Ischemic preconditioning attenuates lactate release by the liver during hepatectomies under vascular control: a case-control study

The effect of low central venous pressure on hepatic surgical field bleeding and serum lactate in patients undergoing partial hepatectomy: a prospective randomized controlled trial

Background

This prospective randomized controlled study was designed to evaluate the effect of fluid restriction alone versus fluid restriction + low central venous pressure (CVP) on hepatic surgical field bleeding, intraoperative blood loss, and the serum lactate concentration in patients undergoing partial hepatectomy.

Methods

One hundred forty patients undergoing partial hepatectomy with intraoperative portal triad clamping were randomized into a fluid restriction group (Group F) or fluid restriction + low CVP group (Group L). Both groups received limited fluid infusion before the liver lesions were removed. Ephedrine was administered if the systolic blood pressure (SBP) decreased to <90 mmHg for 1 min. When the urine output was <20 ml/h or the SBP was <90 mmHg for 1 min more than three times, an additional 200 ml of crystalline solution was quickly infused within 10 min. In addition to fluid restriction, patients in Group L received continuous nitroglycerin and esmolol infusion to maintain a low CVP. The duration of portal triad clamping, frequency of additional fluid infusion, frequency of ephedrine administration, intraoperative blood loss, extent of liver resection, and bleeding score of the hepatic surgical field were recorded. Arterial blood gas analysis was performed before anesthesia (T1), after liver dissection and immediately before liver resection (T2), 10 min after removal of the liver lesion (T3), and before the patient was discharged from the postanesthesia care unit (T4).

Results

Being in the fluid restriction Group (Group F) (odds ratio = 5.04) and cirrhosis (odds ratio = 3.28) were risk factors for hepatic surgical field bleeding. Factors contributing to intraoperative blood loss were the operation time, duration of portal triad clamping, and extent of resection. No significant between-group difference was observed for blood loss or blood transfusion. The serum lactate concentration peaked at T3 in both groups.

Conclusions

Maintaining a lower CVP during hepatectomy provides an optimal surgical field but has no significant effect on intraoperative blood loss. Moreover, lower CVP does not increase the serum lactate concentration.

Trial registration

“A comparative study of the effect fluid restriction and low CVP pressure on the oozing of blood in liver wounds and blood lactate in patients undergoing partial hepatectomy” was prospectively registered as a trial (registration number: ChiCTR-INR-17014172, date of registration: 27 December 2017).

Interaction between anesthetic conditioning and ischemic preconditioning on metabolic function after hepatic ischemia-reperfusion in rabbits

BACKGROUND

Both anesthetic-induced and ischemic preconditioning are protective against hepatic ischemia-reperfusion injury. However, the effects of these preventive methods on the metabolic function remain to be elucidated. We investigated the anesthetic conditioning and ischemic preconditioning on the metabolic function of the rabbit model of hepatic ischemia-reperfusion.

METHODS

After approval by the institutional animal care and use committee, 36 Japanese White rabbits underwent partial hepatic ischemia for 90 min either under sevoflurane or propofol anesthesia. All the rabbits underwent 90 min of hepatic ischemia, and half of the rabbits in each group underwent additional 10-min ischemia and 10-min reperfusion before index ischemia. Hepatic microvascular blood flow was intermittently measured during reperfusion period, and galactose clearance, serum aminotransferase activities, and lactate concentrations were determined 180 min after reperfusion.

RESULTS

Neither anesthetic conditioning with sevoflurane nor ischemic preconditioning altered hepatic microvascular blood flow during reperfusion and serum transaminase activities after reperfusion. However, galactose clearance of reperfused liver was significantly higher under sevoflurane anesthesia than propofol (0.016 ± 0.005/min vs. 0.011 ± 0.004/min). Statistically significant interaction between anesthetic choice and application of ischemic preconditioning suggests that the ischemic preconditioning is selectively protective under propofol anesthesia. Increase of blood lactate concentration was significantly suppressed under sevoflurane anesthesia compared to propofol (1.5 ± 0.8 vs. 3.9 ± 1.4 mmol/l) without any statistically significant interaction with the application of ischemic preconditioning.

CONCLUSION

Sevoflurane attenuated the decrease of galactose clearance and increase of the blood lactate after reperfusion compared to propofol. Application of ischemic preconditioning was significantly protective under propofol anesthesia.

Beyond Preconditioning: Postconditioning as an Alternative Technique in the Prevention of Liver Ischemia-Reperfusion Injury

Liver ischemia/reperfusion injury may significantly compromise hepatic postoperative function. Various hepatoprotective methods have been improvised, aiming at attenuating IR injury. With ischemic preconditioning (IPC), the liver is conditioned with a brief ischemic period followed by reperfusion, prior to sustained ischemia. Ischemic postconditioning (IPostC), consisting of intermittent sequential interruptions of blood flow in the early phase of reperfusion, seems to be a more feasible alternative than IPC, since the onset of reperfusion is more predictable. Regarding the potential mechanisms involved, it has been postulated that the slow intermittent oxygenation through controlled reperfusion decreases the burst production of oxygen free radicals, increases antioxidant activity, suppresses neutrophil accumulation, and modulates the apoptotic cascade. Additionally, favorable effects on mitochondrial ultrastructure and function, and upregulation of the cytoprotective properties of nitric oxide, leading to preservation of sinusoidal structure and maintenance of blood flow through the hepatic circulation could also underlie the protection afforded by postconditioning. Clinical studies are required to show whether biochemical and histological improvements afforded by the reperfusion/reocclusion cycles of postconditioning during early reperfusion can be translated to a substantial clinical benefit in liver resection and transplantation settings or to highlight more aspects of its molecular mechanisms.

Arterial Lactate Concentration at the End of an Elective Hepatectomy Is an Early Predictor of the Postoperative Course and a Potential Surrogate of Intraoperative Events

OBJECTIVES

To test the prognostic impact of arterial lactate concentration at the end-of-surgery (LCT-EOS) on postoperative outcome after elective liver-resections and to identify the predictors of an increase in LCT-EOS.

BACKGROUND DATA

A recent systematic-review of risk-prediction-models for liver resections has evidenced their poor accuracy and a deficit in the evaluation of intraoperative events. LCT-EOS is a marker of impaired tissue oxygenation.

METHODS

This prospectively-designed study was based on a training-cohort of 519 patients and a validation-cohort of 466 patients. For each of the endpoints (high comprehensive complication index (CCI) scores, 90-day-mortality and severe-morbidity), prognostic-models were built by logistic-regression using the training-cohort. These models were thereafter tested in the validation-cohort and their performance (discrimination, accuracy, calibration) assessed. Independent predictors of LCT-EOS were also identified.

RESULTS

In the training-cohort, LCT-EOS cutoff best discriminating high-CCI, 90-day-mortality and severe-morbidity were 3, 3 and 2.8 mmol/L (and the corresponding AUROC 0.86, 0.87 and 0.76). LCT-EOS was an independent predictor of endpoints and adding LCT-EOS to the other predictors increased by 16.4%, 34.5% and 17.7% the accuracy of the models for high-CCI, 90-day-mortality and severe-morbidity, respectively. The models had high calibration and accuracy. Diabetes, repeat-hepatectomy, major-hepatectomy, synchronous-major-procedure, inflow-occlusion and blood-transfusion were independent predictors of LCT-EOS >3 mmol/L.

CONCLUSIONS

LCT-EOS >3 mmol/L is an early predictor of postoperative-outcome and should be used as a tool to determine patients requiring critical-care and as an endpoint in studies measuring the impact of perioperative interventions.

Impact of ischemic preconditioning on outcome in clinical liver surgery: a systematic review

Background. Ischemia-reperfusion injury is a major cause of post-liver-surgery complications. Ischemic preconditioning (IPC) has been demonstrated to protect against ischemia-reperfusion injury. Clinical studies have examined IPC in liver surgery but with conflicting results. This systematic review aimed to evaluate the effects of IPC on outcome in clinical liver surgery. Methods. An electronic search of OVID Medline and Embase databases was performed to identify studies that reported outcomes in patients undergoing liver surgery subjected to IPC. Basic descriptive statistics were used to summarise data from individual clinical studies. Results. 1093 articles were identified, of which 24 met the inclusion criteria. Seven topics were selected and analysed by subgroup. There were 10 studies in cadaveric liver transplantation, 2 in living-related liver transplantation, and 12 in liver resection. IPC decreases hepatocellular damage in liver surgery as determined by transaminases but does not translate to any significant clinical benefit in orthotopic liver transplant or liver resection. Conclusions. Available clinical evidence does not support routine use of IPC in liver surgery as it does not offer any apparent benefit in perioperative outcome. Further clinical studies will need to be carried out to determine the subset of patients that will benefit from IPC.