The optimal dose of succinylcholine for rapid sequence induction: a systematic review and meta-analysis of randomized trials.

Background: The evidence base for the widely accepted standard regimen of succinylcholine for rapid sequence induction (1.0 mg kg) remains unclear.

Methods: We performed a systematic review and meta-analysis of randomized trials comparing any succinylcholine regimen with the standard regimen (1.0 mg kg) and reporting on intubating conditions and/or apnoea times. Results were expressed as absolute risk differences (ARD) for dichotomous data and mean differences (MD) for continuous data.

Results: We retrieved six trials with relevant data of 864 patients (ASA 1 or 2, aged 18-65 years, body mass index < 30 kg m). Four regimens (0.3, 0.4, 0.5, 0.6 mg kg) were compared with 1.0 mg kg in at least three trials each, and three (0.8, 1.5, 2 mg kg) in one each. With 0.3 to 0.5 mg kg, the likelihood of excellent intubating conditions was significantly decreased (ARD - 22% to - 67%). With 0.3 and 0.4 mg kg, but not with 0.5, 0.6, 0.8, 1.5 and 2.0 mg kg, the likelihood of unacceptable intubating conditions was significantly increased (ARD + 22% and + 32%, respectively). With 2.0 mg kg, but not with 0.8 or 1.5 mg kg, the likelihood of excellent intubating conditions was significantly increased (ARD + 23%). Apnoea times were significantly shorter with regimens ≤0.8 mg kg (MD - 1.0 to - 3.4 min) but were not reported with 1.5 or 2.0 mg kg.

Conclusions: With succinylcholine regimens ≤0.5 mg kg, excellent intubating conditions are less likely and apnoea times are shorter, compared with 1 mg kg. With 0.3 and 0.4 mg kg, unacceptable intubating conditions are more common. Succinylcholine 1.5 mg kg does not produce more often excellent conditions compared with 1 mg kg, while 2.0 mg kg does, but the database with these regimens is weak and apnoea times remain unknown. Limited information size and strong statistical heterogeneity decrease the certainty of the evidence.