Comparison of the efficacy of atracurium pretreatment versus magnesium sulphate for prevention of suxamethonium-induced fasciculation and post-operative myalgia

Background: Suxamethonium remains the best option for rapid sequence induction, it is the only depolarizing muscle relaxant in clinical use. However, fasciculation and myalgia are frequent adverse effects of the drug. Myalgia can last for several days with associated discomfort. Non-depolarizing muscle relaxant and magnesium sulphate have been tried as pretreatments to attenuate the fasciculation and myalgia with varying results.Methods: A double blind, randomized study of 100 adult surgical patients of ASA I or II Class were recruited to receive either intravenous atracurium (0.05mg/kg) (Group A) or intravenous magnesium sulphate (30mg/kg)(Group B). The occurrence, severity and duration of fasciculation as well as the occurrence and severity of post-operative myalgia were also recorded.Results: Muscle fasciculation occurred in 39 (78%) patients in Group A and 27(54%) patients in Group B (p= 0.001). The severity of fasciculation was mild to moderate in Group B while Group A in addition also recorded some cases of severe episodes of fasciculation. Mean duration of fasciculation in Group A waslonger (28.48 ± 1.07sec) than in group B (19.44± 1.93seconds) (p= 0.001). Post-operative myalgia was not experienced at 6hrs and 48hrs, while 2 patients (1 in each Group) had it at 12hrs. At 24hrs, postoperative myalgia was present in 13(26%) patients in group A and 5(10%) patients in group B, (p=0.043). The severity of post-operative myalgia recorded both at 12hrs and 24hrs was mild.Conclusion: Magnesium sulphate demonstrated better efficacy at reducing fasciculation and postoperative myalgia than atracurium