A BOLUS PLUS CONTINUOUS-INFUSION PROTOCOL FOR CONTROLLING NEUROMUSCULAR BLOCKADE DURING ANESTHESIA

Neuromuscular blockade is controlled during anesthesia by administerin g either bolus doses or a continuous infusion of a blocking agent. To test whether a constant infusion technique requires less attention and provides better control we used a computer to simulate neuromuscular blockade. Using the model we maintained 95% blockade with mivacurium, atracurium, and vecuronium. It required 1.2 changes per hour to mainta in the blockade by continuous infusion; an average of 4.5 bolus per ho ur were required to maintain blockade by the bolus technique. When the bolus and continuous infusion techniques were combined, only 0.16 cha nges per hour were required. Atracurium was then given to ten patients during anesthesia, following the bolus plus continuous infusion proto col. After a bolus was given to obtain 100% twitch depression, for tra cheal intubation, neuromuscular function was assessed by train-of-four stimulation of the ulnar or facial nerves by observing the resultant muscle movement. When the first twitch of the train-of-four returned, relaxation was maintained by continuous infusion. A bolus was given an d the drug infusion rate was changed whenever the level of relaxation changed from the desired one twitch of the train-of-four. The infusion rate was adjusted only 1.12 +/- 0.79 times per hour. The desired leve l of muscle relaxation was easily controlled using the bolus plus cont inuous infusion protocol. The infusion scheme might be implemented in future drug infusion pumps.