[Blood gas changes after laparoscopy].

Blood gas changes after laparoscopy under general anesthesia were examined. Thirty-six ASA I or II women were allocated to one of the two groups: carbon dioxide was used for pneumoperitoneum in group C and nitrous oxide in group N. Anesthesia was maintained with enflurane, buprenorphine, and supplemental midazolam. Arterial blood gases were measured in patients breathing room air. A significant fall in PaO2 (from 92.8 mmHg to 71.5 mmHg) was observed 5 minutes after extubation in group N as compared with the preoperative level and with group C, but there is no change in PaO2 in group C. PaCO2 showed no significant changes in both groups. In 6 out of 36 patients, PaO2 decreased below 60 mmHg. Possible causes of the difference between the two groups are diffusion hypoxia produced by nitrous oxide, gas embolism, or postoperative hyperventilation in response to hypercarbia during laparoscopy by carbon dioxide insufflation, and the last one is most probable. This may have prevented hypoxia in group C.