Neuromuscular blocking and cardiovascular effects of Org 9487, a new short-acting aminosteroidal blocking agent, in anaesthetized animals and in isolated muscle preparations:

The hemodynamic effects of rapacuronium in patients with coronary artery disease: succinylcholine and vecuronium compared

Rapacuronium is a nondepolarizing muscle relaxant similar in structure to pancuronium, rocuronium, and vecuronium. Rapacuronium has a mild to moderate effect on heart rate and arterial blood pressure in ASA physical status I and II patients. However, rapacuronium was often administered after, e.g., thiopental, an inhaled anesthetic, and fentanyl, thus modifying or masking the hemodynamic effects of rapacuronium. In this study, we investigated the hemodynamic effects of rapacuronium and compared its effects with those of vecuronium and succinylcholine. Sixty patients scheduled to undergo routine coronary artery bypass grafting were selected to receive rapacuronium 1.5 mg/kg, vecuronium 0.1 mg/kg, or succinylcholine 1 mg/kg. Heart rate, blood pressure, pulmonary artery pressures, and cardiac index were measured at 30- and 60-s intervals during the 2 min after the induction of anesthesia with diazepam and for a 3-min period after study drug administration. The Rapacuronium group exhibited significantly larger decreases in blood pressure and systemic vascular resistance than the Vecuronium or Succinylcholine groups. One patient in the Rapacuronium group experienced cutaneous flushing associated with a 33% decrease in blood pressure.

IMPLICATIONS

Rapacuronium is associated with a significantly larger decrease in blood pressure than succinylcholine or vecuronium, and this decrease should be considered when using rapacuronium in patients who cannot tolerate this decrease.

Spontaneous recovery profile of rapacuronium during desflurane, sevoflurane, or propofol anesthesia for outpatient laparoscopy

We evaluated the spontaneous recovery characteristics of rapacuronium during desflurane-, sevoflurane-, or propofol-based anesthesia in 51 consenting women undergoing laparoscopic tubal ligation procedures. After the induction of the anesthesia with standardized doses of propofol and fentanyl, 1.5 mg/kg IV rapacuronium was administered to facilitate tracheal intubation. Patients were randomized to receive either 1 minimum alveolar anesthetic concentration of desflurane, 1 minimum alveolar concentration of sevoflurane, or 100 microg. kg(-1). min(-1) propofol infusion in combination with 66% nitrous oxide in oxygen for maintenance of anesthesia. Neuromuscular blockade was monitored at the wrist by using electromyography. The degree of maximum blockade and the times for first twitch recovery (T(1)) to 5%, 25%, 50%, 75%, and 90%, as well as the recovery index, were similar in all three anesthetic groups. However, recovery times for the train-of-four ratio to achieve 0.7 and 0.8 were significantly longer with desflurane (44.4 +/- 18.9 and 53.5 +/- 22.4 min) and sevoflurane (44.8 +/- 15.1 and 53.2 +/- 15.8 min) compared with propofol (31.8 +/- 5.3 and 36.5 +/- 6.5 min). Eight patients (16%) required a maintenance dose of 0.5 mg/kg rapacuronium and reversal of rapacuronium residual block occurred in three (6%) patients. We conclude that spontaneous recovery after an intubating dose of 1.5 mg/kg rapacuronium was significantly prolonged by both desflurane and sevoflurane compared with propofol-based anesthesia. Routine monitoring of neuromuscular activity is recommended even when a single bolus dose of rapacuronium is administered during ambulatory anesthesia.

IMPLICATIONS

When administered for laparoscopic surgery, the duration of action of an intubating dose of rapacuronium was prolonged 40%-50% by desflurane and sevoflurane, respectively, (versus propofol). Monitoring recovery of neuromuscular blockade produced by rapacuronium is particularly important when desflurane or sevoflurane is administered to ensure that an adequate recovery (train-of-four > or = 0.8) is achieved by the end of anesthesia.

Onset/offset characteristics and intubating conditions of rapacuronium: a comparison with rocuronium

We compared onset and offset of action and tracheal intubating conditions after rapacuronium and rocuronium in 60 patients in a randomized, assessor-blinded study. Following induction of anaesthesia with propofol 2.5 mg kg-1, either rapacuronium 1.5 mg kg-1 (n = 30) or rocuronium 0.6 mg kg-1 (n = 30) was administered to facilitate tracheal intubation. Anaesthesia was maintained with either a propofol infusion (100 micrograms kg-1 min-1) or sevoflurane (1% end-tidal) with 66% nitrous oxide (N2O), n = 15 in each subgroup. Neuromuscular monitoring was performed using an electromyographic (EMG) device (Datex Relaxograph). The lag times (mean 42 (SD 11) s and 44 (16) s), maximum block (99 (2)% and 98 (3)%) and intubating conditions at 60 s (good-to-excellent in 86% and 84% of patients) were similar for rapacuronium and rocuronium, respectively. The onset time of rapacuronium was shorter than rocuronium (87 (20) vs 141 (65) s, P < 0.001), and the degree of block at 60 s was greater (69 (26) vs 50 (27)%, P < 0.05). Twenty-five per cent recovery was shorter with rapacuronium than rocuronium during propofol (15.0 (3.2) vs 39.1 (14.2) min, P < 0.001) and sevoflurane (15.1 (4.2) vs 47.8 (19.0) min, P < 0.001) anaesthesia. We conclude that rapacuronium 1.5 mg kg-1 had a more rapid onset, similar intubating conditions, and shorter recovery times than rocuronium 0.6 mg kg-1.