Glycemic responses to intermittent hepatic inflow occlusion in living liver donors

Improvement of compliance to the Portland intensive insulin therapy during liver transplantation after introducing an application software: a retrospective single center cohort study

Background

The Portland intensive insulin therapy effectively controls acute hyperglycemic change after graft reperfusion during liver transplantation. However, the time-consuming sophistication acts as a barrier leading to misinterpretation and decreasing compliance to the protocol; thus, we newly introduced an application software “Insulin protocol calculator” which automatically calculates therapeutic bolus/continuous insulin doses based on the Portland protocol.

Methods

Of 144 patients who underwent liver transplantation, 74 patients were treated before the introduction of "Insulin protocol calculator" by using a paper manual, and 70 patients were treated by using the application. Compliance was defined as the proportion of patients treated with exact bolus/continuous insulin dose according to the Portland protocol.

Results

Compliance was significantly greater in app group than in paper group regarding bolus dose (94.5% and 86.9%, P < 0.001), continuous dose (88.9% and 77.3%, P = 0.001), and both doses (86.6% and 73.8%, P < 0.001). Blood glucose concentration was significantly lower in app group at 3 h (125 ± 17 mg/dl vs. 136 ± 19 mg/dl, P = 0.014) and 4 h (135 ± 22 mg/dl vs. 115 ± 15 mg/dl, P = 0.029) after graft reperfusion. Acute hyperglycemic change during 30 min was more prominent in app group while hyperglycemia incidence was 71.4% vs. 54.1% (P = 0.031). However, hyperglycemia risk was comparable at 2 h (31.4% vs. 31.1%, P = 0.964), and even insignificantly lower in app group at 3 h (7.1% vs. 19.5%, P = 0.184).

Conclusions

Compliance to the Portland protocol was significantly improved after introducing the application software; post-reperfusion hyperglycemia was better controlled. “Insulin protocol calculator” is cost-effective and time-saving with potential clinical benefits.

The Endothelial Glycocalyx and Organ Preservation-From Physiology to Possible Clinical Implications for Solid Organ Transplantation

The endothelial glycocalyx is a thin layer consisting of proteoglycans, glycoproteins and glycosaminoglycans that lines the luminal side of vascular endothelial cells. It acts as a barrier and contributes to the maintenance of vascular homeostasis and microperfusion. During solid organ transplantation, the endothelial glycocalyx of the graft is damaged as part of Ischemia Reperfusion Injury (IRI), which is associated with impaired organ function. Although several substances are known to mitigate glycocalyx damage, it has not been possible to use these substances during graft storage on ice. Normothermic machine perfusion (NMP) emerges as an alternative technology for organ preservation and allows for organ evaluation, but also offers the possibility to treat and thus improve organ quality during storage. This review highlights the current knowledge on glycocalyx injury during organ transplantation, presents ways to protect the endothelial glycocalyx and discusses potential glycocalyx protection strategies during normothermic machine perfusion.

Postoperative hyperglycemia may negatively impact cytomegalovirus infection in seropositive liver transplant recipients: a retrospective cohort study

The aim of the study was to evaluate the association between postoperative hyperglycemia and CMV infection. We analyzed 741 CMV seropositive recipients, of livers from seropositive living donors, who underwent preemptive CMV treatment without CMV prophylaxis. The primary outcome was early CMV infection within 1 month after surgery. Hyperglycemia was defined when mean postoperative blood glucose concentration was >180 mg/dl based on previous research and guidelines. Survival analysis was performed using the Fine and Gray model by accounting for the competing risk of CMV infection-unrelated death. Of the 741 recipients (hyperglycemic group, n = 287; nonhyperglycemic group, n = 454), 372 (50.2%) recipients developed cytomegalovirus (CMV) infection within 1 month after surgery. CMV infection risk was significantly higher in hyperglycemic group than in nonhyperglycemic group in univariable analysis [hazard ratio (HR) 1.34, 95% confidence interval (CI), 1.08-1.66; P = 0.007] and in multivariable analysis (HR 1.25, 95% CI 1.0-1.54; P = 0.038). CMV infection risk was also significantly associated with recipient age, graft ischemia time, model for end-stage liver disease score, and preoperative neutrophil-to-lymphocyte ratio (P < 0.05). In conclusion, preventing postoperative hyperglycemia appears to be an important factor decreasing the risk of CMV infection in seropositive liver transplant recipients undergoing preemptive CMV treatment.

Portland Intensive Insulin Therapy During Living Donor Liver Transplantation: Association with Postreperfusion Hyperglycemia and Clinical Outcomes

Many liver transplant recipients experience intraoperative hyperglycemia after graft reperfusion. Accordingly, we introduced the Portland intensive insulin therapy (PoIIT) in our practice to better control blood glucose concentration (BGC). We evaluated the effects of PoIIT by comparing with our conventional insulin therapy (CoIT). Of 128 patients who underwent living donor liver transplantation (LDLT) during the phaseout period of CoIT, 89 were treated with the PoIIT and 39 were treated with CoIT. The primary outcome was hyperglycemia (BGC > 180 mg/dL) during the intraoperative postreperfusion phase. The secondary outcomes were postoperative complications such as infection. The incidence of hyperglycemia (22.5% vs. 53.8%, p = 0.001) and prolonged hyperglycemia for >2 hours (7.9% vs. 30.8%, p = 0.002) was significantly lower in PoIIT group than in CoIT group. A mixed linear model further demonstrated that repeatedly measured BGCs were lower in PoIIT group (p < 0.001). The use of PoIIT was significantly associated with decreases in major infections (OR = 0.23 [0.06-0.85], p = 0.028), prolonged mechanical ventilation (OR = 0.29 [0.09-0.89], p = 0.031), and biliary stricture (OR = 0.23 [0.07-0.78], p = 0.018) after adjustments for age, sex, and diabetes mellitus. In conclusion, the PoIIT is effective for maintaining BGC and preventing hyperglycemia during the intraoperative postreperfusion phase of living donor liver transplantation with potential clinical benefits.

Preconditioning methods in the management of hepatic ischemia reperfusion- induced injury: Update on molecular and future perspectives

Hepatic IR (ischemia reperfusion) injury is a commonly encountered obstacle in the post-operative management of hepatic surgery. Hepatic IR occurs during 'Pringle maneuver' for reduction of blood loss or during a brief period of cold storage followed by reperfusion of liver grafts. The stress induced during hepatic IR, triggers a spectrum of cellular responses leading to the varying degrees of hepatic complications which in turn affect the post operative care. Different preconditioning methods either activate or subdue different sets of molecular signals, resulting in varied levels of protection against hepatic IR injury. Yet, there is a serious lacuna in the knowledge regarding the choice of preconditioning methods and the resulting molecular changes in order to assess the efficiency and choice of these methods correctly. This review provides an update on the various preconditioning approaches such as surgical/ischemic, antioxidant, pharmaceutical and genetic preconditioning strategies published during last six years (2009-2015). Further, we discuss the attenuation or inhibition of specific inflammatory, apoptotic and necrotic markers in the various experimental models of liver IR subjected to different preconditioning strategies. While enlisting the controversies in the ischemic preconditioning strategy, we bring out the uncertainties in the existing molecular targets and their reliability in the attenuation of hepatic IR injury. Future research studies would include the novel preconditioning strategies employ i) the targeted gene silencing of key molecular targets inducing IR, ii) hyper expression of beneficial molecular signals against IR via gene transfer techniques. The above studies would see the combination of these latest techniques with the established preconditioning strategies for better post-operative hepatic management.

Association between Serum Bilirubin and Acute Intraoperative Hyperglycemia Induced by Prolonged Intermittent Hepatic Inflow Occlusion in Living Liver Donors

Background

Intermittent hepatic inflow occlusion (IHIO) is associated with acute hyperglycemia during living donor hepatectomy when the ischemia is prolonged. Bilirubin is a potent antioxidant to play an important role for maintaining insulin sensitivity and preventing hyperglycemia. Thus, we aimed to test whether serum bilirubin level is associated with prolonged IHIO-induced intraoperative hyperglycemia.

Methods

Seventy-five living liver donors who underwent a prolonged IHIO with a >30 minute cumulative ischemia were included. The association between preoperative serum bilirubin concentrations and the risk of intraoperative hyperglycemia (blood glucose concentration >180 mg/dl) was analyzed using binary logistic regression with adjusting for potential confounders including age and steatosis.

Results

The number of donors who underwent 3, 4, 5, and 6 rounds of IHIO was 41, 22, 7, and 5, respectively. Twenty-nine (35%) donors developed intraoperative hyperglycemia. Total bilirubin concentration was inversely associated with hyperglycemia risk (odds ratio [OR] 0.033, 95% confidence interval [CI] 0.004–0.313, P = 0.003). There was an interaction between age and total bilirubin concentration: the effect of lower serum total bilirubin (≤0.7 mg/dl) on the development of hyperglycemia was greater in older donors (>40 years) than in younger donors (P = 0.0.028 versus P = 0.212). Both conjugated bilirubin (OR 0.001 95% CI 0.001–0.684) and unconjugated bilirubin (OR 0.011 95% CI 0.001–0.246) showed an independent association with hyperglycemia risk.

Conclusions

Lower preoperative serum bilirubin was associated with greater risk of prolonged IHIO-induced hyperglycemia during living donor hepatectomy particularly in older donors. Thus, more meticulous glycemic management is recommended when prolonged IHIO is necessary for surgical purposes in old living donors with lower serum bilirubin levels.

Protective Mechanisms of Hypothermia in Liver Surgery and Transplantation

Hepatic ischemia/reperfusion (I/R) injury is a side effect of major liver surgery that often cannot be avoided. Prolonged periods of ischemia put a metabolic strain on hepatocytes and limit the tolerable ischemia and preservation times during liver resection and transplantation, respectively. In both surgical settings, temporarily lowering the metabolic demand of the organ by reducing organ temperature effectively counteracts the negative consequences of an ischemic insult. Despite its routine use, the application of liver cooling is predicated on an incomplete understanding of the underlying protective mechanisms, which has limited a uniform and widespread implementation of liver-cooling techniques. This review therefore addresses how hypothermia-induced hypometabolism modulates hepatocyte metabolism during ischemia and thereby reduces hepatic I/R injury. The mechanisms underlying hypothermia-mediated reduction in energy expenditure during ischemia and the attenuation of mitochondrial production of reactive oxygen species during early reperfusion are described. It is further addressed how hypothermia suppresses the sterile hepatic I/R immune response and preserves the metabolic functionality of hepatocytes. Lastly, a summary of the clinical status quo of the use of liver cooling for liver resection and transplantation is provided.

Macrosteatotic and nonmacrosteatotic grafts respond differently to intermittent hepatic inflow occlusion: Comparison of recipient survival

Intermittent hepatic inflow occlusion (IHIO) during liver graft procurement is known to confer protection against graft ischemia/reperfusion injury and thus may benefit the recipient's outcome. We evaluated whether the protective effect of IHIO differs with the presence of macrosteatosis (MaS) and with an increase or decrease in the cumulative occlusion time. The subgroup of 188 recipients who received grafts with MaS was divided into 3 groups according to the number of total IHIO rounds during graft procurement: no IHIO, n = 70; 1 to 2 rounds of IHIO, n = 50; and ≥3 rounds of IHIO, n = 68. Likewise, the subgroup of 200 recipients who received grafts without MaS was divided into 3 groups: no IHIO, n = 108; 1 to 2 rounds of IHIO, n = 40; and ≥3 rounds of IHIO, n = 52. The Cox model was applied to evaluate the association between the number of total IHIO rounds and recipient survival separately in the subgroup of MaS recipients and the subgroup of non-MaS recipients. Analyzed covariables included the etiology, Milan criteria, transfusion, immunosuppression, and others. In the subgroup of MaS recipients, 1 to 2 rounds of IHIO were favorably associated with recipient survival [hazard ratio (HR), 0.29; 95% confidence interval (CI), 0.10-0.80; P = 0.03 after Bonferroni correction], whereas ≥3 rounds of IHIO were not associated with recipient survival (HR, 0.56; 95% CI, 0.25-1.23). In the subgroup of non-MaS recipients, neither 1 to 2 rounds of IHIO (HR, 0.69; 95% CI, 0.30-1.61) nor ≥3 rounds of IHIO (HR, 0.91; 95% CI, 0.42-1.96) were associated with recipient survival. In conclusion, 1 to 2 rounds of IHIO may be used for the procurement of MaS grafts with potential benefit for recipient survival, whereas IHIO has a limited impact on recipient survival regardless of the cumulative occlusion time when it is used for non-MaS grafts.