Incorporating a hemodialysis filter into a commercial normothermic perfusion system to facilitate long-term preservation of human split-livers.

BACKGROUND: Normothermic machine perfusion (NMP) allows for the assessment and resuscitation of ex-vivo human livers prior to transplantation. Commercially available NMP systems are closed circuits that accumulate metabolic waste and cytokines over time, potentially limiting organ preservation times. Dialysis has been proposed as a method to remove waste and excess fluid from such systems. This study aimed to demonstrate the utility of integrating dialysis into a commercially available system by quantifying solute removal. METHODS: A dialysis filter was attached in parallel to a commercially available liver perfusion system. Three livers declined for transplantation were split before undergoing long-term NMP with blood using the modified system. During perfusion, dialysate flow rates were set in the range of 100-600 mL/h for short periods of time. At each flow rate, perfusate and spent dialysate samples were collected and analyzed for solute clearance. RESULTS: The addition of dialysis to a commercial NMP system removed water-soluble waste and helped regulate electrolyte concentrations. Interleukin-6 was successfully removed from the perfusate. Solute clearance was proportional to dialysate flow rate. A guide for our perfusion setup was created for the appropriate selection of dialysis flow rates and duration based on real-time perfusate composition. CONCLUSIONS: Dialysis circuits can efficiently remove waste and regulate perfusate composition, and can be easily incorporated to improve the performance of commercially available systems. Quantification of the effect of dialysis on perfusate composition enables refined dialysis control to optimize electrolyte profiles and avoid the over- or under-correction of key solutes.

The Impact of Homemade Laparoscopic Box Trainers on Medical Student Surgical Skills: A Randomized Control Pilot Study.

Objective: While instructional videos are commonly used in surgical education, there is a paucity of data on home laparoscopic box trainers. This pilot study evaluated impacts of augmenting instructional videos with these devices. Design: This was a randomized controlled pilot study evaluating laparoscopic surgical performance on the LapSim virtual surgical simulator before and after a 2 week curriculum of instructional videos alone (n = 8, 47.1%) vs videos plus a home laparoscopic box trainer (n = 9, 52.9%). The LapSim recorded mistake number, time, and instrument path length to complete each task. Participants completed surveys about their perceptions of surgery before and after the course. Participants: Preclinical medical students were recruited. Those with extensive surgical experience or did not complete the course were excluded. Results: For the box trainer group vs the videos alone group: mean change in mistakes was -10.0 (standard deviation [SD]:17.1) vs +.5 (SD:21.59) (P = .28); mean change in time was -433.24 (SD:304.67) seconds vs -366.16 (SD:240.10) seconds (P = .62); mean change in instrument path length was -4.27 (SD:4.38) meters vs -3.19 (SD:4.86) meters (P = .64). The box trainer group ranked "I feel as though surgery comes naturally" 1.58 points higher (95% confidence interval [CI]: .85, 2.32; P < .01) and "I am worried about being skilled at surgery" 1.26 points lower (95% CI: 2.29, -.24; P = .02) upon completing the study. The videos alone group reported no significant changes in survey responses. Conclusion: Home laparoscopic box trainers can generate confidence and reduce anxiety regarding surgical fields. This study provides a framework for future larger scale works.

Long-term ex situ normothermic perfusion of human split livers for more than 1 week.

Current machine perfusion technology permits livers to be preserved ex situ for short periods to assess viability prior to transplant. Long-term normothermic perfusion of livers is an emerging field with tremendous potential for the assessment, recovery, and modification of organs. In this study, we aimed to develop a long-term model of ex situ perfusion including a surgical split and simultaneous perfusion of both partial organs. Human livers declined for transplantation were perfused using a red blood cell-based perfusate under normothermic conditions (36 °C) and then split and simultaneously perfused on separate machines. Ten human livers were split, resulting in 20 partial livers. The median ex situ viability was 125 h, and the median ex situ survival was 165 h. Long-term survival was demonstrated by lactate clearance, bile production, Factor-V production, and storage of adenosine triphosphate. Here, we report the long-term ex situ perfusion of human livers and demonstrate the ability to split and perfuse these organs using a standardised protocol.