Alterations in oxygen saturation and ventilation after intravenous sedation for peritoneoscopy.

The effect of intravenous sedation on oxygen saturation and ventilation was studied in 11 patients undergoing peritoneoscopy. Oxygen saturation (mean +/- SD) decreased from baseline (94.7% +/- 1.7%) to nadir (78.6% +/- 10.7%) after sedation. Respiratory depression was evident in these patients by concomitant decreases in minute ventilation and tidal volume. Baseline to nadir arterial blood gas changes in eight patients were consistent with hypoventilation and also suggested a superimposed ventilation perfusion mismatch. Mean respiratory rate did not significantly change during peritoneoscopy. Peritoneal gas insufflation stimulated increased ventilation and oxygen saturation, but no further changes in PCO2 or pH. We conclude that serious arterial oxygen desaturation and possibly some ventilation perfusion mismatch occur after sedation with intravenously administered meperidine-diazepam for peritoneoscopy with resultant hypoxemia, hypercarbia, and acidosis.