Five healthy young women undergoing pelvic laparoscopy were selected for measurement of end-expired breath levels of nitrous oxide (N2O) after N2O pneumoperitoneum and laparoscopy, a preinduction control sample of end-expired air being collected from each. All subjects were induced with ketamine anesthesia, intubated, and maintained with ketamine, 100 percent oxygen (O2), and succinylcholine drip. End-expired breath samples were measured at intervals during and after the end of the procedure.
N2O in preinduction samples of operating-room (O.R.) air ranged from 6 to 183 (JOURNAL/asag/04.02/00000539-197407000-00011/ENTITY_OV0395/v/2017-07-21T014722Z/r/image-png 58) ppm. Pre-induction control end-expired breath levels ranged from 5 to 47 (JOURNAL/asag/04.02/00000539-197407000-00011/ENTITY_OV0395/v/2017-07-21T014722Z/r/image-png 26) ppm. Postinduction controls ranged from 204 to 537 (JOURNAL/asag/04.02/00000539-197407000-00011/ENTITY_OV0395/v/2017-07-21T014722Z/r/image-png 373) ppm, due to residual N2O in the anesthesia circuit. Peak end-expired breath levels for N2O occurred from 10 to 25 minutes into the procedure, and ranged from 1770 to 3800 (JOURNAL/asag/04.02/00000539-197407000-00011/ENTITY_OV0395/v/2017-07-21T014722Z/r/image-png 2492) ppm. N2O remained measurable in end-expired air of patients up to 13 hours after the procedure.