In training, we routinely used 1 -1.5 mg/kg of sux for intubation (2mg/kg with pretreatment). Several studies have suggested that this is too much and may not improve intubating conditions while prolonging the apneic period. This study from the BJA revealed good or excellent intubating conditions with .6mg/kg in 96% of patients irrespective of the other induction drugs. Another study in Anesthesiology showed that .6 mg/kg may be the optimal dose as well. The time of return of diaphragmatic movement was 3 minutes with visible respiration (bag moving) was less than 4 minutes. This was a small study ( < 200 patients) but interesting nonetheless.

http://bja.oxfordjournals.org/content/95/5/710.full