Clinical Professor Dept Anesthesiology SUNY @ Buffalo
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Introduction: The BIS monitor is an FDA approved multiprocessed EEG that can be used to guide general anesthesia, sedation procedures and ICU sedation. Over and under sedation can be avoided, allowing for a more efficient sedation process and reducing the risks of awareness. During sedation procedures the correct timing of titration is important to reduce the risk of over-sedation. If the sedatives are repeated before their peak effect has occurred this may result in respiratory depression. The aim of this study was to use the BIS monitor to determine the time to IV bolus peak effect for 3 sedative agents; Midazolam (MID), Fentanyl (FENT) and Propofol (PROP). The second aim was to determine the BIS value at which no movement to stimulus occurs, i.e. the ideal target depth.
Methods: After IRB approval and informed consent meeting the inclusion criteria were patients of ages 10-17 undergoing a surgical dental extraction under deep intravenous sedation. All patients received the same sedative based regimen: Midazolam, Propofol and Fentanyl. Sedation doses were age and weight based. The only difference was the sequence of sedative administration prior to procedure start. On initial local anesthetic placement (a “sharp” stimulus of palatal LA), the BIS monitor to computer data stream was real-time highlighted. Patient movement in response to stimulation was assessed by two observers.
Results: We have recruited 70 patients so far, ages ranged from 10 to 17 years, average procedure time of 16.6 minutes and recovery time of 34.3 minutes. The peak effect onset time for MID, PROP and FENT were ~ 95 seconds, ~ 55 seconds, Unable (FENT had a minimal BIS effect), these take into account a BIS recording delay of about 25 seconds for our model. About 25% patients moved with stimulus. The risk of movement was 4 x greater if the BIS was 50 or higher.
Conclusions: The peak onset time for MID and PROP were identified which suggests that repeat dosing should be about 2 minutes apart for MID and 1 minute for PROP. Due to minimal FENT BIS effect no peak onset could be established. Movement was minimized with lower BIS, c/w deeper sedation, in GA territory. Deep sedation even with A BIS in the 50’s may not prevent patient movement to surgical stimulation.
