Comparison of pulmonary artery and aortic transpulmonary thermodilution for monitoring of cardiac output in patients with severe heart failure: validation of a novel method

A comparison of hemodynamic measurement methods during orthotopic liver transplantation: evaluating agreement and trending ability of PiCCO versus pulmonary artery catheter techniques

BACKGROUND

Significant hemodynamic changes occur during liver transplantation, emphasizing the importance of precious and continuous monitoring of cardiac output, cardiac index, and other parameters. Although the monitoring of cardiac output by pulse indicator continuous cardiac output (PiCCO) was statistically homogeneous compared to the clinical gold standard pulmonary artery catheterization (PAC) in previous studies of liver transplantation, there are fewer statistical methods for the assessment of its conclusions, and a lack of comparisons of other hemodynamic parameters (e.g., SVRI, systemic vascular resistance index). Some studies have also concluded that the agreement between PiCCO and PAC is not good enough. Overall, there are no uniform conclusions regarding the agreement between PiCCO and PAC in previous studies. This study evaluates the agreement and trending ability of relevant hemodynamic parameters obtained with PiCCO compared to the clinical gold standard PAC from multiple perspectives, employing various statistical methods.

METHODS

Fifty-two liver transplantation patients were included. Cardiac output (CO), cardiac index (CI), SVRI and stroke volume index (SVI) values were monitored at eight time points using both PiCCO and PAC. The results were analyzed by Bland-Altman analysis, Passing-bablok regression, intra-class correlation coefficient (ICC), 4-quadrant plot, polar plot, and trend interchangeability method (TIM).

RESULTS

The Bland-Altman analysis revealed high percentage errors for PiCCO: 54.06% for CO, 52.70% for CI, 62.18% for SVRI, and 51.97% for SVI, indicating poor accuracy. While Passing-Bablok plots showed favorable agreement for SVRI overall and during various phases, the agreement for other parameters was less satisfactory. The ICC results confirmed good overall agreement between the two devices across most parameters, except for SVRI during the new liver phase, which showed poor agreement. Additionally, four-quadrant and polar plot analyses indicated that all agreement rate values fell below the clinically acceptable threshold of over 90%, and all angular deviation values exceeded ± 5°, demonstrating that PiCCO is unable to meet the acceptable trends. Using the TIM, the interchangeability rates were found to be quite low: 20% for CO and CI, 16% for SVRI, and 13% for SVI.

CONCLUSIONS

Our study revealed notable disparities in absolute values of CO, CI, SVRI and SVI between PiCCO and PAC in intraoperative liver transplant settings, notably during the neohepatic phase where errors were particularly pronounced. Consequently, these findings highlight the need for careful consideration of PiCCO's advantages and disadvantages in liver transplantation scenarios, including its multiple parameters (such as the encompassing extravascular lung water index), against its limited correlation with PAC.

Complex Heart-Lung Ventilator Emergencies in the CICU

This review aims to enhance the comprehension and management of cardiopulmonary interactions in critically ill patients with cardiovascular disease undergoing mechanical ventilation. Highlighting the significance of maintaining a delicate balance, this article emphasizes the crucial role of adjusting ventilation parameters based on both invasive and noninvasive monitoring. It provides recommendations for the induction and liberation from mechanical ventilation. Special attention is given to the identification of auto-PEEP (positive end-expiratory pressure) and other situations that may impact hemodynamics and patients' outcomes.

Reliability of Pulse Contour Cardiac Output Analysis in a Piglet Model of Multi-step Intra-abdominal Hypertension

BACKGROUND

Pulse contour cardiac output (PCCO) analysis is a minimally invasive technique for continuous cardiac output (CO) measurement monitoring. PCCO requires calibration by transpulmonary thermodilution (TPTD). Studies showed good agreement between PCCO, TPTD CO and CO measured by pulmonary artery thermodilution (PATD) during stable hemodynamics. However, data are limited in patients with intra-abdominal hypertension (IAH). The objective is to compare the agreement between PCCO, TPTD CO, and PATD CO in a piglet model of multi-step IAH.

MATERIALS AND METHODS

Ten female domestic piglets were enrolled in this study. IAH was induced by stepwise carbon dioxide inflation into peritoneal cavity in anesthetized piglets. Following baseline registrations, intra-abdominal pressure (IAP) was increased and maintained at each IAP plateau of 10, 20, 30, and 40 mmHg for 15 min before CO measurements. CO was measured by PATD and simultaneously by 2 femoral artery PCCO catheters. One PCCO catheter was recalibrated by TPTD at each IAP plateau while the other was only calibrated at baseline.

RESULTS

In pooled data of different IAP stages, TPTD CO and recalibrated PCCO (R-PCCO) showed excellent correlation (r² = 0.94 and 0.93) and small bias (-0.09 and -0.09 L/min), respectively, compared with PATD CO. However, PCCO without recalibration (NR-PCCO) were not accurate during IAH (r² = 0.58, bias: +0.32 L/min). When IAP increased to 30 mmHg, NR-PCCO failed to agree with PATD CO (r² = 0.47, bias: +0.52 L/min). On the contrary, a clinically accepted agreement between TPTD CO, R-PCCO, and PATD CO was observed at different IAP stages.

CONCLUSIONS

TPTD CO and R-PCCO agreed with PATD CO in this piglet model of multi-step IAH. On the contrary, NR-PCCO failed to agree with PATD CO when IAP increased to 30 mmHg or more. PCCO analysis needs recalibration in this condition.

Evaluation of pulse wave transit time analysis for non-invasive cardiac output quantification in pregnant patients

Pregnant patients undergoing minimally-invasive foetoscopic surgery for foetal spina bifida have a need to be subjected to advanced haemodynamic monitoring. This observational study compares cardiac output as measured by transpulmonary thermodilution monitoring with the results of non-invasive estimated continuous cardiac output monitoring. Transpulmonary thermodilution-based pulse contour analysis was performed for usual anaesthetic care, while non-invasive estimated continuous cardiac output monitoring data were additionally recorded. Thirty-five patients were enrolled, resulting in 199 measurement time points. Cardiac output measurements of the non-invasive estimated continuous cardiac output monitoring showed a weak correlation with the corresponding thermodilution measurements (correlation coefficient: 0.44, R2: 0.19; non-invasive estimated continuous cardiac output: 7.4 [6.2-8.1]; thermodilution cardiac output: 8.9 [7.8-9.8]; p ≤ 0.001), while cardiac index experienced no such correlation. Furthermore, neither stroke volume nor stroke volume index correlated with the corresponding thermodilution-based data. Even though non-invasive estimated continuous cardiac output monitoring consistently underestimated the corresponding thermodilution parameters, no trend analysis was achievable. Summarizing, we cannot suggest the use of non-invasive estimated continuous cardiac output monitoring as an alternative to transpulmonary thermodilution for cardiac output monitoring in pregnant patients undergoing minimally-invasive foetoscopic surgery for spina bifida.

Quantitative estimation of extravascular lung water volume and preload by dynamic 15O-water positron emission tomography

AIMS

Left ventricular filling pressure (preload) can be assessed by pulmonary capillary wedge pressure (PCWP) during pulmonary arterial catheterization (PAC). An emerging method [pulse indexed contour cardiac output (PICCO)] can estimate preload by global end-diastolic volume (GEDV) and congestion as extravascular lung water (EVLW) content. However, no reliable quantitative non-invasive methods are available. Hence, in a porcine model of pulmonary congestion, we evaluated EVLW and GEDV by positron emission tomography (PET). The method was applied in 35 heart failure (HF) patients and 9 healthy volunteers.

METHODS AND RESULTS

Eight pigs were studied. Pulmonary congestion was induced by a combination of beta-blockers, angiotensin-2 agonist and saline infusion. PAC, PICCO, computerized tomography, and 15O-H2O-PET were performed. EVLW increased from 521 ± 76 to 973 ± 325 mL (P < 0.001) and GEDV from 1068 ± 170 to 1254 ± 85 mL (P < 0.001). 15O-H2O-PET measures of EVLW increased from 566 ± 151 to 797 ± 231 mL (P < 0.001) and GEDV from 364 ± 60 to 524 ± 92 mL (P < 0.001). Both EVLW and GEDV measured with PICCO and 15O-H2O-PET correlated (r2 = 0.40, P < 0.001; r2 = 0.40, P < 0.001, respectively). EVLW correlated with Hounsfield units (HU; PICCO: r2 = 0.36, P < 0.001, PET: r2 = 0.46, P < 0.001) and GEDV with PCWP (PICCO: r2 = 0.20, P = 0.01, PET: r2 = 0.29, P = 0.002). In human subjects, measurements were indexed (I) for body surface area. Neither EVLWI nor HU differed between chronic stable HF patients and healthy volunteers (P = 0.11, P = 0.29) whereas GEDVI was increased in HF patients (336 ± 66 mL/m2 vs. 276 ± 44 mL/m2, P = 0.01).

CONCLUSION

The present study demonstrates that 15O-H2O-PET can assess pulmonary congestion and preload quantitatively. Hence, prognostic information from 15O-H2O-PET examinations should be evaluated in clinical trials.

Cardiovascular Parameters Associated With Troponin I as Indicators for 14-Day Mortality in Patients With Septic Shock

BACKGROUND

Troponin I is better than other troponin isoforms for monitoring cardiocyte damage, and correlates with sepsis-related mortality. However, hemodynamic factors possibly interact with cardiac function to affect mortality in sepsis. Thus, this study used parameters from pulse-induced contour cardiac output (PiCCO) to investigate the possibility.

METHODS

Patients with troponin I tests and sequential organ failure assessment score ≥2 were selected and divided into survivors and nonsurvivors groups and blood troponin I levels between them were compared. Additionally, 65 patients with septic shock and PiCCO records were selected and divided into high cardiac function index (CFI) and low CFI groups and their cardiac function associated with troponin I levels was checked. Furthermore, the patients were classified into 4 subgroups based on CFI and another hemodynamical parameter of PiCCO for identifying if any interaction between CFI and the parameter existed.

RESULTS

High blood troponin I levels correlated with high mortality, and with low cardiac function (CFI < 4.5) alone or with low CFI combined with high stroke volume variation (SVV), but did not correlate with global end-diastolic index (GEDI), or systemic vascular resistance index. However, only the subgroup with low CFI and high SVV (CFI < 4.5 and SVV > 10) increased mortality.

CONCLUSIONS

Our data give an insight into interactions between cardiac and hemodynamic factors to cause cardiocyte damage and suggest that multiple factors (i.e., low CFI and high SVV) should be considered together to evaluate cardiocyte damage and mortality in sepsis.

Role of PiCCO monitoring for the integrated management of neurogenic pulmonary edema following traumatic brain injury: A case report and literature review

Neurogenic pulmonary edema (NPE) is occasionally observed in patients with traumatic brain injury (TBI); however, this condition is often underappreciated. NPE is frequently misdiagnosed due to its atypical clinical performance, thus delaying appropriate treatment. A comprehensive management protocol of NPE in patients with TBI has yet to be established. The current study reported the case of a 67-year-old man with severe TBI who was transferred to our intensive care unit (ICU). On day 7 after hospitalization, the patient suddenly suffered tachypnea, tachycardia, systemic hypertension and hypoxemia during lumbar cistern drainage. Intravenous diuretics, tranquilizer and glucocorticoid were administered due to suspected left heart failure attack. Chest radiography examination supported the diagnosis of pulmonary edema; however, hypotension and hypovolemia were subsequently observed. Pulse index continuous cardiac output (PiCCO) hemodynamic monitoring and bedside echocardiography were performed, which excluded the diagnosis of cardiac pulmonary edema, and thus the diagnosis of NPE was confirmed. Goal-directed therapy by dynamic PiCCO monitoring was then implemented. In addition, levosimendan, an inotropic agent, was introduced to improve cardiac output. The patient had complete recovered from pulmonary edema and regained consciousness on day 11 of hospitalization. The current case demonstrated that PiCCO monitoring may serve a central role in the integrated management of NPE in patients with TBI. Levosimendan may be a potential medicine in treating cardiac dysfunction, along with its benefit from improving neurological function in NPE patients.

Similar hemodynamic decongestion with vasodilators and inotropes: systematic review, meta-analysis, and meta-regression of 35 studies on acute heart failure

BACKGROUND

Acute heart failure (AHF) with reduced left-ventricular ejection fraction (LVEF) is often a biventricular congested state. The comparative effect of vasodilators and inotropes on the right- and/or left-sided congestion is unknown.

METHODS AND RESULTS

A systematic review, meta-analysis, and meta-regression of AHF studies using pulmonary artery catheter were performed using PubMed, Embase, and Cochrane library. Data from 35 studies, including 3016 patients, were studied. Included patients had a weighted mean age of 60 years, left-ventricular ejection fraction (LVEF) of 24 %, and plasma B-type natriuretic peptide (BNP) of 892 pg/ml. Both the left- and right-ventricular filling pressures were elevated: weighted mean pulmonary artery wedge pressure (PAWP) was 25 mmHg (range 17-31 mmHg) and right atrial pressure (RAP) 12 mmHg (range 7-18 mmHg). Vasodilators and inotropes had similar beneficial effects on PAWP [-6.3 mmHg (95 % CI -7.4 to -5.2 mmHg) and -5.8 mmHg (95 % CI -7.6 to -4.0 mmHg), respectively] and RAP [-2.9 mmHg (95 % CI -3.8 to -2.1 mmHg) and -2.8 mmHg (95 % CI -3.8 to -1.7 mmHg), respectively]. Among inotropes, inodilators, such as levosimendan, have greater beneficial effect on the left-ventricular filling pressure than dobutamine. Drug-induced improvement of PAWP tightly paralleled that of RAP with all studied drugs (r ² = 0.90, p < 0.001). Vasodilators and inotropes had no short-term effect of renal function.

CONCLUSION

The left- and right-sided filling pressures are similarly improved by vasodilators or inotropes, in AHF with reduced LVEF.

Pulse waveform hemodynamic monitoring devices: recent advances and the place in goal-directed therapy in cardiac surgical patients

Hemodynamic monitoring has evolved and improved greatly during the past decades as the medical approach has shifted from a static to a functional approach. The technological advances have led to innovating calibrated or not, but minimally invasive and noninvasive devices based on arterial pressure waveform (APW) analysis. This systematic clinical review outlines the physiologic rationale behind these recent technologies. We describe the strengths and the limitations of each method in terms of accuracy and precision of measuring the flow parameters (stroke volume, cardiac output) and dynamic parameters which predict the fluid responsiveness. We also analyzed the place of the APW monitoring devices in goal-directed therapy (GDT) protocols in cardiac surgical patients. According to the data from the three GDT-randomized control trials performed in cardiac surgery (using two types of APW techniques PiCCO and FloTrac/Vigileo), these devices did not demonstrate that they played a role in decreasing mortality, but only decreasing the ventilation time and the ICU and hospital length of stay.

Accuracy of an autocalibrated pulse contour analysis in cardiac surgery patients: a bi-center clinical trial

BACKGROUND

Less-invasive and easy to install monitoring systems for continuous estimation of cardiac index (CI) have gained increasing interest, especially in cardiac surgery patients who often exhibit abrupt haemodynamic changes. The aim of the present study was to compare the accuracy of CI by a new semi-invasive monitoring system with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB).

METHODS

Sixty-five patients (41 Germany, 24 Spain) scheduled for elective coronary surgery were studied before and after CPB, respectively. Measurements included CI obtained by transpulmonary thermodilution (CITPTD) and autocalibrated semi-invasive pulse contour analysis (CIPFX). Percentage changes of CI were also calculated.

RESULTS

There was only a poor correlation between CITPTD and CIPFX both before (r (2) = 0.34, p < 0.0001) and after (r (2) = 0.31, p < 0.0001) CPB, with a percentage error (PE) of 62 and 49 %, respectively. Four quadrant plots revealed a concordance rate over 90 % indicating an acceptable correlation of trends between CITPTD and CIPFX before (concordance: 93 %) and after (concordance: 94 %) CPB. In contrast, polar plot analysis showed poor trending before and an acceptable trending ability of changes in CI after CPB.

CONCLUSIONS

Semi-invasive CI by autocalibrated pulse contour analysis showed a poor ability to estimate CI compared with transpulmonary thermodilution. Furthermore, the new semi-invasive device revealed an acceptable trending ability for haemodynamic changes only after CPB.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02312505 Date: 12.03.2012.

[Hemodynamic monitoring in the critically patient. Recomendations of the Cardiological Intensive Care and CPR Working Group of the Spanish Society of Intensive Care and Coronary Units]

Hemodynamic monitoring offers valuable information on cardiovascular performance in the critically ill, and has become a fundamental tool in the diagnostic approach and in the therapy guidance of those patients presenting with tissue hypoperfusion. From introduction of the pulmonary artery catheter to the latest less invasive technologies, hemodynamic monitoring has been surrounded by many questions regarding its usefulness and its ultimate impact on patient prognosis. The Cardiological Intensive Care and CPR Working Group (GTCIC-RCP) of the Spanish Society of Intensive Care and Coronary Units (SEMICYUC) has recently impulsed the development of an updating series in hemodynamic monitoring. Now, a final series of recommendations are presented in order to analyze essential issues in hemodynamics, with the purpose of becoming a useful tool for residents and critical care practitioners involved in the daily management of critically ill patients.

Monitoring cardiac function: echocardiography, pulse contour analysis and beyond

Haemodynamic monitoring has developed considerably over the last decades, nowadays comprising a wide spectrum of different technologies ranging from invasive to completely non-invasive techniques. At present, the evidence to continuously measure and optimise stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion in the perioperative setting and consequently to improve patients' outcome is substantial. Surprisingly, there is a striking discrepancy between the developments in advanced haemodynamic monitoring combined with evidence-based knowledge on the one hand and daily clinical routine on the other hand. Recent trials have shown that perioperative mortality is higher than anticipated, emphasising the need for the speciality of anaesthesiology to face the problem and to translate proven concepts into clinical routine to improve patients' outcome. One basic principle of these concepts is to monitor and to optimise cardiac function by means of advanced haemodynamic monitoring, using echocardiography, pulse contour analysis and beyond.

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

BACKGROUND

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).

METHODS

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).

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

Diagnostic study, level II.

Pulmonary artery vs. transpulmonary thermodilution for the assessment of cardiac output in mitral regurgitation: a prospective observational study

CONTEXT

With increasing prevalence of mitral regurgitation, even noncardiac anaesthesiologists will be confronted by this disorder and will need to be familiar with the extended haemodynamic monitoring required. The assessment of cardiac output (CO) measured by transpulmonary thermodilution (COTP) has become an accepted alternative to the CO measured by thermodilution via pulmonary artery catheter (COPAC). However, the integrity of COTP in severe mitral regurgitation requires systematic evaluation.

OBJECTIVE

This study was designed to test the hypothesis that transpulmonary thermodilution is compromised by severe mitral regurgitation.

DESIGN

Prospective method comparison study.

SETTING

Single university-affiliated hospital.

PARTICIPANTS

Thirty patients with mitral regurgitation undergoing elective mitral valve repair.

MAIN OUTCOME MEASURE

COTP and COPAC were determined in triplicate after induction of anaesthesia, and at the end of surgery after closure of the chest. The methods were compared using bias and precision statistics.

RESULTS

Echocardiography revealed severe mitral regurgitation in most patients (n  =  27) after induction of anaesthesia. The least significant change in COTP (the minimum change in COTP required to detect a real change with a probability of 95%) was increased under the condition of mitral regurgitation (15.4  ±  10.2% after anaesthesia induction vs. 9.3  ±  5.9% after valve repair, P = 0.008), whereas it remained constant in COPAC (9.6  ±  5.4 vs. 8.5  ±  7.2%, P = 0.55). There was no significant bias between COTP and COPAC after anaesthesia induction [mean CO, 4.03 ± 0.92 l  min; bias 0.12 l  min (95% confidence interval, CI, -0.073 to 0.311)], and after valve repair [mean CO 7.47  ±  1.44 l  min; bias 0.045 l  min (95% CI, -0.147 to 0.237)]. The percentage error was 28.4 and 13.6%, respectively.

CONCLUSION

The results suggest that even severe mitral regurgitation has no significant impact on the accuracy of COTP. The precision of COTP was reduced under the condition of mitral regurgitation.

The estimation of cardiac output by the Nexfin device is of poor reliability for tracking the effects of a fluid challenge

Introduction

The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CI_noninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge.

Methods

We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CI_inv, PiCCO device) and in CI_noninv were recorded.

Results

In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CI_inv and CI_noninv was 0.2 (-1.8 to 2.2) L/min/m². The mean change in CI_noninv was 10 ± 11%. The percentage error of CI_noninv was 57%. The correlation between the changes in CI_inv and CI_noninv observed during volume expansion was significant (P = 0.0002) with an r² = 0.31.

Conclusions

The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion.

A comparison of third-generation semi-invasive arterial waveform analysis with thermodilution in patients undergoing coronary surgery

Uncalibrated semi-invasive continous monitoring of cardiac index (CI) has recently gained increasing interest. The aim of the present study was to compare the accuracy of CI determination based on arterial waveform analysis with transpulmonary thermodilution. Fifty patients scheduled for elective coronary surgery were studied after induction of anaesthesia and before and after cardiopulmonary bypass (CPB), respectively. Each patient was monitored with a central venous line, the PiCCO system, and the FloTrac/Vigileo-system. Measurements included CI derived by transpulmonary thermodilution and uncalibrated semi-invasive pulse contour analysis. Percentage changes of CI were calculated. There was a moderate, but significant correlation between pulse contour CI and thermodilution CI both before (r² = 0.72, P < 0.0001) and after (r² = 0.62, P < 0.0001) CPB, with a percentage error of 31% and 25%, respectively. Changes in pulse contour CI showed a significant correlation with changes in thermodilution CI both before (r² = 0.52, P < 0.0001) and after (r² = 0.67, P < 0.0001) CPB. Our findings demonstrated that uncalibrated semi-invasive monitoring system was able to reliably measure CI compared with transpulmonary thermodilution in patients undergoing elective coronary surgery. Furthermore, the semi-invasive monitoring device was able to track haemodynamic changes and trends.

Pulmonary artery catheter monitoring in 2011

PURPOSE OF REVIEW

Hemodynamic monitoring has gained widespread acceptance in intensive care units. Despite ongoing debate regarding its safety and efficacy, monitoring with the pulmonary artery catheter (PAC) remains used for the management of severe heart failure and shock.

RECENT FINDINGS

To reanalyze using the most recently published literature in the field, the role of the PAC to manage critically ill patients with right ventricular failure, pulmonary hypertension and weaning failure from cardiac origin. The role of PAC as a gold standard to validate new cardiac output monitoring devices was also reported.

SUMMARY

Despite competition with less invasive hemodynamic monitoring devices or ultrasonic methods, the PAC remains a useful monitoring device in situations in which the knowledge of pulmonary artery pressure, pulmonary artery occlusion pressure and oxygenation parameters are needed. The proper use of PAC requires, however, a perfect knowledge of the numerous pitfalls and difficulties in interpretation of its measurements.

Precision of the transpulmonary thermodilution measurements

Introduction

We wanted to determine the number of cold bolus injections that are necessary for achieving an acceptable level of precision for measuring cardiac index (CI), indexed global end-diastolic volume (GEDVi) and indexed extravascular lung water (EVLWi) by transpulmonary thermodilution.

Methods

We included 91 hemodynamically stable patients (age 59 (25% to 75% interquartile range: 39 to 79) years, simplified acute physiologic score (SAPS)II 59 (53 to 65), 56% under norepinephrine) who were monitored by a PiCCO2 device. We performed five successive cold saline (15 mL, 6°C) injections and recorded the measurements of CI, GEDVi and EVLWi.

Results

Considering five boluses, the coefficient of variation (CV, calculated as standard deviation divided by the mean of the five measurements) was 7 (5 to 11)%, 7 (5 to 12)% and 7 (6 to 12)% for CI, GEDVi and EVLWi, respectively. If the results of two bolus injections were averaged, the precision (2 × CV/√ number of boluses) was 10 (7 to 15)%, 10 (7 to 17)% and 8 (7 to 14)% for CI, GEDVi and EVLWi, respectively. If the results of three bolus injections were averaged, the precision dropped below 10%, that is, the cut-off that is generally considered as acceptable (8 (6 to 12)%, 8 (6 to 14)% and 8 (7 to 14)% for CI, GEDVi and EVLWi, respectively). If two injections were performed, the least significant change, that is, the minimal change in value that could be trusted to be significant, was 14 (10 to 21)%, 14 (10 to 24)% and 14 (11 to 23)% for CI, GEDVi and EVLWi, respectively. If three injections were performed, the least significant change was 12 (8 to 17)%, 12 (8 to 19)% and 12 (9 to 19)% for CI, GEDVi and EVLWi, respectively, that is, below the 15% cut-off that is usually considered as clinically relevant.

Conclusions

These results support the injection of at least three cold boluses for obtaining an acceptable precision when transpulmonary thermodilution is used for measuring CI, GEDVi and EVLWi.

Methods in pharmacology: measurement of cardiac output

Many methods of cardiac output measurement have been developed, but the number of methods useful for human pharmacological studies is limited. The 'holy grail' for the measurement of cardiac output would be a method that is accurate, precise, operator independent, fast responding, non-invasive, continuous, easy to use, cheap and safe. This method does not exist today. In this review on cardiac output methods used in pharmacology, the Fick principle, indicator dilution techniques, arterial pulse contour analysis, ultrasound and bio-impedance are reviewed.

Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery

Introduction

Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB).

Methods

Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CI_TPTD) or CI derived by pulse power analysis (CI_PP), before and after calibration (CI_PPnon-cal., CI_PPcal.). Percentage changes of CI (ΔCI_TPTD, ΔCI_{PPnon-cal./PPcal.}) were calculated to analyse directional changes.

Results

Before CPB there was no significant correlation between CI_PPnon-cal. and CI_TPTD (r² = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CI_PPnon-cal. (r² = 0.26, P < 0.0001). After CPB, CI_PPcal. revealed a significant correlation compared with CI_TPTD (r² = 0.77, P < 0.0001) with PE of 28%. Changes in CI_PPcal. (ΔCI_PPcal.) showed a correlation with changes in CI_TPTD (ΔCI_TPTD) only after CPB (r² = 0.52, P = 0.005).

Conclusions

Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

Effects of extravascular lung water on the measurement of transpulmonary thermodilution cardiac output in acute respiratory distress syndrome patients

OBJECTIVE

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).

DESIGN

A prospective study.

SETTING

The medical intensive care unit of one medical center.

PARTICIPANTS

Twenty-four ARDS patients.

INTERVENTIONS

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.

MEASUREMENTS AND MAIN RESULTS

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).

CONCLUSION

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.

Cardiac output monitoring using indicator-dilution techniques: basics, limits, and perspectives

The ability to monitor cardiac output is one of the important cornerstones of hemodynamic assessment for managing critically ill patients at increased risk for developing cardiac complications, and in particular in patients with preexisting cardiovascular comorbidities. For >30 years, single-bolus thermodilution measurement through a pulmonary artery catheter for assessment of cardiac output has been widely accepted as the "clinical standard" for advanced hemodynamic monitoring. In this article, we review this clinical standard, along with current alternatives also based on the indicator-dilution technique, such as the transcardiopulmonary thermodilution and lithium dilution techniques. In this review, not only the underlying technical principles and the unique features but also the limitations of each application of indicator dilution are outlined.