[Hemodynamic response to intubation with Macintosh and McCoy blades]

The McCoy laryngoscope incorporates a modification of the Macintosh blade designed to facilitate laryngoscopy and difficult intubation. One end is articulated to allow better viewing of the larynx. Use of this blade reduces pressure placed on tissues in the supraglottic area during laryngoscopy.

We designed this study to compare the hemodynamic repercussions of laryngoscopy and tracheal intubation (LTI) performed with either a Macintosh or the McCoy blade.

Sixty ASA I-II patients scheduled for elective surgery requiring LTI were randomly assigned to 2 groups of 30 patients each. In both groups anesthetic induction was achieved with 0.04 mg.kg-1 midazolam, 0.002 mg.kg-1 fentanyl, 2 mg.kg-1 propofol and 0.1 mg.kg-1 vecuronium. In group 1 LTI laryngoscopy and intubation were performed using the Macintosh size 3 blade and in group 2 the McCoy size 3 blade was used. Systolic and diastolic arterial pressures and heart rate were recorded in each patient before anesthetic induction (baseline), 1 minute after induction and 5 minutes after start of LTI.

We found no significant differences between the 2 groups at any of the recording times.

The data obtained do not allow us to assert that there is any difference in hemodynamic response to LTI associated to type of blade used.