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The Incidence of Low Plasma Cholinesterase Level and Prolonged Suxamethonium Apnoea in Sub-Saharan Africa
Abstract
Background: Plasma cholinesterase is involved in the metabolism of numerous drugs including the short acting muscle relaxants suxamethonium and mivacurium. Patients deficient in BChE will exhibit a prolonged reaction to suxamethonium, and apnoea can persist for a period varying from minutes to hours. Prolonged suxamethonium apnoea may arise from inherited or acquired abnormalities of BChE, this study aimed to determine the incidence of low plasma cholinesterase and prolonged apnoea following suxamethonium.
Methods: One hundred healthy patients with the American Society of Anesthesiologists (ASA) physical status I and II scheduled for elective surgery under general anaesthesia requiring endotracheal intubation were studied. Blood samples were obtained before induction of anaesthesia for estimation of baseline cholinesterase using an automated spectrophotometric method employing benzoylthiocholine. Suxamethonium 2mg/kg was administered after induction of anaesthesia and its onset was determined as the time from the administration of suxamethonium to the time of cessation of spontaneous respiration. The duration of apnoea is time from cessation of respiration to the first evidence of return of spontaneous respiration, or using peripheral nerve stimulator the time from the cessation of respiration until the response to TOF stimulation of the ulnar nerve reappears as evidenced by adduction of the thumb.
Results: The mean cholinesterase level was 6573.29 ±2128.29 (ranged from 1227-14536) IU/L, the cholinesterase activity was similar in both children and adults (p = 0.97). The mean duration of apnoea was 5.88 ±2.00 minutes. Normal cholinesterase level constituted 81%, high cholinesterase level 3%, and low cholinesterase level 16% of the patient population (11% in adults and 5% in children). Prolonged apnoea with a mean duration of 10.69 ± 0.52 minutes occurred in 7% of patients with cholinesterase levels between 1227-4206 IU/L.
Conclusion - Low cholinesterase level is not uncommon among healthy Nigerians. The incidence of prolonged apnoea however is small.
Key words: Plasma cholinesterase, suxamethonium, prolonged apnoea
Methods: One hundred healthy patients with the American Society of Anesthesiologists (ASA) physical status I and II scheduled for elective surgery under general anaesthesia requiring endotracheal intubation were studied. Blood samples were obtained before induction of anaesthesia for estimation of baseline cholinesterase using an automated spectrophotometric method employing benzoylthiocholine. Suxamethonium 2mg/kg was administered after induction of anaesthesia and its onset was determined as the time from the administration of suxamethonium to the time of cessation of spontaneous respiration. The duration of apnoea is time from cessation of respiration to the first evidence of return of spontaneous respiration, or using peripheral nerve stimulator the time from the cessation of respiration until the response to TOF stimulation of the ulnar nerve reappears as evidenced by adduction of the thumb.
Results: The mean cholinesterase level was 6573.29 ±2128.29 (ranged from 1227-14536) IU/L, the cholinesterase activity was similar in both children and adults (p = 0.97). The mean duration of apnoea was 5.88 ±2.00 minutes. Normal cholinesterase level constituted 81%, high cholinesterase level 3%, and low cholinesterase level 16% of the patient population (11% in adults and 5% in children). Prolonged apnoea with a mean duration of 10.69 ± 0.52 minutes occurred in 7% of patients with cholinesterase levels between 1227-4206 IU/L.
Conclusion - Low cholinesterase level is not uncommon among healthy Nigerians. The incidence of prolonged apnoea however is small.
Key words: Plasma cholinesterase, suxamethonium, prolonged apnoea
