Swiss medical weekly
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Apnea is an essential criterion for the diagnosis of brain death and is often difficult to determine in artificially ventilated patients. Absolute apnea is the absence of respiration when the respiratory center is maximally stimulated by hypercapnia. ⋯ The duration of apnea necessary to reach this level is highly variable. It does not induce hypoxemia when the technique of apneic oxygenation is used.