Laryngoscopic and tracheal intubation often causes an increase in blood pressure and heart rate. The purpose of this study was to evaluate the influence of the duration of laryngoscopy and tracheal intubation on hemodynamic response.

We studied 110 patients undergoing elective surgery. Anesthesia was induced with fentanyl 1µgram/kg and thiopental 5 mg/kg, and rocuronium 0.6 mg/kg was administrated prior to intubation. The duration of laryngoscopy and tracheal intubation was defined as the interval between the insertion of a laryngoscope into a patient's mouth and its removal after successful tracheal intubation. Patients were divided into three groups according to the duration of intubation: Group 1 (duration ≤ 15 seconds); Group 2 (15 < duration ≤ 30 seconds); Group 3 (duration > 30 seconds). Systolic blood pressure, diastolic blood pressure and heart rate were measured before intubation, after induction, immediately after intubation, and 1 min and 3 min after intubation.

Systolic blood pressure at 1 min after intubation was significantly higher in Group 3 than in Group 1, but no significant differences were observed in diastolic blood pressure or heart rate. Regarding the correlation between systolic blood pressure and the duration of laryngoscopy and tracheal intubation, the linear regression r² value was 0.03.

This study suggests that the duration of laryngoscopy and tracheal intubation is not significantly correlated with blood pressure. However, it also shows that when the time to intubation exceeds 30 seconds, that the systolic blood pressure is significantly increased. Thus, when the duration of tracheal intubation is anticipated to be prolonged, attempts to attenuate hemodynamic response to tracheal intubation are necessary.