Predictors of Apnea and Prediction of Time to Death in Donation After Cardiac Death

Donation after cardiac death (DCD) is a method by which patients have the opportunity to donate organs following elective withdrawal of life-sustaining therapies (WLST). Often these patients have suffered a catastrophic neurological injury although not progressed to brain death or have a severe medical condition for which ongoing medical care is considered non-beneficial. DCD has become an increasingly significant source of organs for transplantation in a time of growing wait lists and organ shortfall.

In order to donate organs through DCD, the potential donor must progress to death within a certain time window after withdrawal of life sustaining therapies. This timeframe varied but is usually less than 120 minutes following WLST. Up to 40% of potentially eligible DCD donors in Ontario do not proceed to organ procurement for these reasons (internal data from Trillium Gift of Life).

The uncertainty and variability in the potential for successful organ procurement has an impact on families, health care teams and organ retrieval teams. It is important that this emotional and resource burden only occurs in candidates with a reasonable likelihood of being eligible to donate organs. The amount of time elapsing between WLST and circulatory arrest (and organ procurement) has important implications for the quality of the procured organs, and some organs are unable to be transplanted after death. Finally, maintaining organ procurement teams and an operating room on standby consumes valuable hospital resources and removes these human and physical resources from other clinical duties.

Several different prediction tools have been proposed to predict time to death following WLST in potential DCD donors, but none has been proven useful. To derive a more generalizable prediction tool it is necessary to identify valid predictors that are common to a wide variety of patients undergoing WLST. We propose the addition of features that predict apnea or respiratory insufficiency in the development of a new predictive model.

While previous studies propose important variables for prediction of time to death, we hypothesize that features that are focused on apnea (neurologic and non-neurologic) will be independently predictive of time of death following WLST.