PID control strategies for the automatic control of neuromuscular blockade

A digital PID controller incorporating several modifications to accommodate the characteristics of the neuromuscular blockade is described in this paper. The initial design was performed by the Ziegler-Nichols step response method. The controller gains are automatically adjusted to the specified target by a gain-scheduling technique. The control system was evaluated in 30 patients. Subsequent analysis of all the data collected during surgery indicates that the variability of the patient responses is much wider than that inferred from the literature. This observation clearly suggests the desirability of individual tuning of the controller parameters. A technique for an improved tuning of the PID controller parameters to the patient's individual dynamics is presented. (C) 1998 Elsevier Science Ltd. All rights reserved.