The Influence of Gender on Loss of Consciousness with Sevoflurane or Propofol

Emory University, Atlanta, Georgia, United States
Anesthesia & Analgesia (Impact Factor: 3.47). 09/2005; 101(2):377-81, table of contents. DOI: 10.1213/01.ANE.0000154534.71371.4F
Source: PubMed


Studies have suggested that hypnotic requirements for general anesthesia and emergence may be influenced by gender. In this study, we examined the effect of gender on the hypnotic requirement for loss of consciousness (LOC) using either a volatile (sevoflurane) or an IV (propofol) anesthetic. One-hundred-fifteen unpremedicated, ASA physical status I-II patients, aged 18-40 yr old, received either sevoflurane by mask to a predetermined end-tidal concentration (%ETsevo) or propofol by target-controlled infusion (effect site) while breathing spontaneously. After sufficient time for equilibration, LOC was assessed by lack of response to mild prodding. The up-down method of Dixon was used to determine the hypnotic target concentration at 50% response (LOC50). No statistically significant difference in LOC50 was noted between men and women for sevoflurane (0.83% +/- 0.1% and 0.92% +/- 0.09% ET, respectively). Men required significantly more propofol than women (2.9 +/- 0.2 versus 2.7 +/- 0.1 mu g/mL, respectively). However, there was no difference in the bispectral index (BIS) at LOC for men or women with either hypnotic anesthetic. This investigation identified a small, statistically significant difference in hypnotic requirement at LOC50 between men and women with propofol but not with sevoflurane. As defined by BIS, men and women had equivalent hypnotic states at LOC50, indicating that gender had no clinically significant effect on hypnotic requirements. However, BIS at a defined clinical end-point (LOC50) was significantly different between the sevoflurane and propofol groups, suggesting that neurophysiological effects of these anesthetics may be different.

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Available from: Jay W. Johansen, Jun 24, 2015
    • "The female patients in our study required a lower dose of propofol for induction compared to males whether clinically or BIS guided with comparable BIS values. Kodaka et al.[10] found that men required significantly more propofol than women at induction (2.9±0.2 v/s 2.7±0.1 mg/kg respectively) but there was no difference in the BIS value at loss of consciousness for men and women. Our study also showed that the decrease in dose of propofol in females compared to males and utilization of propofol for induction in both sexes were less compared to the study of Kodala et al. "
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    ABSTRACT: Clinically optimized focusing of drug administration to specific need of patient with bispectral index (BIS) monitoring results in reduced dose and faster recovery of consciousness. This study was planned with an aim to study and compare the conventional clinical end point or BIS on the requirement of dosage of propofol, hemodynamic effects, and BIS alterations following propofol induction. 70 patients, ASA I and II, 20-60 years undergoing elective surgical procedure under general anesthesia with endotracheal intubation were selected and divided into two groups. Group A received (inj.) fentanyl (2 μg/kg), followed 3 min later by inj. propofol at the rate of 30 mg/kg/hr infusion till the loss of response to verbal command while group B received inj. fentanyl (2 μg/kg), followed 3 min later by inj. propofol at the rate of 30 mg/kg/hr infusion. The end point of hypnosis was when the BIS value was sustained for 1 min at 48±2. The patients were intubated. Total induction dose of propofol was noted in each group. The value of BIS and hemodynamic parameters (heart rate, systolic/diastolic blood pressure) were noted at the time of loss of consciousness, at the time of intubation, and 1 min after intubation, thereafter every minute for first 10 min and thereafter every 10 min till end of surgery. Any involuntary muscle activity such as jerky movements, dystonic posturing, and opisthotonos were also recorded. The mean dose of propofol used in groups A and B were 1.85±0.48 mg/kg and 1.79±0.41 mg/kg, respectively. The dosage used in group B were less but not clinically significant (P=0.575). On comparing the dosage of propofol in males among the groups there was a significantly lower dosage of propofol required in group B (2.06±0.45 mg/kg and 1.83±0.32 mg/kg, respectively, P=0.016). This decrease however was not seen in female patients dosage being 1.65±0.44 mg/kg and 1.75±0.49 mg/kg, respectively (P=0.372). The hemodynamic variables including heart rate, systolic/diastolic blood pressure and BIS were comparable within the group at induction, post-induction, and intubation. However, there was a significant increase in all the parameters at postintubation readings (P<0.001). No significant difference in the induction dose of propofol was observed when assessed clinically (loss of verbal response) or by BIS monitoring. Traditional teaching to titrate the dose of propofol and depth of anesthesia during intubation by loss of verbal response is as good as BIS value monitoring.
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    • "First, it is important to consider patient demographic characteristics, such as gender and age, prior to use of this method. Gender differences can affect the pharmacodynamics and pharmacokinetics of propofol [21], and women have significantly higher propofol serum concentrations at the point of loss of consciousness [22]. In addition, older patients are more sensitive to opioids than younger ones. "
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    ABSTRACT: Propofol and remifentanil are used for tracheal intubation in the absence of neuromuscular blocking agents. We hypothesized that the addition of sevoflurane to propofol and remifentanil would improve intubation conditions and provide hemodynamic stability. Seventy-six patients scheduled for elective surgery were randomly allocated to be ventilated with either 4% (group I) or 7% sevoflurane (group II) after propofol injection (2 mg/kg). All patients received remifentanil (1 microg/kg) 30 seconds after administration of propofol. Ninety seconds after remifentanil was given, laryngoscopy and tracheal intubation were performed. Intubation conditions and hemodynamic changes were evaluated. The overall incidence of clinically acceptable intubation conditions was significantly higher in group II (92%) than group I (58%) (P = 0.001). Scores for vocal cord position, coughing, and limb movement were significantly better in group II (P < 0.05). Mean blood pressure remained significantly lower than the pre-induction level throughout the investigation in both groups (P < 0.001), but there was no incidence of bradycardia or hypotension requiring treatment. Tracheal intubation without neuromuscular blocking agents can be achieved safely and reliably by adding 7% sevoflurane to propofol (2 mg/kg) and remifentanil (1 microg/kg).
    Full-text · Article · Aug 2010 · Korean journal of anesthesiology
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    ABSTRACT: To determine propofol concentration in the cerebral spinal fluid (CSF) of neurosurgical patients and carry out a preliminary population pharmacodynamic study. Twenty-seven elective neurosurgical patients (12 men and 15 women) aged 17-74 years received propofol in a bolus dose of 2 mg/kg for 5 min and an infusion of 10 mg/kg per h for 5 min. Frequent CSF samples were drawn and assayed for propofol concentration. The bispectral index (BIS) was used to measure the drug effect. All data were analyzed first with the Excel software package, then pharmacodynamics modeling was performed using the NONMEM software package. The CSF concentration was related to the drug effect with linear and sigmoid Emax models. The parameters for the linear addictive model were a=1.11 and b=95.4. The parameters for the linear exponential model were a=1.05 and b=92.7. The parameters for the sigmoid E(max) model were E(max)=119, EC(50)=53.6 ng/mL, and N=1.51. When the covariates of age, weight and sex were considered, the parameters of models, objective function, the standard error of the mean and the prediction error were not optimized. Linear additive, linear exponential and sigmoid E(max) models can be used to describe the pharmacodynamics of propofol with respect to the concentration in CSF. In this small population, age (17-74 years), weight (47-98 kg) and sex did not influence any of the pharmacodynamic parameters of propofol. To verify these preliminary results, a larger study population is required.
    Preview · Article · Jun 2006 · Acta Pharmacologica Sinica
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