Examination of the safety and effectiveness of low-concentration nitrous oxide anesthesia in cataract surgery

To investigate the effects in cataract surgery using local anesthesia along with a 30% low-concentration nitrous oxide (N2O) anesthesia compared with local anesthesia only.

Saneikai Tsukazaki Hospital.

Retrospective, consecutive study.

Patients who underwent bilateral cataract surgery were enrolled. 37 patients using room air inhalation (Air group) and 45 patients using 30% low-concentration N2O anesthesia (70% oxygen, total 6 L/min) at surgery start (N2O group) were retrospectively reviewed. Systolic blood pressure (BPs), diastolic blood pressure (BPd), and heart rate (HR) at surgery start and end, and mean intraoperative oxygen saturation (% SpO2) were examined. Immediately following surgery, a questionnaire using the Visual Analog Scale score was done to determine intraoperative pain, anxiety, memory, and nausea.

No systemic symptoms in all patients and ocular complications requiring treatment were observed. For the N2O and air groups, changes in BPs were -5.38 ± 11.07(P = .01) and 1.27 ± 13.61 mm Hg, and HR were -2.24 ± 6.76 and 0.89 ± 5.18 bpm (P = .001), respectively; intraoperative SpO2 was 99.05% ± 0.74% and 97.44% ± 1.31% (P < .001), intraoperative anxiety was 21.76 ± 23.2 and 37.17 ± 32.79 (P = .002), and intraoperative memory was 55.24 ± 36.8 and 68.91 ± 33.81 (P = .01), respectively. No patients experienced intraoperative nausea. There was no statistically difference in BPd (P = .47) and intraoperative pain (P = .62).

Low-concentration N2O anesthesia may not cause respiratory depression, abnormal vital signs, or nausea in cataract surgery. It can suppress intraoperative anxiety and memory and decrease and stabilize vital signs.