| Changes in Bispectral Index during Coinduction with Intravenous Anesthetics Using Synergistic Interaction. |
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Ho Yeong Kil, Hoon Park, Hyun Wha Lee, Tae Hyun Han, Sung Il Shin |
1Departments of Anesthesiology, Kangdong Sacred Heart Hospital, Hallym University.
2Departments of Orthopaedic Surgery, College of Medicine, Kangdong Sacred Heart Hospital, Hallym University, Seoul, Korea. |
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| Abstract |
BACKGROUND
Coinduction according to a hypnotic synergistic effect of intravenous anesthetics has an advantage of reducing hemodynamic change, induction dose and side effects of each drug. Meanwhile, the bispectral index has been used to monitor objective measurement of the hypnotic effect of intravenous anesthetics. The aim of this study was to evaluate the changes in the bispectral index during coinduction with two intravenous anesthetics that were known to have synergistic interactions.
METHODS
Sixty ASA I or II adult patients undergoing elective surgery were assigned to one of three groups according to induction methods: group 1, thiopental + propofol; group 2, thiopental + midazolam; group 3, midazolam propofol. Anesthesia induction was performed by injecting half of a hypnotic ED50 dose of both drug according to the known time to peak effect. For example, in group 1, propofol was injected first, and then thiopental 1 min. later. The Bispectral index, vital signs, and SpO2 were checked every minute for 5 minutes after injection of a drug.
RESULTS
Each group showed the lowest point of the BIS at time to peak effect, but the reduction of the BIS for each group showed no regular pattern between time and amount of degree compared to the lowest BIS of the two drugs when they were used alone.
CONCLUSIONS
The BIS has limitations in expressing a synergistic interaction phenomenon when anesthesia induction with two intravenous anesthetics that have a synergistic interaction. |
| Key Words:
Anesthesia: coinduction; Anesthetics, intravenous: midazolam; propofol; thiopental; Equipment: bispectral index; monitoring device |
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