Bispectral index monitoring in isoflurane anesthesia in laparoscopic cholecystectomy of morbid obese patients

Morbid obesity is associated with a some of significant comorbidities.
Early and uneventful postoperative recovery of obese patients remains a challenge for
anesthesiologists. It seems Bispecteral Index (BIS) monitoring may reduce drug usage
and hasten recovery time in inhalation anesthesia. The aim of this study was to investigate
the effect of BIS monitoring on intraoperative isoflurane utilization and the early
recovery profile.
Methods: Fifty morbidly obese adult patients (Body Mass Index (BMI) of 35 kg/m2 or
grater) undergoing elective laparoscopic cholecystectomy in Urmia Imam Khomeini
Hospital were enrolled in this prospective, Cohort and single blind study. Duration of
this study was six months between April to September 2012. Patients were randomly
divided two groups (25 patients per group). In the first phase of the study, patients were
anesthetized without the use of BIS monitoring and isoflurane being administered according
to standard clinical practice (this group formed the control group). In a second
phase, with use of BIS monitoring isoflurane was titrated to maintain a BIS value between
40 and 60 during surgery, and then 60-70 during 15 min before the end of surgery
(this group formed the BIS group). Isoflurane consumption and recovery time
were compared between two groups.
Results: All patients completed the study. No differences were noted between demographic
data. The isoflurane consumption in the BIS group was 30-35% lower than in
the control group (P< 0.001). The time to awakening and duration of extubation in the
BIS group were significantly less than the control group (P< 0.001). Furthermore, analgesic
consumption in the recovery room and sedation score during postoperative phase
were similar between the groups. Significant differences were noted in recovery time
between two groups (P< 0.001).
Conclusion: The addition of Bispectral index monitoring to standard monitoring reduced
isoflurane usage. We found use of BIS hastened recovery time after isoflurane
anesthesia.