Arterial hypoxemia caused by intravenous ketamine.

Ketamine given IV in a dose of 2 mg/kg caused a significant reduction in Pao2 in 7 patients spontaneously breathing with an unassisted airway. Under the same conditions, in 7 patients, ketamine (2 mg/kg IV) preceded by diazepam (0.2 mg/kg IV) also caused a reduction in Pao2 not significantly different from that caused by ketamine. In some patients, alarmingly low levels of Pao2 ( less than or equal to 40 torr) were seen following ketamine administration. Based on these findings, the authors recommend that O2 and ventilatory assistance accompany ketamine given IV for anesthesia.