Organ Viability Assessment Research Articles

Assessment of Critical Renal Ischemia With Real-Time Infrared Imaging

Currently visual and tactile clues such as color, mottling, and tissue turgor are used in the operating room for subjective assessments of organ ischemia. Studies have demonstrated that infrared (IR) imaging is a reliable tool to identify perfusion of brain tumors and kidneys during human surgery. Intraoperative IR imaging has the potential for more objective real-time detection and quantitative assessment of organ viability including early ischemia. We hypothesize, by detecting variations of the IR signal, we can assess the degree to which renal surface temperature reflects underlying renal ischemia. To address this hypothesis, IR imaging-derived temperature fluctuations were evaluated during laparotomy in a porcine model (n = 15). These temperature profiles then underwent spectral (frequency) analysis to assess their relationship to well-described oscillations of the microcirculation. An IR camera was positioned 30-60 cm above the exposed kidneys. Images (3-5 mum wavelength) were collected (1.0/s) at baseline, during warm renal ischemia, and during reperfusion. Dominant frequency (DF) of the tissue temperature fluctuations were determined by a Fourier transformation (spectral) analysis. IR images immediately showed which segments of the kidney were ischemic. DF at approximately 0.008 Hz that corresponds to blood flow oscillations was observed in thermal profiles. The oscillations were diminished or disappeared after 25 min of warm ischemia and were recovered with reperfusion in a time-dependent fashion. Oscillations were attenuated substantially in ischemic segments, but not in perfused segments of the kidney. The described oscillations can be measured noninvasively using IR imaging in the operating room, as represented by the DF, and may be an early marker of critical renal ischemia.

Deceased Organ Donation in Brazil: How Can We Improve?

Methods We retrospectively analyzed the registry data from one organ procurement organization obtained between January 1 and December 31, 2005. Results Among the 378 potential deceased donors, 182 (48.2%) were lost, mainly due to clinical conditions (27%) or cardiac arrest (19.3%). Of the remaining 196 (51.8%) potential donors, family consent was obtained in 94 cases (48%). Family refusal was higher for potential donors aged between 18 and 59 years (70%). Of the 94 donors, 72 (77%) had their organs harvested. Cardiac arrest before harvesting (56.5%) and positive viral serology (26%) were the main reasons for further losses. The mean donor age was 40 years and 51% were men. Causes of death were cerebral vascular accidents (55.5%), cranium encephalic traumas (29%), and gun shot wounds (8%). The rate of organ donation was 100% for kidneys and livers, 96% for hearts, 86% for pancreatas, 76% for lungs, and 74% for corneas. After assessment of organ viability, 94% of corneas, 91% of kidneys, and 88% of livers were transplanted, but only 52% of pancreata and 42% of hearts. The most frequent causes of discarded organs were age and concomitant donor infection. Conclusion Areas for potential improvements are: (1) earlier identification and adequate maintenance of potential donors; (2) campaigns for organ donation; and (3) careful evaluation of donated organs and selection of a suitable population to increase utilization of expanded criteria organs.

Assessment of liver function during extracorporeal membrane oxygenation in the non–heart beating donor swine

Introduction Although the use of non–heart beating donors (NHBD) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to warm ischemia (WI), biliary tree injury, and inadequate organ assessment. Warm blood reperfusion using extracorporeal membrane oxygenation (ECMO) can be a suitable option to reduce WI in organs from NHBD, allowing one to determine hepatic flow characteristics and bile production and facilitating assessment of organ viability. Methods This work evaluates the use of warm blood veno-arterial ECMO reperfusion in NHBD swine. Systemic and hepatic hemodynamics, bile, urine, and mixed venous blood were measured. After baseline data collection, 10 kU heparin was given intravenously followed by 1 g KCl to elicit cardiac arrest (CA). ECMO was started after 30 or 60 minutes of CA and kept running for 120 minutes. Results One-way repeated measures analysis of variance (ANOVA) with Tukey test analysis was used within a group. Two-way ANOVA was used between groups. ECMO can restore venous SO 2 and pH in both groups; the values were close to baseline in the 30-minute CA group. Also, in this group, bile production was >65% from baseline early during reperfusion and its value was lower in the longer CA group <55% ( P < .001). Aspartate aminotransferase (AST) was doubled at the end of ECMO support in the 60-minute CA group ( P < .05). Conclusion In this preheparinized NHBD swine model, ECMO support restores liver perfusion, oxygenation, and bile production after 60 minutes of CA. Quantification and analysis of bile production could be a determinant of liver function during ECMO resuscitation, and it may be a predictor of graft viability before transplantation.