The intensity of stimulation of intubation was expressed as the product of its force and duration. Theoretically, use of a lightwand might cause less adrenergic stimulation because the elevation of the epiglottis by the laryngoscope blade was not required. However, whether the hemodynamic responses to intubation with the lightwand differ from those with direct laryngoscope was a controversial topic. Additionally, there has been no clear study showing that the hemodynamic response to intubation is affected by intubation time. This study was designed to analyze the relationship between the magnitude of hemodynamic responses and the intubation time.

50 ASA class 1, 2 elective surgical patients were randomly allocated into two groups; lightwand or direct laryngoscope group. Anesthesia was induced by a standardized technique. The changes in MAP and HR were recorded just before intubation, after intubation and 1 minute after intubation. Also the intubation time was recorded.

There were no differences in MAP, HR, and intubation time between the groups. The following was the final regression equation from multiple linear regression analysis : the degrees of blood pressure elevation = + 11.2239 (P = 0.0296) + 6.6331 (P = 0.0846) × (group) + 1.0400 (P = 0.0004) × (intubation time). Adjusted R² is 0.84 (P < 0.05).

There was a linear relation between the degree of blood pressure elevation and intubation time in direct laryngoscope group and lightwand group.