USING SMALL DOSES OF SUCCINYLCHOLINE FOR FACILITATING TRACHEAL INTUBATION .

Succinylcholine 1 mg/kg usually produces excellent tracheal intubation in 60 s. Recovery of respiratory muscle function after this dose, however, is not fast enough to forestall oxyhemoglobin desaturation when ventilation can not be assisted. In this study, smaller doses of succinylcholine effects were investigated for producing satisfactory intubation conditions fast enough to allow rapid-sequence tracheal intubation with shorter recovery time of respiratory function. Materials &Methods: In this prospective randomized double-blind and case-controlled clinical trial, 120 patients class I or II of American Society of Anesthesiologists (ASA), were investigated. After induction of anesthesia with fentanyl/thiopental, all patients were randomly allocated to three groups according to the dose of succinylcholine 0.3 mg/kg (1ÍED95), 0.6 mg/kg (2ÍED95), and 1 mg/kg (3ÍED95). Evoked adductor pollicicis responses to Train-of-four (TOF) in ulnar nerve stimulation were rewarded using nerve stimulator. Onset time, maximal twitch depression, tracheal intubation conditions, respiration recovery time (apnea time), and time to 90% twitch height recovery were recorded. Results: Onset times ranged between 81s and 49s, decreased with increasing doses of succinylcholine but not differing between 0.6 and 1 mg/kg. Maximum twitch depression was similar after 0.6 and 1 mg/kg (98.2%-100%). Intubation conditions were often unacceptable after 0.3 mg/kg doses, but acceptable intubations were achieved in all patients receiving a 0.6 and 1 mg/kg dose of succinylcholine. Time to respiration function recovery was significantly shorter in 0.3 and 0.6 mg/kg doses (1.8±0.6 min and 2.4±0.6 min, respectively) versus patients receiving 1 mg/kg (6.3±0.8 min p< 0.0001 v.s 0.3 mg/kg, p< 0.001 v.s 0.6 mg/kg doses respectively). Twitch recovery time to T1=90% (regular spontaneous respiration) were significantly lower in 0.6 mg/kg dose (5.2 ±1.0 min) than 1.0 mg/kg group (8.8±1.3 min p<0.001). Conclusion: The use of 0.6 mg/kg of succinylcholine can produce acceptable intubation conditions after 60 seconds of administration. The conditions achieving after 0.6 mg/kg are similar to those after 1mg/kg. These smaller doses are associated with shorter apnea time and faster twitch recovery.