ABSTRACT
Bispectral Index is an objective tool to assess electroencephalographic activity and measure the effect of certain sedatives and hypnotics on the brain. In addition, there are certain subjective tools such as the observer's assessment of alertness and sedation which are used. The correlation between BIS and the concentration of propofol in the brain, and the relationship between these subjective and objective tools in assessing sedation levels are the subject of this study. Thirty healthy volunteers enrolled in this prospective observational study. They were sedated with a target controlled infusion of propofol with an initial target of 0.8 microg.mL[-1] and an increase in target to 0.2 microg.mL[-1] ten minutes after equilibration of the predicted and set target concentrations. In each sedation score, the Bispectral Index value and predicted effect site concentration of propofol were recorded and analyzed. Analysis of variance and significant differences between groups were analyzed by paired f-test. Correlations between Bispectral Index and effect site concentration of propofol at each sedation score and the relationship of BIS and effect site concentration of propofol to each sedation score were assessed and analyzed by nonparametric Spearman's rho [p]. The means of Bispectral Index and effect site concentration of propofol at each sedation score showed a significant difference with the following score. Additionally, Bispectral Index and effect site concentration of propofol showed a significant negative correlation in sedation scores 3 and 2 when inducing sedation. In other sedation scores or when reversing the sedation, no strong correlation was noted. Both Bispectral Index and effect site concentration of propofol indicate a good estimate of sedation levels; however their correlations are significant and negative only at moderate and deep sedation levels, and during the induction of sedation
Subject(s)
Humans , Adult , Propofol , Prospective Studies , ElectroencephalographyABSTRACT
Target-controlled infusion [TCI] system is increasingly used in anesthesia to control the concentration of selected drugs in the plasma or at the site of drug effect [effect-site]. The performance of propofol TCI delivery when combined with remifentanil in patients undergoing elective surgeries has been investigated. Our aim in this study was to assess the anesthesia profile of the propofol and remifentanil target controlled infusion [TCI] anesthesia as compared to the manually controlled infusion [MCI], in mastoidectomy surgery, where a bloodless field is of utmost importance to the surgeon. Sixty patients, aged 18-60 years ASA I-II enrolled in the study, were divided into two equal groups. Group MCI received propofol and remifentanil by conventionaldose-weight infusion method, and Group TCI received propofol 4 micro g/ml and remifentanil 4 ng/ml as effect-site target concentration. The hemodynamic variability, recovery profile, postoperative nausea and vomiting [PONV], surgeons satisfaction were assessed. Results were analyzed by SPSS version 11.5. The two groups were comparable with respect to age, ASA class, sex, weight, basal vital signs, operation time. The blood pressure and pulse were above desired levels in some data points in the MCI Group [P
ABSTRACT
Target-controlled infusion is a new delivery system for intravenous anesthetic agents with which the anesthetist targets a plasma or effect-site drug concentration to achieve a predetermined effect. With this system, the tedious task of calculating the amount of administered drug required to achieve the target concentration is left in charge of a microprocessor which commands the infusion device. In this prospective study we compared alterations in blood pressure and heart rate from initiation of induction of anesthesia until 3 minutes after tracheal intubation in two methods of drug infusion, target-controlled infusion [TCI] and manually controlled infusion [MCI]. Total anesthetic drug used until 3 minutes after intubation and level of produced hypnosis also were compared between two methods. 40 patients were enrolled in this clinical trial study and were allocated randomly in two groups, each group consisting of 20 patients. In TCI group, patients received propofol and remifentanil with TCI pump to achieve 7 3g/ml and 4 ng/ml as plasmatic target drug levels, respectively. In MCI group, patients received propofol 2 mg/kg and remifentanil 1 3g/kg of body weight with manually controlled infusion. Both groups received succinylcholine as muscle relaxant to facilitate laryngoscopy and tracheal intubation. Bispectral index [BIS] was passively recorded in two groups to compare the level of hypnosis. Blood pressure [BP] and heart rate [HR] were recorded at 5 different times [T-1, T0, T1, T2 and T3]. Independent t-test and paired t-test were used for data analysis. Systolic arterial pressure [SAP] was not different at T-1 between two groups but systolic hypotension was seen in MCI group more than TCI group at T0 [P<0.05]. Systolic hypertension was more common in MCI group after intubation; i.e. SAP showed significant differences in T1, T2 and T3 between two groups [P<0.05]. Mean arterial pressure [MAP] showed significant difference only at T0 and T1 between two groups. Also, heart rate in MCI group was higher than that in TCI group at T1 and T2. Mean used propofol was 128.10 +/- 11.30 mg in MCI group versus 140.90 +/- 16.21 mg in TCI group [P<0.05] and the least BIS value recorded was 31.4 +/- 10 in MCI group versus 42.5 +/- 12.3 in TCI group [P<0.05]. Hypotension in MCI group was seen more frequently than that in TCI group after induction and before laryngoscopy [T0]. Hypertension and tachycardia were seen in MCI group more commonly than those in TCI group after laryngoscopy and tracheal intubation. Then, we recommend TCI technique in high risk patients for attenuation of the pressor response to laryngoscopy and tracheal intubation. Also, we recommend further researches in other educational centers to compare the effect-site TCI with plasmatic TCI in controlling pressor response