Transpulmonary Thermodilution Cardiac Output Research Articles

Invasive and non-invasive assessment of macro- and micro-circulatory effects of vasopressors during sevoflurane anesthesia in a pediatric experimental model: A randomized trial.

While non-invasive assessment of macro- and micro-circulation has the promise to optimize anesthesia management, evidence is lacking for the relationship between invasive and non-invasive measurements of cardiac output and microcirculatory indices. We aimed to compare the abilities of non-invasive techniques to detect changes in macro- and micro-circulation following deep anesthesia and subsequent restoration of the compromised hemodynamic by routinely used vasopressors in a randomized experimental study. A 20%-25% drop in mean arterial pressure was induced by sevoflurane in anesthetized mechanically ventilated just-weaned piglets (n=12) prior to the administration of vasopressors in random order (dopamine, ephedrine, noradrenaline, and phenylephrine). Simultaneous transpulmonary thermodilution cardiac output assessment with the invasive pulse index continuous contour (PiCCO) method was compared with non-invasive estimates obtained with electrical conductivity (ICON) and echo Doppler (Cardio Q). Changes in microcirculation were characterized by sublingual red blood cell velocity, jugular cerebral venous oxygen saturation, and arterial lactate. Cardiac output indices obtained by invasive and non-invasive methods. Changes in cardiac output measured invasively and non-invasively correlated significantly after sevoflurane (r=.78, p=.003 and r=.76, p=.006 between PiCCO and ICON or Cardio Q, respectively). Following the administration of vasopressors, invasive and non-invasive cardiac output assessments were unrelated with significant correlations observed only between PiCCO and ICON after dopamine and ephedrine. Sevoflurane-induced hypotension decreased jugular cerebral venous oxygen saturation significantly and was recovered by all vasopressors. Sevoflurane and vasopressors had no effect on red blood cell velocity, which increased only after dopamine. No consistent changes in lactate were observed during the study period. The results of this study suggest that non-invasive cardiac output measurements may not accurately reflect changes in macrocirculation after hemodynamic optimization by vasopressors. Due to the incoherence between macro- and micro-circulation, monitoring microcirculation is essential to guide patient management.

Comparison of the diagnostic accuracy of dynamic and static preload indexes to predict fluid responsiveness in mechanically ventilated, isoflurane anesthetized dogs

ObjectiveTo compare the diagnostic accuracy of pulse pressure variation (PPV), stroke volume variation from pulse contour analysis (SVVPCA), plethysmographic variability index (PVI), central venous pressure (CVP) and global end-diastolic volume index measured by transpulmonary thermodilution (GEDVITPTD) to predict fluid responsiveness (FR) in dogs. Study designProspective study. AnimalsA group of 40 bitches (13.8–26.8 kg) undergoing ovariohysterectomy. MethodsAnesthesia was maintained with isoflurane under volume-controlled ventilation (tidal volume 12 mL kg–1; inspiratory pause during 40% of inspiratory time; inspiration:expiration ratio 1:1.5). Transpulmonary thermodilution cardiac output was recorded through a femoral artery catheter. FR was evaluated by a fluid challenge (lactated Ringer's, 20 mL kg–1 over 15 minutes) administered once (n = 21) or twice (n = 18) before surgery. Individuals were responders if stroke volume index measured by transpulmonary thermodilution increased >15% after the last fluid challenge. ResultsOf the 39 animals studied, 21 were responders and 18 were nonresponders. Area under the receiver operating characteristics curve (AUROC) was 0.976, 0.906, 0.868 and 0.821 for PPV, PVI, CVP and SVVPCA, respectively (p < 0.0001 from AUROC = 0.5). GEDVITPTD failed to predict FR (AUROC: 0.660, p = 0.078). Best cut-off thresholds discriminating responders and nonresponders, with respective zones of diagnostic uncertainty (gray zones) were: PPV >16% (15–16%), PVI >11% (10–13%), SVVPCA >10% (9–18%) and CVP ≤1 mmHg (0–3 mmHg). Percentage of animals within gray zone limits was 13% (PPV), 28% (PVI), 51% (SVVPCA) and 67% (CVP). Conclusions and clinical relevancePPV has better diagnostic accuracy to predict FR (conclusive results in nearly 90% of population) than other preload indexes in healthy dogs. When invasive blood pressure is unavailable, PVI will predict FR with reasonable accuracy (conclusive results in approximately 70% of the population). PPV and PVI values above gray zone limits (>16% and >13%, respectively) can reliably predict responders to volume expansion.

Effects of 6% Tetrastarch and Lactated Ringer's Solution on Extravascular Lung Water and Markers of Acute Renal Injury in Hemorrhaged, Isoflurane-Anesthetized Healthy Dogs.

BackgroundTetrastarch can cause acute kidney injury (AKI) in humans with sepsis, but less likely to result in tissue edema than lactated Ringer's solution (LRS).ObjectivesCompare effects of volume replacement (VR) with LRS and 6% tetrastarch solution (TS) on extravascular lung water (EVLW) and markers of AKI in hemorrhaged dogs.AnimalsSix healthy English Pointer dogs (19.7–35.3 kg).MethodsProspective crossover study. Animals underwent anesthesia without hemorrhage (Control). Two weeks later, dogs hemorrhaged under anesthesia on 2 occasions (8‐week washout intervals) and randomly received VR with LRS or TS at 3 : 1 or 1 : 1 of shed blood, respectively. Anesthesia was maintained until 4 hour after VR for EVLW measurements derived from transpulmonary thermodilution cardiac output. Neutrophil gelatinase‐associated lipocalin (NGAL) and creatinine concentrations in plasma and urine were measured until 72 hour after VR.ResultsThe EVLW index (mL/kg) was lower at 1 hour after TS (10.0 ± 1.9) in comparison with controls (11.9 ± 3.4, P = 0.04), and at 4 hour after TS (9.7 ± 1.9) in comparison with LRS (11.8 ± 2.7, P = 0.03). Arterial oxygen partial pressure‐to‐inspired oxygen fraction ratio did not differ among treatments from 0.5 to 4 hour after VR. Urine NGAL/creatinine ratio did not differ among treatments and remained below threshold for AKI (120,000 pg/mg).Conclusions and Clinical ImportanceAlthough TS causes less EVLW accumulation than LRS, neither fluid produced evidence of lung edema (impaired oxygenation). Both fluids appear not to cause AKI when used for VR after hemorrhage in healthy nonseptic dogs.

Plethysmography variability index for prediction of fluid responsiveness during graded haemorrhage and transfusion in sevoflurane-anaesthetized mechanically ventilated dogs

ObjectiveTo examine the accuracy of plethysmography variability index (PVI) as a noninvasive indicator of fluid responsiveness in hypovolaemic dogs. Study designProspective experimental study. AnimalsSix adult healthy sevoflurane-anaesthetized Beagle dogs. MethodsDogs were anaesthetized with 1.3-fold their individual minimum alveolar concentration of sevoflurane. The lungs were mechanically ventilated after neuromuscular blockade with vecuronium bromide. Cardiopulmonary variables including mean arterial blood pressure (MAP), central venous pressure (CVP), transpulmonary thermodilution cardiac output (TPTDCO), stroke volume (SV), perfusion index (PI), pulse pressure variation (PPV), stroke volume variation (SVV) and PVI were determined during six stages of graded venous blood withdrawal (5 mL kg−1 increments) and six stages of graded blood infusion (5 mL kg−1 increments). The cardiopulmonary variables were analysed using paired t test or Wilcoxon signed rank test. Correlations between PPV and SVV or PVI were analysed by linear regression. The accuracy of PPV, SVV and PVI for predicting fluid responsiveness was examined by using receiver operating characteristic curve analysis. A value of p < 0.05 was considered statistically significant. ResultsBlood withdrawal resulted in significant increases in PPV and PVI and decreases in MAP, CVP, TPTDCO, SV and PI. Blood infusion resulted in significant increases in MAP, CVP, TPTDCO, SV and PI and decreases in PPV and PVI. PPV and PVI showed a relevant correlation (p < 0.001, r2 = 0.62) and threshold values of PPV ≥ 16% (sensitivity 71%, specificity 82%) and PVI ≥ 12% (sensitivity 78%, specificity 72%) for identifying fluid responsiveness. SVV did not change. Conclusions and clinical relevanceNoninvasive measurement of PVI predicted fluid responsiveness with moderate accuracy equal to PPV in sevoflurane-anaesthetized mechanically ventilated dogs. Provisional threshold values for identification of fluid responsiveness were PPV ≥ 16% and PVI ≥ 12%. Clinical trials are needed to confirm these threshold values in dogs.

Comparison of pulmonary artery and transpulmonary thermodilution cardiac output measurements in unsedated newborn calves

ObjectiveTo compare the agreement, repeatability and trending ability of transpulmonary thermodilution (TPTD) and pulmonary artery thermodilution (PATD) cardiac output ( Q˙t) measurements in unsedated newborn calves. Study designProspective experimental trial. AnimalsEight newborn calves weighing a median (range) of 53 (46–59) kg. MethodsPulmonary and femoral artery thermodilution catheters were placed under local anaesthesia. A total of 382 PATD and TPTD Q˙t measurements were performed simultaneously. Cardiac output was influenced by intravenous doxapram and theophylline in a randomized crossover fashion. Bland–Altman analysis for multiple comparisons, concordance and polar plots were used to assess TPTD against PATD. ResultsMedian (range) cardiac index values measured with PATD and TPTD were 197 mL kg−1 minute−1 (74–335 mL kg−1 minute−1) and 196 mL kg−1 minute−1 (59–395 mL kg−1 minute−1), respec-tively. A small mean bias of -3 mL kg−1 minute−1 with limits of agreement (LOA) of -64 to 58 mL kg−1 minute−1 and a percentage error of 31% were found. Eighty-two mean values were calculated. This reduced the LOA to -50 to 41 mL kg−1 minute−1 with a similar small bias and a percentage error of 23%. Mean TPTD tracked changes in Q˙t compared with mean PATD with 90% concordance, a mean polar angle of 6° and radial LOA of 43°, indicating marginal trending ability. Keeping the femoral artery catheter patent and obtaining acceptable measurements were very challenging because the calves were not used to being restrained. Calf movement had less influence on PATD. Conclusions and clinical relevanceWe recommend that PATD remains the reference method to measure Q˙t in unsedated newborn calves. However, the robust results of the evaluation of the less invasive TPTD technique warrants further evaluation taking into account the difficulties reported in this study.

Constant infusion transpulmonary thermodilution for the assessment of cardiac output in exercising humans.

To determine the accuracy and precision of constant infusion transpulmonary thermodilution cardiac output (CITT-Q) assessment during exercise in humans, using indocyanine green (ICG) dilution and bolus transpulmonary thermodilution (BTD) as reference methods, cardiac output (Q) was determined at rest and during incremental one- and two-legged pedaling on a cycle ergometer, and combined arm cranking with leg pedaling to exhaustion in 15 healthy men. Continuous infusions of iced saline in the femoral vein (n = 41) or simultaneously in the femoral and axillary (n = 66) veins with determination of temperature in the femoral artery were used for CITT-Q assessment. CITT-Q was linearly related to ICG-Q (r = 0.82, CITT-Q = 0.876 × ICG-Q + 3.638, P < 0.001; limits of agreement ranging from -1.43 to 3.07 L/min) and BTD-Q (r = 0.91, CITT-Q = 0.822 × BTD + 4.481 L/min, P < 0.001; limits of agreement ranging from -1.01 to 2.63 L/min). Compared with ICG-Q and BTD-Q, CITT-Q overestimated cardiac output by 1.6 L/min (≈ 10% of the mean ICG and BTD-Q values, P < 0.05). For Q between 20 and 28 L/min, we estimated an overestimation < 5%. The coefficient of variation of 23 repeated CITT-Q measurements was 6.0% (CI: 6.1-11.1%). In conclusion, cardiac output can be precisely and accurately determined with constant infusion transpulmonary thermodilution in exercising humans.

Trending ability and limitations of transpulmonary thermodilution and pulse contour cardiac output measurement in cats as a model for pediatric patients.

The present study evaluated transpulmonary thermodilution (TPTD) and pulse contour cardiac output (PCCO) both measured by the PiCCO Plus™ monitor (Pulsion Medical Systems, Munich, Germany) against pulmonary artery thermodilution (PATD) in cats as a hemodynamic model for small children. A wide range of cardiac outputs (CO) was simultaneously measured. Accuracy and trending abilities were critically evaluated. Three cats were studied under isoflurane anesthesia and 160 CO measurements were performed with 3 mL ice-cold 5 % dextrose with PATD and TPTD. The results were compared with the PCCO measurement before the bolus measurement. Cardiac output was manipulated from 32 to 224 mL/kg/min by dobutamine, dopamine, phenylephrine, medetomidine and increased concentrations of isoflurane. Bland-Altman analysis, concordance and polar plot analysis were performed to assess accuracy and trending ability. TPTD was measuring constantly higher than PATD with a mean bias of 73 mL/kg/min and limits of agreement of 34-112 mL/kg/min, a concordance rate of 94 % and a mean polar angle of -5° with radial limits of agreement (RLOA) of 33°. Concordance rate of the PCCO versus PATD was 82 % with a mean polar angle of -10° and RLOA of 46° and versus TPTD 90 % with a mean polar angle of -6° and RLOA of 46°. Both tested methods constantly overestimated simultaneous PATD measurements. The small size, low flows and the relative short catheter not reaching the abdominal aorta may explain that. However TPTD tracked changes accurately opposed to a poor trending ability of the PCCO measurement.

Performance of a new pulse contour method for continuous cardiac output monitoring: validation in critically ill patients

BackgroundA new calibrated pulse wave analysis method (VolumeView™/EV1000™, Edwards Lifesciences, Irvine, CA, USA) has been developed to continuously monitor cardiac output (CO). The aim of this study was to compare the performance of the VolumeView method, and of the PiCCO2™ pulse contour method (Pulsion Medical Systems, Munich, Germany), with reference transpulmonary thermodilution (TPTD) CO measurements. MethodsThis was a prospective, multicentre observational study performed in the surgical and interdisciplinary intensive care units of four tertiary hospitals. Seventy-two critically ill patients were monitored with a central venous catheter, and a thermistor-tipped femoral arterial VolumeView™ catheter connected to the EV1000™ monitor. After initial calibration by TPTD CO was continuously assessed using the VolumeView-CCO software (CCOVolumeView) during a 72 h period. TPTD was performed in order to obtain reference CO values (COREF). TPTD and arterial wave signals were transmitted to a PiCCO2™ monitor in order to obtain CCOPiCCO values. CCOVolumeView and CCOPiCCO were recorded over a 5 min interval before assessment of COTPTD. Bland–Altman analysis, %errors, and concordance (trend analysis) were calculated. ResultsA total of 338 matched sets of data were available for comparison. Bias for CCOVolumeView−COREF was −0.07 litre min−1 and for CCOPiCCO–COREF +0.03 litre min−1. Corresponding limits of agreement were 2.00 and 2.48 litre min−1 (P<0.01), %errors 29 and 37%, respectively. Trending capabilities were comparable for both techniques. ConclusionsThe performance of the new VolumeView™-CCO method is as reliable as the PiCCO2™-CCO pulse wave analysis in critically ill patients. However, an improved precision was observed with the VolumeView™ technique. Clinicaltrials.gov identifierNCT01405040.

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

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

Effects of cardiac output levels on the measurement of transpulmonary thermodilution cardiac output in patients with acute respiratory distress syndrome

Transpulmonary thermodilution cardiac output (CO) correlates closely with pulmonary artery (PA) thermodilution CO. Levels of CO may contribute to varying amounts of thermal indicator loss and recirculation during thermodilution CO measurement. This study aimed to investigate the effects of CO levels on the agreement between transpulmonary and PA thermodilution CO in patients with acute respiratory distress syndrome (ARDS). Twenty-two patients with ARDS were prospectively enrolled. Paired bolus transpulmonary thermodilution cardiac index (BCItp) and continuous PA thermodilution cardiac index (CCIpa) data were recorded at baseline and repeated immediately and at 2, 4, and 6 hours after volume expansion with a 500-mL infusion of 10% pentastarch (HES 200/0.5). One hundred and ten paired cardiac index measurements were recorded and divided into 4 quartiles from the lowest to the highest CCIpa. The mean BCItp was higher than CCIpa, and the Bland and Altman analysis revealed a mean (SD) bias of 0.57 (0.75) L L min(-1) m(-2). The limits of agreement (2SD) were +2.07 to -0.93 L min(-1) m(-2). BCItp correlated closely with CCIpa (R = 0.887). CCIpa negatively correlated with the difference between BCItp and CCIpa (R = -0.26). The bias of quartile 1 with the least CCIpa was significantly greater than those of the three other quartiles. In patients with ARDS, transpulmonary thermodilution is a clinically acceptable and interchangeable alternative to PA thermodilution for CO measurement. Levels of CO weakly and negatively correlate with the difference between BCItp and CCIpa. There is greater overestimation of BCItp over CCIpa in low than in high CO states. Diagnostic study, level II.

Effects of cardiac output levels on the measurement of transpulmonary thermodilution cardiac output in patients with acute lung injury

Transpulmonary thermodilution cardiac output (CO) correlates closely with pulmonary artery (PA) thermodilution CO. Levels of CO may contribute varying amounts of thermal indicator loss and recirculation during thermodilution CO measurement. This study aimed to investigate the effects of CO levels on the agreement between transpulmonary and PA thermodilution CO in acute lung injury (ALI) patients.

Performance of Cardiac Output Measurement Derived From Arterial Pressure Waveform Analysis in Patients Requiring High-Dose Vasopressor Therapy

Background Arterial pressure waveform analysis of cardiac output (APCO) without external calibration (FloTrac/Vigileo™) is critically dependent upon computation of vascular tone that has necessitated several refinements of the underlying software algorithms. We hypothesized that changes in vascular tone induced by high-dose vasopressor therapy affect the accuracy of APCO measurements independently of the FloTrac software version. Methods In this prospective observational study, we assessed the validity of uncalibrated APCO measurements compared with transpulmonary thermodilution cardiac output (TPCO) measurements in 24 patients undergoing vasopressor therapy for the treatment of cerebral vasospasm after subarachnoid haemorrhage. Results Patients received vasoactive support with [mean (sd)] 0.53 (0.46) µg kg−1 min−1 norepinephrine resulting in mean arterial pressure of 104 (14) mm Hg and mean systemic vascular resistance of 943 (248) dyn s−1 cm−5. Cardiac output (CO) data pairs (158) were obtained simultaneously by APCO and TPCO measurements. TPCO ranged from 5.2 to 14.3 litre min−1, and APCO from 4.1 to 13.7 litre min−1. Bias and limits of agreement were 0.9 and 2.5 litre min−1, resulting in an overall percentage error of 29.6% for 68 data pairs analysed with the second-generation FloTrac® software and 27.9% for 90 data pairs analysed with the third-generation software. Precision of the reference technique was 2.6%, while APCO measurements yielded a precision of 29.5% and 27.9% for the second- and the third-generation software, respectively. For both software versions, bias (TPCO–APCO) correlated inversely with systemic vascular resistance. Conclusions In neurosurgical patients requiring high-dose vasopressor support, precision of uncalibrated CO measurements depended on systemic vascular resistance. Introduction of the third software algorithm did not improve the insufficient precision (>20%) for APCO measurements observed with the second software version.

Disagreement between pulse contour analysis and transpulmonary thermodilution for cardiac output monitoring after routine therapeutic interventions in ICU patients with acute circulatory failure

The present prospective study was aimed at assessing the reliability of the pulse contour method for measuring cardiac output (CO) after different routinely used therapeutic interventions that can influence vascular compliance and systemic vascular resistances in ICU patients (fluid challenges, changes in norepinephrine or dobutamine infusion rates and changes in ventilatory settings). In ICU patients requiring CO monitoring, transpulmonary thermodilution CO (COTD) and pulse contour CO (COPC) were measured with a PiCCO device after therapeutic manoeuvre-free periods (≤ and >1 h) and after therapeutic interventions without recalibration. Three hundred fifty-two sets of CO measurement pairs in 63 ICU patients were performed. The biases (and percentage errors) between COPC and COTD for the overall paired measurement, therapeutic manoeuvre-free periods and therapeutic manoeuvres were 0.20 ± 1.09 (33%), -0.01 ± 0.93 (29%) and 0.37 ± 1.18 (34%), respectively. The percentage errors were 36 and 39% for fluid challenges and changes in norepinephrine infusion rate, respectively. In ICU patients requiring therapeutic interventions, COPC is frequently in disagreement with COTD.

Haemodynamic response to abdominal decompression in acute Budd–Chiari syndrome

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome commonly occur in patients with liver disease. We compared haemodynamic variables pre- and post-abdominal decompression in patients with acute Budd-Chiari syndrome (BCS) and patients with chronic liver disease (CLD), ascites and IAH. Patients with IAH admitted to the Liver ICU, King's College Hospital were studied. Transpulmonary thermodilution cardiac output (CO) monitoring was performed with the PiCCO(®) system. Ten patients with decompensated BCS (median age 39 years, 20-52) and eight patients with CLD (59 years, 33-65) and tense ascites requiring paracentesis were studied. Intra-abdominal pressure (IAP) was raised in both groups pre-intervention (BSC 23 mmHg, 17-40; CLD 26, 20-40). Intrathoracic blood volume (ITBVI) was persistently low in the BCS group (632 ml/m(2) , 453-924) despite volume resuscitation. Post-intervention, reduction in IAP was noted in both groups (BCS P<0.001, CLD P<0.0001). The ITBVI increased (P=0.001) in the BCS group only. An increase in cardiac index (CI) and stroke volume index (SVI) was noted in both groups (BCS: CI P=0.003, SVI: P=0.007; CLD: CI P=0.005, SVI P=0.02). The central venous pressure did not change in either group and did not correlate with markers of flow (CI, SVI) or IAP. Both groups demonstrated an inverse relationship between IAP, CI and SVI. Patients with BCS and IAH have evidence of central hypovolaemia. In addition to raised IAP, hepatic venous obstruction and caudate lobe hypertrophy limit venous return in patients with BCS. Reduction in IAP and re-establishment of caval flow restores preload with improvement in CO.

Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients requiring high-dose vasopressor therapy

Arterial pressure waveform analysis of cardiac output (APCO) without external calibration (FloTrac/Vigileo™) is critically dependent upon computation of vascular tone that has necessitated several refinements of the underlying software algorithms. We hypothesized that changes in vascular tone induced by high-dose vasopressor therapy affect the accuracy of APCO measurements independently of the FloTrac software version. In this prospective observational study, we assessed the validity of uncalibrated APCO measurements compared with transpulmonary thermodilution cardiac output (TPCO) measurements in 24 patients undergoing vasopressor therapy for the treatment of cerebral vasospasm after subarachnoid haemorrhage. Patients received vasoactive support with [mean (sd)] 0.53 (0.46) µg kg(-1) min(-1) norepinephrine resulting in mean arterial pressure of 104 (14) mm Hg and mean systemic vascular resistance of 943 (248) dyn s(-1) cm(-5). Cardiac output (CO) data pairs (158) were obtained simultaneously by APCO and TPCO measurements. TPCO ranged from 5.2 to 14.3 litre min(-1), and APCO from 4.1 to 13.7 litre min(-1). Bias and limits of agreement were 0.9 and 2.5 litre min(-1), resulting in an overall percentage error of 29.6% for 68 data pairs analysed with the second-generation FloTrac(®) software and 27.9% for 90 data pairs analysed with the third-generation software. Precision of the reference technique was 2.6%, while APCO measurements yielded a precision of 29.5% and 27.9% for the second- and the third-generation software, respectively. For both software versions, bias (TPCO-APCO) correlated inversely with systemic vascular resistance. In neurosurgical patients requiring high-dose vasopressor support, precision of uncalibrated CO measurements depended on systemic vascular resistance. Introduction of the third software algorithm did not improve the insufficient precision (>20%) for APCO measurements observed with the second software version.

Arterial pressure allows monitoring the changes in cardiac output induced by volume expansion but not by norepinephrine*

To evaluate to which extent the systemic arterial pulse pressure could be used as a surrogate of cardiac output for assessing the effects of a fluid challenge and of norepinephrine. Observational study. Medical intensive care unit. Patients with an acute circulatory failure who received a fluid challenge (228 patients, group 1) or in whom norepinephrine was introduced or increased (145 patients, group 2). We measured the systolic, diastolic, and mean arterial pressure, pulse pressure, and the transpulmonary thermodilution cardiac output before and after the therapeutic interventions. In group 1, the fluid challenge significantly increased cardiac output by 24% ± 25%. It significantly increased cardiac output by ≥15% (+35% ± 27%) in 142 patients ("responders"). The fluid-induced changes in cardiac output were correlated with the changes in pulse pressure (r = .56, p < .0001), systolic arterial pressure (r = .55, p < .0001), diastolic arterial pressure (r = .37, p < .0001), and mean arterial pressure (r = .52, p < .0001). At multivariate analysis, changes in pulse pressure were significantly related to changes in stroke volume (multiple r = .52) and to age (r = .12). A fluid-induced increase in pulse pressure of ≥17% allowed detecting a fluid-induced increase in cardiac output of ≥15% with a sensitivity of 65[56-72]% and a specificity of 85[76-92]%. The area under the receiver operating characteristic curves for the fluid-induced changes in mean arterial pressure and in diastolic arterial pressure was significantly lower than for pulse pressure. In group 2, the introduction/increase of norepinephrine significantly increased cardiac output by 14% ± 18%. The changes in cardiac output induced by the introduction/increase in the dose of norepinephrine were correlated with the changes in pulse pressure and systolic arterial pressure (r = .21 and .29, respectively, p = .001) but to a significantly lesser extent than in group 1. Pulse pressure and systolic arterial pressure could be used for detecting the fluid-induced changes in cardiac output, in spite of a significant proportion of false-negative cases. By contrast, the changes in pulse pressure and systolic arterial pressure were unable to detect the changes in cardiac output induced by norepinephrine.

Effects of Extravascular Lung Water on the Measurement of Transpulmonary Thermodilution Cardiac Output in Acute Respiratory Distress Syndrome Patients

Transpulmonary thermodilution cardiac output is used in calculating aortic impedance for calibrating the pulse-contour analysis and is applied to calculate extravascular lung water (EVLW). Whether pulmonary edema affects the accuracy of transpulmonary thermodilution is controversial. This study aimed to investigate the effects of extravascular lung water index (EVLWI) on the transpulmonary thermodilution measurement in acute respiratory distress syndrome (ARDS). A prospective study. The medical intensive care unit of one medical center. Twenty-four ARDS patients. The continuous pulmonary artery thermodilution cardiac index (CCIpa) and the bolus transpulmonary thermodilution cardiac index (BCItp) data were recorded at baseline and repeated immediately and at 2, 4, and 6 hours after volume expansion with a 500-mL infusion of 10% pentastarch (hydroxyethyl starch 200/0.5) at a rate of 10 mL/kg/h. A total of 120 paired CI measurements were analyzed. Linear regression analysis showed a close correlation between BCItp and CCIpa (R = 0.87). The mean BCItp was higher than CCIpa, and the Bland-Altman analysis revealed a bias of 0.51 ± 0.78 L/min/m(2). The limits of agreement (2 standard deviations) was 1.66 L/min/m(2) (+2.07 and -1.05 L/min/m(2)), and the percentage error was 31.5%. Levels of EVLWI negatively correlated with the difference between BCItp and CCIpa (R = -0.19). In ARDS patients, the agreement between transpulmonary thermodilution and pulmonary artery thermodilution for cardiac output measurement is marginally acceptable. The severity of pulmonary edema expressed as EVLWI weakly and negatively correlates with the difference between BCItp and CCIpa derived from the two techniques.

P10 High troponin I in acute liver failure: a marker of myocardial injury or metabolic stress?

IntroductionALF is a life-threatening multi-system illness resulting from massive hepatic necrosis. Acute liver failure (ALF), in its more severe forms is invariably complicated by progressive haemodynamic disturbances with a pattern...

Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients undergoing triple-H-therapy of cerebral vasospasms after subarachnoidal hemorrhage

The validity of an arterial waveform-based device for measuring cardiac output (CO) without the need for invasive calibration (FloTrac/Vigileo) in patients needing large doses of vasoactive medication has not yet been thoroughly studied. We performed the present study to assess the validity of both the second-generation and the third-generation software compared with transpulmonary thermodilution CO measurement using the PiCCO technology in patients undergoing triple-H-therapy (hypertonia, hypervolemia, hemodilution) of cerebral vasospasms after subarachnoidal hemorrhage.

Transpulmonary versus continuous thermodilution cardiac output after valvular and coronary artery surgery

Residual left-sided valvular insufficiencies after valvular surgery may confound transpulmonary thermodilution cardiac output (COtp). We compared the technique with the continuous right-sided thermodilution technique (CCO) after valvular surgery (n=8) and coronary artery surgery (n=8). Patients with pulmonary and femoral artery catheters in the intensive care unit (ICU) were included. After valvular surgery, there was minimal aortic insufficiency in four patients and minimal to moderate mitral valve insufficiency in six. Five fluid loading steps (250 ml) were done in each patient. CCO and COtp were measured prior to and 15 min after each step. The cardiac output was lower after valvular than coronary artery surgery but responses to fluid loading steps were similar among surgery types and techniques. After valvular and coronary artery surgery, cardiac output was lower prior to responses than in non-responses to fluids, by either technique. After valvular surgery, COtp and CCO correlated (r=0.64, P<0.001, n=48) but fluid-induced changes did not. After coronary artery surgery, COtp and CCO correlated (r=0.81, P<0.001) and changes also did (r=0.55, P<0.001). At fluid-induced CCO increases <20%, the r for changes in cardiac output measured by both techniques was similar after valvular and coronary artery surgery. Thus, COtp and CCO were of similar value in predicting and monitoring fluid responses after both surgery types. This argues against left-sided valvular insufficiencies confounding COtp.