Effect of ephedrine on the onset time of succinylcholine

Background:  The aim of this study was to evaluate the effect of ephedrine administered prior to induction of anaesthesia on the onset time of succinylcholine for endotracheal intubation. Methods:  Patients were randomly assigned to receive intravenously (i.v.) either 70 µg kg −1 of ephedrine (Group I; n = 25) or saline (Group II; n = 25) 3 min before induction of anaesthesia. Induction of anaesthesia was provided with propofol 2 mg kg −1 plus remifentanil 1 µg kg −1 . Onset time and duration of muscle fasciculation and onset time of succinylcholine were recorded. Intubation was attempted after establishment of 100% thumb relaxation and difficulties were recorded. Heart rate, pulse oxymetry (SpO 2 ) and mean arterial pressure (MAP) were also recorded. Results:  The onset time of succinylcholine were significantly ( P <  0.001) shorter in Group I (26 ± 4 s), when compared with Group II (43 ± 6 s). Patients in Group I were intubated at 49 ± 7 s compared with 68 ± 10 s in Group II. The score of intubation was similar in both groups. Duration of muscle fasciculation was longer in Group II. Heart rate and MAP increased significantly ( P <  0.05) after ephedrine injection, compared with the baseline value in Group I. Conclusions:  The onset time of succinylcholine can be shortened with ephedrine pretreatment.