Effects of Nitrous Oxide Administration on Para-aortic Line Obliteration in Postoperative Chest Film.

Abstract

To examine the effects of nitrous oxide administration on atelectasis produced during general anesthesia evaluated by para-aortic line obliteration on postoperative plain chest X-ray films, 175ASA 1-2 patients undergoing elective major surgery (82 upper abdominal, 54 lower abdominal and 39head/neck operations) were evaluated. Subjects were allocated to Group G (with nitrous oxide) or Group A (no nitrous oxide) and postoperative chest X-ray film was studied within 1hr of emerging from anesthesia and para-aortic line obliteration ratio (PALO) was measured as division of obliterated by the total para-aortic line length. Upper abdominal surgery patients resulted in a significant increase of PALO than lower or head/neck surgery patients in both Group G and A. PALO of Group G was significantly higher than of Group A in upper abdominal surgery patients. However, there was no difference of PALO between two groups in lower abdominal and head/neck surgery patients. In conclusion, nitrous oxide results in minimal effects on PALO during lower abdominal and head/neck surgery, while it increases PALO during upper abdominal surgery.