Comparison of three techniques monitoring depth of anesthesia during brain surgery / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the performance of bispectral index (BIS),auditory evoked potential index (AEPI) and cardiovascular response to electrical tetanus stimulus (ETS) for monitoring depth of sedation induced by propofol , analgesia produced by fenanyl and depth of isoflurane anesthesia. Methods Twenty ASA Ⅰ or Ⅱ patients of both sexes (11 males,9 females) aged 18-56 yr, weighing 50-80 kg undergoing elective brain surgery were studied. The patients were unpremedicated. The baseline BIS, AEPI, BP(SP, DP) and HR were measured before anesthesia. Propofol was infused at 0.25 mg?kg-1?min-1 and the infusion was stopped when the total amount of propofol infused reached 5 mg?kg-1 at the end of 20 min infusion. Fentanyl 2 ?g?kg-1 was then given i.v. Three minutes later the patients were intubated and mechanically ventilated. Tracheal intubation was facilitated by vecuronium 0.1 mg?kg-1. Anesthesia was maintained with isoflurane. Depth of sedation was measured using OAA/S scale during propofol infusion. ETS was given at the following time points when the amount of propofol infused reached 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 mg?kg-1,2 min after fentanyl administration and at 0.7, 1.0, 1.3 MAC isoflurane (end-tidal isoflurane concentration). BIS and AEPI values before and after ETS and changes in BP and HR (ABP, AHR) after ETS and the time for BP and HR to return to the pre-ETS value in 50% and 90% of the patients (TBP50%,TBP90%,THR50%,THR90% ) were recorded. Results BIS and AEPI were positively correlated with sedation depth. There were no significant changes in BIS and AEPI after ETS, but SP, DP and HR increased significantly after ETS( P