Remifentanil Effect-site Concentration Blunting Cardiovascular Responses to Tracheal Intubation for Different Sex during Propofol Infusion

Effect-site concentration of remifentanil for blunting hemodynamic responses to tracheal intubation using light wand during target controlled infusion-total intravenous anesthesia

Background

Transillumination using a light wand is an alternative type of laryngoscope used for tracheal intubation. There is little information available on the effect-site concentration of remifentanil required to control hemodynamic changes induced by tracheal intubation using the transillumination method during total IV anesthesia. We therefore conducted this study to determine the effect-site concentration of remifentanil blunting hemodynamic responses after tracheal intubation in patients receiving propofol anesthesia.

Methods

We enrolled 26 healthy adult patients (ASA physical status I-II), aged 16-67 scheduled for surgery within 2 hours. All patients received a target-controlled infusion of 4 µg/ml propofol. The effect-site target-concentration of remifentanil of 5.0 ng/ml was chosen for the first patient. We used the Dixon's up-and-down sequential allocation method for determining the next remifentanil concentration. The time required for tracheal intubation was measured as the level of intubation stimulation.

Results

The average intubation time was 13.9 ± 9.1 seconds. From the Dixon's method, the EC₅₀ of remifentanil blunting the hemodynamic response to tracheal intubation was 2.94 ng/ml.

Conclusions

This study shows that effect-site concentrations of remifentanil of 2.94 ng/ml is effective in blunting sympathetic responses to tracheal intubation in 50% of patients with normal airway anatomy when combined with a target controlled infusion of propofol (4 µg/ml).

The effect of pretreatment with two different concentrations of remifentanil on propofol injection pain

BACKGROUND

Propofol produces anesthesia with rapid recovery but also causes pain on injection. This study was designed to evaluate the effects of two different concentrations of remifentanil for minimizing the pain caused by propofol and to compare the hemodynamic changes during propofol-remifentanil infusion.

METHODS

In a randomized, double-blind study of 80 patients, we compared the severity of the injection pain of propofol between two groups of patients. The initial effect-site target concentration of remifentanil was set at 4 ng/ml (the R4 group, n = 40) or 8 ng/ml (the R8 group, n = 40). After the effect-site concentration of remifentanil was achieved, the infusion of propofol was started with the concentration of 4 microgram/ml. The remifentanil-related complications were evaluated and the severity of the pain caused by propofol was compared by using a four-point scale during the propofol infusion. The heart rate and arterial blood pressure were measured at pre-induction, just before intubation and at 1 minute after intubation.

RESULTS

The severity of injection pain of propofol was significantly lower in the R8 group than in the R4. There was no significant difference in the incidence of remifentanil-related complications between the two groups. Compared with the pre-induction values, the heart rate and arterial blood pressure were significantly lower at pre-intubation and at 1 minute after intubation in the R4 and R8 groups.

CONCLUSIONS

Pretreatment with an effect-site concentration of 8 ng/ml remifentanil may be useful for minimizing the propofol injection pain compared with 4 ng/ml remifentanil.

The effect of tracheal intubation with the McCoy or Macintosh laryngoscope on the blood pressure and heart rate during propofol-remifentanil induction

BACKGROUND

This study was designed to compare the hemodynamic changes in response to direct laryngoscopy with using the McCoy or Macintosh blade.

METHODS

Seventy seven patients were randomly allocated into two groups. The induction of anesthesia was done with target controlled infusion of propofol (5 microgram/ml) and remifentanil (3 ng/ml) and vecuronium 0.1 mg/kg was also given. The vocal cords were visualized with either the McCoy or the Macintosh laryngoscope blade, and then tracheal intubation was performed. The heart rate and blood pressure were measured just before induction, at intubation and at 1, 3 and 5 minutes after intubation.

RESULTS

There were no significant differences in the blood pressure and heart rate responses to tracheal intubation with using the McCoy or Macintosh blade. But, in the Macintosh groups, the blood pressure at 1 and 3 minutes and the heart rate at 1 minute after intubation were increased significantly compared with the preintubation values. Also, in the McCoy groups, the blood pressure and heart rate at 1 minute after intubation were significantly higher than the preintubation values.

CONCLUSIONS

The McCoy and the Macintosh blade show similar changes in heart rate and blood pressure after tracheal intuba tion.