a clinical situation.     

Cardiac output assessed by non-invasive monitoring is associated with ECG changes in children with critical asthma

The primary aim of this study was to determine changes in CI and SI, if any, in children hospitalized with status asthmatics during the course of treatment as measured by non-invasive EC monitoring. The secondary aim was to determine if there is an association between Abnormal CI (defined as <5 or >95 % tile adjusted for age) and Abnormal ECG (defined as ST waves changes) Non-invasive cardiac output (CO) recordings were obtained daily from admission (Initial) to discharge (Final). Changes in CI and SI measurements were compared using paired t tests or 1-way ANOVA. The association between Abnormal CI on Initial CO recording and Abnormal ECG was analyzed by Fischer’s exact test. Data are presented as mean ± SEM with mean differences reported with 95 % confidence interval; p < 0.05 was considered significant. Thirty-five children with critical asthma were analyzed. CI decreased from 6.2 ± 0.2 to 4.5 ± 0.1 [?1.6 (?0.04 to ?0.37)] L/min/m² during hospitalization. There was no change in SI. There was a significant association between Abnormal Initial CI and Abnormal ECG (p = 0.02). In 11 children requiring prolonged hospitalization CI significantly decreased from 7.2 ± 0.5 to 4.0 ± 0.2 [?3.2 (?4.0 to ?2.3)] L/min/m² and SI decreased from 51.2 ± 3.8 to 40.3 ± 2.0 [?11.0 (?17.6 to ?4.4)] ml/beat/m² There was a significant decrease in CI in all children treated for critical asthma. In children that required a prolonged course of treatment, there was also a significant decrease in SI. Abnormal CI at Initial CO recording was associated with ST waves changes on ECG during hospitalization. Future studies are required to determine whether non-invasive CO monitoring can predict which patients are at risk for developing abnormal ECG.