ACCELERATED ONSET OF VECURONIUM NEUROMUSCULAR BLOCK WITH PULMONARY ARTERIAL ADMINISTRATION

The purpose of this study was to determine the onset times of vecuroni um neuromuscular block adminir;tered into either the central circulati on or a peripheral vein. One hundred and twenty adult patients with a pulmonary artery (PA) catheter were randomly divided into one of three groups with respect to the routes of vecuronium administration (n = 4 0 in each group). Anaesthesia was induced with midazolam 2.5 mg iv and fentanyl 10-50 mu g. kg(-1) iv and maintained with intermittent doses of fentanyl 50 mu g iv and nitrous oxide 60-70%, in oxygen. After imm obilization of the forearm in a splint the ulnar nerve was stimulated supramaximally every 12 sec. The resulting force of the evoked thumb t witch was recorded (Myograph 2000, Biometer, Denmark). The times from the injection to the first depression of twitch response (latent onset ) inpatients given vecuronium 0.08 mg kg(-1) into the pulmonary artery , the right atrium, and a peripheral vein on the hand were 58.0 +/- 19 .5, 71.5 +/- 171, and 82.4 +/- 18.0 sec (mean +/- SD), respectively. T he latent onset of neuromuscular block occurred sooner in patients giv en vecuronium into the central vein than when administered into a vein on the hand (P < 0.01). In comparing the patients given vecuronium in to the central vein, the onset limes to 95% twitch depression (onset) were 152.3 +/- 40.7 and 168.2 +/- 35.5 sec. The onset of block was fou nd to be faster when vecuronium was administered into the pulmonary ar tery than into the right atrium (P < 0.01). These findings suggest tha t the administration of vecuronium into the pulmonary artery is one ap proach to accelerate neuromuscular blockade in patients with a PA cath eter.