Hypoxemia after gastric bypass surgery for morbid obesity

Fifty-six patients who underwent Roux-en-Y gastrojejunostomy for morbid obesity had arterial blood gas analysis before surgery and during the first five postoperative days. Preoperatively, seven subjects were hypoxemic and three were hypercapneic. Twenty-four hours after gastric bypass, 75% of the patients had an arterial oxygen pressure (Pao2) less than 60 mm Hg. Compared with preoperative measurements, blood gas values on the first postoperative day showed a 13.7-mm Hg decrease in the mean arterial Pao2 and a 5.0-mm Hg increase in the mean arterial carbon dioxide pressure. Arterial Pao2 determinations on the third, fourth, and fifth postoperative days returned toward, but remained significantly less than, paired values obtained before surgery. Patients with hypoxemia after gastrojejunostomy were significantly older and had significantly lower preoperative arterial Pao2 measurements than patients who were not hypoxemic after surgery. Weight, body mass index, and preoperative spirometric measurements did not distinguish between those patients who did and did not become hypoxemic postoperatively. We conclude that hypoxemia commonly follows gastric bypass for morbid obesity, and thus we recommend that all patients undergoing this procedure be treated with supplemental oxygen for at least the first three postoperative days.