Tension Pneumothorax During Apnea Testing for the Determination of Brain Death

Abstract

The apnea test (AT) is considered as the ‘condition sine qua non’ by most of the intesivists for determining brain death (BD) as it provides an important information for a definitive loss of brainstem function. It is the most difficult clinical test in BD protocols and is also potentially harmful and lengthy. The possible complications of this test include severe decrease in blood pressure, pneumothorax, excessive CO2 retention, hypoxia, acidosis, and cardiac arrhythmia or asystole. It is important to abort the test in the setting of any of the above mentioned complication, which will compromise BD diagnosis. It is important to ensure that certain prerequisites are satisfied before the AT is carried out. These include body temperature 32°C or more, normal PO2 or preoxygenation to obtain an arterial PO2 ≥ 200 mmHg, arterial PCO2 or PaCO2 normal or above 40 mmH, blood pH normal or in the low basic range, pretest systolic blood pressure of at least 90 mmHg, Euvolemia or a positive fluid balance during the previous 6 hours, no drug that can paralyze the respiratory muscles. If continuous or intermittent oxygen supply is preceded by decreasing nitrogen levels of blood gases, high PaO2 levels can be maintained for very long periods of time. Preoxygenation removes alveolar nitrogen stores and helps oxygen transport. There are several techniques for ascertaining that there is sufficient oxygenation during AT .1-5