The effects of different doses of dexmedetomidine on the requirements for propofol for loss of consciousness in patients monitored via the bispectral index: a double-blind, placebo-controlled trial

Abstract

Background: The α 2-adrenergic agonist dexmedetomidine (DEX) is a sedative and can be used as an adjunct to hypnotics. The study sought to evaluate the effects of different doses of DEX on the requirements for propofol for loss of consciousness (LOC) in patients monitored via the bispectral index (BIS). Methods: In this randomized, double-blind, three arm parallel group design and placebo-controlled trial, 73 patients aged between 18 and~65 years with a BMI range of 18.0-24.5 kg•m − 2 and an American Society of Anesthesiologists (ASA) grade I or II who were scheduled for general anesthesia at the General Hospital of Ningxia Medical University were included in this study. Anesthesiologists and patients were blinded to the syringe contents. All patients were randomly assigned in a 1:1:1 ratio to receive a 0.5 μg•kg − 1 DEX infusion (0.5 μg•kg − 1 DEX group; n = 24), a 1.0 μg•kg − 1 DEX infusion (1.0 μg•kg − 1 DEX group; n = 25) or a saline infusion (control group; n = 24) for 10 min. Propofol at a concentration of 20 mg•kg − 1 •h − 1 was then infused at the end of the DEX or saline infusion. The propofol infusion was stopped when the patient being infused lost consciousness. The primary endpoint were propofol requirements for LOC and BIS value at LOC.

Opioid-free anesthesia compared to opioid anesthesia for lung cancer patients undergoing video-assisted thoracoscopic surgery: A randomized controlled study

“…Our results showed that with similar PTI readings between the two groups, WLI readings in the OFA group showed a more apparent decrease (10%) than those readings in the OA group. In addition, dexmedetomidine produced a state resembling stage 2 NREM sleep in the EEG with delta and alpha ranges of activity and characteristic arousal sedation [ 39 ]. Xu and colleagues [ 37 ] reported that, after dexmedetomidine infusion (a loading dose of 0.75 μg kg -1 and a continuous infusion of 0.5 μg kg -1 h -1 ), the calculated cutoff WLI readings ranged from 55.8–93.7.…”

“…Zhang and colleagues reported that, in patients undergoing posterior lumbar interbody fusion surgery with inhalation sevoflurane ranging from 1.5 vol % to 4 vol %, the WLI readings at the incision were 46.7 and 60 at skin closure [ 41 ]. Gu and colleagues [ 39 ] reported that due to less propofol consumption, as well as different action sites between dexmedetomidine and propofol, the BIS value for loss consciousness was higher in a loading dose of dexmedetomidine (1μg kg -1 ) with propofol than with an infusion propofol alone. In our study, the consumption of sevoflurane during surgery was not recorded; therefore, we were not sure whether the lower WLI in OFA is caused by the effects of sevoflurane that requires further research.…”

Changes in electroencephalographic power and bicoherence spectra according to depth of dexmedetomidine sedation in patients undergoing spinal anesthesia

“…For propofol anesthesia, the effect site concentration and level of sedation are known to be well correlated with BIS values 19 ; however, there are only few studies assessing how BIS reflects dexmedetomidine sedation in a clinical setting. Previous clinical studies mostly investigated the performance of BIS when dexmedetomidine was used as an adjuvant to other anesthetics 20 , 21 . In volunteer studies, the exact values were different depending on the studies; BIS was approximately 45-60 and 25-45 during moderate (MOAA/S 3) and deep (MOAA/S 1) sedation of dexmedetomidine, respectively 4 , 22 .…”