Improved model for neuromuscular blockade and reversal

In the operating room, neuromuscular blockade is induced, maintained, and reversed using pharmacological means. It is monitored using the thumb twitch response to electrical stimulus of the ulnar nerve. Learning of the pharmacology and clinical management of neuromuscular blockade can be facilitated by using educational simulators. Jaklitsch and Westenskow describe a model for educational simulation of neuromuscular blockade and reversal. This model does not reflect the irreversibility of deep neuromuscular block. We developed a model that overcomes this and others shortcomings. Two independent pharmacokinetic models generate effect site concentrations of muscle relaxant and reversal agent. One pharmacodynamic model predicts single twitch height in absence of reversal agent (sth0), another the reversal effect. These outputs are combined in the actual single twitch height. "Reversibility" as a function of sth0, based on experimental data, is part of this relationship. We simulated reversal of atracurium and vecuronium induced neuromuscular blocks with edrophonium and neostigmine. The response of the developed model fits published experimental data more closely than the response of the Jaklitsch and Westenskow model. Similar results were obtained for the commonly used train-of- four stimulus pattern.