Examination of the Safety and Effectiveness of Low-Concentration Nitrous Oxide Anesthesia in Cataract Surgery.

PURPOSE 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. SETTING Saneikai Tsukazaki Hospital. DESIGN Retrospective, consecutive study. METHODS Patients who underwent bilateral cataracts surgeries 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 the surgery's beginning (N2O group) were retrospectively reviewed. Systolic blood pressure (BPs), diastolic blood pressure (BPd), and heart rate (HR) at the surgery's beginning 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. RESULTS No systemic symptoms and ocular complications requiring treatment were observed. For the N2O and Air groups, changes in BPs were -5.38 ± 11.07(P = 0.01) and 1.27 ± 13.61 mmHg, and HR were -2.24 ± 6.76 and 0.89 ± 5.18 bpm (P = 0.001), respectively; intraoperative SpO2 was 99.05 ± 0.74% and 97.44 ± 1.31% (P < 0.001), intraoperative anxiety was 21.76 ± 23.2 and 37.17 ± 32.79(P = 0.002), and intraoperative memory was 55.24 ± 36.8 and 68.91 ± 33.81(P = 0.01), respectively. No patients experienced intraoperative nausea. There was no statistically difference in BPd and intraoperative pain. CONCLUSIONS 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.