Incidental finding of elevated pulmonary arterial pressures during liver transplantation and postoperative pulmonary complications.

BACKGROUND: In patients with end stage liver disease (ESLD) scheduled for liver transplantation (LT), an intraoperative incidental finding of elevated mean pulmonary arterial pressure (mPAP) may be observed. Its association with patient outcome has not been evaluated. We aimed to estimate the effects of an incidental finding of a mPAP > 20 mmHg during LT on the incidence of pulmonary complications. METHODS: We examined all patients who underwent a LT at Paul-Brousse hospital between January 1,2015 and December 31,2020. Those who received: a LT due to acute liver failure, a combined transplantation, or a retransplantation were excluded, as well as patients for whom known porto-pulmonary hypertension was treated before the LT or patients who underwent a LT for other etiologies than ESLD. Using right sided pulmonary artery catheterization measurements made following anesthesia induction, the study cohort was divided into two groups using a mPAP cutoff of 20 mmHg. The primary outcome was a composite of pulmonary complications. Univariate and multivariable logistic regression analyses were performed to identify variables associated with the primary outcome. Sensitivity analyses of multivariable models were also conducted with other mPAP cutoffs (mPAP ≥ 25 mmHg and ≥ 35 mmHg) and even with mPAP as a continuous variable. RESULTS: Of 942 patients who underwent a LT, 659 met our inclusion criteria. Among them, 446 patients (67.7%) presented with an elevated mPAP (mPAP of 26.4 ± 5.9 mmHg). When adjusted for confounding factors, an elevated mPAP was not associated with a higher risk of pulmonary complications (adjusted OR: 1.16; 95%CI 0.8-1.7), nor with 90 days-mortality or any other complications. In our sensitivity analyses, we observed a lower prevalence of elevated mPAP when increasing thresholds (235 patients (35.7%) had an elevated mPAP when defined as ≥ 25 mmHg and 41 patients (6.2%) had an elevated mPAP when defined as ≥ 35 mmHg). We did not observe consistent association between a mPAP ≥ 25 mmHg or a mPAP ≥ 35 mmHg and our outcomes. CONCLUSION: Incidental finding of elevated mPAP was highly prevalent during LT, but it was not associated with a higher risk of postoperative complications.

Assessing the discriminative ability of the respiratory exchange ratio to detect hyperlactatemia during intermediate-to-high risk abdominal surgery.

BACKGROUND: A mismatch between oxygen delivery (DO2) and consumption (VO2) is associated with increased perioperative morbidity and mortality. Hyperlactatemia is often used as an early screening tool, but this non-continuous measurement requires intermittent arterial line sampling. Having a non-invasive tool to rapidly detect inadequate DO2 is of great clinical relevance. The respiratory exchange ratio (RER) can be easily measured in all intubated patients and has been shown to predict postoperative complications. We therefore aimed to assess the discriminative ability of the RER to detect an inadequate DO2 as reflected by hyperlactatemia in patients having intermediate-to-high risk abdominal surgery. METHODS: This historical cohort study included all consecutive patients who underwent intermediate-to-high risk surgery from January 1st, 2014, to April 30th, 2019 except those who did not have RER and/or arterial lactate measured. Blood lactate levels were measured routinely at the beginning and end of surgery and RER was calculated at the same moment as the blood gas sampling. The present study tested the hypothesis that RER measured at the end of surgery could detect hyperlactatemia at that time. A receiver operating characteristic (ROC) curve was constructed to assess if RER calculated at the end of the surgery could detect hyperlactatemia. The chosen RER threshold corresponded to the highest value of the sum of the specificity and the sensitivity (Youden Index). RESULTS: Among the 996 patients available in our study cohort, 941 were included and analyzed. The area under the ROC curve was 0.73 (95% CI: 0.70 to 0.76; p < 0.001), with a RER threshold of 0.75, allowing to discriminate a lactate > 1.5 mmol/L with a sensitivity of 87.5% and a specificity of 49.5%. CONCLUSION: In mechanically ventilated patients undergoing intermediate to high-risk abdominal surgery, the RER had moderate discriminative abilities to detect hyperlactatemia. Increased values should prompt clinicians to investigate for the presence of hyperlactatemia and treat any potential causes of DO2/VO2 mismatch as suggested by the subsequent presence of hyperlactatemia.

Intraoperative measurement of the respiratory exchange ratio predicts postoperative complications after liver transplantation.

BACKGROUND: During surgery, any mismatch between oxygen delivery (DO2) and consumption (VO2) can promote the development of postoperative complications. The respiratory exchange ratio (RER), defined as the ratio of carbon dioxide (CO2) production (VCO2) to VO2, may be a useful noninvasive tool for detecting inadequate DO2. The primary objective of this study was to test the hypothesis that RER measured during liver transplantation may predict postoperative morbidity. Secondary objectives were to assess the ability of other variables used to assess the DO2/VO2 relationship, including arterial lactate, mixed venous oxygen saturation, and veno-arterial difference in the partial pressure of carbon dioxide (VAPCO2gap), to predict postoperative complications. METHODS: This retrospective study included consecutive adult patients who underwent liver transplantation for end stage liver disease from June 27th, 2020, to September 5th, 2021. Patients with acute liver failure were excluded. All patients were routinely equipped with a pulmonary artery catheter. The primary analysis was a receiver operating characteristic (ROC) curve constructed to investigate the discriminative ability of the mean RER measured during surgery to predict postoperative complications. RER was calculated at five standardized time points during the surgery, at the same time as measurement of blood lactate levels and arterial and mixed venous blood gases, which were compared as a secondary analysis. RESULTS: Of the 115 patients included, 57 developed at least one postoperative complication. The mean RER (median [25-75] percentiles) during surgery was significantly higher in patients with complications than in those without (1.04[0.96-1.12] vs 0.88[0.84-0.94]; p < 0.001). The area under the ROC curve was 0.87 (95%CI: 0.80-0.93; p < 0.001) with a RER value (Youden index) of 0.92 giving a sensitivity of 91% and a specificity of 74% for predicting the occurrence of postoperative complications. The RER outperformed all other measured variables assessing the DO2/VO2 relationship (arterial lactate, SvO2, and VAPCO2gap) in predicting postoperative complications. CONCLUSION: During liver transplantation, the RER can reliably predict postoperative complications. Implementing this measure intraoperatively may provide a warning for physicians of impending complications and justify more aggressive optimization of oxygen delivery. Further studies are required to determine whether correcting the RER is feasible and could reduce the incidence of complications.

Safety of laparoscopic hepatectomy in patients with hepatocellular carcinoma and portal hypertension: interim analysis of an open prospective study.

BACKGROUND: The laparoscopic approach might increase the number of cirrhotic patients with hepatocellular carcinoma (HCC) indicated for liver resection, otherwise contraindicated due to portal hypertension. The goal of this study was to confirm the safety of laparoscopic liver resection (LLR) in patients with portal hypertension. METHODS: This prospective, single-center, open study (ClinicalTrials.gov ID: NCT02145013) included all consecutive cirrhotic patients who underwent LLR for HCC from 2014 to 2017. Short-term outcomes were compared between patients with and without clinically significant portal hypertension (CSPH, defined by hepatic venous pressure gradient ≥ 10 mmHg). RESULTS: The study population included 45 patients, comprising 27 patients (60%) in the no CSPH group and 18 patients (40%) in the CSPH group. All planned procedures could be performed. The two groups did not differ in the extent of resection, transfusion, duration of clamping, and need for conversion. Overall, the 90-day mortality and severe morbidity rates were nil. Moderate morbidity was significantly higher in the CSPH group (39 vs. 4%, p = 0.01); however, the two groups did not differ in the rate of unresolved liver decompensation. Intensive care unit and hospital stays were significantly longer in the CSPH group. At 2 years, overall survival was 77% in the no CSPH group and 100% in the CSPH group (p = 0.17), and recurrence-free survival was 55% in the no CSPH group and 79% in the CSPH group (p = 0.10). CONCLUSION: LLR is safe in BCLC 0-A patients with CSPH, with no mortality and good short-term outcomes. Re-evaluation of the BCLC guidelines is needed.

Safety and feasibility of elective liver resection in adult Jehovah's Witnesses: the Henri Mondor Hospital experience.

BACKGROUND: Elective liver resection (LR) in Jehovah's Witness (JW) patients, for whom transfusion is not an option, involves complex ethical and medical issues and surgical difficulties. METHODS: Consecutive data from a LR program for liver tumors in JWs performed between 2014 and 2017 were retrospectively reviewed. A systematic review of the literature with a pooled analysis was performed. RESULTS: Ten patients were included (median age = 61 years). None needed preoperative erythropoietin. Tumor biopsy was not performed. Major hepatectomy was performed in 4 patients. The median estimated blood loss was 200 mL. A cell-saver was installed in 2 patients, none received saved blood. The median hemoglobin values before and at the end of surgery were 13.4 g/dL and 12.6 g/dL, respectively (p = 0.04). Nine complications occurred in 4 patients, but no postoperative hemorrhage occurred. In-hospital mortality was nil. Nine studies including 35 patients were identified in the literature; there was reported no mortality and low morbidity. None of the patients were transfused. CONCLUSIONS: By using a variety of blood conservation techniques, the risk/benefit ratio of elective liver resection for liver was maintained in selected adult JW patients. JW faith should not constitute an absolute exclusion from hepatectomy.