Right Ventricular End-Diastolic Volume Index as a Predictor of Preload Status in Patients With Low Right Ventricular Ejection Fraction During Orthotopic Liver Transplantation

The Prognostic Role of Right Ventricular Stroke Work Index during Liver Transplantation

Right heart-associated hemodynamic parameters including intraoperative pulmonary vascular resistance (PVR) were reported to be associated with patient survival after liver transplantation. We investigated whether intraoperative stroke work indexes of both ventricles could have a better prognostic value than PVR. We reviewed 683 cases at a tertiary care academic medical center. We collected intraoperative variables of baseline central venous pressure, baseline right ventricle end-diastolic volume, mixed venous oxygen saturation, intraoperative PVR and right and left ventricular stroke work indexes. Time-weighted means or area under the curve of intraoperative right and left ventricular stroke work indexes were calculated as exposure variables. One-year all-cause mortality or graft failure was our primary outcome. Cox proportional hazard regression analysis was performed to evaluate the association between exposure variables and one-year all-cause mortality or graft failure. Kaplan–Meier survival curve analysis of our primary outcome was performed for different time-weighted mean ventricular stroke work index groups. Cubic spline curve analysis was performed to evaluate the linear relationship between our exposure variables and primary outcome. Time-weighted mean right ventricular stroke work index was significantly associated with one-year all-cause mortality or graft failure (hazard ratio 1.21, 95% confidence interval (CI) 1.12–1.36, p < 0.001). However, there was no significant association between time-weighted mean left ventricular stroke work index, time-weighted mean PVR, PVR at the end of surgery and one-year mortality. Area under the curve of right ventricular stroke work index was also significantly associated with one-year mortality or graft failure (hazard ratio 1.24, 95% CI 1.15–1.37, p < 0.001). Kaplan–Meier survival curve analysis showed a significant difference in the survival between different mean right ventricular stroke work index groups (Log-rank test: p = 0.002). Cubic spline function curve showed the gradual increase in the risk of mortality with a positive slope with time-weighted mean right ventricular stroke work index. In conclusion, intraoperative elevated right ventricular stroke work index was significantly associated with poor patient or graft survival after liver transplantation. Intraoperative right ventricular stroke work index could be an intraoperative hemodynamic goal and prognostic marker for mortality after liver transplantation.

Evaluation of the right ventricular ejection fraction during classic orthotopic liver transplantation without venovenous bypass

BACKGROUND

Right ventricular (RV) function is sensitive to changes in cardiac loading conditions, and RV dysfunction may contribute to hemodynamic instability during orthotopic liver transplantation (OLT). Thus, we evaluated RV function and its role in hemodynamic instability during classic OLT without venovenous bypass (VVB).

METHODS

Thirty patients undergoing classic OLT without VVB were studied. Right ventricular ejection fraction (RVEF) was measured using a modified pulmonary artery catheter. Hemodynamic data were recorded at pre-determined time points: T0, baseline; T1-T3: 5, 15, and 30 min after clamping; T4-T7: 5, 15, 30, and 120 min after reperfusion; T8 and T9: 24 and 48 h after surgery.

RESULTS

The baseline RVEF was lower than normal value. RVEF decreased significantly from T1 to T4 and returned to baseline beginning at T5. At 24 and 48 h after surgery, RVEF was higher than baseline value. RVEF was correlated with stroke volume index and post-reperfusion syndrome during OLT. Compared to the low MELDs group, RVEF in the high MELDs group was lower at T1, T2, and T4.

CONCLUSIONS

Right ventricular function was compromised during the anhepatic and early reperfusion stages in patients undergoing classic OLT without VVB, particularly in the high MELD score patients. Close monitoring of RV function in these patients should be considered.

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.

The impact of portopulmonary hypertension on intraoperative right ventricular function of living donor liver transplant recipients

BACKGROUND

Portopulmonary hypertension (PPH) burdens a right ventricle (RV) already exposed to physiologic stress during liver transplantation. The magnitude of the impact of PPH on RV function, especially early reperfusion, has not been evaluated adequately by prospective controlled trials. In this study, we prospectively quantified the impact of PPH on the RV function in living donor liver transplant recipients.

METHODS

Twenty patients undergoing living donor liver transplant were stratified based on mean pulmonary artery pressure (mPAP) into a control group (mPAP <25 mm Hg) and a PPH group (mPAP ≥25 mm Hg). Standard anesthetic technique and monitoring were used. Fiberoptic pulmonary artery catheters enabled to measure RV ejection fraction (RVEF) were used. Hemodynamics were recorded after induction of anesthesia, the end of hepatectomy, before portal unclamping, 5 and 30 minutes after reperfusion, and at skin closure.

RESULTS

The PPH group had significantly lower RVEF, stroke volume, and higher central venous pressure and RV end-diastolic volume index after portal unclamping versus the controls. Pulmonary vascular resistance index and mPAP were significantly higher throughout the operation in the PPH group, but RV stroke work index did not differ significantly between groups. RVEF was significantly reduced in the PPH group after reperfusion compared with baseline, but the control group did not experience such a reduction.

CONCLUSIONS

Mild to moderate PPH was associated with reduced RVEF during liver transplantation, especially after reperfusion, likely because of a reduced RV contractile reserve in PPH patients. This reduction in RVEF was clinically well tolerated by patients with mild to moderate PPH.

Modeling and simulation of right ventricular volume measurement system during right heart catheterization

Haemodynamic monitoring is necessary for the effective management of critically ill cardiac patients. Pulmonary artery catheterization has been used for monitoring the circulation, for measurement of intracardiac pressures and to estimate preload and afterload. However, pressures may not be accurate reflection of the circulation and simultaneous measurement of volumes would improve patient treatment. However, measurement of cardiac volumes especially of the right ventricle is difficult in everyday clinical practice In this work we propose the use of pulmonary artery catheter (PAC) with ultrasonic sensors built on it, to calculate the right ventricular end-diastolic (RVEDV) and end-systolic volume (RVESV). This is achieved by using the Ultrasonic (US) beam, to measure the distances between the transducers on the catheter and the RV walls. These distances, will be used as an input to a Volume calculating algorithm, which finally provides the RVEDV and RVESV, using a Neural Network (NN). For that reason, we have used cardiac Magnetic Resonance Imaging (MRI) and have modeled the catheter and the US transducers, to get as input the distances to the surface of the cavity. With these distances, and the known cardiac volumes (calculated using MR images) we trained and validated a NN for volume calculation. The results show that the algorithm accurately calculates the RVEDV. For the RVESV, greater deviations are observed between values calculated with our algorithm and cardiac MRI.

[Haemodynamic monitoring in the perioperative phase. Available systems, practical application and clinical data]

A regular hydration status and compensated vascular filling are targets of perioperative fluid and volume management and, in parallel, represent precautions for sufficient stroke volume and cardiac output to maintain tissue oxygenation. The physiological and pathophysiological effects of fluid and volume replacement mainly depend on the pharmacological properties of the solutions used, the magnitude of the applied volume as well as the timing of volume replacement during surgery. In the perioperative setting surgical stress induces physiological and hormonal adaptations of the body, which in conjunction with an increased permeability of the vascular endothelial layer influence fluid and volume management. The target of haemodynamic monitoring in the operation room is to collect data on haemodynamics and global oxygen transport, which enable the anaesthetist to estimate the volume status of the vascular system. Particularly in high risk patients this may improve fluid and volume therapy with respect to maintaining cardiac output. A goal-directed volume management aiming at preventing hypovolaemia may improve the outcome after surgery. The objective of this article is to review the monitoring devices that are currently used to assess haemodynamics and filling status in the perioperative setting. Methods and principles for measuring haemodynamic variables, the measured and calculated parameters as well as clinical benefits and shortcomings of each device are described. Furthermore, the results for monitoring devices from clinical studies of goal-directed fluid and volume therapy which have been published will be discussed.

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.

Continuous right ventricular end diastolic volume and right ventricular ejection fraction during liver transplantation: a multicenter study

Cardiac preload is traditionally considered to be represented by its filling pressures, but more recently, estimations of end diastolic volume of the left or right ventricle have been shown to better reflect preload. One method of determining volumes is the evaluation of the continuous right ventricular end diastolic volume index (cRVEDVI) on the basis of the cardiac output thermodilution technique. Because preload and myocardial contractility are the main factors determining cardiac output during liver transplantation (LTx), accurate determination of preload is important. Thus, monitoring of cRVEDVI and cRVEF should help with fluid management and with the assessment of the need for inotropic and vasoactive agents. In this multicenter study, we looked for possible relationships between the stroke volume index (SVI) and cRVEDVI, cRVEF, and filling pressures at 4 predefined steps in 244 patients undergoing LTx. Univariate and multivariate autoregression models (across phases of the surgical procedure) were fitted to assess the possible association between SVI and cRVEDVI, pulmonary artery occlusion pressure (PAOP), and central venous pressure (CVP) after adjustment for cRVEF (categorized as < or =30, 31-40, and >40%). SVI was strongly associated with both cRVEDVI and cRVEF. The model showing the best fit to the data was that including cRVEDVI. Even after adjustment for cRVEF, there was a statistically significant (P < 0.05) relationship between SVI and cRVEDVI with a regression coefficient (slope of the regression line) of 0.25; this meant that an increase in cRVEDVI of 1 mL m(-2) resulted in an increase in SVI of 0.25 mL m(-2). The correlations between SVI and CVP and PAOP were less strong. We conclude that cRVEDVI reflected preload better than CVP and PAOP.