Optimal dose of succinylcholine revisited.
BACKGROUND
The authors reappraised the conventional wisdom that the intubating dose of succinylcholine must be 1.0 mg/kg and attempted to define the lower range of succinylcholine doses that provide acceptable intubation conditions in 95% of patients within 60 s.


METHODS
This prospective, randomized, double-blind study involved 200 patients. Anesthesia was induced with 2 mug/kg fentanyl and 2 mg/kg propofol. After loss of consciousness, patients were randomly allocated to receive 0.3, 0.5, or 1.0 mg/kg succinylcholine or saline (control group). Tracheal intubation was performed 60 s later. A blinded investigator performed all laryngoscopies and also graded intubating conditions.


RESULTS
Intubating conditions were acceptable (excellent plus good grade combined) in 30%, 92%, 94%, and 98% of patients after 0.0, 0.3, 0.5, and 1.0 mg/kg succinylcholine, respectively. The incidence of acceptable intubating conditions was significantly greater (P < 0.05) in patients receiving succinylcholine compared with those in the control group but was not different among the different succinylcholine dose groups. The calculated doses of succinylcholine (and their 95% confidence intervals) that were required to achieve acceptable intubating conditions in 90% and 95% of patients at 60 s were 0.24 (0.19-0.31) mg/kg and 0.56 (0.43-0.73) mg/kg, respectively.


CONCLUSIONS
The use of 1.0 mg/kg of succinylcholine may be excessive if the goal is to achieve acceptable intubating conditions within 60 s. Comparable intubating conditions were achieved after 0.3, 0.5, or 1.0 mg/kg succinylcholine. In a rapid-sequence induction, 95% of patients with normal airway anatomy anesthetized with 2 mug/kg fentanyl and 2 mg/kg propofol should have acceptable intubating conditions at 60 s after 0.56 mg/kg succinylcholine. Reducing the dose of succinylcholine should allow a more rapid return of spontaneous respiration and airway reflexes.
Department of Anesthesia, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
Mohamed
M
Naguib
Abdulhamid
A
Samarkandi
Waleed
W
Riad
Saleh W
SW
Alharby
D000328:Adult; D000769:Anesthesia, Inhalation; D004311:Double-Blind Method; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D009467:Neuromuscular Depolarizing Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D013390:Succinylcholine / Q000008:administration & dosage*; D014459:Ulnar Nerve / Q000502:physiology
D009467:Neuromuscular Depolarizing Agents; D013390:Succinylcholine