Target controlled infusion propofol by auditory evoked potential index during anaesthesia: A feasibility analysis

Jie CHEN; Guocai TAO

ABSTRACT

BACKGROUND:

Not only can auditory evoked potential (AEP) reflect electric activities of cerebral cortex and subcortex, but also have dose-effect relationship with many sorts of anesthesia agents; it is a relatively good index for monitoring anesthesia depth at present.

OBJECTIVE:

To analyze target controlled infusion propofol by auditory evoked potentials index during anaesthesia.

DESIGN:

Patients with operations were taken as objects in the randomized controlled trial.

SETTING:

Department of Anesthesia of Southwest Hospital of the Third Military Medical University

PARTICIPANTS:

A total of 16 patients, with selective simply laparoscopic cholecystectomy, admitted to Department of Anesthesia of Southwest Hospital from October to November 2003, were selected and randomly divided into normal control group and auditory evoked potential index monitoring group with 8 in each group. The baseline information of the patients, such as gender, age, weight and operating time etc., was similar between the two groups (P ＞ 0.05).

METHODS:

Same anesthesia induction method was conducted on the patients in both groups; anesthesia was maintained with propofol (10 g/L) according to ALARIS P6003 pump calculation in the two groups; age, weight and target concentration of propofol (4 mg/L) was regulated according to clinical experience, while, in auditory evoked potential monitoring group,the concentration value of propofol in effective site was regulated by maintaining auditory evoked potential index between 15 and 30. Non-invasive blood pressure, heart rate and AAI were monitored at the moment of reposing for 10 minutes after entering operating room (T0), eyelash reflex disappearing after anaesthesia induction (T1), trachea intubation (T2), 3 minutes after intubation (T3), boring abdomenal holes (T4), 30 minutes after aeroperitonia steady (T5), observer's assessment of alertness and sedation (OAA/S) ≥4 at the end of operation (T6).MAIN OUTCOME

MEASURES:

① Comparison of dosages of anaesthetia agents between the two groups. ② Changes of hemodynamics and auditory evoked potential index at each phase point.

RESULTS:

According to intention to treat analysis, all the 16 patients entered results analysis. ①Comparison of dosages of anesthesia agents between the patients in each two The actual dosage of propofol in auditory evoked potential monitoring group was significantly lower than that in normal control group [(247.25±37.11), (337.38±36.72) mg, P ＜ 0.05], while the dosages of fentanyl and vecuronium bromide were no differences between two groups (P ＞ 0.05). ② Changes of hemodynamics and auditory eyoked potential index at each phase points of the two groups Changes of hemodynamics at each phase points were similar between the two groups (P ＞ 0.05). Compared with T0 phase, there was no significant difference in auditory evoked potential index between the two groups in T1, T2 and T3 phases (P ＞ 0.05), however, in T4 and T5 phases, auditory evoked potential index in auditory evoked potential monitoring group was remarkably higher than that in normal control group (28.50±6.19, 21.25±4.06; 28.00±5.66,20.75±3.41; P ＜ 0.05). All patients had no awareness during the operation.

CONCLUSION:

Auditory evoked potential index is a new indicator for monitoring anesthesia depth, which can be helpful to regulate and control depth of anesthesia so as to avoid awareness and recall during general anesthesia.