Neostigmine after spontaneous recovery from neuromuscular blockade

The effect of neostigmine on neuromuscular function was examined after spontaneous recovery from an atracurium-induced neuromuscular blockade, which reached a train-of-four ratio of either 0.5 or 0.9. Two doses of neostigmine 2.5 mg were given 5 minutes apart. Neuromuscular recovery was assessed with train-of-four and tetanic stimuli. The first dose of neostigmine antagonised the neuromuscular blockade. The second dose diminished tetanic height and increased tetanic fade. The train-of-four measured mechanically was adversely affected to a small degree, but when measured with the electromyograph no significant change occurred. Neostigmine may adversely affect neuromuscular function after spontaneous recovery from a non-depolarising block. This is unlikely with a single modest dose and any effects are probably short-lived.