A Comparative Study on Impact of Isobaric and Hyperbaric Bupivacaine on Bispectral Index (Bis) in Patients Undergoing Cesarean Section With Spinal Anesthesia



Jabalameli M¹ ; Hazegh N² Show Affiliations
Source: Journal of Isfahan Medical School Published:2012

Abstract

Background: Bispectral index (BIS) is a parameter derived from the EEG which associated with glucose metabolism speed in brain cells and continuously analyzes patient’s curved electroencephalogram during general anesthesia so as to investigate patient’s consciousness and awareness level. Provided that spinal anesthesia is combined with sedative drugs, it would cause loss of consciousness and BIS in patient; however, some studies have indicated that in spinal anesthesia, patient’s consciousness would be reduced even without combination of sedative drugs. This study was also implemented on patients undergoing cesarean section. Other studies have shown that adding fentanyl in spinal anesthesia caused BIS loss. Bupivacaine can also reduce BIS. One of the other factors influencing on this parameter is baricity2 which is associated with the concentration of added glucose to the drug. This study aimed to review the impact of isobaric and hyperbaric bupivacaine in intrathecal on bispectral index (BIS) during cesarean section. Methods: In this double blinded clinical trial, 82 women were studied who were candidate for elective cesarean section and referred to Shahid Beheshti Hospital, Iran, during 2009-2010. The study subjects randomly were divided into two groups; a group with spinal anesthesia using isobaric marcaine and the other group with spinal anesthesia using hyperbaric marcaine. SQI, EMG, BIS level, ambient temperature, the frequency of spinal block level, MAP in the minutes immediately after spinal anesthesia, and then in minutes 5, 10, 15, 30, 45, 60, 90 and 120, were measured and compared in the two groups. In addition, changes trend of these items at the same times were studied in each group compared with the baseline. The statistical tests consisted of Chi-square test for reviewing the correlation between qualitative variables, and student t-test for comparing quantitative data, ANOVA test for comparing quantitative data with over 2 modes and GLM test for comparing quantitative data between the two groups. Findings: Given to the statistical findings, mean BIS showed no significant difference in any of the studied times between the two groups (P > 0.05). In reviewing the change courses of BIS with the baseline, there was a significant difference only at minute 45 (P < 0.01). Therefore, it seems that baricity of bupivacaine had no significant impact on loss of consciousness in patients. Conclusion: It seems that baricity of bupivacaine has no impact on sedation and higher loss of BIS; and besides, use of sedative drugs is recommended along with anesthetic drugs in spinal anesthesia. © 2012, Isfahan University of Medical Sciences(IUMS). All rights reserved.