Effect of bicarbonate on injection pain and onset of rocuronium

ABSTRACT

BACKGROUND:Rocuronium is a commonly used muscle relaxant, however, it has severe injection pain.We supposed that injection pain of rocuronium was due to acidity of solution.We studied whether pH elevation of rocuronium with bicarbonate relieves injection pain. METHODS:We included 140 adult patients with 18 G intravenous catheter in arm for general anesthesia and they were randomly allocated to two groups.All patients received 0.6 mg/kg of rocuronium, one group (Group C) received rocuronium only (pH = 4.04) and the other group (Group B) received bicarbonate mixed rocuronium (rocuroniumbicarbonate = 5 ml1 ml, pH of mixture = 7.14).The severity (none, mild, severe) of injection pain was assessed.Just after assessment, 5 mg/kg of thiopental was injected for loss of conciousness. Twitch of supramaximal stimuli was monitored and intubation time was considered the interval from injection to 75% depression and onset time the interval from injection to maximal depression. RESULTS:The incidence of injection pain of group C was 96.9% and 18.8% in group B (P< 0.01). Intubation time and onset time were 79.5 +/- 24.4 sec and 114.3 +/- 43.6 sec in group C and 80.6 +/- 27.0 sec and 115.2 +/- 46.2 sec in group B.There was no significant difference between groups. CONCLUSIONS:Our result shows that adding bicarbonate to rocuronium is effective to relieve injection pain of rocuronium without change of onset of rocuronium.