Blood Pressure and Heart Rate Changes During Short-Duration Laryngoscopy for Tracheal Intubation

Changes in mean arterial blood pressure (MAP) and heart rate (HR) during short duration direct laryngoscopy and tracheal intubation were determined in 24 patients scheduled for elective coronary artery bypass graft operations. Direct laryngoscopy was started 1 minute after thiamylal 4 mg/kg and succinylcholine (SCh). Laryngotracheal lidocaine 2 mg/kg was administered immediately before placement of the tracheal tube. In addition, topical oropharyngeal anesthesia was produced with viscous lidocaine 10 minutes before induction of anesthesia in 6 patients, and 6 other patients received IV lidocaine 1.5 mg/kg 30 seconds before thiamylal-SCh administration. The remaining 12 patients received neither viscous nor IV lidocaine and served as a control group. The duration of direct laryngoscopy necessary to accomplish Iaryngotracheal lidocaine administration and tracheal intubation averaged less than 15 seconds. Maximal increases in MAP occurred 5 to 15 seconds after tracheal intubation and were not different (p>0.05) between groups, averaging 17 ± 3 torr (mean ± SE) for control patients, 14 ± 4 torr for patients treated with viscous lidocaine, and 22 ± 5 in patients receiving intravenous lidocaine. MAP decreased spontaneously after laryngoscopy and intubation and within 2 minutes after thiamylal-SCh was near awake levels. Heart rate did not change significantly during laryngoscopy and intubation. We conclude that a short-duration direct laryngoscopy combined with laryngotracheal lidocaine administration just before tracheal intubation minimizes pressor responses and insures a spontaneous return of MAP and HR towards awake levels following intubation. Viscous or IV lidocaine is not helpful when laryngoscopy is of a short duration.