[Feedback control of muscle relaxation with a varying on-off controller using cisatracurium].
BACKGROUND
Under clinical conditions constant neuromuscular blockade can also be maintained by a simple closed-loop system. However, delayed onset time, non-linearity of the dose-response curve and different sensitivity to muscle relaxants for each patient are limiting factors.


METHODS
In 20 patients who underwent elective surgical procedures under continuous propofol/alfentanil anaesthesia and relaxation with cisatracurium, the maintenance of an electromyographically controlled cisatracurium block of 90% was achieved by a varying on-off control system. Using an own computer-aided measuring device, the course of the neuromuscular blockade and deviations from the desired neuromuscular block were registered.


RESULTS
Over a period of 64.2+/-14.0 min, neuromuscular block could be controlled on average at a T(1)-level of 10% (90% block). The mean error of the deviation of the obtained neuromuscular blockade from the set-point was -1.6+/-0.9% on average. To maintain this neuromuscular blockade, a dose rate of 1.4+/-0.9 micro g x kg(-1) x min(-1) cisatracurium was necessary.


CONCLUSIONS
It can be concluded that a simple closed-loop system allows the safe use of the intermediate term muscle relaxant cisatracurium for the performance of surgical procedures.
Pohl
B
B
Klinik und Poliklinik für Anästhesiologie und Intensivtherapie, Universität Rostock. birgit.pohl@med.uni-rostock.de
Hofmockel
R
R
Simanski
O
O
Wende
K
K
Lampe
B P
BP
D000328:Adult; D000768:Anesthesia, General; D001279:Atracurium / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D005246:Feedback / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation / Q000187:drug effects*; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage*; D011786:Quality Control
D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium