Background: The clinical limits and most relevant definition of warm ischemic time (WIT) for donation after cardiac death (DCD) donor lungs are unclear.
Methods: Prospectively collected postwithdrawal and postmortem DCD donor hemodynamics and oximetry were temporally studied to determine the range, pattern, and potential clinical relevance to DCD clinical lung transplant outcomes. Different definitions of WIT were examined including the timing of withdrawal, systolic blood pressure less than 50 mm Hg, initiation of ventilation or the onset of pulmonary arterial flush. Intensive care unit donor management was strictly according to local practice guidelines.
Results: Between May 2006 and August 2008, 24 DCD donor referrals led to 13 attempted lung retrievals, resulting in nine bilateral lung transplantions (three donors did not arrest within prescribed 90 min window and one donor had unacceptable lungs). The mean WIT for the 10 retrieved DCD lungs varied according to the different potential definitions and ranged from 10 to 42 min (absolute range, 3-65 min). Donor blood pressure, heart rate, and oximetry fell linearly from the time of withdrawal, leading to cardiac arrest on average 13.8 min later.
Conclusions: From a practical perspective, a WIT definition starting when systolic blood pressure is less than 50 mm Hg and finishing with cold arterial flush, provides the simplest, most universal definition that encompasses all important elements of warm ischemia. There is a need to prospectively collect data on all potential DCD lung donors and correlate these with clinical outcomes.