The Incidence of Hypoxia Following the Use of Hypnotics and Analgesics during Spinal Anesthesia

Abstract

Background : The purpose of this study was to find out the effect of hypnotics and analgesics on oxygen saturation by pulse oximetry in surgery patients under spinal anesthesia. Methods: Sixty-five patients classified ASA physical status 1 or 2 scheduled for surgery under spinal anesthesia were studied. These patients were divided into three groups. The 22 subjects of the first group did not receive either midazolam or fentanyl. The 22 subjects of the second group received midazolam. The 21 subjects of the third group received midazolam (0.03 mg/kg) and fentanyl (1.0㎍/ kg). Oxygen saturation was measured with a pulse oximetry. Measurements were made before spinal anesthesia, 5 minutes, and 10 minutes after starting of spinal anesthesia, 5 minutes, 10 minutes, 30 minutes, and 60 minutes after the start of the operation or intravenous injectian of drugs. In addition, measurements were made on arrival in the recovery room, and 5 minutes, 10 minutes, 20 minutes, and 30 minutes after amval in the recovery room. Results : There were statistically significant differences in oxygen saturation at 5 minutes after the start of the operation or intravenous injection of drugs. The mean oxygen saturation for the first group was 98.2±1.8%, for the second group 97.9±2.6%, and for the third group 92.4±2.8%. Hypoxia cases at 5 minutes after the start of the operation or intravenous injection of a drug occurred in 4.5% of the first group, 9.1% of the second group, and 57.1% of the third group Conclusions: We concluded that oxygen saturation monitoring should be done routinely in patients receiving hypnotics and analgesics during spinal anesthesia, and oxygen should be administered to patients who develope hypoxia during spinal anesthesia. (Korean J Anesthesiol 2000; 39: 792-797)