Attenuation of the cardiovascular intubation response with N2O, halothane or enflurane.
The circulatory intubation response was studied in 75 normotensive, otolaryngological patients after a thiopentone-suxamethonium induction followed by 2 min artificial ventilation with 100% oxygen (control), 70% nitrous oxide in oxygen (N2O), halothane 2% with N2O, enflurane 3% with N2O or enflurane 5% in oxygen. The above study groups (n = 15) were chosen after preliminary experiments performed in 25 different patients with halothane 2% (n = 8) or enflurane 3% (n = 6) in oxygen, which did not prevent the increase of arterial pressure after intubation, or with halothane 3% (n = 11) which attenuated the pressor response but caused cardiac arrhythmias in 55% of patients. Enflurane 5% in oxygen attenuated the increase of systolic arterial pressure by 53%, enflurane 3% with N2O by 34% and halothane 2% with N2O by 31%. The increase in heart rate after intubation was lowest in the halothane 2% with N2O group, but there were no statistically significant differences between the groups. Cardiac arrhythmias were commonest in the enflurane 3% with N2O group (20%) and they did not occur in the halothane 2% with N2O group. Considering the total effect on arterial pressure, heart rate and rate-pressure product, we recommend the combination of halothane 2% with N2O.
D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D004562:Electrocardiography; D004737:Enflurane / Q000494:pharmacology*; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects*; D007828:Laryngoscopy / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000494:pharmacology*; D011229:Preanesthetic Medication; D011897:Random Allocation
D004737:Enflurane; D009609:Nitrous Oxide; D006221:Halothane