Hypoxic events in the surgical intensive care unit. An oxygen-monitoring protocol was established in the surgical intensive care unit (SICU) at the Denver General Hospital in July 1988. A 3-month surveillance audit ending March 1989 prospectively documented 100 consecutive hypoxic events in 51 of 241 (21%) SICU patients. These episodes occurred during mechanical ventilation in 46 patients, during spontaneous ventilation in 15 patients with artificial airways, and the remaining 39 occurred in nonintubated patients. Hypoxemia was recognized by pulse oximetry in 59, arterial blood gas analysis in 24, mixed venous oximetry in 15, and transcutaneous oxygen monitoring in 2. These events were due to problems with the ventilator or airway in 42, recent interventions in 21, new pulmonary process in 19, progression of underlying disease in 11, and unknown causes in 7. Two thirds resulted from mechanical problems amenable to simple intervention; there were two adverse outcomes. In conclusion, acute hypoxia is a frequent potentially morbid SICU event. Advances in continuous oxygen monitoring permit early identification and thereby may limit adverse outcomes, but should not prompt an expensive diagnostic work-up. 