Effects of ephedrine on intubating conditions following priming with atracurium: A randomized clinical trial

Background: Priming is a well-known method to accelerate the onset of action of non-depolarizing neuromuscular-blocking agents. It consists of administration of a small dose of neuromuscular blocking agent several minutes before the principal dose is given. Ephedrine has been shown to improve the intubating conditions of rocuronium following its priming with a small dose. However, the potential effects of ephedrine on intubating conditions using atracurium after its priming with a small dose have not yet been studied. Since rocuronium is not available in Iran, atracurium is widely used as an alternative. Methods: We studied two groups of patients, each group consisting of 32 patients. One group received ephedrine after priming (PE) and the other received placebo following priming (P). There were no significant differences between the two groups in age, sex, physical status (assessed using the American Society of Anesthesiologists classification), baseline mean arterial pressure and baseline heart rate. Patients with anticipated difficult airway, hypertension, obesity, any evidence of neuromuscular, cardiovascular, respiratory, hepatic, or renal disease, as well as those taking medications known to interact with atracurium or ephedrine were excluded. The anesthesiologist, the physician responsible for recording the results, and the statistician interpreting them were blinded to group allocations. Intubating conditions were graded according to Cooper's criteria. A clinically acceptable outcome was defined as good or excellent intubating conditions, represented by overall scores of 6-7 and 8-9, respectively. Results: Intubating conditions were clinically acceptable in 22 patients in the PE group and 15 patients in the P group (p=0.13). Vocal cord position and jaw relaxation scores during intubation and response to intubation did not differ significantly between the two groups. The mean arterial pressure showed significant differences over the course of time between the two groups (p<0.01). Heart rate exceeded 120bpm more frequently in the PE than in the P group (p<0.01). Conclusion: The effects of ephedrine on improving intubating conditions following atracurium priming were not statistically significant. Given the risk of exacerbation of coronary ischemia by tachycardia, and the negative results on intubating conditions in our study, we cannot recommend the use of ephedrine for improving intubating conditions following priming with atracurium.