Proof of concept: liver splitting during normothermic machine perfusion.

INTRODUCTION: Despite utilizing extended criteria donors, there remains a shortage of livers for transplantation. No data exists on splitting donor livers with concurrent NMP-L. METHODS: A liver recovered from a donor after circulatory death was subjected to NMP-L using a red cell based fluid. During NMP-L, a 'classical' left lateral + right trisegmentectomy split was performed using an integrated bipolar/ultrasonic device. After splitting, blood flow was confirmed using Doppler ultrasound in each lobe. RESULTS: Prior to splitting, flow rates were maintained physiologically. Lactate decreased from 13.9 to 3.0 mmol/L. Lactate before and after splitting were similar in the hepatic arteries, portal veins and IVC. Doppler ultrasound demonstrated arterial and venous waveforms in both lobes after splitting. CONCLUSIONS: 'Classical' liver splitting during NMP-L is feasible, maintaining viability of both lobes. Establishing this procedure may attenuate cold ischaemic injury, allow pre-implantation monitoring of both grafts and facilitate logistics of transplanting two grafts.

The Use of an Acellular Oxygen Carrier in a Human Liver Model of Normothermic Machine Perfusion.

BACKGROUND: Normothermic machine perfusion of the liver (NMP-L) is a novel technique that preserves liver grafts under near-physiological conditions while maintaining their normal metabolic activity. This process requires an adequate oxygen supply, typically delivered by packed red blood cells (RBC). We present the first experience using an acellular hemoglobin-based oxygen carrier (HBOC) Hemopure in a human model of NMP-L. METHODS: Five discarded high-risk human livers were perfused with HBOC-based perfusion fluid and matched to 5 RBC-perfused livers. Perfusion parameters, oxygen extraction, metabolic activity, and histological features were compared during 6 hours of NMP-L. The cytotoxicity of Hemopure was also tested on human hepatic primary cell line cultures using an in vitro model of ischemia reperfusion injury. RESULTS: The vascular flow parameters and the perfusate lactate clearance were similar in both groups. The HBOC-perfused livers extracted more oxygen than those perfused with RBCs (O2 extraction ratio 13.75 vs 9.43 % ×10 per gram of tissue, P = 0.001). In vitro exposure to Hemopure did not alter intracellular levels of reactive oxygen species, and there was no increase in apoptosis or necrosis observed in any of the tested cell lines. Histological findings were comparable between groups. There was no evidence of histological damage caused by Hemopure. CONCLUSIONS: Hemopure can be used as an alternative oxygen carrier to packed red cells in NMP-L perfusion fluid.

Quantitative assessment of the cell surface proteome to identify novel therapeutic targets in cholangiocarcinoma.

BACKGROUND: Cholangiocarcinoma has a high mortality and morbidity. Median survival is less than 6 months. Surgical resection is appropriate in certain circumstances. Because distal cholangiocarcinoma is difficult to distinguish from pancreatic cancers, patients might not receive optimum therapy. Proteomics is the study of complex cellular proteins using mass spectrometry. The aim of this study was to determine the constituent proteins on the cell surface of a model of cholangiocarcinoma. METHODS: A sample preparation technique to enrich for cell surface proteins of the intrahepatic cholangiocarcinoma cell line CC-SW-1 was developed by modifying a NeutrAvidin-biotin system. After isolation, trypsin digestion, and purification, peptides were fractionated for tandem mass spectrometry before being analysed with the NCBInr database and the Mascot search algorithm. Results were confirmed by immunohistochemistry using a peroxidase detection technique on paraffin-embedded sections from resected specimens. FINDINGS: Peptide enrichment was confirmed by electrophoresis. 862 proteins were consistently expressed between samples (n=3). 271 of these proteins were attributed only to the cell surface. They included proteins used clinically for staging disease (cytokeratin 19 [CK19]), identifying cancer stem cells (epithelial cell adhesion molecule [EpCAM], neural cell adhesion molecule [NCAM], epithelial growth factor receptor [EGFR]), and indicating potential for differentiation (Frozzled receptor, Notch pathway). Novel markers from the tumour necrosis factor (TNF) receptor superfamily were also identified. Immunohistochemistry confirmed these findings. INTERPRETATION: The results from this surface proteomic profiling could help to identify novel therapeutic targets in cholangiocarcinoma. Further development of this technique could be translated to distinguish between distal cholangiocarcinoma and pancreatic cancers. FUNDING: UK Medical Research Council.

Reticulocyte count and hemoglobin concentration predict survival in candidates for liver transplantation.

BACKGROUND: Prognostic scores are used to assess the likelihood of mortality in cirrhosis and the necessity of liver transplantation. These models are imperfect and refinement would allow more accurate prognostication and selection of patients for transplant. This study investigated association of red cell parameters and mortality in liver transplant candidates. METHODS: Data from patients with cirrhosis assessed for transplantation from 2008 to 2010 at Queen Elizabeth Hospital Birmingham, UK were reviewed retrospectively. Kaplan-Meier analysis and Cox regression models were used to generate indices predicting mortality. Accuracy of existing and updated models was tested by calculation of c-statistics. Results were validated in a cohort of patients assessed for liver transplant in Jena, Germany. RESULTS: Data were collected from 386 patients in the study cohort. Median follow-up was 15 months (0-45). During follow-up, 151 patients (39%) were transplanted, 138 (36%) died, and 97 (25%) survived without transplant. Abnormal reticulocyte count (P<0.001, c-statistic 0.623) and hemoglobin concentration (P<0.001, c-statistic 0.609) predicted mortality in Cox regression analysis. Abnormal reticulocyte count was also found to predict mortality in competing risk analysis. Refining the Model for End-Stage Liver Disease (MELD) to incorporate reticulocyte count and hemoglobin concentration (MELD-red) improved predictive power from 0.701 to 0.731 (c-statistics). This was confirmed in an independent validation cohort of 157 patients with c-statistics of 0.787 and 0.816, respectively, for MELD and MELD-red. CONCLUSIONS: Abnormal red cell indices, in particular increased reticulocyte count and decreased hemoglobin concentration, are associated with increased risk of death in liver transplant candidates. Refining MELD to incorporate these indices improves prediction of mortality.

Effects of a backboard, bed height, and operator position on compression depth during simulated resuscitation.

OBJECTIVE: To investigate the effect of a backboard, cardiopulmonary resuscitation (CPR) provider body position and bed height on the quality of chest compression during simulated in-hospital resuscitation. DESIGN AND SETTING: Randomised controlled cross-over trial in a university hospital. PARTICIPANTS: Second-year medical student basic life support instructors. INTERVENTIONS: Chest compressions performed on a resuscitation manikin placed on a hospital bed with/without a CPR backboard, kneeling on the bed adjacent to the manikin and lowering the height of the bed. MEASUREMENTS AND RESULTS: Sub-optimal chest compressions were performed on all surfaces. There were no differences in compression depth: standard CPR, 29+/-7 mm; backboard CPR, 31+/-10 mm; kneeling on the bed, 30+/-7 mm; lowering bed height, 32+/-10 mm. Compression rate and duty cycle were similar on each surface. Participants failed to recognise their poor quality CPR, and there was no difference in assessment of fatigue or efficacy of CPR between surfaces. CONCLUSIONS: In contrast to current guidelines, the use of a CPR backboard did not improve chest compressions. Furthermore, kneeling on the bed adjacent to the victim or lowering bed height did not impact materially on the quality of chest compression. These findings should be validated in clinical studies.

Birmingham assessment of breathing study (BABS).

BACKGROUND: Current international resuscitation guidelines for lay people rely on the assessment of "normal breathing" as a key sign of breathing and circulation. However, it is not known how accurately laypersons can discriminate between "normal" and "abnormal" breathing. The aim of this study was to test the ability of medical students to discriminate between simulated normal and abnormal breathing patterns and select the correct treatment. METHODS: Six video clips of simulated breathing were recorded showing: normal; abnormal -shallow, rapid, agonal (obstructed and unobstructed airways); or absent breathing. The clips were validated by three experienced emergency practitioners and then shown in a random order to 48 second-year medical students. For each clip observers were asked to indicate: "Is this patient breathing?" (yes-normal, yes-abnormal, no) and "What action would you take?" (rescue breathing or recovery position). RESULTS: All experts correctly identified the breathing type and agreed on an appropriate emergency action. Students identified normal breathing as: normal 61%, abnormal 33% and absent 6%; abnormal breathing as: normal 29%, abnormal 61%, absent 10%; and absent breathing as: normal 8%, abnormal 6%, absent 85%. Correct actions were selected in 86% during normal breathing, 51% during abnormal breathing and 86% during absent breathing. The sensitivity for observers correctly identifying normal from abnormal breathing was 60% and specificity 75% and for selecting the correct action was 42% and 80%, respectively. CONCLUSIONS: Medical students were unable to identify normal breathing from abnormal breathing reliably resulting in a high number of inappropriate, potentially harmful actions. Further evaluation of the optimal method for assessing for signs of breathing and circulation is required.