The effects of callander modification of laryngoscopic blade on hemodynamic changes according to the degree of difficult airway.

Background: Laryngoscopy and tracheal intubation are known to have profound cardiovascular effects. The Callander modification of Macintosh blade is associated with greater field of laryngoscopic view and decreased risk of dental contact. The purpose of this study was to compare the hemodynamic responses to laryngoscopy and tracheal intubation according to the degree of difficult airway, and to evaluate the usefulness of Callander modification of Macintosh blade for attenuating the hemodynamic responses.

Methods: One hundred, forty-eight patients scheduled for elective surgery were divided into Easy group and Difficult group by Wilson's risk sum score. Laryngoscopy was performed using either an ordinary Macintosh No. 3 blade or the modified Macintosh blade. The modification consisted of reducing the height of the flange by partial removal, as described by Callander et al. Hemodynamic variables (systolic, diastolic, mean blood pressure, heart rate and rate pressure product) were noted before induction (baseline) and immediately after intubation.

Results: The hemodynamic changes after tracheal intubation in Difficult group were significantly greater than those in Easy group (P < 0.05). When using the modified blade, systolic, diastolic and mean blood pressure after tracheal intubation were lower than those using the conventional blade regardless of Wilson's risk sum score, but no statistical significances could be found.

Conclusions: The hemodynamic changes after tracheal intubation increased as the degree of airway difficulty increased. Laryngoscopy with the Callander's modified blade did not reduce the degree of hemodynamic stimulation compared with the conventional Macintosh blade.