Postoperative alveolar-arterial oxygen tension difference: its relation to the operative incision in obese patients.

Forty-eight markedly obese patients for elective jejunoileal bypass were studied during spontaneous ventilation preoperatively and then postoperatively after 2 to 4 hours and on each of days 1 to 5 to determine the effect of the operative incision (midline versus transverse) on the alveolar-arterial oxygen tension difference (A-aDO2). Compared with control (Pre-op.) A-aDO2, there was a significant increase in A-aDO2 in all patients, beginning in the postanesthetic recovery area and continuing through postoperative (P.O.) day 4. Comparing the mean increase in A-aDO2 (P.O.-Pre-op.) between the two incision groups, patients with a midline incision had a significantly greater (p smaller than 0.001) increase in A-aDO2 on control (Pre-op.) value by day 5. The authors conclude that in markedly obese subjects, the midline incision can be expected to result in both more profound and more prolonged reduction in arterial oxygenation postoperatively.