Development of a Prediction Model for Donation after Circulatory Death Lung Donor Progression

Purpose Although use of donation-after-circulatory-death (DCD) donors has significantly increased lung transplant (LTx) rates, 25-40% of intended DCD do not convert to actual donors due to non-progression to asystole in the required 90 minute time frame from withdrawal of cardio-respiratory support (WCRS). Predicting which intended DCD patient will progress remains problematic & impacts resourcing. Methods This retrospective study reviewed intended DCD lung donors referred between 2014-2018 to our program, to determine specific factors that may predict the likelihood of progression to death in ≤90mins. Donor demographics, relevant medical history, reason for WCRS, ICU hemodynamic/ventilation/admission data were compared between non-progresses and LTx DCD donor cohorts. Significant variables were included in multivariable logistic regression analysis and construction of a classification and regression tree (CART) prediction model. Results 159 of 334 referred DCD donors were accepted for LTx: 100 (63%) progressed to donation, 59 (37%) did not progress. Comparing non-progressed & LTx DCD donors, significant factors associated with death ≤90mins were: length of ICU stay ≤4 days, Glascow Coma Score=3, ventilation mode and severe infra-tentorial brain damage on imaging by CT/MRI . These factors were used to develop a CART predictive model for progression ≤90mins post-WCRS, which had a sensitivity of 0.95 and predictive value of 0.69 (Figure 1). Of the 59 who did not progress, 26 patients (44%) died within the subsequent 6 hours. Conclusion Intended DCD lung donors referred early after ICU admission, in a deep coma with severe infra-tentorial damage suggesting a significant neurological injury, are to most likely to progress within 90-minute post-WCRS. This CART prediction model is now being utilized prospectively to assist LTx team re decisions on potential DCD lung donor retrievals & resource allocation. Use of a time-extended DCD lung protocol up to 6 hours post WCRS, further expands the lung donor pool.