A comparative study of depth of anesthesia monitored by BIS values in two anesthesia techniques and their cost-effectiveness
Abstract
Objective: Propofol is an intravenous agent used extensively in total venous anesthesia (TIVA), but its acquisition cost is nearly 1 to 3 folds higher than other intravenous or inhalation agents. Thiopental is an ultra short acting barbiturate which can reduce the cost of induction to one seventh of Propofol induction cost. In this study, by BIS monitoring of the depth of anesthesia, we evaluated maintaining anesthesia with Propofol while Thiopental has been used for induction of anesthesia and the aim of study was to find a cost effective method.
Methodology: In a single blind clinical trial, 82 patients with ASA II & I scheduled for cataract surgery were randomized in two groups. In the first group (A), induction of anesthesia was done with Propofol 2 mg/kg and then anesthesia maintained with Propofol 100 micro/kg. In the other group (B), induction was Thiopental 5 mg/kg and anesthesia maintained with Propofol 160 micro/ kg. BIS monitored depth of anesthesia throughout the procedure. We compared the BIS values in each step of the procedure in both groups.
Results: After extubation, mean of BIS score were 87.53(±2.52) and 88.79(±2.07) for groups A and B respectively. This difference was not clinically significant. Multiple linear regression analysis, identified decreased maintenance dose of Propofol and duration of surgery as independent predictors for BIS span 40-60.(P < 0.000,r2 =0.558). Cost effectiveness (acquisition cost/percent of 40-60 BIS span) for groups A and B were 2.95 $ and 1.03 $ respectively.
Conclusion: Minor surgeries like ophthalmic surgery can be conducted with maintenance of Propofol while induction is with Thiopental. Monitoring the depth of anesthesia with BIS showed that if we choose 160 micro/kg Propofol for maintenance then it is not necessary to have a loading dose and induction can be done by Thiopental. Further studies with different type of surgery and different maintenance doses of Propofol must be done.
Methodology: In a single blind clinical trial, 82 patients with ASA II & I scheduled for cataract surgery were randomized in two groups. In the first group (A), induction of anesthesia was done with Propofol 2 mg/kg and then anesthesia maintained with Propofol 100 micro/kg. In the other group (B), induction was Thiopental 5 mg/kg and anesthesia maintained with Propofol 160 micro/ kg. BIS monitored depth of anesthesia throughout the procedure. We compared the BIS values in each step of the procedure in both groups.
Results: After extubation, mean of BIS score were 87.53(±2.52) and 88.79(±2.07) for groups A and B respectively. This difference was not clinically significant. Multiple linear regression analysis, identified decreased maintenance dose of Propofol and duration of surgery as independent predictors for BIS span 40-60.(P < 0.000,r2 =0.558). Cost effectiveness (acquisition cost/percent of 40-60 BIS span) for groups A and B were 2.95 $ and 1.03 $ respectively.
Conclusion: Minor surgeries like ophthalmic surgery can be conducted with maintenance of Propofol while induction is with Thiopental. Monitoring the depth of anesthesia with BIS showed that if we choose 160 micro/kg Propofol for maintenance then it is not necessary to have a loading dose and induction can be done by Thiopental. Further studies with different type of surgery and different maintenance doses of Propofol must be done.
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