Argon as Distending Medium in Laparoscopy Compared with Carbon Dioxide and Nitrous Oxide

The study investigated the inert gas argon as a distending medium during laparoscopic tubal sterilization under local anesthesia, and compared it with carbon dioxide (CO2) and nitrous oxide (N2O). Ninety women were assigned to three groups of 30 each, and one of three gases was randomly selected for abdominal distention. The chosen gas was blinded to surgeon, patient, and anesthetist. Induction and maintenance analgesia with midazolam and alfentanil were given by the anesthetist at a predetermined dosage as needed. Lidocaine 1% was given for paracervical block and in the subumbilical suprapubic areas for local anesthesia. A modified McGill pain assessment rating was used to record patients' pain at 1, 24, and 48 hours postoperatively. Postoperative analgesia requirement and time to return to work were also recorded. Intraoperatively, argon required similar analgesia as CO2 and N2O, but at 72 hours was associated with greater discomfort, probably relating to its lower solubility and retention in the abdomen. Time to return to work was not affected. Owing to its similar density (atomic weight 40) compared with molecular weight of 44 for CO2 and N2O, argon can be used interchangeably for distention in the standard insufflator machine. It should undergo further study for this purpose, however.