P4 Stump Approach for Intraoperative Portal Vein Stenting in Pediatric Living Donor Liver Transplantation: An Innovative Technique for a Challenging Problem.

OBJECTIVE: The aim of this study was to evaluate the utility of the P4 stump stenting approach for treating portal vein (PV) complications in pediatric living donor liver transplantation (LDLT). BACKGROUND: PV complications cause significant morbidity and mortality in pediatric LDLT. Biliary atresia in the backdrop of pathological PV hypoplasia and sclerosis heightens the complexity of PV reconstruction. The authors developed a novel approach for intraoperative PV stenting via the graft segment 4 PV stump (P4 stump) to address this challenge. METHODS: From April 2009 to December 2016, 15 pediatric LDLT recipients (mean age 10.3 ±â€Š5.0 months, mean graft-recipient weight ratio 3.70%) underwent intraoperative stenting for suboptimal PV flow (<10 cm/s) or PV occlusion after collateral ligation and graft repositioning. Under portography, metallic stents were deployed via the reopened P4 stump of the left lateral segment grafts. RESULTS: PV diameter and peak flow increased significantly after stent placement (2.93 ±â€Š1.74 to 7.01 ±â€Š0.91 mm and 2.0 ±â€Š9.2 to 17.3 ±â€Š3.5 cm/s, respectively, P = 0.001 for both), and there were no technical failures. Stents in all surviving patients remained patent up to 8 years (mean 27.7 months), with no vascular or biliary complications. After implementation of the P4 approach, the incidence of variceal bleeding as a late complication decreased from 7% to zero. CONCLUSION: The P4 stump stenting approach affords procedural convenience, ease of manipulation, and consistent results with the potential for excellent long-term patency in children despite continued growth. This technique obviates the need for more demanding post-transplant stenting, and may become a substitute for complicated revision surgery, portosystemic shunting, or retransplantation.

Tubby-like protein 3 (TULP3) regulates patterning in the mouse embryo through inhibition of Hedgehog signaling.

Tubby-like protein 3 (TULP3) is required for proper embryonic development in mice. Disruption of mouse Tulp3 results in morphological defects in the embryonic craniofacial regions, the spinal neural tube and the limbs. Here, we show that TULP3 functions as a novel negative regulator of Sonic hedgehog (Shh) signaling in the mouse. In Tulp3 mutants, ventral cell types in the lumbar neural tube, which acquire their identities in response to Shh signaling, are ectopically specified at the expense of dorsal cell types. Genetic epistasis experiments show that this ventralized phenotype occurs independently of Shh and the transmembrane protein Smoothened, but it is dependent on the transcription factor Gli2. The ventralized phenotype is also dependent on the kinesin II subunit Kif3A, which is required for intraflagellar transport and ciliogenesis. In addition, TULP3 is required for proper Shh-dependent limb patterning and for maintaining the correct balance between differentiation and proliferation in the neural tube. Finally, the localization of TULP3 to the tips of primary cilia raises the possibility that it regulates the Hedgehog pathway within this structure.

Inpatient Respiratory Arrest Associated With Sedative and Analgesic Medications: Impact of Continuous Monitoring on Patient Mortality and Severe Morbidity.

OBJECTIVES: The primary study objective was to investigate the impact of surveillance monitoring (i.e., continuous monitoring optimized for deterioration detection) on mortality and severe morbidity associated with administration of sedative/analgesic medications in the general care setting. A second objective was consideration of the results in the context of previous investigations to establish practice recommendations for this approach to patient safety. METHODS: Retrospective review of available rescue event and patient safety data from a tertiary care hospital in a rural setting was performed for a 10-year period. Systematic analysis of all adult general care inpatient data followed by chart review for individual patients was used to identify patient death or permanent harm (i.e., ventilator dependency, hypoxic encephalopathy) related to administration of sedative/analgesics. RESULTS: Of 111,488 patients in units with surveillance monitoring available, none died or were harmed by opioid-induced respiratory depression when surveillance monitoring was in use. One patient died from opioid-induced respiratory depression in a unit where surveillance monitoring was available; however, the patient was not monitored at the time of the adverse event. In unmonitored units (15,209 patients during 29 months of incremental implementation), three patients died from opioid overdose (19.73 deaths per 100,000 at risk patients). The reduced death rate when surveillance monitoring was available (0.0009%) versus not available (0.02%) was significant (P = 0.03). CONCLUSIONS: For a 10-year period, the rescue system with continuous surveillance monitoring had a profound effect on death from sedative/analgesic administration in the general care setting. This approach to patient safety can help address the risk of sedative/analgesic-related respiratory arrests in hospitals.

Tryptophan Metabolism via the Kynurenine Pathway: Implications for Graft Optimization during Machine Perfusion.

Access to liver transplantation continues to be hindered by the severe organ shortage. Extended-criteria donor livers could be used to expand the donor pool but are prone to ischemia-reperfusion injury (IRI) and post-transplant graft dysfunction. Ex situ machine perfusion may be used as a platform to rehabilitate discarded or extended-criteria livers prior to transplantation, though there is a lack of data guiding the utilization of different perfusion modalities and therapeutics. Since amino acid derivatives involved in inflammatory and antioxidant pathways are critical in IRI, we analyzed differences in amino acid metabolism in seven discarded non-steatotic human livers during normothermic- (NMP) and subnormothermic-machine perfusion (SNMP) using data from untargeted metabolomic profiling. We found notable differences in tryptophan, histamine, and glutathione metabolism. Greater tryptophan metabolism via the kynurenine pathway during NMP was indicated by significantly higher kynurenine and kynurenate tissue concentrations compared to pre-perfusion levels. Livers undergoing SNMP demonstrated impaired glutathione synthesis indicated by depletion of reduced and oxidized glutathione tissue concentrations. Notably, ATP and energy charge ratios were greater in livers during SNMP compared to NMP. Given these findings, several targeted therapeutic interventions are proposed to mitigate IRI during liver machine perfusion and optimize marginal liver grafts during SNMP and NMP.

Metabolic and lipidomic profiling of steatotic human livers during ex situ normothermic machine perfusion guides resuscitation strategies.

There continues to be a significant shortage of donor livers for transplantation. One impediment is the discard rate of fatty, or steatotic, livers because of their poor post-transplant function. Steatotic livers are prone to significant ischemia-reperfusion injury (IRI) and data regarding how best to improve the quality of steatotic livers is lacking. Herein, we use normothermic (37°C) machine perfusion in combination with metabolic and lipidomic profiling to elucidate deficiencies in metabolic pathways in steatotic livers, and to inform strategies for improving their function. During perfusion, energy cofactors increased in steatotic livers to a similar extent as non-steatotic livers, but there were significant deficits in anti-oxidant capacity, efficient energy utilization, and lipid metabolism. Steatotic livers appeared to oxidize fatty acids at a higher rate but favored ketone body production rather than energy regeneration via the tricyclic acid cycle. As a result, lactate clearance was slower and transaminase levels were higher in steatotic livers. Lipidomic profiling revealed ω-3 polyunsaturated fatty acids increased in non-steatotic livers to a greater extent than in steatotic livers. The novel use of metabolic and lipidomic profiling during ex situ normothermic machine perfusion has the potential to guide the resuscitation and rehabilitation of steatotic livers for transplantation.

Split-Liver Ex Situ Machine Perfusion: A Novel Technique for Studying Organ Preservation and Therapeutic Interventions.

Ex situ machine perfusion is a promising technology to help improve organ viability prior to transplantation. However, preclinical studies using discarded human livers to evaluate therapeutic interventions and optimize perfusion conditions are limited by significant graft heterogeneity. In order to improve the efficacy and reproducibility of future studies, a split-liver perfusion model was developed to allow simultaneous perfusion of left and right lobes, allowing one lobe to serve as a control for the other. Eleven discarded livers were surgically split, and both lobes perfused simultaneously on separate perfusion devices for 3 h at subnormothermic temperatures. Lobar perfusion parameters were also compared with whole livers undergoing perfusion. Similar to whole-liver perfusions, each lobe in the split-liver model exhibited a progressive decrease in arterial resistance and lactate levels throughout perfusion, which were not significantly different between right and left lobes. Split liver lobes also demonstrated comparable energy charge ratios. Ex situ split-liver perfusion is a novel experimental model that allows each graft to act as its own control. This model is particularly well suited for preclinical studies by avoiding the need for large numbers of enrolled livers necessary due to the heterogenous nature of discarded human liver research.

Impact of Autologous Blood Transfusion on Survival and Recurrence among Patients Undergoing Partial Hepatectomy for Colorectal Cancer Liver Metastases.

BACKGROUND: Autologous transfusion (AT) has long been considered unsafe in major oncologic operations due to a theoretic risk of spreading metastatic disease, however, few data support this assumption. STUDY DESIGN: We conducted a retrospective analysis of 147 patients who underwent partial hepatectomy for colorectal cancer metastases at a single institution. Seventy-four patients received AT only and 73 received no transfusion (NT). We compared the overall survival and recurrence-free survival of these groups using Kaplan-Meier survival curves and adjusted hazard ratios. RESULTS: Patients who received AT had greater blood loss, more extensive resections, and longer procedure times. There were no differences in age, sex, proportion colon vs rectal cancer, or Fong Clinical Risk Score. Mean follow-up was 54 months. Median overall survival in the AT group was 59 months compared with 54 months in the NT group (p = 0.69) on log-rank test. No difference in overall survival was noted after adjusting for age, sex, Fong score, type of cancer (colon vs rectal), receipt of neoadjuvant therapy, receipt of adjuvant therapy, extent of resection and blood loss (hazard ratio AT vs NT 0.58; 95% CI 0.31 to 1.11; p = 0.10). Recurrence-free survival was also similar in the AT and NT groups (27% vs 37%; p = 0.22). The adjusted hazard ratio for recurrence-free survival was 0.95 (95% CI 0.54 to 1.65; p = 0.85). CONCLUSIONS: Autologous blood transfusion is not associated with an increased recurrence risk or a higher mortality rate. Surgeons performing liver resections for patients with colorectal cancer metastases can safely transfuse filtered autologous blood.

Bilateral proficiency over time leads to reduced donor morbidity in living donor hepatectomy.

BACKGROUND: Although left-lobe donation is considered safer, right-sided donor hepatectomy predominates in adult living donor liver transplantation (LDLT). We hypothesized that bilateral proficiency with donor hepatectomy reduces overall donor complications. METHODS: A retrospective review of 834 adult LDLT donors (221 left lobes) from January 2004 to December 2014 was performed, dividing cases into two eras based on left-graft experience. Donor complications within 6 months were investigated, focusing on graft side and surgical era. RESULTS: The overall complication rate was 17.6%, and was higher in right-lobe donors. In Era 2, during which left-lobe donation rates were three times higher, total complications decreased (14.7% vs. 20.9%, P=0.02). A significant reduction in postoperative ascites accounted for the lower overall complication rate. The proportion of major biliary complications (BCs) was halved from 62.5% to 25.0%. Right-lobe donor complications also decreased significantly (15.8% vs. 22.9%, P=0.032), demonstrating that it was not only increased left-lobe donations leading to lowered complication rates, but also greater experience with donor hepatectomy in general. CONCLUSIONS: Accumulating experience with bilateral donor hepatectomy leads to decreased donor morbidity and comparable outcomes for right and left lobes, further enhancing the goal of donor safety while balancing recipient needs.

Subnormothermic Machine Perfusion of Steatotic Livers Results in Increased Energy Charge at the Cost of Anti-Oxidant Capacity Compared to Normothermic Perfusion.

There continues to be significant debate regarding the most effective mode of ex situ machine perfusion of livers for transplantation. Subnormothermic (SNMP) and normothermic machine perfusion (NMP) are two methods with different benefits. We examined the metabolomic profiles of discarded steatotic human livers during three hours of subnormothermic or normothermic machine perfusion. Steatotic livers regenerate higher stores of ATP during SNMP than NMP. However, there is a significant depletion of available glutathione during SNMP, likely due to an inability to overcome the high energy threshold needed to synthesize glutathione. This highlights the increased oxidative stress apparent in steatotic livers. Rescue of discarded steatotic livers with machine perfusion may require the optimization of redox status through repletion or supplementation of reducing agents.

Endothelial Dysfunction in Steatotic Human Donor Livers: A Pilot Study of the Underlying Mechanism During Subnormothermic Machine Perfusion.

BACKGROUND: Steatosis is a major risk factor for primary nonfunction in liver transplantations. Steatotic livers recover poorly from ischemia reperfusion injury, in part due to alterations in the microcirculation, although the exact mechanism is unclear. In this study, we tested if there were any alterations in the shear stress sensing Kruppel-like factor 2 (KLF2) and its likely downstream consequences in the ex vivo perfused human liver endothelium, which would imply perturbations in microcirculatory flow in macrosteatotic livers disrupts laminar flow to evaluate if this is a potential therapeutic target for steatotic livers. METHODS: Using a subnormothermic machine perfusion system, 5 macrosteatotic and 4 nonsteatotic human livers were perfused for 3 hours. Flow, resistance, and biochemical profile were monitored. Gene expression levels of nitric oxide synthase 3 (eNOS), KLF2, and thrombomodulin were determined. Nitric oxide (NO) was measured in the perfusion fluid and activation of eNOS was measured with Western blotting. RESULTS: Flow dynamics, injury markers, and bile production were similar in both groups. Kruppel-like factor 2 expression was significantly higher in nonsteatotic livers. Western blotting analyses showed significantly higher levels of activated eNOS in nonsteatotic livers, consistent with an increase in NO production over time. Macrosteatotic livers showed decreased KLF2 upregulation, eNOS activity, and NO production during machine perfusion. CONCLUSIONS: These results indicate a perturbed KLF2 sensing in steatotic livers, which aligns with perturbed microcirculatory state. This may indicate endothelial dysfunction and contribute to poor posttransplantation outcomes in fatty livers, and further studies to confirm by evaluation of flow and testing treatments are warranted.