Figure 13-38 Electromyographic response to ulnar nerve stimulation by train-of-four stimulation every 20 seconds. Shown is the effect of 1.5 mg/kg succinylcholine in three myasthenic patients with differing butyrylcholinesterase activity. Upper tracing, butyrylcholinesterase = 5.16 U/mL; middle tracing, butyrylcholinesterase = 1.45 U/mL; lower tracing, butyrylcholinesterase = 0.73 U/mL. (From Baraka A: Suxamethonium block in the myasthenic patient. Correlation with plasma cholinesterase. Anaesthesia 47:217–219, 1992.)