Comparison of continuous, stat, and intermittent cardiac output measurements in patients undergoing minimally invasive direct coronary artery bypass surgery

OBJECTIVE: To compare intermittent cardiac output (ICO) with continuous cardiac output (CCO) and stat cardiac output (SCO) measurements in patients undergoing minimally invasive direct coronary artery bypass (MIDCAB) surgery. DESIGN: Prospective, clinical study. SETTING: Single, tertiary referral center. PARTICIPANTS: Twenty adult patients undergoing off-pump MIDCAB surgery from January through June 2000. INTERVENTIONS: Each patient had a 7.5F 5-lumen pulmonary artery thermodilution catheter (CCO catheter, Baxter Healthcare Corporation, Irvine, CA) inserted for measurement of cardiac output (CO). ICO, CCO, and SCO were compared at 10 predefined time points. RESULTS: A total of 400 data pairs for CO were obtained. ICO values ranged from 1.8 to 8.4 L/min; CCO, 1.9 to 7.5 L/min; and SCO, 2.25 to 6.35 L/min. Correlation between ICO and CCO was significant (correlation coefficient, r = 0.78, p < 0.001), accompanied by a bias of -0.095 L/min and precision of 0.729 L/min. Similarly, the correlation between ICO and SCO was significant (r = 0.79, p < 0.001), accompanied by good accuracy (bias, 0.084 L/min) and precision (0.843 L/min). There were statistically significant decreases in mean arterial pressure, CO, cardiac index, stroke volume, stroke volume index, and left and right ventricular stroke work indices during anastomosis of the left internal mammary artery to left anterior descending artery. These parameters returned to baseline preinduction values 1 minute after completion of the anastomosis. CONCLUSION: Excellent correlation, accuracy, and precision were found among the 3 methods of measuring CO in patients undergoing MIDCAB surgery. Further studies are needed to assess their accuracy in multivessel off-pump coronary artery bypass graft surgery and in patients with poor left ventricular function.     

Pulse contour analysis versus thermodilution in cardiac surgery patients

BACKGROUND: Previous studies have demonstrated that there is a lack of agreement between intermittent cold bolus thermodilution (ICO) and a semicontinuous method with dilution of heat (CCO) in cardiac surgical patients following hypothermic extracorporeal circulation (HCPB). Therefore, the aim of the present study was to compare both ICO and CCO with continuous pulse contour analysis (PCCO): a method based on a fundamentally different principle of determining cardiac output (CO). METHODS: A prospective criterion standard study of 25 cardiac surgery patients undergoing HCPB. Cardiac output was determined using the three methods (ICO, CCO, and PCCO) before and after HCPB up to 12 h after arrival on the ICU. Bias and precision were evaluated. RESULTS: A total of 380 triple determinations of CO could be analyzed. During the entire study period bias PCCO-ICO was -0.14 l*/min (precision 1.16 l*/min) and bias CCO-ICO was -0.40 l*/min (precision 1.25 l*/min). Up to 45 min after bypass PCCO agreed with ICO (bias -0.21 l*/min, precision 1.37 l*/min), while bias CCO-ICO was -1.30 l*/min (precision 1.45 l*/min). CONCLUSION: The agreement between PCCO and ICO in contrast to CCO in the first 45 min after HCPB indicates that CCO underestimates CO during this period.     

Thermal filament continuous thermodilution cardiac output delayed response limits its value during acute hemodynamic instability.

BACKGROUND: It has been suggested that measurement of continuous cardiac output (CCO) is an advancement in the management of critically ill patients. Our objective was to determine the accuracy of CCO during the rapid hemodynamic changes induced by hemorrhage and resuscitation. METHODS: In 12 anesthetized dogs (20.2+/-0.9 kg), pulmonary artery blood flow, our "gold standard" cardiac output, was measured with an sonographic flowprobe, whereas CCO, intermittent bolus cardiac output (ICO), and mixed venous oxygen saturation were measured with a thermodilution fiberoptic pulmonary artery catheter with a thermal filament. A graded hemorrhage (20 mL/min) was produced to a mean arterial pressure of 40 mm Hg, which was maintained at this level for 30 minutes. Total shed blood volume (701+/-53 mL) was retransfused at a rate of 40 mL/min, over 30 minutes, after which a massive hemorrhage (100 mL/min) was produced over 10 minutes. RESULTS: Hemorrhage induced significant decreases in mean arterial pressure, mixed venous oxygen saturation, and oxygen delivery, which were all restored during early resuscitation. However, CCO showed a delayed response after hemorrhage and resuscitation, compared with pulmonary blood flow, throughout the study (r = 0.549), matching only at baseline and at the end of both graded hemorrhage and resuscitation periods. There was a good correlation between ICO and pulmonary artery blood flow (r = 0.964) and no significant differences between them throughout the study. CONCLUSION: CCO has a delayed response during acute hemodynamic changes induced by hemorrhage and resuscitation. When sudden changes in mean arterial pressure or in mixed venous oxygen saturation are detected, cardiac output must be estimated by the standard bolus thermodilution technique, not by CCO.     

The level of cardiac output affects the relationship and agreement between pulmonary artery and transpulmonary aortic thermodilution measurements in an animal model

OBJECTIVE: The authors investigated the relationship between pulmonary artery and transpulmonary aortic thermodilution cardiac output measurements under conditions of increasing cardiac output (CO). DESIGN: Animal study with repeated simultaneous measurements comparing 2 cardiac output measurement techniques. SETTING: Experimental animal facility of a university hospital. PARTICIPANTS: Ten female pigs. INTERVENTIONS: In anesthetized pigs, an aortic thermistor catheter and a pulmonary artery catheter (PAC) were inserted. Then dobutamine was infused under continuous cardiac output (CCO) monitoring to target different levels of CO. After each L/min increase of CCO simultaneous aortic and PAC thermodilution, CO measurements were performed by using a bolus injection of cooled normal saline and the amount of thermal indicator loss (TL) was calculated. MEASUREMENTS AND MAIN RESULTS: Pooled analysis of CO data with the method of Bland and Altman showed that aortic thermodilution CO was higher than PAC thermodilution CO with a bias of 3.8% +/- 11.1%. The range of TL was 30.4% to -10.1%. Differential analysis according to the range of CO revealed that, in each animal under conditions of low CO, aortic thermodilution CO was higher than PAC thermodilution CO, whereas results were inverse under conditions of high CO. CONCLUSIONS: The authors concluded that the amount of CO differentially affects the relationship between aortic and PAC thermodilution CO. TL and recirculation may be the explanation for this finding.     

Cardiac output measured by a new arterial pressure waveform analysis method without calibration compared with thermodilution after cardiac surgery

OBJECTIVES: To investigate whether measuring cardiac output and its course after cardiac surgery by a new analysis technique of radial artery pressure waves, without need for calibration (FloTrac/Vigileo [FV]; Edwards Lifesciences, Irvine, CA), conforms to the standard bolus thermodilution method via a pulmonary artery catheter (PAC). DESIGN: Prospective study. SETTING: Intensive care unit of university hospital. PARTICIPANTS: Twenty patients for up to 24 hours after cardiac surgery. INTERVENTIONS: Simultaneous and triplicate PAC thermodilution and FV cardiac output measurements at 1 and 3 hours after surgery and the following morning. MEASUREMENTS AND MAIN RESULTS: Fifty-six simultaneous measurement sets were obtained. Mean cardiac output (PAC) ranged between 2.8 and 10.3 L/min and for the FV method between 3.3 and 8.8 L/min. The coefficient of variation for pooled measurements was 7.3% for the PAC and 3.0% for the FV method. For pooled data, the r2 was 0.55 (p < 0.001), with a bias of -0.14, precision of 1.00 L/min, and 95% limits of agreement between -2.14 and 1.87 L/min in a Bland-Altman plot. Also, the FV method tended to overestimate cardiac output when <7 L/min and increased with time, whereas mean arterial pressure increased and PAC cardiac output did not change. Changes in cardiac output correlated (r2 = 0.52, p < 0.001). CONCLUSIONS: The FV arterial pressure waveform analysis method is a clinically applicable method for cardiac output assessment without calibration, after cardiac surgery. It performs well at low cardiac outputs but remains sensitive to changes in vascular tone.     

Cardiac output monitoring: aortic transpulmonary thermodilution and pulse contour analysis agree with standard thermodilution methods in patients undergoing lung transplantation

PURPOSE: The PiCCO System is a relatively new device allowing intermittent cardiac output monitoring by aortic transpulmonary thermodilution technique (Aorta intermittent) and continuous cardiac output monitoring by pulse contour analysis (Aorta continuous). The objective of this study was to assess the level of agreement of Aorta intermittent and Aorta continuous with intermittent (PA intermittent) and continuous cardiac output (PA continuous) measured through a special pulmonary artery catheter (Vigilance System SvO(2)/CCO Monitor) in patients undergoing single- or double-lung transplantation. METHODS: Measurements were obtained in 58 patients: at four time points in patients undergoing single-lung transplantation and at six time points in those undergoing double-lung transplantation. Bland and Altman and correlation analyses were used for statistical evaluation. RESULTS: We found close agreement between the techniques. Mean bias between Aorta intermittent and PA intermittent and between Aorta continuous and PA continuous was 0.18 L x min(-1) (2SD of differences between methods = 1.59 L x min(-1)) and -0.07 L x min(-1) (2SD of differences between methods = 1.46 L x min(-1)) respectively. Mean bias between PA continuous and PA intermittent and Aorta continuous and PA intermittent was 0.15 L x min(-1) (2SD of differences between methods = 1.39 L x min(-1)) and 0.08 L x min(-1) (2SD of differences between methods = 1.43 L x min(-1)). CONCLUSION: Measurements with the aortic transpulmonary thermodilution technique give continuous and intermittent values that agree with the pulmonary thermodilution method which is still the current clinical standard.     

Uncalibrated arterial pulse contour analysis versus continuous thermodilution technique: effects of alterations in arterial waveform

OBJECTIVE: To compare an arterial pressure-derived cardiac output (APCO) (Vigileo software version 1.07; Edwards Lifesciences, Irvine, CA) and a thermodilution cardiac output (CCO) as methods for measuring cardiac output under different pathologic and experimental conditions that induce changes in arterial waveform morphology. DESIGN: A prospective study. SETTING: A university hospital, single institutional. PARTICIPANTS: Fifty-two patients undergoing elective cardiac surgery. INTERVENTIONS: Simultaneous APCO and CCO were compared in low-risk patients undergoing elective coronary artery surgery (without valvular disease) (control, n = 20), patients with aortic stenosis (AS, n = 10), aortic insufficiency (AI, n = 10), and intra-aortic balloon pump (IABP, n = 12). In the control group, additional data were registered before and after median sternotomy and phenylephrine administration. MEASUREMENTS AND MAIN RESULTS: In the control group, Bland-Altman showed a bias of -3% (95% limits of agreement: -59% to +53%) before cardiopulmonary bypass (CPB) and of -1% (95% limits of agreement: -51% to +50%) after CPB. In the AS group, the bias was -5% (95% limits of agreement: -34% to +24%) before CPB and 1% (95% limits of agreement: -28 to +30%) after CPB. In the AI group bias was +32% (95% limits of agreement: -4% to +68%) before CPB and -2% (95% limits of agreement: -35% to +32%) after CPB. Median sternotomy decreased CCO by 10% +/- 10%, whereas it increased APCO by 56% +/- 28%. Phenylephrine administration decreased CCO by 11% +/- 16%, whereas it increased APCO by 55% +/- 34%. CONCLUSIONS: Cardiac output measurement based on uncalibrated pulse contour analysis is able to reflect cardiac output measured with the continuous thermodilution method in patients undergoing uncomplicated coronary artery surgery. However, in situations in which the arterial pressure waveform is changed, agreement between techniques may be altered and data obtained with uncalibrated pulse contour analysis may become less reliable.     

心脏瓣膜手术期间CCO与TCO的一致性变化

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Clinical evaluation of the FloTrac/Vigileo system and two established continuous cardiac output monitoring devices in patients undergoing cardiac surgery

Background: Assessment of cardiac output (CO) by the FloTrac/Vigileo^TM systemmay offer a less invasive means of determining the CO than eitherthe pulmonary artery catheter (PAC) or the PiCCOplus^TM system.The aim of this study was to compare CO measurements made usingthe FloTrac/Vigileo^TM system with upgraded software (FCO, EdwardsLifesciences, Irvine CA, USA), the PiCCOplus^TM system (PCO,Pulsion Medical Systems, Munich, Germany) and continuous COmonitoring using a PAC (CCO; Vigilance^TM monitoring, EdwardsLifesciences, Irvine CA, USA) with intermittent pulmonary arterythermodilution (ICO). The study was conducted in patients undergoingelective cardiac surgery. Methods: Thirty-one patients with preserved left ventricular functionwere enrolled. CCO, FCO, and PCO were recorded in the perioperativeperiod at six predefined time points after achieving stablehaemodynamic conditions; ICO was determined from the mean ofthree bolus injections. Bland–Altman analysis was usedto compare CCO, FCO, and PCO with ICO. Results: Bland–Altman analysis revealed a comparable mean biasand limits of agreement for all tested continuous CO monitoringdevices using ICO as reference method. Agreement for all devicesdecreased in the postoperative period. Conclusion: The performance of the FloTrac/Vigileo^TM system, the PiCCOplus^TM,and the Vigilance^TM CCO monitoring for CO measurement were comparablewhen tested against intermittent thermodilution in patientsundergoing elective cardiac surgery.     

Cardiac output by femoral arterial thermodilution-calibrated pulse contour analysis during liver transplantation: comparison with pulmonary artery thermodilution

PURPOSE: The continuous monitoring of the cardiac output during liver transplantation (LT) is an essential part of the intraoperative management of the patient's hemodynamics. To verify the accuracy of a new method based on femoral artery thermodilution-calibrated pulse contour analysis (PCCO) during LT, we compared the technique with the results of an intermittent pulmonary artery thermodilution method (ICO). METHOD: A prospective study included 314 paired cardiac output measurements at 10 sampling times in 35 patients undergoing LT. After initial calibration of the pulse contour analysis, no further recalibrations were performed. Bland and Altman's statistical method, one-way ANOVA, and one sample t tests were used for the analysis of the data. A P<.05 was considered significant. RESULTS: There was a small bias 0.18 L x min(-1) (6.29% from the ICO) for the whole sample of paired measurements, associated with 95% limits of agreement of +/-4.72 (68.89%) L x min(-1). The additional analysis showed comparable biases and limits of agreement for any single time in the study period. The difference PCCO-ICO showed a negative sign for ICO >10 L x min(-1) (P<.001) and a positive sign for ICO <5 L x min(-1) (P<.001). It was greater during infusion of a vasoactive drug (P<.001). CONCLUSION: The pulse contour analysis was found to be an unsatisfactory substitute for intermittent thermodilution measurement of cardiac output during the LT.     

The impact of intra-aortic balloon pumping on cardiac output determination by pulmonary arterial and transpulmonary thermodilution in pigs

OBJECTIVE: The aim of this study was to evaluate the impact of intra-aortic balloon pumping (IABP) on the comparison of simultaneous measurements of cardiac output via pulmonary arterial and transpulmonary thermodilution (PiCCO; Pulsion Medical Systems, Munich, Germany). DESIGN: Prospective. SETTINGS: University research laboratory. PARTICIPANTS: The data were derived from 9 anesthetized (fentanyl, propofol, flunitrazepam, rocuronium) and ventilated pigs. INTERVENTIONS: A thermodilution catheter was inserted into the pulmonary artery, a PiCCO catheter into the abdominal aorta through the right femoral artery, epicardial atrial pacing wires through a thoracotomy, and a balloon catheter for counterpulsation into the descending thoracic aorta through the left femoral artery. Cardiac output was varied over a wide range by cardiac pacing between 80 and 150/min in steps of 10/min and was measured without and during IABP at an assist frequency of 1:1. MEASUREMENTS AND MAIN RESULTS: A total of 236 paired cardiac output measurements were carried out in a range of cardiac output between 1.4 to 4.9 L/min. A close correlation was found between transpulmonary and pulmonary arterial thermodilution both without and during IABP (r = 0.94 and 0.93, respectively) and a good agreement of both methods (bias of 0.30 and 0.26 L/min, respectively; precision 0.47 and 0.52 L/min, respectively). CONCLUSIONS: Transpulmonary thermodilution is suitable for cardiac output measurement during IABP. Hence, in critically ill patients with cardiac pump failure, blood flow may be determined as accurately with the less-invasive transpulmonary method as with the traditional pulmonary arterial thermodilution one.     

Comparison of continuous cardiac output measurements in patients after cardiac surgery

OBJECTIVE: To investigate in a direct comparison accuracy and precision of continuous cardiac output measurements assessed by continuous pulmonary artery thermodilution technique (TDCCO), continuous pulse contour analysis (PCCO), and noninvasive partial CO(2)-rebreathing technique (NICO) in patients after coronary artery bypass grafting (CABG) during the postoperative period. DESIGN: Prospective, controlled clinical study. SETTING: University hospital. PARTICIPANTS: Twenty-two patients undergoing elective CABG surgery. INTERVENTIONS: Hemodynamic measurements were performed after admission to the ICU and in sequence every 2 hours during the subsequent 6-hour period. Simultaneously, cardiac output (CO) was measured using a TDCCO, PCCO, and NICO. After the continuous cardiac output measurements were read, bolus thermodilution-derived cardiac output was obtained from thermodilution curves detected in the pulmonary artery (TDBCO(pa)). Four intermittent consecutive boli consisting of 10 mL of ice-cold saline were randomly injected over the ventilatory cycle. MEASUREMENTS AND MAIN RESULTS: The comparison between the continuous cardiac output measurement methods TDCCO versus PCCO showed a bias of -0.12 L/min, between TDCCO versus NICO -0.17 L/min, and between PCCO versus NICO -0.44 L/min. The comparison to the reference technique between TDBCO(pa) versus TDCCO revealed a bias of -0.28 L/min, between TDBCO(pa) versus PCCO -0.40 L/min, and between TDBCO(pa) versus NICO -0.64 L/min. CONCLUSIONS: The results of this clinical investigation show agreement between TDCCO and PCCO to satisfy clinical requirements in a setting of postoperative patients after cardiac surgery. In contrast, the NICO monitor is of very limited use in these patients.     

Measurement of cardiac output before and after cardiopulmonary bypass: Comparison among aortic transit-time ultrasound, thermodilution, and noninvasive partial CO2 rebreathing

OBJECTIVES: A noninvasive continuous cardiac output system (NICO) has been developed recently. NICO uses a ratio of the change in the end-tidal carbon dioxide partial pressure and carbon dioxide elimination in response to a brief period of partial rebreathing to measure CO. The aim of this study was to compare the agreement among NICO, bolus (TDCO), and continuous thermodilution (CCO), with transit-time flowmetry of the ascending aorta using an ultrasonic flow probe (UFP) before and after cardiopulmonary bypass (CPB). DESIGN: Prospective, observational human study. SETTING: Veterans Affairs Medical Center Hospital. PARTICIPANTS: Sixty-eight patients. METHODS: Matched sets of CO measurements between NICO, TDCO, CCO, and UFP were collected in 68 patients undergoing elective CABG at specific time periods before and after separation from CPB. After anesthetic induction, all patients had an NICO sensor attached between the endotracheal tube and the breathing circuit, a PAC floated into the pulmonary artery for TDCO and CCO monitoring, and a UFP positioned on the ascending aorta and used for the reference CO. Bland-Altman analysis was used to compare the agreement among the different methods. MEASUREMENTS AND MAIN RESULTS: Bland-Altman analysis of CO measurements before CPB yielded a bias, precision, and percent error of 0.04 L/min +/- 1.07 L/min (44.8%) for NICO, 0.18 L/min +/- 1.01 L/min (41.7%) for TDCO, and 0.29 L/min +/- 1.40 L/min (57.5%) for CCO compared with simultaneous UFP CO measurements, respectively. After separation from CPB (average 29 mins), bias, precision, and percent error were -0.46 L/min +/- 1.06 L/min (37.3%) for NICO, 0.35 L/min +/- 1.39 L/min (46.1%) for TDCO, and 0.36 L/min +/- 1.96 L/min (64.7%) for CCO compared with UFP CO measurements, respectively. CONCLUSIONS: Before initiation of CPB, the accuracy for all 3 techniques was similar. After separation from CPB, the tendency was for NICO to underestimate CO and for TDCO and CCO to overestimate it. NICO offers an alternative to invasive CO measurement.     

Transpulmonary thermodilution cardiac output measurement using the axillary artery in critically ill patients

STUDY OBJECTIVE: To compare cardiac output (CO) as measured by the arterial thermodilution technique using only a central venous catheter and an arterial catheter inserted into the axillary artery, with conventional CO measurement with thermodilution using a pulmonary artery (PA) catheter (PAC). DESIGN: Prospective clinical study in which each patient served as his/her own control. SETTING: General ICU of a large tertiary-care teaching hospital. PATIENTS: 22 patients who required invasive hemodynamic monitoring in the ICU. INTERVENTIONS AND MEASUREMENTS: CO measurements made using the PAC (COpa) were compared to bolus arterial thermodilution measurements (COax). The significance of acute changes in the continuous CO measurements during acute hemodynamic episodes was observed. MAIN RESULTS : The correlation between the two techniques (COpa and COax) was R(2) = 0.82. There was a tendency for 5% overestimation of COpa by the COax. The SEM% (SEM/average CO) for COax and COpa was 2.6% and 3.2%, respectively. The bias between measurements was 0.27 +/- 0.67 L/min, and the limits of agreement (mean difference +/- 2 SD) from minus 1.07 L/min to 1.63 L/min. CONCLUSIONS: In critically ill patients, in whom the measurement of CO is required, arterial thermodilution, using a central vein and the axillary artery is accurate and reproducible.     

Continuous cardiac output measurements do not agree with conventional bolus thermodilution cardiac output determination

PURPOSE: To evaluate the performance of two different continuous cardiac output monitoring systems based on the thermodilution principle in critically ill patients. METHODS: Nineteen cardiac surgical patients were randomly assigned to continuous cardiac output monitoring using one of the two systems under study (group I, IntelliCath(TM) catheter, n=9; group II, Opti-Q(TM) catheter, n=10). Each patient was studied over a period of three hours. Conventional bolus thermodilution cardiac output measurements were carried out every 15 min leading to 13 measurements in each patient. The continuous cardiac output values were compared with the bolus thermodilution measurements. Bias (mean difference between continuous and bolus thermodilution) and precision (SD of differences) were calculated as a measure of agreement between the respective continuous method and conventional bolus thermodilution. RESULTS: The range of measured cardiac outputs was 3.8-15.4 L*min(-1) (IntelliCath(TM)) and 3.5-8.3 L*min(-1) (OptiQ(TM)). Bias and precision was 0.06 +/- 0.76 L*min(-1) (IntelliCath(TM)) and -0.04 +/- 0.74 L*min(-1) (OptiQ(TM)), respectively. There was no difference in bias between the two systems (P=0.38). +/- 2 SD of the differences (i.e., 95% of the differences) did not fall within the predetermined limits of agreement of +/- 0.5 L*min(-1). CONCLUSIONS: There was no difference between the two systems regarding the agreement with conventional bolus thermodilution as the standard. A discrepancy between bolus and continuous thermodilution cardiac output measurement techniques above the clinically acceptable limits suggest that they are not interchangeable.     

连续温度稀释法测定心排血量的临床应用及评价

目的与方法：２０例心脏手术病人采用连续温度稀释法进行转术期ＣＯ和Ｓ＾－ｖＯ２测定。结果：（１）ＣＣＯ从诱导后至ＣＰＢ启动明显降低,ＣＰＢ后升高,关胸后下降,术后２ｈ降至最低,随后缓慢升高,４８ｈ后显著升高;（２）ＣＣＯ和ＩＣＯ高度相关,ｒ＝０．９３２（ｎ＝４０）;（３）机器Ｓ＾－ｖＯ２和血气Ｓ＾－ｖＯ２高度相关,ｒ＝０．９５４（ｎ＝３１）。结论：（１）本法测定ＣＯ和Ｓ＾－ｖＯ２标准可靠;（２）动态     

Comparaison du débit cardiaque mesuré en continu par thermodilution et celui calculé selon le principe de Fick

Recently, a thermodilution technique for continuous measurement of cardiac output was introduced. The aim of this study was to evaluate the accuracy of continuous cardiac output measurement using the thermodilution technique (CCO) and to assess the correspondence between CCO and cardiac output obtained with the Fick's principle (Fick-CO). Nine patients were studied in the postoperative period after cardiac surgery. A new pulmonary artery catheter modified by attachment of a thermal filament (Intellicath™, Model PA3-H-8Fr) was inserted and connected to a continuous cardiac output computer (Vigilance™ Monitor). Oxygen consumption was continuously measured using the gas exchange method (Deltatrac Metabolic Monitor™). Fick-CO was calculated according to the Fick's principle. The study in each patient consisted of 6 serial determinations of both CCO and Fick-CO at 10 min intervals. For 54 pairs of measurements, the mean difference (Fick-CO - CCO) was 0,6 L · min⁻¹. The limits of agreement were — 0,6 to 1,8 L · min⁻¹ respectively. The relative error was 6 % for CCO and 10 % for Fick-CO. It is concluded that CCO and Fick-CO cannot be considered as being interchangeable. However, the accuracy of CCO is acceptable. The technique does not require any user calibration and eliminates the need of bolus injections. Further studies are necessary to determine the benefits of this new technique in the various clinical situations.     

Cardiac output monitoring using a brachial arterial catheter during off-pump coronary artery bypass grafting

OBJECTIVE: To investigate the accuracy of cardiac output measurements by transpulmonary thermodilution and pulse contour analysis using a brachial arterial catheter. STUDY DESIGN: Criterion standard study. SETTING: University hospital, single institution. POPULATION: Twenty-three adult patients undergoing off-pump coronary artery bypass grafting. MEASUREMENTS AND MAIN RESULTS: Cardiac output was measured with a thermistor-tipped brachial arterial catheter using pulse contour analysis (COpc) and transpulmonary thermodilution (COba), which serves to calibrate COpc in the system tested. Both methods were compared separately with standard pulmonary artery thermodilution (COpa). COba was closely correlated with COpa (r = 0.93, p < 0.001). Bland-Altman analysis showed a bias of 0.91 L/min with limits of agreement of +/-0.98 L/min. COpc was also closely correlated (r = 0.80, p < 0.001) with COpa and was found to have a bias of 1.08 L/min with limits of agreement of +/-1.50 L/min. During the surgical procedure, changes in COpa from baseline were closely correlated with changes in COba (r = 0.90, p < 0.01) and COpc (r = 0.81, p < 0.01). CONCLUSIONS: The brachial arterial access allows a reliable assessment of cardiac output by transpulmonary thermodilution and pulse contour analysis in patients undergoing off-pump coronary artery bypass grafting.     

Performance of Noninvasive Partial CO2 Rebreathing Cardiac Output and Continuous Thermodilution Cardiac Output in Patients Undergoing Aortic Reconstruction Surgery

Background: In the partial CO2 rebreathing method, monitored changes in CO2 elimination and end-tidal CO2 in response to a brief rebreathing period are used to estimate cardiac output. However, dynamic changes in CO2 production during ischemia and reperfusion may affect the accuracy of these estimates. This study was designed to compare measurements of cardiac output as produced by the partial CO2 rebreathing (NICO), bolus (BCO), and continuous thermodilution (CCO) methods of monitoring cardiac output.

Methods: Cardiac output was continuously monitored using both NICO and CCO in 28 patients undergoing aortic reconstruction. BCO measurements were taken at the following intervals when hemodynamic stability was achieved: (1) after anesthetic induction; (2) during aortic cross-clamp; (3) at reperfusion of the iliac artery; and, (4) during peritoneal closure.

Results: The bias and precision (1 SD) derived from all the measurements between NICO and BCO was -0.58 +/- 0.9 l/min, whereas for CCO and BCO it was 0.38 +/- 1.17 l/min. The bias between NICO and BCO was small after anesthetic induction and during cross-clamp, but increased following reperfusion. The bias between CCO and BCO was relatively small until reperfusion but increased significantly at peritoneal closure.     

Comparison of esophageal Doppler, pulse contour analysis, and real-time pulmonary artery thermodilution for the continuous measurement of cardiac output

OBJECTIVE: Continuous measurement of cardiac output (CCO) is of great importance in the critically ill. However, pulmonary artery thermodilution has been questioned for possible complications associated with right heart catheterization. Furthermore, measurements are delayed in the continuous mode during rapid hemodynamic changes. A new pulmonary artery catheter CCO device (Aortech, Bellshill, Scotland) enabling real-time update of cardiac output was compared with 2 different, less-invasive methods of CCO determination, esophageal Doppler and pulse contour analysis. DESIGN: Prospective, observational study. SETTING: University hospital, single institution. PARTICIPANTS: Patients scheduled for elective coronary artery bypass grafting (CABG). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: CCO measurements were analyzed using a Bland-Altman plot. Bias between CCO and pulse contour cardiac output (PCCO), and Doppler-derived cardiac output (UCCO) was (mean +/- 1 SD) -0.71 +/- 1 L/min versus -0.15 +/- 1.09 L/min, and between UCCO and PCCO -0.58 +/- 1.06 L/min. Bias was not significantly different among methods, nor were comparative values before and after cardiopulmonary bypass (p > 0.05). CONCLUSIONS: Agreement between the CCO method and both less-invasive measurements was clinically acceptable. There were no adverse events associated with the use of either device.