title: Evaluation of a closed-loop muscle relaxation control system.
abstract: Automatic muscle relaxation control may reduce anesthesiologists' workload freeing them for other patient care requirements. In this report we describe a muscle relaxation controller designed for routine clinical application using rocuronium and the train-of-four count. A muscle relaxation monitor (TOF Watch SX) was connected to a laptop computer running a controller algorithm program that communicates with a syringe pump to form a closed-loop muscle relaxation system. The control algorithm uses proportional-integral and lookup table components and is designed to avoid the usability restrictions of existing controllers. The controller is optimized using an objective method to avoid the uncertainties of ''hand-crafted'' controller algorithms. Controller target was train-of-four count 1 or 2 and controller performance was evaluated in 15 patients. During 39 hours of closed-loop control, 96.1% of all twitches recorded were in the target range. Average rocuronium infusion rate was 0.36 mg.kg(-1).h(-1) (sd 0.18 mg.kg(-1).h(-1)). We show that the controller remains useful even in the presence of disturbances that can arise in routine clinical conditions. The muscle relaxation controller maintained the target train-of-four count values and may serve as a basis for the design of hardware and user interfaces for closed-loop muscle relaxation control in clinical conditions.
authors.affiliation: Research Group for Experimental Anesthesiology and Clinical Pharmacology, Groningen, The Netherlands.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Eleveld
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Proost
authors.forename: J Mark K H
authors.initials: JMKH
authors.lastname: Wierda
mesh_terms: D000368:Aged; D000465:Algorithms; D000732:Androstanols / Q000008:administration & dosage; D000758:Anesthesia; D000776:Anesthesiology / Q000295:instrumentation*; D001331:Automation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009126:Muscle Relaxation / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects*; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage; D000077123:Rocuronium
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium