Original article Comparison of energy metabolism in liver grafts from donors after circulatory death and donors after brain death during cold storage and reperfusion M. T. P. R. Perera 1 , D. A. Richards 4 , M. A. Silva 1 , N. Ahmed 1 , D. A. Neil 2 , N. Murphy 3 and D. F. Mirza 1 1 Liver Unit, and Departments of 2 Pathology and 3 Critical Care, Queen Elizabeth Hospital Birmingham, 4 Pharmacy, Pharmacology and Therapeutics, School of Clinical and Experimental Medicine, Medical School, University of Birmingham, Edgbaston, Birmingham, UK Correspondence to: Mr M. T. P. R. Perera, Liver Unit, Queen Elizabeth Hospital Birmingham, Edgbaston, Birmingham B15 2TH, UK (e-mail: thamara.perera@uhb.nhs.uk) Background: Donation after circulatory death (DCD) liver grafts have supplemented the donor organ pool, but certain adverse outcomes have prevented exploration of the full potential of such organs. The aim of this study was to determine key differences in basic energy metabolism between DCD and donation after brainstem death (DBD) grafts. Methods: Microdialysis samples from DCD and DBD allograft parenchyma from cold storage to 48 h after reperfusion were analysed by colorimetric methods. Interstitial lactate, pyruvate and glycerol levels were measured and the lactate/pyruvate ratio was calculated to estimate energy depletion of the grafts. Histological features of ischaemia and reperfusion injury were assessed. Results: Donor age, extent of steatosis and cold ischaemia time were comparable between ten DCD and 20 DBD organs. DCD grafts had higher levels of interstitial lactate (median 11·6 versus 1·2 mmol/l; P = 0·015) and increased lactate/pyruvate ratio (792 versus 38; P = 0·001) during cold storage. There was no significant difference in glycerol levels between DCD and DBD grafts (225·1 versus 127·5 μmol/l respectively; P = 0·700). Rapid restoration of energy levels with lactate clearance, increased pyruvate levels and reduced lactate/pyruvate ratio was seen following reperfusion of functioning DCD grafts, parallel with levels in DBD grafts. Histology revealed more pronounced glycogen depletion in DCD grafts. Three allografts that failed owing to primary non-function showed energy exhaustion with severe glycogen depletion. Conclusion: Liver grafts from DCD donors exhibited depletion of intracellular energy reserves during cold storage. Failed allografts showed severe energy depletion. Modified organ preservation techniques to minimize organ injury related to altered energy metabolism may enable better utilization of donor organs after circulatory death. Paper accepted 28 January 2014 Published online 28 April 2014 in Wiley Online Library (www.bjs.co.uk). DOI: 10.1002/bjs.9478 Introduction Liver grafts from donation after circulatory death (DCD) donors have increased the number of organs available for transplantation 1 . An increased incidence of primary graft non-function and initial poor function are the main barriers preventing the wider use of DCD liver grafts 2 . In addition, ischaemic-type biliary strictures occur later in DCD liver grafts, resulting in hesitant use of liver grafts from such donors 3 . Most of these complications are attributed to the initial donor warm ischaemia incurred between withdrawal of treatment and the time of actual circulatory death 4 . The pathophysiology of donor warm ischaemia is understood to involve continued energy consumption by living cells at body temperature. Lack of tissue perfusion with adequately oxygenated blood results in anaerobic metabolism, owing to rapid depletion of oxidative energy. Energy exhaustion is probably related to permanent cellular damage 5 . Preservation–reperfusion injury augments the cellular damage leading to widespread cell death. Although energy depletion contributes to the  2014 BJS Society Ltd BJS 2014; 101: 775–783 Published by John Wiley & Sons Ltd