Apnea testing with continuous positive airway pressure for the diagnosis of brain death in a patient with poor baseline oxygenation status.

Abstract

Apnea testing is a key component in the clinical diagnosis of brain death. Patients with poor baseline oxygenation may not tolerate the standard 8-10 min apnea testing with oxygen insufflation through tracheal tube. No studies have assessed the safety and feasibility of other methods of oxygenation during apnea testing in these types of patients. Here, we safely performed apnea testing in a patient with baseline PaO2 of 99.1 mm Hg at 100% oxygen. We used continuous positive airway pressure (CPAP) of 10 cm of H2O and 100% oxygen at the flow rate of 12 L/min using the circle system of anesthesia machine. After 10 min of apnea testing, PaO2 decreased to 75.7 mm Hg. There was a significant rise in PaCO2 and fall in pH, but without hemodynamic instability, arrhythmias, or desaturation. Thus, the apnea test was declared positive. CPAP can be a valuable, feasible and safe means of oxygenation during apnea testing in patients with poor baseline oxygenation, thus avoiding the need for ancillary tests.