Bispectral Index Profile During General Anaesthesia Using Nitrous Oxide For Lower Segment Caesarean Delivery

Because of its antinociceptive effect N2O decreases the minimum alveolar concentration (MAC) of volatile anesthetics and may attenuate the increase in blood pressure and heart rate caused by surgical stimulation. Nitrous oxide used alone has no effect on BIS in humans even when it produces loss of consciousness. Patients undergoing lower segment caesarean section (LSCS) under general anesthesia are at increased risk of intraoperative awareness and subsequent recall. We have studied the effect of N2O/O2/sevoflurane anesthesia on bispectral index (BIS) values, versus O2/air/sevoflurane anesthesia for LSCS. Twenty ASA I&II patients receiving general anesthesia (GA) for elective LSCS were studied. During anesthesia, BIS values and other observations were recorded. Neither BIS nor mean blood pressure were significantly different between the two groups (p >0.05). A median BIS of 60 (range 40-70) recorded during surgery. Hemodynamic stability all over study period was satisfactory in both groups. We concluded that, BIS during O2/N2O/sevoflurane anesthesia for LSCS did not change significantly compared to O2/air/sevoflurane anesthesia.