To the Editor:—  We read with interest the article by Naguib et al.  1in which the authors recommended using 0.5–0.6 mg/kg succinylcholine to facilitate tracheal intubation in a rapid-sequence induction. In their study, all of patients were intubated successfully; however, the authors did not provide data regarding whether all patients were successfully intubated on the first try or some patients required two or more tries.

We work in a teaching hospital, and half of the employees in our department are residents and trainees. Routinely, these young anesthesiologists have at most two tries; if they fail, the attending anesthesiologists perform the intubation, when at least 2–3 min has passed since succinylcholine was injected. Although recovery of adductor pollicis from a dose of 0.5–0.6 mg/kg succinylcholine (T1to 10%) occurs at approximately 5 min after drug is given, 2the duration could be much shorter at the laryngeal muscles. During rapacuronium-induced (1.5 mg/kg) neuromuscular blockade, the time of recovery of T1to 25% was 3.7 min at the larynx and 10.2 min at the adductor pollicis. 3Therefore, the attending anesthesiologist may face a worse intubation condition than the resident or fellow met. Sometimes an additional dose of succinylcholine is required.

We want to emphasize the advantages of using 1.0 or 1.5 mg/kg succinylcholine for intubation in this condition. First, the quality of the intubation condition is expected to increase with dose. In the study of Naguib et al. , 1the incidence of acceptable intubation was not significantly different whether patients received 0.6 or 1.0 mg/kg succinylcholine, but the incidence of excellent intubation condition was higher if 1.0 mg/kg was administered (80%vs. < 60%, 1.0 mg/kg vs.  0.6 mg/kg, respectively). This is important for an inexperienced anesthesiologist to perform a difficult intubation under better conditions. Second, the senior anesthesiologist will still have chance for intubation under good conditions without giving additional succinylcholine when a junior doctor fails after one or two tries. The duration of apnea after 1.5 mg/kg succinylcholine is approximately 2 min longer than that after 0.5 mg/kg succinylcholine. 4This 2 min is enough for one attempt at performing intubation but is not a difficult problem for anesthesiologists to maintain the artery oxygen saturation of patients by manual ventilation via  facemask or laryngeal mask airway.

Naguib M, Samarkandi A, Riad W, Alharby SW: Optimal dose of succinylcholine revisited. Anesthesiology 2003; 99:1045–9
Kopman AF, Zhaku B, Lai KS: The “intubating dose” of succinylcholine: The effect of decreasing doses on recovery time. Anesthesiology 2003; 99:1050–4
Debaene B, Lieutaud T, Billard V, Meistelman C: ORG 9487 neuromuscular block at the adductor pollicis and laryngeal adductor muscles in human. Anesthesiology 1997; 86:1300–5
Stewart KG, Hopkins PM, Dean SG: Comparison of high and low doses of suxamethonium. Anaesthesia 1991; 46:833–6