Preload and haemodynamic assessment during liver transplantation: a comparison between the pulmonary artery catheter and transpulmonary indicator dilution techniques

Utility of the central venous-to-arterial CO2 difference to predict adverse outcomes after liver transplantation

OBJECTIVE

Test whether the development of abnormal venous-to arterial CO₂ difference (ΔPCO₂) during the early phases of postoperative care after a liver transplantation (LT) is related to multi-organ dysfunction and outcomes.

MATERIALS AND METHODS

Prospective cohort study accomplished in a mixed intensive care unit (ICU) at a university hospital. We included 150 eligible patients after a LT between 2015 and 2018. Patients were classified in four predefined groups according to the ΔPCO₂ evolution during the first 6 h of resuscitation: (1) persistently normal ΔPCO₂ (normal at T0 and T6); (2) decreasing ΔPCO₂ (high at T0, normal at T6); (3) increasing ΔPCO₂ (normal at T0, high at T6); and (4) persistently high ΔPCO₂ (high at T0 and T6). Multiorgan dysfunction at day-3 was compared for predefined groups and a Kaplan Meier curve was constructed to show the survival probabilities using a log-rank test to evaluate differences between groups. A Spearman-Rho was used to test the agreement between cardiac output and ΔPCO₂.

RESULTS

There were no significant differences between the study groups regarding higher SOFA scores at day-3 (P = .86), Δ-SOFA (P = .088), as well as global mortality rates (χ² = 5.72; P = .126) and mortality rates at day-30 (χ² = 2.23; P = .5252). A significantly poor inverse agreement between cardiac output and ΔPCO₂ was observed (r2 -0,17; P = ,002) at different points of resuscitation.

CONCLUSIONS

After a LT, central venous-to-arterial CO2 difference was not associated with survival or postoperative adverse outcomes in a critical care patients population.

What is the optimal anesthetic monitoring regarding immediate and short-term outcomes after liver transplantation?-A systematic review of the literature and expert panel recommendations

BACKGROUND

Liver transplant centers vary in approach to intraoperative vascular accesses, monitoring of cardiac function and temperature management. Evidence is limited regarding impact of selected modalities on postoperative outcomes.

OBJECTIVES

To review the literature and provide expert panel recommendations on optimal intraoperative arterial blood pressure (BP), central venous pressure (CVP), and vascular accesses, monitoring of cardiac function and intraoperative temperature management regarding immediate and short-term outcomes after orthotopic liver transplant (OLT).

METHODS

Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. Recommendations made for: (1) Vascular accesses, arterial BP and CVP monitoring, (2) cardiac function monitoring, and (3) Intraoperative temperature management (CRD42021239908).

RESULTS

Of 2619 articles screened 16 were included. Studies were small, retrospective, and observational. Vascular access studies demonstrated low rates of insertion complications. TEE studies demonstrated low rates of esophageal hemorrhage. One study found lower hospital-LOS and 30-day mortality in patients monitored with both PAC and TEE. Other monitoring studies were heterogenous in design and outcomes. Temperature studies showed increased blood transfusion and ventilation times in hypothermic groups.

CONCLUSIONS

Recommendations were made for; routine arterial and CVP monitoring as a minimum standard of practice, consideration of discrepancy between peripheral and central arterial BP in patients with hemodynamic instability and high vasopressor requirements, and routine use of high flow cannulae while monitoring for extravasation and hematoma formation. Availability and expertise in PAC and/or TEE monitoring is strongly recommended particularly in hemodynamic instability, portopulmonary HT and/or cardiac dysfunction. TEE use is recommended as an acceptable risk in patients with treated esophageal varices and is an effective diagnostic tool for emergency cardiovascular collapse. Maintenance of intraoperative normothermia is strongly recommended.

Extravascular Lung Water and Intrathoracic Blood Volume Index Are Associated With Liver Function in Brain Dead Donors for Organ Transplant

OBJECTIVES

Hemodynamic measurements during organ transplant procedures are essential.

MATERIALS AND METHODS

In this observational study, we measured clinical and hemodynamic parameters in 11 patients with advanced pulse indicator continuous cardiac output monitoring. Normally distributed clinical data were calculated as means ± standard deviation; hemodynamic, metabolic, and respiratory parameters related to liver and renal function were compared by linear regression analysis using Pearson correlation.

RESULTS

Compared with the normal range, systemic vascular resistance was high (2278.02 ± 719.6 dyne·s/cm²/m²) and intrathoracic blood volume was low (787.37 ± 224.01 mL/m²) in our patient group. C-reactive protein and interleukin 6 levels were 96.26 ± 68.10 mg/mL and 246.24 ± 355.74 mmol/L, respectively. Liver and renal function parameters were in normal ranges. Extravascular lung water was correlated with total, conjugated, and unconjugated bilirubin and albumin (r = 0.342/P = .005; r = 0.338/ P = .005; r = 0.394/P = .001, and r = 0.358/P = .003) but not with aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Intrathoracic blood volume index was correlated with total bilirubin, unconjugated bilirubin, and albumin (r = 0.324/P = .007; r = 0.394/P = .001, and r = 0.296/P = .015) but not with conjugated bilirubin, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Lactate was not correlated with total bilirubin, unconjugated bilirubin, albumin, and serum creatinine, but base excess was correlated with total bilirubin, unconjugated bilirubin, alanine aminotransferase, and albumin. PO₂ and Pco₂ were not correlated with liver function, although PO₂ was correlated with albumin.

CONCLUSIONS

No correlations were shown between intrathoracic blood volume index, extravascular lung water, and liver function, but metabolic parameters, including base excess and lactate, were correlated with liver function. Pulse indicator continuous cardiac output monitoring may be a useful method to assess organ function and tissue perfusion in organ transplant.

Accuracy of dynamic preload variables for predicting fluid responsiveness in patients with pediatric liver cirrhosis: A prospective study

BACKGROUND

We have previously reported that dynamic preload variables predicted fluid responsiveness in adult patients with liver cirrhosis. However, pediatric patients with cirrhosis may present with unique hemodynamic characteristics, and therefore, the predictive accuracy of these variables in such patients must be clarified.

AIMS

To investigate the accuracy of dynamic preload variables for predicting fluid responsiveness in pediatric patients with cirrhosis.

METHODS

A total of 27 pediatric patients with cirrhosis undergoing orthotopic liver transplantation were enrolled in this study. Patients' pulse pressure variation, stroke volume variation, stroke volume index, and central venous pressure were measured using the calibrated pulse contour cardiac output system. The plethysmographic variability index was measured using a Masimo Radical 7 co-oximeter. During the hepatic dissection phase of the surgery, repeated intraoperative fluid challenges with 10 mL kg^-1 of crystalloid within 15 minutes were administered. Fluid responsiveness was defined as an increase in stroke volume index of ≥15% after fluid challenge.

RESULTS

A total of 61 fluid challenges were administered resulting in 15 fluid responders and 46 fluid nonresponders. Fluid challenge induced significant decreases in all three dynamic preload variables but not in the fluid nonresponders. However, the area under the receiver operating characteristic curves for pulse pressure variation, stroke volume variation, plethysmographic variability index, and central venous pressure for predicting fluid responsiveness were 0.67 (95% confidence interval: 0.52-0.82; P = .0255), 0.68 (95% confidence interval: 0.54-0.83; P = .0140), 0.56 (95% confidence interval: 0.40-0.71; P = .4724), and 0.57 (95% confidence interval: 0.40-0.74; P = .4192), respectively.

CONCLUSIONS

Dynamic preload variables do not predict fluid responsiveness in pediatric patients with liver cirrhosis.

Association between Early Acute Respiratory Distress Syndrome after Living-Donor Liver Transplantation and Perioperative Serum Biomarkers: The Role of Club Cell Protein 16

Background

Acute respiratory distress syndrome (ARDS) after living-donor liver transplantation (LDLT) is not uncommon, but it lacks the biomarkers for early detection. Club cell protein 16 (CC16), high-motility group box 1 protein (HMGB1), interleukin-1β (IL-1β), and IL-10 have been reported as relevant to the development of ARDS. However, they have not been investigated during LDLT.

Methods

Seventy-three consecutive recipients undergoing LDLT were enrolled and received the same perioperative care plan. Perioperative serum CC16, HMGB1, IL-1β, and IL-10 levels were measured at the pretransplant state, 30 minutes after reperfusion, postoperative day 1 (POD1), and POD3. ARDS was diagnosed according to the 2012 Berlin definition.

Results

Of the 73 recipients, 13 developed ARDS with significantly longer durations of mechanical ventilation and intensive care unit stay. Serum CC16 levels on POD1 increased significantly from the pretransplant state in the ARDS group but not in the non-ARDS group. Pretransplant serum CC16 levels were also higher in the ARDS group. The area under the receiver operating characteristic curves for POD1 serum CC16 levels used to discriminate ARDS was 0.803 (95% confidence interval: 0.679 to 0.895; p < 0.001). By comparison, HMGB1, IL-1β, and IL-10 were not associated with ARDS after LDLT.

Conclusion

The higher pretransplant serum CC16 level and its increased level on POD1 were associated with the development of early ARDS after LDLT. This trial is registered with NCT01936545, 27 August 2013.

Assessment of fluid responsiveness by inferior vena cava diameter variation in post-pneumonectomy patients

Aim

First, the inferior vena cava dilatation index (DIVC) was measured by ultrasound, and then the reliability of DIVC as an indicator to predict volume responsiveness in patients undergoing mechanical ventilation after pneumonectomy was evaluated.

Methods

Pulse indicator continuous cardiac output (Picco) as gold standard was performed to sedated mechanically ventilated post‐pneumonectomy patients in intensive care unit of Nanjing Thoracic Hospital from August 2014 to December 2016. Meanwhile, ultrasound measurement to inferior vena cava (IVC) diameter at the end inspiration (D_max) and the end of expiration (D_min) was performed. DIVC = (D_max − D_min)/D_min. Above values were recorded at baseline and then after fluid resuscitation challenge (7 mL/kg hydroxyethyl starch). An increase in cardiac index of more than 15% was used as the standard for fluid responsiveness. Patients were divided into responsive group and non‐responsive group. A receiver operating characteristic (ROC) curve was then used to determine the sensitivity and specificity of DIVC in predicting fluid responsiveness after pneumonectomy.

Results

Eighteen patients were enrolled. 10 patients were divided into responsive group and eight in non‐responsive group. DIVC in responsive group was significantly higher than in non‐responsive group (P < 0.01). By setting DIVC ≥ 15% as a measure of fluid responsiveness, sensitivity was 81.8% and specificity was 85.7%.

Conclusion

DIVC is a reliable indicator of capacity responsiveness in mechanically ventilated post‐pneumonectomy patients.

Prediction of Fluid Responsiveness by a Non-invasive Respiratory Systolic Time Interval Variation Using Heart Sound Signals in Recipients Undergoing Liver Transplantation

BACKGROUND

The fluid management of cirrhotic patients undergoing liver transplantation (LT) is challenging. Phonocardiography, a graphic recording of heart sounds, provides valuable information concerning heart function and hemodynamic condition. We assessed whether the systolic time interval (STI) and its respiratory variation could predict fluid responsiveness in cirrhotic patients undergoing LT.

METHODS

Thirty LT recipients who needed volume expansion were included. The fluid challenge consisted of 500 mL 5% albumin administered over a period of 10 minutes. STI was measured as the time interval between the maximal amplitude of each heart sound corrected with the corresponding RR interval (cSTI). The respiratory variation in STI (STV) induced by mechanical ventilation was calculated. Responders were defined as those showing a ≥10% increase in stroke volume index after volume expansion.

RESULTS

In all, 14 of the 30 patients were responders. Significant increases in cSTI were observed after volume expansion in both responders (P < .001) and non-responders (P = .008). Responders showed significant decreases in STV (11.1% ± 4.3% vs 6.1% ± 2.6%, P < .001) after fluid loading, whereas STV in non-responders remained unchanged (6.4% ± 2.6% vs 6.4% ± 4.2%, P = .86). A cut-off value of ≥7.5% STV from baseline could predict fluid responsiveness with an area under the receiver operating characteristic curve of 0.804 (95% confidence interval, 0.618-0.925).

CONCLUSIONS

Intra-operative STV can predict fluid responsiveness in patients undergoing LT. Beat-to-beat monitoring of STI and STV may be useful as a non-invasive hemodynamic index and for fluid management.

Anaesthesia and intensive care for simultaneous liver-kidney transplantation: A single-centre experience with 12 recipients

Background and Aims:

The perioperative management of patients presenting for simultaneous liver and kidney transplantation (SLKT) is a complex process. We analysed SLKTs performed in our institution to identify preoperative, intraoperative and post-operative challenges encountered in the management.

Methods:

We retrospectively studied the case records of 12 patients who underwent SLKT between 2009 and 2014 and analysed details of pre-operative evaluation and optimisation, intraoperative anaesthetic management and the implications of use of perioperative continuous renal replacement therapy (CRRT) and the post-operative course of these patients.

Results:

Of the total 12 cases, 4 were under 16 years of age. The indications for SLKT were primary hyperoxaluria (5), congenital hepatic fibrosis with polycystic kidney disease (2), ethanol-related end-stage liver disease (ESLD) with hepatorenal syndrome type 1 (1). Four patients had ESLD with end-stage renal disease due to other causes. Six recipients received live donor grafts and 6 patients received cadaveric grafts. Seven patients received intraoperative CRRT. Mean duration of surgery was 12.5 h. Cardiac output monitors used were trans-oesophageal echocardiogram (2), pulmonary artery catheter (1) and pulse contour cardiac output monitor (3). There was 1 sepsis-related mortality on 7^th post-operative day.

Conclusion:

A thorough pre-operative evaluation and optimisation, knowledge and anticipation of potential problems, and meticulous intraoperative fluid management guided by appropriate monitoring and use of CRRT when needed can help in achieving successful outcomes.

Evaluation of pleth variability index as a predictor of fluid responsiveness during orthotopic liver transplantation

Fluid management is challenging and still remains controversial in orthotopic liver transplantation (OLT). The pleth variability index (PVI) has been shown to be a reliable predictor of fluid responsiveness of perioperative and critically ill patients; however, it has not been evaluated in OLT. This study was designed to examine whether the PVI can reliably predict fluid responsiveness in OLT and to compare PVI with other hemodynamic indexes that are measured using the PiCCO2 monitoring system. Twenty-five patients were enrolled in this study. Each patient was monitored using the noninvasive Masimo and PiCCO2 monitoring system. PVI was obtained with a Masimo pulse oximeter. Cardiac index was obtained using a transpulmonary thermodilution technique (CITPTD). Stroke volume variation (SVV), pulse pressure variation, and systemic vascular resistance index were measured using the PiCCO2 system. Fluid loading (10 mL/kg colloid) was performed at two different phases during the operation, and fluid responsiveness was defined as an increase in CITPTD ≥ 15%. During the dissection phase and the anhepatic phase, respectively, 14 patients (56%) and 18 patients (75%) were classified as responders. There were no differences between the baseline values of the PVI of responders and nonresponders. Area under the curve for PVI was 0.56 (sensitivity 35%, specificity 90%, p = 0.58) at dissection phase, and was 0.55 (sensitivity 55%, specificity 66%, p = 0.58) at anhepatic phase. Of the parameters, a higher area under the curve value was found for SVV. We conclude that PVI was unable to predict fluid responsiveness with sufficient accuracy in patients undergoing OLT, but the SVV parameter was reliable.

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.

Ultrasonographic measurements of the inferior vena cava variation as a predictor of fluid responsiveness in patients undergoing anesthesia for surgery

BACKGROUND

Both hypovolemia and hypervolemia are connected with increased morbidity and mortality in the treatment and prognosis of patients. An accurate assessment of volume state allows the optimization of organ perfusion and oxygen supply. Recently, ultrasonography has been used to detect hypovolemia in critically ill patients and perioperative patients. The objective of our study was to assess the correlation between inferior vena cava (IVC) variation obtained with ultrasound and stroke volume variation (SVV) measured by the Vigileo/FloTrac monitor, as fluid responsiveness indicators, in patients undergoing anesthesia for surgery.

METHODS

Forty patients (American Society of Anesthesiologists grades I and II) scheduled for elective gastrointestinal surgery were enrolled in our study. After anesthesia induction, 6% hydroxyethyl starch solution was administered to patients as an intravenous (IV) fluid. The IVC diameters were measured with ultrasonography. SVV and stroke volume index (SVI) were obtained from the Vigileo monitor. All data were collected both before and after fluid challenge.

RESULTS

Forty patients underwent IVC sonographic measurements and SVV calculation. After fluid challenge, mean arterial pressure, central venous pressure, SVI, and IVC diameters increased significantly, whereas SVV decreased markedly. The correlation coefficient between the increase in SVI and the baseline of IVC variation after an IV fluid was 0.710, and receiver operating characteristic (ROC) curve was 0.85. The correlation coefficient between the increase in SVI and the baseline of SVV was 0.803 with an ROC curve of 0.93. Central venous pressure had no significant correlation with SVI.

CONCLUSIONS

Our data show that IVC variation and SVV proved to be reliable predictors of fluid responsiveness in patients undergoing anesthesia for surgery with mechanical ventilation.

A hemodynamic, metabolic and histopathological study of a heterotopic auxiliary swine liver graft with portal vein arterialization

BACKGROUND

Auxiliary heterotopic liver transplantation with portal vein arterialization (AHLT-PVA) is a model that has been hardly studied, despite its therapeutic potential.

METHODS

Hemodynamic and biochemical characterization was carried out during graft implantation, in a pig-to-pig model (n=15 AHLT-PVA). Furthermore a histopathological study was performed to establish microscopic alterations due to PVA.

RESULTS

Reperfusion of the arterialized graft produced an increase in heart rate (HR) vs. baseline (P=.004) and vs. inferior vena cava clamping phase (P=.004); and a decrease in systemic vascular resistance vs. cava clamping phase (P=.021). At the end of implantation, cardiac output remained elevated (P=.001), likewise HR remained increased vs. baseline phase (P=.002). Mean arterial pressure decreased with cava clamping, but was not affected by the reperfusion of the graft, nor the skin closure. The histopathological study at 3, 10, and 21 days post-PVA revealed that functional liver structure was maintained although it is common to find foci of perilobular necrosis on day 3 (P=.049), and perilobular connective tissue proliferation at day 10 (P=.007), vs. native liver.

CONCLUSIONS

The described arterialized liver graft model minimizes the number of vascular anastomoses vs. previously described models. It is hemodynamically and metabolically well tolerated and the double arterial vascularization of the graft does not cause significant changes in liver histology.

The safety of transesophageal echocardiography in patients undergoing orthotopic liver transplantation

OBJECTIVE

To evaluate the safety of transesophageal echocardiography for the evaluation and intraoperative monitoring of patients during orthotopic liver transplantation.

DESIGN

Retrospective observational study.

SETTING

Tertiary care, university teaching hospital.

PARTICIPANTS

Patients (n = 116) who underwent intraoperative transesophageal echocardiography during liver transplantation.

INTERVENTIONS

Intraoperative transesophageal echocardiography during liver transplantation.

MEASUREMENTS AND MAIN RESULTS

The authors evaluated the safety of intraoperative transesophageal echocardiography in patients undergoing liver transplantation through a retrospective chart review. Complications associated with transesophageal echocardiography use were divided into minor and major complications. Out of 116 patients who underwent intraoperative transesophageal echocardiography, there was one minor and one major complication. The major complication rate was 0.86% (1/116) and the overall complication rate was 1.7% (2/116). There was no statistically significant correlation between pre-transplant sclerotherapy for treatment of varices and intraoperative transesophageal echocardiography-related gastrointestinal bleeding. Although the reported complication rate is higher than what has been quoted in the cardiac literature, intraoperative transesophageal echocardiography during liver transplantation has a low complication rate.

CONCLUSIONS

Intraoperative transesophageal echocardiography is a relatively safe method of monitoring cardiac performance in liver transplant patients.

Is stroke volume variation a useful preload index in liver transplant recipients? A retrospective analysis

BACKGROUND

The right ventricular end-diastolic volume index (RVEDVI) is a good indicator of preload in patients undergoing liver transplantation. Although dynamic indices, such as stroke volume variation (SVV), have been used as reliable indicators in predicting fluid responsiveness, the evaluation of the relationship between SVV and direct preload status is limited. We investigated the relationship between SVV and RVEDVI, and tested the cutoff value of SVV to predict RVEDVI during liver transplantation.

METHODS

A total of 150 data pairs in 30 living donor liver transplant recipients were retrospectively investigated. Hemodynamic parameters, including SVV and RVEDVI were obtained from each patient at the 5 specific time points. Linear regression and receiver operating characteristic (ROC) curve analyses were performed.

RESULTS

The SVV significantly correlated with the RVEDVI (r = -0.616, P < 0.001). Cutoff values for the upper and lower tertiles of RVEDVI were 157 mL/m(2) and 128 mL/m(2), respectively. Tertile analysis indicated that upper tertile of RVEDVI had a significantly lower SVV than the middle tertile (median; 5% vs 8%, P < 0.05), and middle tertile of RVEDVI had a significantly lower SVV than the lower tertile (median; 8% vs 11%, P < 0.05). A 6% cutoff value of SVV estimated the upper tertile RVEDVI (>157 mL/m(2)) with the area under the curve of ROC curve of 0.832. A 9% cutoff value of SVV estimated the lower tertile RVEDVI (<128 mL/m(2)) with the area under the curve of ROC curve of 0.792.

CONCLUSION

SVV may be a valuable estimator of RVEDVI in patients undergoing liver transplantation.

Transesophageal echocardiography during orthotopic liver transplantation in patients with esophagoastric varices

BACKGROUND

Hemodynamic monitoring using transesophageal echocardiography (TEE) in patients with signs of portal hypertension undergoing orthotopic liver transplantation (OLT) carries potential risk of esophageal and gastric variceal hemorrhage. The aim of our retrospective analysis was to evaluate the safety of intraoperative TEE monitoring during OLT in patients with esophagogastric varices.

METHODS

A retrospective analysis of 396 liver transplant recipients was performed at the Medical University of Vienna monitored by TEE during OLT between 2003 and 2010.

RESULTS

Varices were documented by esophagogastroduodenoscopy in 287 (72.5%) of 396 analyzed patients: 130 (32.8%) varices grade I (<5 mm under insufflation) and 157 (39.6%) varices grade II (>5 mm under insufflation). Red spot signs were identified in 40 patients (10.1%). Most varices (82.2%) were documented in the esophagus, 4.2% in the stomach, and 13.6% in both (esophagus and stomach). Only one major bleeding occurred, and it was only in a case of one patient with an esophageal varix, which was treated with a balloon tamponade during OLT. Although patients with varices demonstrated a significantly longer prothrombin time and lower platelet count, there was no significant difference in the requirement for blood products among patients with and without varices.

CONCLUSIONS

TEE is a relatively safe method for monitoring cardiac performance with a low incidence of major hemorrhagic complications in patients with documented esophagogastric varices undergoing OLT.

Perioperative monitoring in liver transplant patients

Liver transplant (LT) is a major surgical undertaking involving major fluid shifts, hemodynamic instability and metabolic derangements in a patient with preexisting liver failure and multisystemic derangements. Monitoring and organ support initiated in the preoperative phase is continued intraoperatively and into the postoperative phase to ensure an optimal outcome. As cardiovascular events are the leading cause of non-graft related death among LT recipients, major emphasis is placed on cardiovascular monitoring. The other essential monitoring are the continuous assessment of coagulapathy, extent of metabolic derangements, dyselectrolytemis and intracranial pressure monitoring in patients with fulminant hepatic failure. The type and extent of monitoring differs with need according to preexisting child status of the patient and the extent of systemic derangements. It also varies among transplant centers and is mainly determined by individual or institutional practices.

Anaesthetic and cardiorespiratory effects of a constant-rate infusion of alfaxalone in desflurane-anaesthetised sheep

A prospective, randomised, blinded controlled study was performed to determine the anaesthetic and cardiorespiratory effects of a constant-rate infusion (CRI) of alfaxalone in 12 sheep anaesthetised with desflurane, and undergoing experimental orthopaedic surgery. Sheep were sedated with dexmedetomidine (4 μg/kg, intravenously) and butorphanol (0.3 mg/kg, intravenously). Anaesthesia was induced with alfaxalone (1 mg/kg/minute to effect, intravenously) and maintained with desflurane in oxygen and alfaxalone 0.07 mg/kg/minute or saline for 150 minutes (range 150-166 minutes). The anaesthetic induction dose of alfaxalone, the desflurane expiratory fraction required for anaesthetic maintenance, cardiorespiratory measurements and blood-gases were recorded at predetermined intervals. Quality of sedation, anaesthetic induction and recovery were assessed. The alfaxalone induction dose was 1.7 mg/kg (1.2 to 2.6 mg/kg). The desflurane expiratory fraction was lower (22 per cent) in sheep receiving alfaxalone CRI (P=0). Also, heart rate (P=0), cardiac index (P=0.002), stroke index (P=0) and contractility (P=0) were higher, and systemic vascular resistance (P=0.002) was lower. Although respiratory rate tended to be higher with alfaxalone, there was no difference in PCO2 between the groups. Recovery times were significantly longer in sheep given alfaxalone (25.4 v 9.5 minutes) but recovery quality was similar. Alfaxalone reduced requirements of desflurane and maintained similar cardiorespiratory function, but recovery time was more prolonged.

Volumetric hemodynamic changes and postoperative complications in hypothermic liver transplanted patients

INTRODUCTION

Hepatic diseases decrease the liver's involvement in thermoregulation. Removal of the liver during transplantation increases the incidence of hypothermia during the surgery. The aims of the present study were to analyze the hemodynamic changes among hypothermic liver transplantations and to determine its relationship to postoperative complications.

METHODS

Conventional and volumetric hemodynamic monitoring and intramucosal pH measurements were performed during 54 liver transplantations. According to the core temperature until graft reperfusion, patients were classified into group A, hypothermic patients (temperature < 35 °C; n=25) versus group B, normothermic patients (temperature > 36 °C; n=29). We examined the relationships between central venous pressure (CVP), intrathoracic blood volume index, cardiac index (CI), and oxygen delivery index, oxygen consumption index, as well as the fluctuation of the mean arterial pressure (MAP) and gastric intramucosal pH and activated clotting time. We recorded prolonged ventilation time, vasopressor and hemodialysis requirements, occurrence of infections, and intensive care days.

RESULTS

There were no significant differences in the MELD scores. More Child-Pugh class C patients (P<.01) showed significantly higher APACHE II scores (P<.02) among group A. During hepatectomy and at the same intrathoracic blood volumes, the hypothermic group showed significantly higher CVP levels (P<.02). During the anhepatic and postreperfusion phases, the decreased CI levels (P<.05) were associated with increased MAP values (P<.05). Without differences in oxygen delivery, the oxygen consumption was lower in group A (P<.05). The intramucosal pH levels were the same in the both groups during the whole examination period. More instances of infection, intensive care, and hemodialysis treatment days, were observed as well as significantly longer vasopressor requirements and coagulopathy among the hypothermic group (P<.007).

Hemodynamic monitoring in sepsis

Arterial waveform analysis that does not require continuous calibration, impedance cardiography, electrical cardiometry, velocity-encoded phase contrast magnetic resonance imaging (MRI), pulsed dye densitometry, noninvasive pulse pressure analysis using tonometry, suprasternal Doppler, partial CO2 rebreathing techniques, and transcutaneous Doppler are just some of the other emerging technologies not described in this review that may be used routinely in the management of sepsis and septic shock in the very near future. These innovative approaches may further increase our ability to optimize patients' fluid status and hemodynamics. We also have ability to monitor the microcirculation. This increasingly sophisticated approach to the management of sepsis and septic shock will hopefully translate into better patient outcomes. However, optimal use of any hemodynamic monitoring requires an understanding of its physiologic underpinnings. Accurate interpretation of the hemodynamic information coupled with a protocolized management algorithm is the cornerstone of an effective resuscitation effort. Many forms of hemodynamic monitoring have emerged over the past 20 to 30 years with no convincing evidence for the superiority of any single techniques (Table 2). The goal of hemodynamic monitoring and optimization is to combat the systemic imbalance between tissue oxygen supply and demand ranging from global tissue hypoxia to overt shock and multiorgan failure. It remains unproven that hemodynamic monitoring of disease progression can effectively change patient outcome. However, despite our increased understanding of sepsis pathophysiology, mortality and morbidity from the disease remains high. Therefore, the search for the optimal parameters in resuscitation and the best way they can be monitored will continue.

Effects of fluid resuscitation methods on the pro- and anti-inflammatory cytokines and expression of adhesion molecules after burn injury

Fluid resuscitation management can influence inflammatory response after burn injury. The aim of this study was to analyze the effects of two fluid resuscitation methods on the cytokine production and on the expression of the leukocyte surface markers. Thirty patients were included in this prospective randomized study with burn injury affecting more than 20% of the body surface area. Fluid resuscitation was guided by hourly urine output (HUO, n = 15) or by intrathoracic blood volume index (ITBVI, n = 15). Blood samples were taken on admission and on the next five consecutive mornings. Concentrations of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor-alpha were measured in phorbol myristate acetate-stimulated and -nonstimulated samples. Leukocyte surface marker expressions (CD11a, CD11b, CD14, CD18, CD49d, and CD97) were also determined. In the ITBVI group, IL-6 levels on days 2 to 3 and IL-6/IL-10 ratios on days 2 to 3, and the IL-8/IL-10 ratios on days 3 to 5 were significantly higher than those in HUO group (P < .05). In the HUO group, IL-10 levels were significantly higher (P < .05) on days 4 and 5. Granulocyte CD11a levels on day 2, CD11b levels on days 4 to 6, lymphocyte CD11a on days 5 to 6, CD11b on days 3 to 6, CD49d on days 2 to 6, CD97 on day 6, monocyte CD11a, CD11b, CD18 levels on days 4 to 6, and CD14 levels on days 3 to 5 were significantly higher in the HUO group (P < .05). Our study suggests that ITBVI-guided fluid resuscitation of burned patients suppresses the shift toward anti-inflammatory imbalance and the expression of leukocyte surface markers more than HUO-guided resuscitation.

[Clinical validation of minimally invasive evaluation of systolic function]

BACKGROUND AND OBJECTIVE

Pulse contour continuous cardiac output (PiCCO) monitoring by means of transpulmonary thermodilution provides 2 indices of systolic function: the cardiac function index and the global ejection fraction. Our aim was to compare these 2 PiCCO indices to the left-ventricular ejection fraction obtained by transthoracic echocardiography.

MATERIAL AND METHODS

This was a prospective clinical study of 35 adult patients in the critical care unit of a university hospital. Each patient provided his or her own control data. Patients with marked changes in regional segment contractility or nonsinus rhythm were excluded. We collected patient variables, reason for admission to the critical care unit, the Acute Physiology and Chronic Health Evaluation II score, the reason for hemodynamic monitoring, and the infusion of vasoactive drugs at the time of the procedure.

RESULTS

Statistically significant correlations were found between the left-ventricular ejection fraction and the global ejection fraction (r=0.79, P<.001) and the cardiac function index (r=0.66, P<.001). The mean (SD) difference between the left-ventricular ejection fraction and the global ejection fraction and the cardiac function index were 1.05% (10.2%) (range, 19.0% to 29.1%) and 0.001% (12.4%) (range, -24.3% to 24.3%), respectively. For predicting a left-ventricular ejection fraction of less than 40%, the area under the curve was 0.879 for the global ejection fraction and 0.805 for the cardiac function index of A global ejection fraction less than 13.5% and a cardiac function index less than 3.15 min(-1) predicted a left-ventricular ejection fraction less than 40% with sensitivities of 97% and 96% and specificities of 85% and 77%, respectively.

CONCLUSIONS

In patients without marked changes in regional segment contractility, the global ejection fraction and the cardiac function index calculated by the PiCCO monitor offer a reliable and simple way to assess left-ventricular systolic function. Low values for these indicators suggest the need for echocardiographic assessment of left- and right-ventricular function.

Inferior vena cava distensibility as a predictor of fluid responsiveness in patients with subarachnoid hemorrhage

BACKGROUND

The objective of our study is to assess the reliability of the distensibility of the inferior vena cava (dIVC), as measured by ultrasound, as an indicator of fluid responsiveness in patients with subarachnoid hemorrhage.

METHODS

We enrolled 29 adult patients requiring advanced hemodynamic monitoring, sedation, and mechanical ventilation. Inferior vena cava diameter was measured during a single mechanical breath. The dIVC was calculated as (the diameter of the inferior vena cava on inspiration-the diameter on expiration)/the diameter on expiration. All the hemodynamic parameters were collected at baseline and after a fluid challenge (7 ml/kg) with 6% hydroxyethyl starch. A 15% increase of cardiac index was the standard criterion used to differentiate patients with and without a response to fluid therapy.

RESULTS

Apart from stroke volume variation (SVV) and dIVC, which were significantly higher in fluid responders (17 patients), the other baseline characteristics did not differ significantly between groups (responders versus non-responders). Significant changes in hemodynamic parameters after volume load were observed only in fluid responders. The area under the ROC curve was 0.779 (95% confidence interval 0.587-0.911) for SVV and 0.902 (95% confidence interval 0.733-0.979, P = NS) for dIVC. Central venous pressure was a less reliable indicator of fluid responsiveness than dIVC. A dIVC value of >16% yielded the most favorable balance of test characteristics, with 70.59% sensitivity and 100% specificity. There was a trend toward a lower incidence of delayed ischemic lesions in fluid responders (11.7 vs. 25%, P = NS).

CONCLUSION

dIVC proved to be a reliable predictor of fluid responsiveness in ICU patients with subarachnoid hemorrhage.

Balancing volume resuscitation and ascites management in cirrhosis

PURPOSE OF REVIEW

Patients with cirrhosis have total extracellular fluid overload but central effective circulating hypovolaemia. The resulting neurohumoral compensatory response favours the accumulation of fluids into the peritoneal cavity (ascites) and may hinder renal perfusion (hepatorenal syndrome). Their deranged systemic haemodynamics (hyperdynamic circulatory syndrome) is characterized by elevated cardiac output with decreased systemic vascular resistance and low blood pressure.

RECENT FINDINGS

Molecular and biological mechanisms determining cirrhosis-induced haemodynamic alterations are progressively being elucidated. The need for a goal-directed assessment of volume resuscitation (especially with volumetric techniques) in patients with cirrhosis is becoming more and more evident. The role of fluid expansion with albumin and the use of splanchnic vasopressors in a variety of cirrhosis-related conditions has recently been investigated.

SUMMARY

The response to fluid loading in patients with advanced cirrhosis is abnormal, primarily resulting in expansion of their noncentral blood volume compartment. Colloid solutions, in particular albumin, are best used in these patients. Albumin may be effective in preventing the haemodynamic derangements associated with large-volume paracentesis (paracentesis-induced circulatory dysfunction), in preventing renal failure during spontaneous bacterial peritonitis and, in association with splanchnic vasopressors, in caring for patients with the hepatorenal syndrome.

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.

Stroke volume variation as a guide to fluid administration in morbidly obese patients undergoing laparoscopic bariatric surgery

BACKGROUND

Perioperative fluid administration in morbidly obese patients is critical. There is scarcity of scientific information in literature on amount and rate of its application. Functional parameters (stroke volume variation (SVV), pulse pressure variation) are considered more accurate predictor of volume status of patients than blood pressure and central venous pressure.

METHODS

SVV was used as a guide for intraoperative fluid administration in 50 morbidly obese patients subjected to bariatric surgery. Pulse contour waveform analysis (LiDCO Cardiac Sensor System, UK Company Regd. 2736561, VAT Regd. 672475708) was utilized to monitor SVV, and a value more than 10% was used as infusion trigger for intraoperative fluid management.

RESULTS

Mean amount of fluid infused was 1,989.90 ml (+/-468.70 SD) for mean 206.94 min (+/-50.30 SD) duration of surgery. All patients maintained hemodynamic parameters (cardiac output, cardiac index, stroke volume, noninvasive blood pressure, heart rate) within 10% of the baseline values. Central venous pressure and SVV showed no correlation, except for short period initially. Renal and metabolic indices remained within normal limits.

CONCLUSION

Obese patients coming for laparoscopic bariatric surgery may not require excessive fluid. Intraoperative fluid requirement is the same as for nonobese patients. SVV is a valuable guide for fluid application in obese patients undergoing bariatric surgery.

Hemodynamic monitoring in sepsis

Tissue hypoperfusion is an important factor in the development of multiple organ failure. Therefore, recognition of sepsis-induced tissue hypoperfusion and timely clinical intervention to prevent and correct this are fundamental aspects of managing patients with sepsis and septic shock. Hemodynamic monitoring plays a key role in the management of the critically ill and is used to identify hemodynamic instability and its cause and to monitor response to therapy. However, the utility of many forms of hemodynamic monitoring that are used in management of sepsis and septic shock remain controversial and unproven. This article examines emerging technologies as well as more established techniques used to monitor hemodynamics in sepsis and assesses their potential roles in optimization of sepsis-induced tissue hypoperfusion.

Emerging trends in minimally invasive haemodynamic monitoring and optimization of fluid therapy

BACKGROUND

For decades the pulmonary artery catheter has been the mainstay of cardiac output monitoring in critically ill patients, and pressure-based indices of ventricular filling have been used to gauge fluid requirements with acknowledged limitations. In recent years, alternative technologies have become available which are minimally invasive, allow beat-to-beat cardiac output monitoring and permit assessment of fluid requirements by volumetric means and by allowing assessment of heart-lung interaction in mechanically ventilated patients.

METHODS

A qualitative review of the basic science behind the transpulmonary dilution technique used in the measurement of cardiac output, global end-diastolic volume and extravascular lung water; the basic science and validation of pulse contour analysis methods of real-time cardiac output monitoring; the application and limitations of these technologies to guide rational fluid therapy in surgical and critically ill patients.

RESULTS

Transpulmonary dilution techniques correlate well with pulmonary artery catheter-derived measurement of cardiac output. Volumetric measures of preload appear to be superior to central venous and pulmonary artery occlusion pressures. Dynamic indices of preload responsiveness such as stroke volume variation are more useful than static measures in mechanically ventilated patients.

CONCLUSION

In fully mechanically ventilated patients, dynamic measurements of heart-lung interaction such as stroke volume variation are superior to static measures of preload in assessing whether a patient is volume-responsive (i.e. will increase stroke volume in response to a fluid challenge). For patients who are not fully mechanically ventilated, pulse contour analysis allows real-time assessment of increases in cardiac output in response to passive leg-raising.

Continuous right ventricular end-diastolic volume in comparison with left ventricular end-diastolic area

BACKGROUND AND OBJECTIVE

Intraoperative management of patients with end-stage liver disease undergoing liver transplantation requires fluid administration to increase cardiac output and oxygen delivery to the tissues. Filling pressures have been widely shown to correlate poorly with changes in cardiac output in the critically ill patient. Continuous right ventricular end-diastolic volume index (cRVEDVI) and left ventricular end-diastolic area index (LVEDAI) monitoring have been increasingly used for preload assessment. The aim of this study was to compare cRVEDVI, LVEDAI, central venous pressure and pulmonary artery occlusion pressure with respect to stroke volume index (SVI) during liver transplantation.

METHODS

Measurements were made in 20 patients at four predefined steps during liver transplantation. Univariate and multivariate panel-data fixed effect regression models (across phases of the surgical procedure) were fitted to assess associations between SVI and cRVEDVI, pulmonary artery occlusion pressure, central venous pressure and LVEDAI after adjusting for ejection fraction (categorized as <or=30, 31-40, >40).

RESULTS

SVI was associated with continuous right ventricular ejection fraction. The model showing the best fit to the data was that including cRVEDVI: even after adjusting for continuous right ventricular ejection fraction and phase, the regression coefficient of cRVEDVI in predicting SVI was statistically significant and indicated an increase in SVI of 0.21 ml m(-2) for each increase of 1 ml m(-2). At the multivariate analysis, an increase in LVEDAI of 1 cm m(-2) led to an increase in SVI of 1.47 ml m(-2) (P = 0.054).

CONCLUSION

cRVEDVI and LVEDAI gave a better reflection of preload than filling pressure, even if only cRVEDVI reached statistical significance.

Intraoperative hemodynamic monitoring during organ transplantation: what is new?

PURPOSE OF REVIEW

To highlight the recent developments in hemodynamic monitoring during liver and lung transplantation.

RECENT FINDINGS

Even though a consensus on intraoperative hemodynamic monitoring is still lacking, the most frequently monitoring tool used is the pulmonary artery catheter (PAC). The filling pressures are widely accepted as not being able to accurately define cardiac preload. On the contrary, the use of transesophageal echocardiography (TEE), although it is operator dependent and requires a prolonged training, is increasing during the intraoperative period to directly evaluate the cardiovascular function. New frontiers have been opened by the transpulmonary thermodilution: intrathoracic blood volume has been shown to have a better correlation with preload than the filling pressures. The advanced modified PAC permits evaluation of the right heart function and preload. Recently, right ventricular end diastolic volume has been shown to correlate better with preload than the filling pressures and also the left ventricular end diastolic area.

SUMMARY

The PAC still represents the most used intraoperative hemodynamic monitoring technique. TEE is increasing in popularity. Recent studies demonstrate that volumetric monitoring conducted with transpulmonary thermodilution and advanced volumetric PAC give good definition of preload and should be implemented in clinical practice.

Current approach to intraoperative monitoring in liver transplantation

PURPOSE OF REVIEW

Although liver transplantation has become a standardized treatment and the only established definite therapy for end-stage liver disease it remains a unique clinical procedure. Increased understanding of the specific pathophysiological changes in end-stage liver disease and the transplantation procedure have led to the adaptation of concepts including overall monitoring of the patient and assessment of specific organ function.

RECENT FINDINGS

Major emphasis is placed on adequate monitoring during perioperative care of liver transplantation patients in order to ensure optimal hemodynamic and respiratory performance. The immediate assessment of metabolism and graft function will also serve to guide therapy according to the individual patient's needs.

SUMMARY

The evolution of monitoring during standardized liver transplantation, as well as currently recommended novel devices and concepts, are described and discussed.

Haemodynamic effects of plasma-expansion with hyperoncotic albumin in cirrhotic patients with renal failure: a prospective interventional study

Background

Patients with advanced cirrhosis of the liver typically display circulatory disturbance. Haemodynamic management may be critical for avoiding and treating functional renal failure in such patients. This study investigated the effects of plasma expansion with hyperoncotic albumin solution and the role of static haemodynamic parameters in predicting volume responsiveness in patients with advanced cirrhosis.

Methods

Patients with advanced cirrhosis (Child B and C) of the liver receiving albumin substitution because of renal compromise were studied using trans-pulmonary thermodilution. Paired measurements before and after two infusions of 200 ml of 20% albumin per patient were recorded and standard haemodynamic parameters such as central venous pressure (CVP), mean arterial pressure (MAP), systemic vascular resistance index (SVRI), cardiac index (CI) and derived variables were assessed, including global end-diastolic blood volume index (GEDVI), a parameter that reflects central blood volume

Results

100 measurements in 50 patients (33 m/17 w; age 56 years (± 8); Child-Pugh-score 12 (± 2), serum creatinine 256 μmol (± 150) were analyzed. Baseline values suggested decreased central blood volumes GEDVI = 675 ml/m² (± 138) despite CVP within the normal range (11 mmHg (± 5). After infusion, GEDVI, CI and CVP increased (682 ml/m² (± 128) vs. 744 ml/m² (± 171), p < 0.001; 4.3 L/min/m² (± 1.1) vs. 4.7 L/min/m² (± 1.1), p < 0.001; 12 mmHg (± 6) vs. 14 mmHg (± 6), p < 0.001 respectively) and systemic vascular resistance decreased (1760 dyn s/cm⁵/m² (± 1144) vs. 1490 dyn s/cm⁵/m² (± 837); p < 0.001). Changes in GEDVI, but not CVP, correlated with changes in CI (r² = 0.51; p < 0.001). To assess the value of static haemodynamic parameters at baseline in predicting an increase in CI of 10%, receiver-operating-characteristic curves were constructed. The areas under the curve were 0.766 (p < 0.001) for SVRI, 0.723 (p < 0.001) for CI, 0.652 (p = 0.010) for CVP and 0.616 (p = 0.050) for GEDVI.

Conclusion

In a substantial proportion of patients with advanced cirrhosis, plasma expansion results in an increase in central blood volume. GEDVI but not CVP behaves as an indicator of cardiac preload, whereas high baseline SVRI is predictive of fluid responsiveness.

How to measure and interpret volumetric measures of preload

PURPOSE OF REVIEW

To update the situation over the past few years on the clinical application of volumetric measures of preload in critically ill patients.

RECENT FINDINGS

Cardiac filling pressures monitoring is unreliable for assessing cardiac preload in mechanically ventilated critically ill patients. The transpulmonary dilution indicator technique was shown to better identify preload than pulmonary arterial catheterization. Measuring static preload index as intrathoracic blood volume or global end diastolic volume provides a good preload index, either in experimental or in different clinical settings.

SUMMARY

Volumetric measures of preload are good preload indexes. These data are to be interpreted together with the clinical patient's condition, conventional hemodynamic data and the course of illness in critically ill patients. In order to evaluate whether the application of a predefined therapy algorithm based on volumetric monitoring can improve patients' outcome, more studies are needed.

[Minimally invasive cardiopulmonary monitoring with the PiCCO Plus system]

Insertion of a central venous catheter and an arterial catheter would be indicated in hemodynamically unstable or severely hypoxic patients in critical care units. In this setting, cardiorespiratory monitoring by transpulmonary thermodilution (TPTD) can be considered minimally invasive given that only a single arterial thermodilution catheter and a single central venous catheter are required to be connected to a specific monitor (the PiCCO Plus, Pulsion Medical Systems, Munich, Germany). TDTP simultaneously measures cardiac output, preloading, and cardiac function in hemodynamically unstable patients and predicts the response to volume. The technique can be managed by any health care professional. In hypoxic patients, TDTP identifies cases of pulmonary edema that might benefit from a negative fluid balance, evaluates pulmonary vascular permeability, facilitates our understanding of pathophysiologic mechanisms of hypoxemia, and predicts the likelihood of deleterious hemodynamic effects of positive end-expiratory pressures.

Haemodynamic monitoring in acute heart failure

Acute Heart Failure is a major cause of hospitalisation, with a rate of death and complications. New guidelines have been developed in order to diagnose and treat this disease. Despite these efforts pathophysiology and treatments options are still limited. There is agreement among the experts that increasing the cardiac output and the stroke volume without fluid overloading the patient should be the goal of every treatment. Despite this, there is no agreement on how to monitor the cardiac function and how to follow it after a therapeutic intervention. In other fields of critical care cardiovascular monitoring and application of early goal directed protocols showed benefits. This review explores the available possibilities of how to monitor the cardiac function in Acute Heart Failure. Standard and more advanced techniques are presented. Cardiac output monitors from the pulmonary artery catheter to the pulse pressure analysis and Doppler techniques are discussed, with focus on this specific clinical setting. Undoubtedly monitoring is valuable tool, but without a protocol of how to manipulate the haemodynamics, no monitor will prove alone to be beneficial. Haemodynamic driven early goal directed therapy are largely awaited in this field of medicine.

Hemodynamic monitoring in shock and implications for management. International Consensus Conference, Paris, France, 27-28 April 2006

OBJECTIVE

Shock is a severe syndrome resulting in multiple organ dysfunction and a high mortality rate. The goal of this consensus statement is to provide recommendations regarding the monitoring and management of the critically ill patient with shock.

METHODS

An international consensus conference was held in April 2006 to develop recommendations for hemodynamic monitoring and implications for management of patients with shock. Evidence-based recommendations were developed, after conferring with experts and reviewing the pertinent literature, by a jury of 11 persons representing five critical care societies.

DATA SYNTHESIS

A total of 17 recommendations were developed to provide guidance to intensive care physicians monitoring and caring for the patient with shock. Topics addressed were as follows: (1) What are the epidemiologic and pathophysiologic features of shock in the ICU? (2) Should we monitor preload and fluid responsiveness in shock? (3) How and when should we monitor stroke volume or cardiac output in shock? (4) What markers of the regional and micro-circulation can be monitored, and how can cellular function be assessed in shock? (5) What is the evidence for using hemodynamic monitoring to direct therapy in shock? One of the most important recommendations was that hypotension is not required to define shock, and as a result, importance is assigned to the presence of inadequate tissue perfusion on physical examination. Given the current evidence, the only bio-marker recommended for diagnosis or staging of shock is blood lactate. The jury also recommended against the routine use of (1) the pulmonary artery catheter in shock and (2) static preload measurements used alone to predict fluid responsiveness.

CONCLUSIONS

This consensus statement provides 17 different recommendations pertaining to the monitoring and caring of patients with shock. There were some important questions that could not be fully addressed using an evidence-based approach, and areas needing further research were identified.

Hemodynamics During Liver Transplantation

Assessing the optimal volemia in the perioperative course of liver transplantation is a challenge for the anesthesiologist. Traditional estimates of intravascular volume status, such as pulmonary artery occlusion pressure (PAOP), have been widely shown to poorly correlate with changes in cardiac output among critically ill patients. Hence, there has been recent interest in alternative, catheter-related, bedside device volume estimates using thermodilution. Continuous end diastolic volume (CEDVI) showed better correlations with cardiac performance than cardiac filling pressures in studies performed in critically ill patients. When compared with conventional pressure-derived data, preload monitoring estimated as intrathoracic blood volume index (ITBVI) with the PiCCO system based on an integrated transpulmonary thermodilution technique better reflected left ventricular filling both in critically ill patients and those who underwent liver transplantation. Moreover, in liver transplantation, the use of transoesophageal echocardiography (TEE) has been increasing for it provides rapid visualization of the dimension and function of heart chambers as well as the left ventricular end diastolic area index (EDAI) that seem to correlate with graded acute hypovolemia, although its validity as on preload index is still under discussion.

Extravascular lung water measurements and hemodynamic monitoring in the critically ill: bedside alternatives to the pulmonary artery catheter

The recently completed Fluid and Catheter Treatment Trial conducted by the National Institutes of Health ARDSNetwork casts doubt on the value of routine pulmonary artery catheterization for hemodynamic management of the critically ill. Several alternatives are available, and, in this review, we evaluate the theoretical, validation, and empirical databases for two of these: transpulmonary thermodilution measurements (yielding estimates of cardiac output, intrathoracic blood volume, and extravascular lung water) that do not require a pulmonary artery catheter, and hemodynamic measurements (including estimates of cardiac output and ejection time, a variable sensitive to intravascular volume) obtained by esophageal Doppler analysis of blood flow through the descending aorta. We conclude that both deserve serious consideration as a means of acquiring useful hemodynamic data for managing shock and fluid resuscitation in the critically ill, especially in those with acute lung injury and pulmonary edema, but that additional study, including carefully performed, prospective clinical trials demonstrating outcome benefit, is needed.

The Impact of Intra-aortic Balloon Pumping on Cardiac Output Determination by Pulmonary Arterial and Transpulmonary Thermodilution in Pigs

OBJECTIVE

The aim of this study was to evaluate the impact of intra-aortic balloon pumping (IABP) on the comparison of simultaneous measurements of cardiac output via pulmonary arterial and transpulmonary thermodilution (PiCCO; Pulsion Medical Systems, Munich, Germany).

DESIGN

Prospective.

SETTINGS

University research laboratory.

PARTICIPANTS

The data were derived from 9 anesthetized (fentanyl, propofol, flunitrazepam, rocuronium) and ventilated pigs.

INTERVENTIONS

A thermodilution catheter was inserted into the pulmonary artery, a PiCCO catheter into the abdominal aorta through the right femoral artery, epicardial atrial pacing wires through a thoracotomy, and a balloon catheter for counterpulsation into the descending thoracic aorta through the left femoral artery. Cardiac output was varied over a wide range by cardiac pacing between 80 and 150/min in steps of 10/min and was measured without and during IABP at an assist frequency of 1:1.

MEASUREMENTS AND MAIN RESULTS

A total of 236 paired cardiac output measurements were carried out in a range of cardiac output between 1.4 to 4.9 L/min. A close correlation was found between transpulmonary and pulmonary arterial thermodilution both without and during IABP (r = 0.94 and 0.93, respectively) and a good agreement of both methods (bias of 0.30 and 0.26 L/min, respectively; precision 0.47 and 0.52 L/min, respectively).

CONCLUSIONS

Transpulmonary thermodilution is suitable for cardiac output measurement during IABP. Hence, in critically ill patients with cardiac pump failure, blood flow may be determined as accurately with the less-invasive transpulmonary method as with the traditional pulmonary arterial thermodilution one.