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Noninvasive Detection of Ischemic Vascular Damage in a Pig Model of Liver Donation After Circulatory Death
Author(s) -
Ember Katherine J.I.,
Hunt Fiona,
Jamieson Lauren E.,
Hallett John M.,
Esser Hannah,
Kendall Timothy J.,
Clutton R. Eddie,
Gregson Rachael,
Faulds Karen,
Forbes Stuart J.,
Oniscu Gabriel C.,
Campbell Colin J.
Publication year - 2021
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.31701
Subject(s) - raman spectroscopy , circulatory system , perfusion , medicine , ischemia , liver transplantation , oxygenation , transplantation , cardiology , nuclear medicine , pathology , physics , optics
Background and Aims Liver graft quality is evaluated by visual inspection prior to transplantation, a process highly dependent on the surgeon’s experience. We present an objective, noninvasive, quantitative way of assessing liver quality in real time using Raman spectroscopy, a laser‐based tool for analyzing biomolecular composition. Approach and Results A porcine model of donation after circulatory death (DCD) with normothermic regional perfusion (NRP) allowed assessment of liver quality premortem, during warm ischemia (WI) and post‐NRP. Ten percent of circulating blood volume was removed in half of experiments to simulate blood recovery for DCD heart removal. Left median lobe biopsies were obtained before circulatory arrest, after 45 minutes of WI, and after 2 hours of NRP and analyzed using spontaneous Raman spectroscopy, stimulated Raman spectroscopy (SRS), and staining. Measurements were also taken in situ from the porcine liver using a handheld Raman spectrometer at these time points from left median and right lateral lobes. Raman microspectroscopy detected congestion during WI by measurement of the intrinsic Raman signal of hemoglobin in red blood cells (RBCs), eliminating the need for exogenous labels. Critically, this microvascular damage was not observed during WI when 10% of circulating blood was removed before cardiac arrest. Two hours of NRP effectively cleared RBCs from congested livers. Intact RBCs were visualized rapidly at high resolution using SRS. Optical properties of ischemic livers were significantly different from preischemic and post‐NRP livers as measured using a handheld Raman spectrometer. Conclusions Raman spectroscopy is an effective tool for detecting microvascular damage which could assist the decision to use marginal livers for transplantation. Reducing the volume of circulating blood before circulatory arrest in DCD may help reduce microvascular damage.