Effect of Different Anesthetics on Pharmacokinetics and Pharmacodynamics of Rocuronium in Closed-Loop Muscle Relaxant Infusion System

Rocuronium is a non-depolarizing neuromuscular blocking agent with intermediate duration of action and without significant cumulative properties, suitable for continuous infusion. This study was designed to determine the dose requirements for rocuronium, administered by continuous infusion to maintain a stable 90-99% T1 depression (depression of the first twitch in the train-of-four, TOF) in adult, elderly and different sex patients under sufentanil and propoful, sevoflurane, or propoful + sevoflurane anaesthesia.

Methods Two hundred and ten patients, ASA physical status group I and II undergoing elective surgical procedures were studied. Pateients with neuromuscular and metabolic diseases, morbid obesity or receiving medication known to influence neuromuscular transmission were excluded from the study.

Anaesthesia Patients will be assigned at random to receive propofuol, sevolurane or propoful+sevoflurane anaesthesia. All patients will induced with midazolam, 0.1 mg/kg, sufentnail, 0.5 μg/kg, etomidate, 0.3 mg/kg and rocuronium, 0.6 mg/kg. In the propoful group, anaesthesia will be continued with propoful and sufentanil. The doseage of propotul and sufentanil will be adjusted by the blood pressure and heart rate of the patients. In the sevoflurane group, anaesthesia will be continued with sevoflurane (2%) and sufentanil. The doseage of sufentanil will be adjusted by the blood pressure and heart rate of the patients. The doseage of propoful and sufentanil will be adjusted by the blood pressure and heart rate of the patients.

Heart rate, invasive blood pressure, pulse and core body temperature were monitored throughout the procedure. The core body temperature was main tained between 36°C and 37°C using a warming blanket. Positive pressure ventilation was used to maintain the end-tidal CO2 between 4.5 kPa and 5.5 kPa. The inspired and end-tidal concentrations of carbon dioxide and volatile anaesthestics were monitored by a multigas monitor.

Neuromuscular transmission was monitored by recording the electromyographic (EMG) activity of the adductor pollicis muscle resulting from the supra- maximal stimulation of the ulnar nerve with train-of- four (TOF), 2 Hz for 2 s, applied at 10-s intervals. The ulnar nerve was stimulated through surface electrodes applied at the wrist, using square-wave currents of 0.2 ms duration. Ten minutes were allowed for the stabilization of anaesthesia and the EMG tracing before the intubating dose of rocuronium, 0.6 mg/kg, was given by the anaesthesiologist.