Pronouncing brain death: Contemporary practice and safety of the apnea test

Little is known of hospital practice in brain death determination, specialty involvement, and followed procedures, including the apnea test.

We reviewed 228 patients pronounced brain dead at Mayo Clinic from 1996 to 2007. We performed a detailed review of clinical determination of brain death, intensive care support, apnea test procedure, and complications.

There were 228 patients who were pronounced brain dead, mostly after traumatic brain injury, cerebral hematoma, or aneurysmal subarachnoid hemorrhage. Brain death was declared within 24 hours of ictus in 30% of the patients and within 3 days in 62%. All patients were using one or more vasopressors, and 61% of the patients received vasopressin for diabetes insipidus. An apnea test could not be performed in 7% of the patients because of hemodynamic instability or poor oxygenation at baseline. In 3% of the patients, the apnea test procedure was aborted because of hypoxemia or hypotension. No major complications (cardiac arrest or pneumothorax) occurred during the apnea test. Polytrauma resulting in brain death was significantly more common in patients with aborted or not attempted apnea tests than in patients with completed apnea tests (p = 0.0004). During the study epoch, we found a shift toward determination of the tests by neurointensivists, pediatric neurologists, and neurosurgeons.

Brain death declaration is frequent within the first 3 days of admission. It is usually performed in hemodynamically unstable patients requiring vasopressors and vasopressin. If preconditions are met, apnea testing using an oxygen-diffusion technique is safe. However, in 1 of 10 patients, an apnea test could not be completed and confirmatory tests were needed.