Apnea testing for the diagnosis of brain death

Objectives-A review is given on various methods, preconditions and pitfalls of apnea testing for the diagnosis of brain death. Materials and methods-An extensive medical data base search was implemented by information gathered from books and our own experience with more than 2000 apnea tests. Results -While testing for apnea (AT) is considered indispensable worldwide, recommendations and handling differ. Rather than relying on elapsed time, a specific target value for the partial arterial pressure of carbon dioxide (PaCO2) should be aimed at being the maximum physiological stimulus for respiration. Methodological points are elaborated upon in detail for apneic oxygenation and hypoventilation. Conclusion -AT is an indispensable element of diagnosing brain death. Although with proper handling and adequate precautions AT is safe, it should be performed as a last resort. An international agreement on target values for the PaCO2 is desirable.