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At least 19 recordsLinked to original sources
PubMed1995

Continuous thermodilution cardiac output: agreement with Fick and bolus thermodilution methods.

OBJECTIVE: Cardiac outputs were determined with continuous thermodilution, bolus thermodilution, and the Fick method during pharmacologically varied hemodynamics. DESIGN: Prospective comparison of techniques. SETTING: University animal laboratory. PARTICIPANTS: Swine. INTERVENTIONS: Swine were anesthetized, tracheally intubated, and instrumented to measure continuous (QTDC) and bolus (QTDB) thermodilution cardiac outputs and sample arterial and mixed venous blood. Continuous thermodilution of blood was facilitated by computer modulation of a thermal filament wrapped around the portion of the pulmonary artery catheter residing in the right atrium and ventricle. QTDC was computed from the thermodilution curve monitored by the thermistor. Bolus thermodilution was performed in triplicate by injecting 10 mL of 5% dextrose in water (0 to 4 degrees C). Oxygen consumption (VO2) was calculated as the averaged minute rate of disappearance of spirometer oxygen over a 6-minute steady state. Cardiac output was determined with the direct Fick method (QF) by dividing VO2 by the difference in arterial and mixed venous oxygen content. Basal QTDC was increased and decreased with an intravenous infusion of dobutamine or labetalol, respectively. Data are summarized as mean +/- SD or 95% confidence interval (CI 95%). Agreement between methods of determining cardiac output was assessed by calculating bias, percent bias, and percent coefficient of determination (100 r2). MEASUREMENTS AND MAIN RESULTS: Eighteen swine (38.9 +/- 1.2 kg) exhibited a range of QTDC from 2.2 to 14.8 L/min. Mean measurement variance of VO2, CaO2, CvO2, and QTDB was 1.5%, 1.5%, 2.0%, and 11.8%, respectively. Mean bias, percent bias, and 100 r2 was 0.004 +/- 1.05 L/min (CI 95%: 0.18 to 0.19 L/min), -0.37 +/- 13.8% (CI 95%: -2.75 to 2.01), and 89% between QTDC and QF, respectively. Bias, percent bias, and 100 r2 was 0.05 +/- 1.09 L/min (CI 95%: -0.14 to 0.23 L/min, 1.21 +/- 13.06% (CI 95%: -1.03 to 3.46%), and 91% between QTDC and QTDB, respectively. Bias, percent bias, and 100 r2 (Fig 6) was -0.04 +/- 0.69 L/min (CI 95%: -0.16 to -.08 L/min), -1.23 +/- 9.17% (CI 95%: -2.8 to 0.35%), and 94% between QTDB and QF, respectively. CONCLUSION: Automatic cardiac output computed with continuous thermodilution appears accurate and reliable. Also, good agreement was confirmed between cardiac output derived by continuous and bolus thermodilution methods and bolus thermodilution and Fick methods.

Adrenergic Agonists↗
PubMed2003

Cardiac output measurement after coronary artery bypass grafting using bolus thermodilution, continuous thermodilution, and whole-body impedance cardiography.

OBJECTIVE: To test the feasibility of continuous cardiac output (CO) monitoring with whole-body impedance cardiography after coronary artery bypass grafting and to compare the values obtained with those measured using the bolus and continuous thermodilution methods. DESIGN: A prospective study. SETTING: Intensive care unit in a university hospital. PATIENTS: Twenty patients after coronary artery bypass grafting. INTERVENTIONS: CO was measured intermittently using the bolus thermodilution method, and continuously using the continuous thermodilution method, and whole-body impedance cardiography immediately after transfer to the intensive care unit. MEASUREMENTS AND MAIN RESULTS: Bolus thermodilution CO was measured in triplicate at up to 14 time points overnight. Continuous thermodilution CO and whole-body impedance cardiography CO values were recorded simultaneously. During the study period, the bias in CO values between bolus thermodilution and whole-body impedance cardiography ranged from 0.07 to 1.05 L/min and the precision (standard deviation of differences) ranged from 0.82 to 1.31 L/min. The bias between the bolus and continuous thermodilution methods ranged from 0.06 to 0.58 L/min and the precision from 0.43 to 1.02 L/min. Pulmonary artery temperature and CO level were the major determinants of the bias and precision in both comparisons. CONCLUSIONS: Agreement between whole-body impedance cardiography and bolus thermodilution is slightly inferior to that between the bolus and continuous thermodilution methods but not to the extent that it hampers the use of whole-body impedance cardiography for the continuous monitoring of CO after coronary artery bypass surgery.

Bias↗
PubMed2004

Measurement of cardiac output by transpulmonary arterial thermodilution using a long radial artery catheter. A comparison with intermittent pulmonary artery thermodilution.

Cardiac output can be measured accurately by transpulmonary arterial thermodilution using the PiCCO (Pulsion Medical Systems, Munich, Germany) system with a femoral artery catheter. We have investigated the accuracy of a new 50 cm 4 French gauge radial artery catheter and the ability to use the system with a shorter radial catheter. We studied 18 patients who had undergone coronary artery surgery and made three simultaneous measurements of cardiac output by arterial thermodilution and with a pulmonary artery catheter. The radial catheter was withdrawn in 5 cm increments and the measurements were repeated. We found close agreement between arterial thermodilution and pulmonary artery thermodilution with a mean (SD) bias of 0.38 (0.77) l x min(-1). Arterial thermodilution became unreliable once the catheter had been withdrawn by more than 5 cm. We conclude that cardiac output measurement with arterial thermodilution with a radial catheter is interchangeable with that derived from a pulmonary artery catheter, and that a centrally sited arterial catheter is required for accurate determination of cardiac output by transpulmonary arterial thermodilution.

Aged↗
PubMed2003

Comparison between cardiac output measured by the pulmonary arterial thermodilution technique and that measured by the femoral arterial thermodilution technique in a pediatric animal model.

This study compares the correlation between two methods for the determination of cardiac output-the pulmonary arterial thermodilution technique using the Swan-Ganz catheter and the femoral arterial thermodilution technique using a pulse contour analysis computer (PiCCO) catheter. We performed a prospective animal study using 16 immature Maryland pigs weighing 9 to 16 kg. A 5.5- or 7.5-Fr Swan-Ganz catheter was introduced into the femoral or jugular vein, and a 4- or 5-Fr arterial PiCCO catheter was introduced into the femoral artery. In each animal, we made measurements of cardiac output at 30-minute intervals, simultaneously by pulmonary arterial thermodilution and femoral arterial thermodilution, before, during, and after hemodiafiltration carried out via different venous catheters, recording a total of 78 measurements. The mean Swan-Ganz cardiac output was 2.22 +/- 0.94 L/min, and mean PiCCO cardiac output was 1.94 +/- 0.80 L/min (no significant difference). The mean difference (bias) of differences (limits of agreement) was 0.2812. The differences between the methods increased with higher cardiac output, but the percentage differences in relation to cardiac output remained stable. Good correlation was found between the two methods: single-measure intraclass correlation was 0.8892 (95% confidence interval, 0.54-0.95). There were no differences between the 5.5- and 7.5-FR Swan-Ganz catheters or between the 4- and 5-Fr PiCCO catheters. Femoral arterial thermodilution cardiac output measurements correlated well with pulmonary arterial thermodilution cardiac output measurements in a pediatric animal model.

Animals↗
PubMed2004

Pulmonary artery thermodilution cardiac output vs. transpulmonary thermodilution cardiac output in two patients with intrathoracic pathology.

In two adult patients, one with a severe hemorrhage and one with a partial anomalous pulmonary vein, cardiac output (CO) measurements were performed simultaneously by means of the bolus transpulmonary thermodilution technique (COao) and continuous pulmonary artery thermodilution method (CCOpa). In both cases, the methods revealed clinically significant different cardiac output values based upon the site of measurement and the underlying pathology. The assessment of cardiac output (CO) is considered an important part of cardiovascular monitoring of the critically ill patient. Cardiac output is most commonly determined intermittently by the bolus thermodilution technique with a pulmonary artery catheter (COpa). As continuous monitoring of CO is preferable to this intermittent technique, two major techniques have been proposed. Firstly, a nearly continuous thermodilution method (CCOpa) using a heating filament mounted on a pulmonary artery catheter (Baxter Edwards Laboratories, Irvine, CA), with a clinically acceptable accuracy compared with the intermittent bolus technique. Based on these results we assumed CCOpa equivalent to real CO during hemodynamically stable conditions, and secondly, a continuous cardiac output system based on pulse contour analysis (PCCO), such as the PiCCO system (Pulsion Medical System, Munchen, Germany). To calibrate this device, which uses a derivation of the algorithm of Wesseling and colleagues, an independently obtained value of CO by the transpulmonary thermodilution method (COao) is used. Clinical validation studies in patients without underlying intrathoracic pathology, comparing transpulmonary COao with the pulmonary technique (COpa), mostly yielded good agreement.

Aged↗
PubMed2006

Agreement between PiCCO pulse-contour analysis, pulmonal artery thermodilution and transthoracic thermodilution during off-pump coronary artery by-pass surgery.

BACKGROUND: Haemodynamic instability during off-pump coronary artery bypass surgery (OPCAB) may appear rapidly, and continuous monitoring of the cardiac index (CI) during the procedure is advisable. With the PiCCO monitor, CI can be measured continuously and almost real time with pulse-contour analysis and intermittently with transthoracic thermodilution. The agreement between pulmonal artery thermodilution CI (Tpa), transthoracic thermodilution CI (Tpc) and pulse-contour CI (PCCI) during OPCAB surgery has not been evaluated sufficiently. METHODS: In 30 patients scheduled for OPCAB surgery, a pulmonary artery catheter and a PiCCO catheter were inserted. At different time points during surgery, Tpa, Tpc and PCCI were compared. Measurements were performed after induction of anesthesia (T1), after pericardiothomy (T2), after grafting on the anterior (T3), posterior (T4) and lateral (T5) walls and after chest closure (T6). The PCCI was recalibrated at time point T2-T6. RESULTS: Mean difference and the limits of agreements (percentage error) between Tpa and Tpc were: -0.14 +/- 0.60 (22.0%) l/min/m2, between Tpa and PCCI: -0.07 +/- 0.92 (33.5%) l/min/m2 and between Tpc and PCCI: 0.10 +/- 1.00 (35.5%) l/min/m2. For changes in CI from one time point to the next (DeltaCI), the limits of agreements between DeltaCI Tpa and DeltaCI Tpc were 0.04 +/- 0.90 l/min/m2, between DeltaCI Tpa and DeltaCI PCCI: -0.02 +/- 1.22 l/min/m2 and between DeltaCI Tpc and DeltaCI PCCI: -0.08 +/- 1.32 l/min/m2. CONCLUSION: In OPCAB surgery, limits of agreement comparing thermodilution methods were smaller than comparing PCCI with thermodilution. Recalibration of PCCI is therefore advisable.

Adult↗
PubMed1999

Continuous cardiac output by femoral arterial thermodilution calibrated pulse contour analysis: comparison with pulmonary arterial thermodilution.

OBJECTIVE: To compare two thermodilution methods for the determination of cardiac output (CO)-thermodilution in the pulmonary artery (COpa) and thermodilution in the femoral artery (COa)-with each other and with CO determined by continuous pulse contour analysis (COpc) in terms of reproducibility, bias, and correlation among the different methods. Good agreement between the methods would indicate the potential of pulse contour analysis to monitor CO continuously and at reduced invasiveness. DESIGN: Prospective criterion standard study. SETTING: Cardiac surgical intensive care unit in a university hospital. PATIENTS: Twenty-four postoperative cardiac surgery patients. INTERVENTIONS: Without interfering with standard hospital cardiac recovery procedures, changes in CO as a result of the postsurgical course, administration of vasoactive substances, and/or fluid administration were recorded. CO was first recorded after a 1-hr stabilization period in the intensive care unit and hourly thereafter for 6 hrs, and by subsequent determinations at 9, 12, and 24 hrs. MEASUREMENTS AND MAIN RESULTS: There were 216 simultaneous determinations of COpa, COa, and COpc. COpc was initially calibrated using COa, and no further recalibration of COpc was performed. COpa ranged from 3.0 to 11.8 L/min, and systemic vascular resistance ranged from 252 to 2434 dyne x sec/cm5. The mean difference (bias) +/-2 SD of differences (limits of agreement) was -0.29+/-1.31 L/min for COpa vs. COa, 0.07+/-1.4 L/min for COpc vs. COpa, and -0.22+/-1.58 L/min for COpc vs. COa. In all but four patients COpc correlated with COa after the initial calibration. Correlation and precision of COpc vs. COa was stable for 24 hrs. CONCLUSIONS: Femoral artery pulse contour CO correlates well with both COpa and COa even during substantial variations in vascular tone and hemodynamics. Additionally, CO determined by arterial thermodilution correlates well with COpa. Thus, COa can be used to calibrate COpc.

Adult↗
PubMed1978

Some aspects of the clinical use of thermodilution in measuring cardiac output. With particular reference to the Swan-Ganz thermodilution catheters.

Accuracy of the thermodilution method in measuring cardiac output was tested in a model and against Fick in ten patients. Reproducibility was determined from 573 thermodilution curves. The influence of catheter position, catheter irrigation, post-injection aspiration, and the substitution of rectal temperature for central blood temperature was also studied. The thermodilution method showed very good correlation to direct measurements in the model (corr. coeff. 1.00) and the Fick method in patients (corr. coeff. 0.97). Mean standard deviation for cardiac outputs calculated from individual thermodilution curves was 5%. Post-injection aspiration and variation in catheter tip location did not influence the results. Catheter irrigation during recordings and the use of rectal temperature for TB resulted in underestimation of cardiac output.

Calibration↗
PubMedDate not supplied

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.

Aorta↗
PubMed2003

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.

Analysis of Variance↗
PubMed1996

Analysis of the accuracy of continuous thermodilution cardiac output measurement. Comparison with intermittent thermodilution and Fick cardiac output measurement.

OBJECTIVE: To evaluate the accuracy of cardiac output measurement obtained by a new continuous thermodilution cardiac output (CCO) pulmonary artery catheter compared to intermittent thermodilution (TCO) and the direct Fick method. DESIGN: Prospective open trial. SETTING: University hospital, intensive care unit. PATIENTS: 23 patients (15 surgical, 8 non-surgical) were monitored with the Intellicath pulmonary catheter. Cardiac output was evaluated by the three methods every 4 to 6h as long as the pulmonary artery catheter was necessary (8-96 h). RESULTS: The correlation coefficient between CCO and TCO was 0.92, no systematic bias was observed, and the relative error increased from 13.9% for a cardiac output of 21/min to 23.7% for an output of 101/min. When comparing CCO and Fick, the correlation coefficient was 0.89, no bias was detected, and the relative error increased from 20.4% for outputs of 21/min to 27.2% for outputs of 101/min. CONCLUSIONS: CCO provides clinically acceptable measurements. At high cardiac outputs, the difference with other methods increases and the results must be cautiously interpreted.

Bias↗
PubMed2003

Validity and reliability of cardiac output by arterial thermodilution and arterial pulse contour analysis compared with pulmonary artery thermodilution in intensive care unit.

Cardiac output measurement has a significat role in the critical care setting. The standard of measurement currently is via pulmonary arterial catheter but it has some technical difficulties and serious complications. The authors performed a new method of measurement that used a catheter in a femoral artery. The results of both methods performed simultaneously in 10 surgical intensive care patients every 2 hours for 24 hours were compared. There was high correlation between the two methods, r = 0.97. The average difference of the cardiac output values was 0.46 l/min with standard deviation 0.56 l/min.

Adult↗
PubMed1995

[The effect of an intracardiac left-right shunt on thermodilution measurements of cardiac output. An extracorporeal circulation model].

Thermodilution measurements of cardiac output (CO) by means of Swan-Ganz catheters, in a strict sense, represent pulmonary arterial blood flow (PBF). In principle, this is also true in the presence of intracardiac left-to-right shunts due to atrial or ventricular septal defects. However, early recirculation of indicator may give rise to serious methodological problems in these cases. We sought to determine the influence of intracardiac left-to-right shunts on different devices for thermodilution measurements of CO using an extra-corporeal flow model. METHODS. Blood flow was regulated by means of a centrifugal pump that at the same time enabled complete mixing of the indicator after injection (Fig. 1). Pulmonary and systemic parts of the circulation were simulated using two membrane oxygenators and a systemic-venous reservoir to delay systemic recirculation of indicator. Control measurements of PBF (Qp) and systemic (Qs) blood flow were performed by calibrated electromagnetic flow-meters (EMF). Blood temperature was kept constant using a heat exchanger without altering the indicator mass balance in the pulmonary circulation. Left-to-right shunt was varied at different systemic flow levels applying a Qp:Qs ratio ranging from 1:1 to 2.5:1. Thermodilution measurements of PBF were performed using two different thermodilution catheters that were connected to commercially available CO computers. Additionally, thermodilution curves were recorded on a microcomputer and analysed with custom-made software that enabled iterative regression analyses of the initial decay to determine that part of the downslope that best fits a mono-exponentially declining function. Extrapolation of the thermodilution curve was then based on the respective curve segment in order to eliminate indicator recirculation due to shunt flow. RESULTS. At moderate left-to-right shunts (Qp:Qs < 2:1) all thermodilution measurements showed close agreement with control measurements. At higher shunt flows (Qp:Qs > or = 2:1), however, conventional extrapolation procedures of CO computers considerably underestimated PBF (Fig. 2). This was particularly true when a slow-response thermistor catheter was used (Fig. 3). The reason for this underestimation of Qp was an overestimation of the area under curve because of inadequate mathematical elimination of indicator recirculation by standard truncation methods (Fig. 4). However, curve-alert messages of the commercially implemented software did not occur. A high level of agreement could be consistently obtained using a fast-response thermistor together with individual definition of extrapolation limits according to logarithmic regression analyses. DISCUSSION AND CONCLUSION. Under varying levels of left-to-right shunt, both the response time of thermodilution catheters and the algorithms for calculation of flow considerably influenced the validity of thermodilution measurements of PBF in an extracorporeal flow model. The use of computer-based regression analyses to define the optimal segment for monoexponential extrapolation could effectively eliminate indicator recirculation from the initial portion of the declining thermodilution curve and showed the closest agreement with EMF measurements of Qp. The quality of thermodilution curves with respect to recirculation peaks in the flow model was slightly better than in clinical routine. Nevertheless, the clinical applicability of the modified extrapolation algorithm could be illustrated during pulmonary thermodilution measurements in an exemplary patient with a ventricular septal defect (Fig. 5). PBF at extremely high shunt ratios, however, cannot be assessed by monoexponential extrapolation in principle (Fig. 6). Insufficient elimination of indicator recirculation resulted in flow values that closely resembled systemic rather than PBF. This finding is in accordance with a mathematical analysis of the underlying Steward-Hamilton equation if an infinite number of recirculations would be

Cardiac Output↗
PubMed1995

Evaluation of a new continuous thermodilution cardiac output monitor in critically ill patients: a prospective criterion standard study.

OBJECTIVE: To evaluate the accuracy of a new continuous cardiac output monitor (one based on the thermodilution principle) in critically ill patients. DESIGN: Criterion standard study. SETTING: Multidisciplinary intensive care unit in a university hospital. PATIENTS: Fourteen critically ill patients, with different diseases, requiring pulmonary artery catheterization. INTERVENTIONS: In two patients with a left ventricular assist system, a defined, sudden 1 L/min change in cardiac output was carried through to evaluate the in vivo response time of the continuous cardiac output monitoring system. In the remaining 12 patients, cardiac output was altered by varying the dose of catecholamines, by volume loading, or by varying the level of sedation. In four patients, a rapid infusion of cold saline was given through a central venous catheter to test the performance of the system under these conditions. MEASUREMENTS AND MAIN RESULTS: Cardiac output was monitored continuously. A total of 163 (13 to 18 per patient) bolus determinations of cardiac output were performed, using the conventional thermodilution technique and simultaneously using the indocyanine green dye dilution technique. The range of cardiac output was 3.8 to 15.6 L/min. The results of the continuous thermodilution method were compared with the results of the bolus thermodilution and the dye dilution methods, respectively. The mean difference (bias) +/- SD of differences (precision) was 0.35 +/- 1.01 L/min for continuous vs. bolus thermodilution and 0.34 +/- 1.01 L/min for continuous thermodilution vs. indocyanine green dye dilution. Linear regression (correlation) analyses were y = 0.95x + 0.76 (r2 = .91) for continuous and bolus thermodilution and y = 0.93x + 0.87 (r2 = .91) for continuous thermodilution and dye dilution. The 75% in vivo response time was 10.5 mins. The infusion of cold isotonic saline led to erroneous continuous cardiac output values. When the conventional bolus thermodilution and dye dilution techniques were compared, mean difference was -0.01 +/- 0.54 L/min and the results of linear regression analyses were y = 0.97x + 0.22 (r2 = .97). CONCLUSIONS: Continuous cardiac output measurement using the thermodilution technique is reasonably accurate and is reliable and applicable in routine clinical practice, and therefore may add to patient safety. However, the response time is too slow for the immediate detection of acute changes in cardiac output. Some clinical conditions such as the rapid infusion of cold solutions can interfere with the continuous cardiac output measurement. Conventional bolus thermodilution and indocyanine green dye dilution methods showed good agreement and can be used interchangeably.

Adult↗
PubMed1990

Right ventricular function computed by thermodilution and ventriculography. A comparison of methods.

Right ventricular ejection fractions have been difficult to estimate clinically. It has been recently suggested that right ventricular ejection fractions can be calculated by thermodilution techniques with a fast-response thermistor and computer. These studies were performed to compare right ventricular ejection fractions obtained from thermodilution and biplane ventriculography. Ten pigs were instrumented with a right ventricular angiographic, thermodilution, and systemic arterial catheter. Right ventricular ejection fractions were determined by thermodilution and ventriculography at four times: (1) baseline, (2) infusion of isoporterenol (5 micrograms/min), (3) 50% of baseline mean arterial pressure produced by hemorrhage, and (4) reinfusion of isoproterenol during hypovolemia. A significant correlation existed between thermodilution and ventriculographic ejection fractions (r = 0.74, p = 0.004). However, during hypovolemia, thermodilution measurements of right ventricular ejection fraction were significantly lower than ventriculographic measurements (p less than 0.05). To determine if the position of the thermistor had a significant effect on thermodilution computations, right ventricular ejection fractions were computed by thermodilution in 10 additional pigs by means of a jugular and femoral insertion, as well as by ventriculography in each pig. Femoral insertion resulted in a greater distance from pulmonic valve to thermistor as compared with jugular placement (p = 0.005). Right ventricular ejection fractions obtained from femoral placement were significantly less than those obtained by jugular insertion (p = 0.008) and ventriculography (p = 0.006). There was no significant difference between jugular and ventriculographic ejection fractions (p = 0.35). Results from these studies demonstrates that thermodilution right ventricular ejection fraction measurements are strongly correlated to ventriculographic methods over a wide hemodynamic range and that improved accuracy is obtained when the pulmonic valve to thermistor distance is minimized. Thus thermodilution may provide a simple and repeatable means to monitor right ventricular function in the critical care setting.

Animals↗