A comparison of lidocaine, fentanyl, and esmolol for attenuation of cardiovascular response to laryngoscopy and tracheal intubation.

BACKGROUND

Laryngoscopy and tracheal intubation are known to increase sympathetic activity that may be detrimental to patients with pre-existing ischemic or hypertensive heart diseases. In order to alter the hyperdynamic consequences resulting from intubation during induction of general anesthesia, we chose esmolol, an ultra-short acting cardioselective beta-adrenergic blocker, to attenuate the cardiovascular responses during tracheal intubation in patients undergoing elective surgery. The efficacy of esmolol in this regard was carefully evaluated.

METHODS

Eighty ASA physical status class I or II patients undergoing elective, non-cardiac procedures were included in a randomized, single-blinded study consisting of 4 groups with each group receiving a designated drug: group A received normal saline as control, while group B, group C and group D received lidocaine 2 mg/kg, fentanyl 3 micrograms/kg and esmolol 2 mg/kg, respectively. Monitoring included EKG, pulse oximetry, capnometry and arterial pressure. All patients were premedicated with diazepam 0.1 mg/kg 30 min before induction of general anesthesia. Each designated drug was given upon induction of anesthesia (time zero). Anesthesia was induced with thiopental 5 mg/kg and succinylcholine 1.5 mg/kg, and maintained with N2O, 1% isoflurane in 50% O2 and vecuronium. Intubation was carried out 3 min after the designated drug was given. Heart rate (HR) and systolic arterial blood pressure (SBP) were obtained every min for 10 min after induction. Either chi-square test or analysis of variances (ANOVA) was used for statistical comparison. A p value less than 0.05 was considered statistically significant.

RESULTS

There was no difference in the demographic data among the four groups. After intubation, the incidence of tachycardia (HR > 100/min) was found in 3 of 20 (15%) patients in esmolol group, significantly lower than 17 of 20 (85%) patients in the control group, 15 of 20 (75%) patients in lidocaine group, and 11 of 20 (55%) patients in fentanyl group, respectively (p < 0.05). The incidence of hypertension (SBP > 180 mmHg) was found in 4 of 20 (20%) patients in esmolol group, significantly lower than 16 of 20 (80%) patients in control group and 14 of 20 (70%) patients in lidocaine group, respectively (p < 0.05), but not in 8 of 20 (40%) patients in fentanyl group. Besides, the incidence of hypertension in fentanyl group (40%) was significantly lower than control group (80%; p < 0.05), but not in lidocaine group (70%).

CONCLUSIONS

Results of this study showed that only esmolol could reliably offer protection against the increase in both HR and SBP, low dose of fentanyl (3 micrograms/kg) prevented hypertension but not tachycardia, and 2 mg/kg lidocaine had no effect to blunt adverse hemodynamic responses during laryngoscopy and tracheal intubation.