Post-tetanic count [PTC]: a new technique of evaluating profound neuromuscular block of different non-depolarizing muscle relaxants

ABSTRACT

Forty five adult patients scheduled for eye or ear surgery were studied to evaluate the PTC as a method to predict neuromuscular recovery. They were given either 0.08 mg kg[-1] pancronium, 0.1 mg kg[-1] vecuronium or 0.5 mg kg[-1] atracurium during thiopental-nitrous oxide-halothane anaesthesia. Ulnar nerve at the wrist was stimulated and the force of contraction of the adductor pollicis was recorded, we focused on the period of intense neuromuscular block [the period of no response] using the PTC method. This study showed that PTC method can give early warning about the onset of neuromuscular recovery offering the opportunity to give supplementary doses of muscle relaxant at the proper time. The first response to post tetanic twitch stimulations appeared on average 35.5, 9 and 11 min. before the first detectable response to TOF stimulation for patients given pancuronium. vecuronium and atracurium respectively. This study proved a close relationship between PTC and time interval between the PTC and the first detectable response to TOF nerve stimulation. We concluded that PTC method can effectively monitor part of the period of no response and can be used to predict the time to appearance of the first detectable response to TOF. It is a valuable supplement to TOF stimulation during clinical anaesthesia