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(− 1)) 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(− 1)) 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(− 2)). Four regimens (0.3, 0.4, 0.5, 0.6 mg kg(− 1)) were compared with 1.0 mg kg(− 1) in at least three trials each, and three (0.8, 1.5, 2 mg kg(− 1)) in one each. With 0.3 to 0.5 mg kg(− 1), the likelihood of excellent intubating conditions was significantly decreased (ARD − 22% to − 67%). With 0.3 and 0.4 mg kg(− 1), but not with 0.5, 0.6, 0.8, 1.5 and 2.0 mg kg(− 1), the likelihood of unacceptable intubating conditions was significantly increased (ARD + 22% and + 32%, respectively). With 2.0 mg kg(− 1), but not with 0.8 or 1.5 mg kg(− 1), the likelihood of excellent intubating conditions was significantly increased (ARD + 23%). Apnoea times were significantly shorter with regimens ≤0.8 mg kg(− 1) (MD − 1.0 to − 3.4 min) but were not reported with 1.5 or 2.0 mg kg(− 1). CONCLUSIONS: With succinylcholine regimens ≤0.5 mg kg(− 1), excellent intubating conditions are less likely and apnoea times are shorter, compared with 1 mg kg(− 1). With 0.3 and 0.4 mg kg(− 1), unacceptable intubating conditions are more common. Succinylcholine 1.5 mg kg(− 1) does not produce more often excellent conditions compared with 1 mg kg(− 1), while 2.0 mg kg(− 1) 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.