Pulmonary Thermodilution Research Articles

Cardiac output monitoring with pulmonary versus trans-cardiopulmonary thermodilution in left ventricular assist devices: Interchangeable methods?

Cardiac output (CO) measurement is mandatory in patients with left ventricular assist devices (LVADs). Thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO in these patients, however it is associated with several complications. Therefore, the agreement between PAC and new, minimally invasive monitoring methods in LVAD needs to be further investigated. The aim of this study was to assess the accuracy and reliability of transpulmonary thermodilution with a PiCCO2 monitor compared with pulmonary artery thermodilution with PAC in a LVAD. Continuous-flow LVADs were implanted in six mini-pigs to assist the left ventricle. We studied two methods of measuring CO—intermittent transpulmonary thermodilution (COTPTD) by PiCCO2 and intermittent pulmonary artery thermodilution by CAP, standard technique (COPTD)—obtained in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading) and hypovolemia (shock hemorrhage). A total of 72 paired measurements were analysed. At the basal moment, COTPTD and COPTD were closely correlated (r 2 = 0.89), with a mean bias of −0.085 ± 0.245 L/min and percentage error of 16%. After 15 min of partial support LVAD, COTPTD and COPTD were closely correlated (r 2 = 0.79), with a mean bias of −0.040 ± 0.417 L/min and percentage error of 26%. After inducing hypervolemia, COTPTD and COPTD were closely correlated (r 2 = 0.78), with a mean bias of −0.093 ± 0.339 L/min and percentage error of 13%. After inducing hypovolemia, COTPTD and COPTD were closely correlated (r 2 = 0.76), with a mean bias of −0.045 ± 0.281 L/min and percentage error of 28%. This study demonstrates a good agreement between transpulmonary thermodilution by PiCCO monitor and pulmonary thermodilution by PAC in the intermittent measurement of CO in a porcine model with a continuous-flow LVAD.

New Advances in Monitoring Cardiac Output in Circulatory Mechanical Assistance Devices. A Validation Study in a Porcine Model.

Cardiac output (CO) measurement by continuous pulmonary artery thermodilution (COCTD) has been studied in patients with pulsatile-flow LVADs (left ventricular assist devices), confirming the clinical utility. However, it has not been validated in patients with continuous-flow LVADs. Therefore, the aim of this study was to assess the validity of COCTD in continuous-flow LVADs. Continuous-flow LVADs were implanted in six miniature pigs for partial assistance of the left ventricle. Both methods of measuring CO—measurement by COCTD and intermittent pulmonary artery thermodilution, standard technique (COITD)—were used in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading), and hypovolemia (shock hemorrhage). At the basal moment, COCTD and COITD were closely correlated (r2 = 0.97), with a mean bias of −0.13 ± 0.16 L/min and percentage error of 11%. After 15 min of partial support LVAD, COCTD and COITD were closely correlated (r2 = 0.91), with a mean bias of 0.31 ± 0.35 L/min and percentage error of 20%. After inducing hypervolemia, COCTD and COITD were closely correlated (r2 = 0.99), with a mean bias of 0.04 ± 0.07 L/min and percentage error of 5%. After inducing hypovolemia, COCTD and COITD were closely correlated (r2 = 0.74), with a mean bias of 0.08 ± 0.22 L/min and percentage error of 19%. This study shows that continuous pulmonary thermodilution could be an alternative method of monitoring CO in a porcine model with a continuous-flow LVAD.

Non-invasive cardiac output measurement with electrical velocimetry in patients undergoing liver transplantation: comparison of an invasive method with pulmonary thermodilution

BackgroundThe goal of this study was to evaluate the accuracy and interchangeability between continuous cardiac output (CO) measured by electrical velocimetry (COEv) and continuous cardiac output obtained using the pulmonary thermodilution method (COPAC) during living donor liver transplantation (LDLT).MethodTwenty-three patients were enrolled in this prospective observational study. CO was recorded by both two methods and compared at nine specific time points. The data were analyzed using correlation coefficients, Bland-Altman analysis for the percentage errors, and the concordance rate for trend analysis using a four-quadrant plot.ResultsIn total, 207 paired datasets were recorded during LDLT. CO data were in the range of 2.8–12.7 L/min measured by PAC and 3.4–14.9 L/min derived from the EV machine. The correction coefficient between COPAC and COEv was 0.415 with p < 0.01. The 95% limitation agreement was − 5.9 to 3.4 L/min and the percentage error was 60%. The concordance rate was 56.5%.ConclusionsThe Aesculon™ monitor is not yet interchangeable with continuous thermodilution CO monitoring during LDLT.Trial registrationThe study was approved by the Institutional Review Board of Chang Gung Medical Foundation in Taiwan (registration number: 201600264B0).

Minimally invasive cardiac output technologies in the ICU: putting it all together.

Haemodynamic monitoring is a cornerstone in the diagnosis and evaluation of treatment in critically ill patients in circulatory distress. The interest in using minimally invasive cardiac output monitors is growing. The purpose of this review is to discuss the currently available devices to provide an overview of their validation studies in order to answer the question whether these devices are ready for implementation in clinical practice. Current evidence shows that minimally invasive cardiac output monitoring devices are not yet interchangeable with (trans)pulmonary thermodilution in measuring cardiac output. However, validation studies are generally single centre, are based on small sample sizes in heterogeneous groups, and differ in the statistical methods used. Minimally and noninvasive monitoring devices may not be sufficiently accurate to replace (trans)pulmonary thermodilution in estimating cardiac output. The current paradigm shift to explore trending ability rather than investigating agreement of absolute values alone is to be applauded. Future research should focus on the effectiveness of these devices in the context of (functional) haemodynamic monitoring before adoption into clinical practice can be recommended.

Agreement between ccNexfin CO-trek cardiac output and intermittent cold-bolus pulmonary thermodilution in a prospective multicenter study.

The ccNexfin System uses the CO-trek algorithm to analyze a non-invasively obtained arterial pressure waveform and calculate cardiac output (NEXCO). It remains matter of debate whether NEXCO can replace invasive, pulmonary artery catheter-derived, cold-bolus pulmonary thermodilution cardiac output measurement (PACCO). This study aimed at testing NEXCO-PACCO agreement in a large sample size, multicenter study. We hypothesized that agreement between NEXCO and PACCO would be demonstrated by a mean accuracy (bias) <0.6 L/min with a percentage error <30%. Patients undergoing cardiac surgery in three academic hospitals clinically requiring pulmonary artery catheterization were included. Exclusion criteria were aortic, pulmonary and tricuspid (valve) abnormalities, non-sinus rhythm and insufficient perfusion of the digits such as in Raynaud's disease. After induction of anesthesia, cardiac output was measured with four cold bolus thermodilution measurements and four averaged 30-second ccNexfin measurements randomized through the respiratory cycle to obtain one measurement pair. Mean accuracy and precision of ccNexfin were expressed as bias (mean of all NEXCO-PACCO differences) and limits of agreement (LOA) (1.96·SD of bias). Percentage error was calculated as [LOA / (NEXCO-PACCO average)]. Fifty-five patients were enrolled in the study, 51 completed the protocol. Median PACCO was 3.7 (IQR: 3.2 to 4.6) L/min and median NEXCO was 3.8 (IQR: 3.1 to 4.7) L/min. NEXCO-PACCO bias was 0.1 (LOA: -1.4 to +1.6) L/min with a 37% percentage error. In this study, cardiac output measurement with ccNexfin failed to meet the predefined criteria for agreement with cold-bolus pulmonary artery thermodilution.

Accuracy, Precision, and Trending Ability of Electrical Cardiometry Cardiac Index versus Continuous Pulmonary Artery Thermodilution Method: A Prospective, Observational Study.

Introduction Evaluation of accuracy, precision, and trending ability of cardiac index (CI) measurements using the Aesculon™ bioimpedance electrical cardiometry (Aesc) compared to the continuous pulmonary artery thermodilution catheter (PAC) technique before, during, and after cardiac surgery. Methods A prospective observational study with fifty patients with ASA 3-4. At six time points (T), measurements of CI simultaneously by continuous cardiac output pulmonary thermodilution and thoracic bioimpedance and standard hemodynamics were performed. Analysis was performed using Bland-Altman, four-quadrant plot, and polar plot methodology. Results CI obtained with pulmonary artery thermodilution and thoracic bioimpedance ranged from 1.00 to 6.75 L min−1 and 0.93 to 7.25 L min−1, respectively. Bland-Altman analysis showed a bias between CIBIO and CIPAC of 0.52 liters min−1 m−2, with LOA of [−2.2; 1.1] liters min−1 m−2. Percentage error between the two techniques was above 30% at every time point. Polar plot methodology and 4-quadrant analysis showed poor trending ability. Skin incision had no effect on the results. Conclusion CI obtained by continuous PAC and CI obtained by Aesculon bioimpedance are not interchangeable in cardiac surgical patients. No effects of skin incision were found. International clinical trial registration number is ISRCTN26732484.

Thermodilution vs pressure recording analytical method in hemodynamic stabilized patients

PurposeMany mini-invasive devices to monitor cardiac output (CO) have been introduced and, among them, the pressure recording analytical method (PRAM). The aim of this study was to assess the agreement of PRAM with the intermittent transpulmonary thermodilution and continuous pulmonary thermodilution in measuring CO in hemodynamically stabilized patients. Materials and MethodsThis is a prospective clinical study in a mixed medical-surgical intensive care unit (ICU) and in a postcardiac surgical ICU. Forty-eight patients were enrolled: 32 patients to the medical-surgical ICU monitored with PiCCO (Pulsion Medical System AG, Munich, Germany) and 16 were cardiac patients monitored with Vigilance (Edwards Lifesciences, Irvine, CA). ResultsA total of 112 measurements were made. Ninety-six comparisons of paired CO measurements were made in patients hospitalized in medical-surgical ICU; 16, in cardiac surgical patients.The mean Vigilance-CO was 4.49 ± 0.99 L/min (range, 2.80-5.90 L/min), and the mean PRAM-CO was 4.27 ± 0.88 L/min (range, 2.85-6.19 L/min). The correlation coefficient between Vigilance-CO and PRAM-CO was 0.83 (95% confidence interval, 0.57-0.94; P < .001). The bias was 0.22 ± 0.55 L/min with limits of agreement between 0.87 and 1.30 L/min. The percentage error was 25%.Mean TP-CO was 6.78 ± 2.04 L/min (range, 4.12-11.27 L/min), and the mean PRAM-CO was 6.11 ± 2.18 L/min (range, 2.82-10.90 L/min). The correlation coefficient between PiCCO-CO and PRAM-CO was 0.91 (95% confidence interval, 0.83-0.96; P < .0001). The bias was 0.67 ± 0.89 L/min with limits of agreement −1.07 and 2.41 L/min. The coefficient of variation for PiCCO was 4% ± 2%, and the coefficient of variation for PRAM was 10% ± 8%. The percentage error was 28%. ConclusionsThe PRAM system showed good agreement with pulmonary artery catheter and PiCCO in hemodynamically stabilized patients.

Dynamic and Volumetric Variables Reliably Predict Fluid Responsiveness in a Porcine Model with Pleural Effusion

BackgroundThe ability of stroke volume variation (SVV), pulse pressure variation (PPV) and global end-diastolic volume (GEDV) for prediction of fluid responsiveness in presence of pleural effusion is unknown. The aim of the present study was to challenge the ability of SVV, PPV and GEDV to predict fluid responsiveness in a porcine model with pleural effusions.MethodsPigs were studied at baseline and after fluid loading with 8 ml kg−1 6% hydroxyethyl starch. After withdrawal of 8 ml kg−1 blood and induction of pleural effusion up to 50 ml kg−1 on either side, measurements at baseline and after fluid loading were repeated. Cardiac output, stroke volume, central venous pressure (CVP) and pulmonary occlusion pressure (PAOP) were obtained by pulmonary thermodilution, whereas GEDV was determined by transpulmonary thermodilution. SVV and PPV were monitored continuously by pulse contour analysis.ResultsPleural effusion was associated with significant changes in lung compliance, peak airway pressure and stroke volume in both responders and non-responders. At baseline, SVV, PPV and GEDV reliably predicted fluid responsiveness (area under the curve 0.85 (p<0.001), 0.88 (p<0.001), 0.77 (p = 0.007). After induction of pleural effusion the ability of SVV, PPV and GEDV to predict fluid responsiveness was well preserved and also PAOP was predictive. Threshold values for SVV and PPV increased in presence of pleural effusion.ConclusionsIn this porcine model, bilateral pleural effusion did not affect the ability of SVV, PPV and GEDV to predict fluid responsiveness.

Measurement of Cardiac Output in Patients With Septic Shock Using Arterial Pressure Waveform Analysis in Comparison With the Pulmonary Artery Catheter: A Pilot Study

PURPOSE: New semi-invasive device (Flotrac/VigileoTM) has been shown to measure cardiac output (CO) reliably in patients undergoing cardiac surgery. However, there are limited data to support its use in patients with low systemic vascular resistance, such as septic shock or liver failure. The aim of the study is to investigate the accuracy of this device in comparison with pulmonary artery catheter (PAC) using bolus pulmonary thermodilution in patients with sepsis. This abstract reports our preliminary findings in the first 13 patients.

Continuous cardiac output monitoring with an uncalibrated pulse contour method in patients supported with mechanical pulsatile assist device

We evaluated the accuracy of an uncalibrated pulse contour method called Pressure Recording Analytical Method (PRAM) compared with continuous thermodilution for cardiac output (CO) monitoring in patients implanted with a pulsatile left ventricular assist device (LVAD). Twelve adult patients implanted with the HeartMate I-XVE device were studied. CO was simultaneously evaluated by PRAM and by continuous thermodilution. Blood flow values displayed by the LVAD's console were also used for the comparison. Bland-Altman and linear regression analyses were applied. A total of 72 CO measurements (range 3.8-6.7 l/min) were obtained. Mean CO was 5.23±0.70 l/min for the 'hot' pulmonary thermodilution (ThD-CCO) method, 5.28±0.63 l/min for PRAM and 4.83±0.67 l/min for LVAD-CO. A high correlation (r=0.90), a good agreement (mean bias -0.04 l/min, precision ±0.38 l/min) and a low percentage of error (7.3%) were observed between PRAM-CO and ThD-CCO. A good correlation was found between LVAD-CO and either ThD-CCO (r=0.88) or PRAM-CO (r=0.86), but an overestimation of 10% was observed for both PRAM-CO (mean bias -0.44 l/min) and ThD-CCO (mean bias -0.40 l/min). Our results demonstrated good agreements between PRAM-CO, ThD-CCO and LVAD-CO. PRAM derives CO from a peripheral artery without calibration and may be a complementary tool in the hemodynamic assessment of patients supported with a VAD.

Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients

PurposeSecond-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low.MethodsFifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3–5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (COG2) and third-generation (COG3) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO).ResultsA total of 401 simultaneous measurements of iCO, COG2, COG3, and CCO were recorded. The mean (95%CI) biases between COG2 and iCO, COG3 and iCO, and CCO and iCO were −10 (−15 to −5)% [−0.8 (−1.1 to −0.4) L/min], 0 (−4 to 4)% [0 (−0.3 to 0.3) L/min], and 9 (6–13)% [0.7 (0.5–1.0) L/min], respectively. The percentage errors were 29 (20–37)% for COG2, 30 (24–37)% for COG3, and 28 (22–34)% for CCO. The difference between iCO and COG2 was significantly correlated with TSVR (r 2 = 0.37, p < 0.0001). A very weak (r 2 = 0.05) relationship was also observed for the difference between iCO and COG3.ConclusionsIn patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software.Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-010-2098-8) contains supplementary material, which is available to authorized users.

Experimental Validation of Cardiac Index Measurement Using Transpulmonary Thermodilution Technique in Neonatal Total Liquid Ventilation

This study aimed to assess the precision and the interchangeability of cardiac index measurement by transpulmonary thermodilution (TPTD) and pulmonary thermodilution (PTD) devices on a neonatal animal model of acute respiratory distress syndrome under total liquid ventilation (TLV) and conventional mechanical ventilation (CMV). After acute respiratory distress induction by tracheal instillation of hydrochloric acid, transpulmonary (CI(TPTD)) and pulmonary (CI(PTD)) cardiac index were simultaneously measured every 30 minutes for a 240-minute experiment. Reproducibility of both thermodilution techniques was very good to excellent in both groups of ventilation with intrainstrument intraclass correlation coefficient >0.60. Disagreement was found between TPTD and PTD in TLV and CMV. Bland-Altman analysis revealed mean biases of 0.98 L/min/m² (22.8%) with limits of agreement of -1.33 to 3.25 L/min/m² in CMV and 1.28 L/min/m² (17.3%) with limits of agreement of -1.17 to 3.72 L/min/m² in TLV. Bias between TPTD and PTD was not statistically different in TLV than in CMV (p = 0.11). Transpulmonary thermodilution and PTD remained precise but not interchangeable techniques under TLV as well as CMV. Because TLV does not bring additional bias between both thermodilution techniques, we advocate the use of the less-invasive TPTD under TLV as currently recommended in CMV.

Assessing fluid responses after coronary surgery: role of mathematical coupling of global end-diastolic volume to cardiac output measured by transpulmonary thermodilution

Mathematical coupling may explain in part why cardiac filling volumes obtained by transpulmonary thermodilution may better predict and monitor responses of cardiac output to fluid loading than pressures obtained by pulmonary artery catheters (PACs). Eleven consecutive patients with hypovolaemia after coronary surgery and a PAC, allowing central venous pressure (CVP) and continuous cardiac index (CCIp) measurements, received a femoral artery catheter for transpulmonary thermodilution measurements of global end-diastolic blood volume index (GEDVI) and cardiac index (CItp). One to five colloid fluid-loading steps of 250 ml were done in each patient (n = 48 total). Fluid responses were predicted and monitored similarly by CItp and CCIp, whereas CItp and CCIp correlated at r = 0.70 (P < 0.001) with a bias of 0.40 l min(-1) m(-2). Changes in volumes (and not in CVP) related to changes in CItp and not in CCIp. Changes in CVP and GEDVI similarly related to changes in CItp, after exclusion of two patients with greatest CItp outliers (as compared to CCIp). Changes in GEDVI correlated better to changes in CItp when derived from the same thermodilution curve than to changes in CItp of unrelated curves and changes in CCIp. After coronary surgery, fluid responses can be similarly assessed by intermittent transpulmonary and continuous pulmonary thermodilution methods, in spite of overestimation of CCIp by CItp. Filling pressures are poor monitors of fluid responses and superiority of GEDVI can be caused, at least in part, by mathematical coupling when cardiac volume and output are derived from the same thermodilution curve.

Cardiac output and blood volume parameters using femoral arterial thermodilution

The pulse-induced continuous cardiac output (PiCCO) system is a less invasive method than pulmonary thermodilution for the measurement of cardiac output and estimating blood volume parameters. The normal values in children have not been defined. The purpose of the present paper was therefore to evaluate cardiac output and parameters of blood volume using femoral arterial thermodilution in critically ill children. A prospective study was performed in 17 critically ill children aged between 2 months and 14 years. Two measurements were taken for each determination of cardiac output, global end diastolic volume (GEDVI), intrathoracic blood volume index (ITBI), extravascular lung water index (ELWI), systolic volume index (SVI), stroke volume variation (SVV), cardiac function index (CFI), left ventricular contractility (dp/dt max), and the systemic vascular resistance index (SVRI). One hundred and seventeen measurements were performed. The mean cardiac index (CI) was 3.5 +/- 1.3 L/min per m(2). The GEDVI (399.7 +/- 349.1 mL/m(2)), ITBI (574.5 +/- 212.2 mL/m(2)) and dp/dt max (804.6 +/- 372.1 mmHg/s) were lower than reported in adults, whereas ELWI (18.9 +/- 9.3 mL/m2) and CFI (8 +/- 2.5 L/min) where higher. The GEDVI, SVI, dp/dt max and CI increased with the weight of the patients whereas the ELWI values decreased. Femoral arterial thermodilution is a suitable technique for the measurement of cardiac output in critically ill children. The intrathoracic and intracardiac volumes are lower than in adults, whereas extrapulmonary water is higher; these values are related to the weight of the patient.

Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis. A comparison with intermittent pulmonary thermodilution in renal transplantation

Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis. A comparison with intermittent pulmonary thermodilution in renal transplantation

Is continuous really continuous?*

The assessment of cardiac output (CO) is a cornerstone in the monitoring of critically ill patients. During the past years, a number of new techniques have been used in clinical practice besides the established pulmonary thermodilution technique (COT) via a pulmonary artery catheter (PAC) (1).The av

Influence of inhaled nitric oxide on plasma nitrate concentrations in patients with adult respiratory distress syndrome and sepsis: results of a pilot study

Study Objective To measure plasma nitrate concentrations after inhalation of nitric oxide for treatment of adult respiratory distress syndrome (ARDS) and sepsis. Design Prospective pilot study. Setting Intensive care unit at a university-affiliated hospital. Patients Nine consecutive medical intensive care unit patients with ARDS and sepsis. Interventions After diagnosis of ARDS, all patients received a balloon-tipped triple-lumen thermodilution pulmonary artery catheter (Baxter Healthcare Corp, Irvine, CA). Inhaled nitric oxide was initiated starting at a dose of one part per million and titrated according to the maximal achievable increase in arterial oxygenation. Hemodynamic measurements including intrapulmonary shunt fraction and blood as analyses were performed before nitric oxide application, as well as 1 and 24 hours after starting nitric oxide, respectively. Plasma samples for determination of nitrate were taken from the arterial line and from the pulmonary thermodilution catheter and analyzed using high-performance liquid chromatography. Measurements and Main Results Eight of 9 patients were nitric oxide responders (intrapulmonary shunt decrease >5%). There was no statistically significant increase in nitrate plasma concentration measured both in peripheral arterial and in mixed venous blood with inhaled nitric oxide up to a concentration of 40 parts per million. Conclusion Inhalation of nitric oxide in patients with ARDS and sepsis does not result in increased plasma nitrate concentrations.

Estimation of cardiac output in a pharmacological trial using a simple method based on arterial blood pressure signal waveform: a comparison with pulmonary thermodilution and echocardiographic methods

Cardiac output (CO) has traditionally been measured using invasive techniques, which involve an element of risk. Thus, a reliable less-invasive method for determining CO would be very valuable for research use. We tested whether simple analysis of the arterial pulse waveform, not requiring large-vessel catheterisation or expensive equipment, could provide an estimate of CO that is accurate enough for pharmacological studies. We measured CO in 11 healthy male subjects who received low and high doses of dexmedetomidine (alpha2-adrenoceptor agonist), using pulse contour analysis, echocardiography and pulmonary thermodilution techniques. At baseline, these methods gave the following mean (SD) values of CO: 6.18 (1.59), 5.22 (1.35) and 7.03 (1.54) l/min, respectively. High-dose dexmedetomidine reduced CO to 4.50 (0.68), 3.65 (0.65) and 4.80 (0.89) l/min, corresponding to -25 (14) %, -28 (12) % and -30 (14) % reductions from baseline, respectively. The pulse contour method described these dexmedetomidine-induced changes in CO very similarly to the thermodilution and echocardiographic methods. The limits of agreement [bias (2SD)] were 0.55 (2.55) and -0.10 (2.04) l/min, respectively. The minimally invasive pulse contour analysis technique might be suitable for pharmacological studies for the detection of major drug-induced reductions in CO.

Haemodynamic monitoring and liver function evaluation by pulsion cold system Z‐201 (PCS) during orthotopic liver transplantation

Pulsion cold system (PCS, COLD) is a haemodynamic monitoring system that allows measurement of cardiac output (CO), partial blood volumes, lung water, and liver function. The aim of the study was to evaluate this monitoring system during human orthotopic liver transplantation (OLT) for the following: (a) to determine agreement between CO measurements via pulmonary artery thermodilution (CO TDpa), and aortic transpulmonary thermodilution (CO TDa); (b) to compare the preload dates obtained with the COLD with central venous pressure (CVP) and pulmonary capillary wedge (PCWP); and (c) to assess the use of the plasma disappearance rate (PDR) of indocyanine green (ICG) as a measure of graft function. Fifteen consecutive patients undergoing OLT were studied. Each patient received a pulmonary artery catheter and a 5F aortic catheter with an integrated thermistor. The thermistor of the aortic catheter were connected to one computer system (COLD-Z201, Pulsion Medical Systems, Munich, Germany). Haemodynamic data were registered an all the phases of OLT. PDR was measured during surgery in 12 patients. Correlations between PDR and the other markers of graft function (transaminases, protrombine time, and bile production) were sought. The correlation coefficient between CO TDa (COLD) and CO TDpa was r = 0.766 (p < 0.001), and an additional analysis according to Bland-Altman was also performed. There was a better correlation between the cardiac index (determined by two monitoring systems) and the volume measurements than the correlation observed with pressure preload parameters. The best correlations were found between the cardiac index in the femoral artery and intrathoracic blood volume index (ITBVI) and pulmonary blood volume index (PBVI) (r = 0.79 and r = 0.72, respectively; p < 0.01). PDR measured in the group patients with bad early graft function were lower (13.6 +/- 2.7) than those in the group with a good graft function (21.6 +/- 9) (p < 0.05). The degree of discrepancy between femoral and pulmonary thermodilution cardiac output measures is very wide during OLT so as to make the techniques using the COLD machine clinically useless. On the other hand, the volumes measured by COLD, specially ITBVI and PBVI, are more useful to asses the pre-load than pressure measurements. In OLT, the PDR measured within the first few hours after liver reperfusion may become a useful tool for early diagnosis of primary graft dysfunction (PDF).

Continuous and intermittent cardiac output measurement: pulmonary artery catheter versus aortic transpulmonary technique

Cardiac output (CO) can be measured intermittently by bolus thermodilution methods in the pulmonary artery (COpa) or in the aorta (COart). A continuous thermodilution method (CCO) and a method for continuous estimation using the arterial pulse wave (PCCO) are also available. We compared two methods of intermittent CO measurements in patients during liver transplantation: COpa, regarded as the current clinical standard, and an aortic transpulmonary thermodilution technique (COart) performed with the PiCCO system. We also compared CCO and PCCO. Measurements were made in 62 patients at three stages: after the induction of anaesthesia, after caval clamping phase, and at the end of surgery. We used Bland-Altman and correlation analysis. We found close agreement between the techniques. Mean bias between COart and COpa and PCCO and CCO was 0.15 (2SD of differences between methods=1.74) litre min(-1) and -0.03 (1.75) litre min(-1), respectively. Mean bias between CCO and COpa and PCCO and COpa was 0.02 (1.48) litre min(-1) and 0.04 (1.69) litre min(-1), respectively. Measurement with the aortic transpulmonary thermodilution technique gives continuous and intermittent values that agree with the pulmonary thermodilution method.