Body position and late postoperative nocturnal hypoxaemia.

Thirteen patients were monitored for nocturnal body position (supine vs. side) and arterial oxygen saturation pre-operatively and on the second postoperative night after major abdominal surgery. The number of positional changes were significantly decreased after operation (p < 0.05) with a trend towards more time spent in the supine position (p = 0.1). Individual mean arterial oxygen saturation decreased postoperatively (p < 0.05) but without a difference between the supine and side positions (p = 0.9). Pre-operatively, episodic desaturations were significantly more frequent in the supine position than on the side (p < 0.05) but not postoperatively. Pain was the most frequent reason for decreased nocturnal movements.