Figure 13-40 Electromyographic response to ulnar nerve stimulation. Injection of 0.1 mg/kg vecuronium in a normal patient resulted in a slow onset of nondepolarizing block (upper trace), whereas injecting one tenth the dose (0.01 mg/kg vecuronium) to a myasthenic patient resulted in a rapid onset of block (lower trace). (From Baraka A: Onset of neuromuscular block in myasthenic patients. Br J Anaesth 69:227–228, 1992.)