Apneic oxygenation in apnea tests for brain death. A controlled trial. We performed a prospective controlled study of apneic oxygenation on 15 patients undergoing apnea tests for brain death. All patients were preoxygenated with 100% oxygen at existing respirator settings. During the 10-minute apnea tests, nine patients were given continuous apneic oxygenation by tracheal cannula. The other six patients had tracheal tubes open to room air. The patients given apneic oxygenation had little or no hypoxia by the end of the test. The patients given room air during the test became hypoxic. Many neurologists perform apnea tests with no oxygenation or with preoxygenation alone. This is the first prospective controlled study (to our knowledge) of apneic oxygenation; it shows that preoxygenation alone does not prevent hypoxia during apnea tests for brain death. We recommend that all apnea tests be performed with apneic oxygenation. 