This study was designed to assess tracheal intubation without muscle relaxants, especially using 8 vol% sevoflurane. The study was designed to compare heart rate and blood pressure changes induced by a 10% lidocaine spray with that of 1% lidocaine IV and a control.

Sixty patients, ASA I or II, undergoing various surgical procedures, were randomly assigned into three anesthetic pretreatment groups: Group I received routine vital capacity rapid induction with sevoflurane; Group II, inhalation induction with a 10% lidocaine spray 5 minutes before intubation; and Group III, inhalation induction with 1% lidocaine IV injection 2 minute before intubation. Intubating conditions were assessed as acceptable or unacceptable on the basis of a scoring system that depended on the ease of laryngoscopy, vocal cord position, and coughing after endotracheal tube insertion. Heart rate and blood pressure changes in each group were assessed before and after intubation.

The overall assessments of the intubating conditions were acceptable in 90%, 95%, and in 95% of patients in groups I, II, and III, respectively. Statistically, supplementing with a lidocaine intravenous injection or a pharyngolaryngeal lidocaine spray did not improve intubating conditions. Moreover, no differences in coughing after intubation, and no improvement in heart rate or in blood pressure changes were observed among the three groups.

Sevoflurane inhalation induction without muscle relaxants offers satisfactory intubation, and heart rate and blood pressure changes without the use of lidocaine IV injection, or lidocaine spray.