Thursday, March 27, 2008
The American Journal of Transplantation has an interesting article about predicting rapid death in a donation after cardiac death (DCD) setting.
Context: DCD is a technique of obtaining organs for transplantation in non-brain dead patients. In brain dead patients you can obtain presumably well-perfused, healthy organs from a patient while their heart is still beating as they are considered dead once they are determined to be brain-dead. There are some circumstances however - usually in patients with severe brain injuries but who aren't brain dead - in which life support is stopped, the patient is kept comfortable, and if they die - their heart stops beating - within a certain period of time - usually 60 minutes - they are declared dead and their organs are harvested. This is called DCD. Patients who don't quickly die continue to receive comfort-oriented terminal care. Predicting who is likely to rapidly die (which would allow them to actually donate their organs) is important because 1) families won't be given false hope that their loved one will die quickly and be able to donate their organs 2) transplant teams won't be 'needlessly' mobilized to be on stand-by to collect the organs. My sense is that palliative care teams are involved with DCD in many institutions (family decision making support prior to attempting DCD, providing symptom management to the patient after cessation of life support) - it has certainly been written about in the palliative care literature.
This paper presents a prospective, multi-institutional observational study of ~500 adults who had life support stopped with the hope of DCD - 45% of whom actually died within 1 hour. They looked at dozens of different parameters to see which ones predicted death within 1 hour. The results are complicated and I'm not going to belabor them here (in fact, depending on what sensitivity you are looking for in predicting death within 1 hour this study provides you with at least 10 different ways of doing so) - more pressors, lower Glasgow coma score, lower arterial oxygen tension, lower blood pressure, etc., etc. were all associated with rapid death. What is really interesting to me is that comfort meds - given either before cessation of life support or afterwards - were associated (in multiple analyses) with not dying rapidly. If you got morphine you lived longer.
God I love findings like that. To be fair, morphine probably didn't make people actually live longer (although it's possible - breathing rapidly and shallowly is not a good way to live a long time). Instead, in this population, healthier patients likely needed the comfort meds (had a stronger respiratory drive and so had more labored breathing, were less severely brain injured and so could show facial signs of distress, etc.) - the nearly brain dead patients breathing 8/minute did not need opioids. That said, any solid data (and this is solid data) that support the observation that many of us who care for the dying have made - that comfort meds don't usually hasten death - is good news, politically, so to speak. The next time you're doing a terminal extubation and a colleague/trainee expresses concern you're going to hasten someone's death by palliating their labored breathing - show them this article.
A thought experiment based on these findings.... Let's say we agree organ donation and DCD (when judiciously and compassionately carried out) are good things. Let's also say that there are instances in which we give opioids and comfort meds in the imminently dying not because we think the patient is suffering (experiencing pain, fear, breathlessness) but because they look like they might be. In my experience this is usually in profoundly brain injured patients who have been completely unresponsive who nevertheless have strong respiratory drives and can breath sharply and rapidly prior to dying - they look bad, to be sure, and I treat them with meds to calm their breathing just in case - but I often doubt that they are aware of anything at all. If these findings bear out under further study, particularly if it looks like comfort meds actually are prolonging life, is it ethical/appropriate to give such meds just to make someone look good if it means someone else dies for a lack of a needed organ? Please comment.
Thanks to Dr. Bob Arnold for alerting me to this paper.
DeVita, M.A., Brooks, M.M., Zawistowski, C. (2008). Donors after cardiac death: validation of identification criteria (DVIC) study for predictors of rapid death.. American Journal of Transplantation, 8, 432-441. DOI: 10.1111/j.1600-6143.2007.02087.x
NEJM has a related article about the ethics of consent for organ donation (free full-text available), which discusses the potential for patients to receive otherwise unwanted invasive medical therapies (including cardiac resuscitation) if their families/docs are trying to keep them alive for DCD. Good reading.