Depth of Anesthesia Determination by using Bispectral Index in Patients underwent Inhalation or Total Intravenous General Anesthesia

BACKGROUND:
Bispectral index (BIS) is a new method for determination depth of anesthesia. In most of our operating rooms depth of anesthesia is measured according to clinical features; however, it has not enough accuracy. The aim of this study was to compare BIS numbers between inhalation and intravenous anesthesia at different times of anesthesia.

METHODS:
This was a prospective descriptive study. One hundred and fourteen patients divided between two groups; inhalation anesthesia and intravenous anesthesia. The patients in each group randomly were divided among three subgroups. BIS was measured in one phase of anesthesia in each group: Immediately after intubation, surgical incision, and wound closer. Then, the data was analyzed by t-test, chi-square and analysis of variance (ANOVA) tests in SPSS software.

FINDINGS:
There was no significant differences in any phases of study for frequency of desired BIS between inhalation and intravenous anesthesia groups. However, mean of BIS in the inhalation anesthesia group was significantly more than other group (p<0.05). There were no significant differences between the frequency of desired BIS in inhalation and intravenous anesthesia in three phases of BIS measurements (p>0.05).

CONCLUSION:
Ordinary used clinical findings are not enough to evaluate desired depth of anesthesia. When we use BIS monitoring, we can produce enough depth of anesthesia; also, sometimes we can decline dose of anesthetic drugs.

KEY WORDS:
Bispectral index (BSI), intravenous anesthesia, inhalation anesthesia, desired BIS, depth of anesthesia