Respiratory function and extraocular muscle paralysis following administration of pancuronium bromide in dogs.

ABSTRACT

Pancuronium bromide, a neuromuscular blocking agent, was evaluated in canine cataract surgical patients under general anesthesia to determine its effects on respiratory function and globe position. Two paralytic, anesthetic regimes were studied one using a standard dosage of 0.066 mg kg-1 pancuronium bromide, given intravenously while providing the patient with ventilatory support, and one using a dosage of 0.022 mg kg-1 in which no ventilatory support was provided. Eye position and anterior vitreal position/displacement were recorded by a surgeon who was blinded as to treatment group. Physiological parameters indicative of respiratory function were monitored. Both dosages of pancuronium produced comparable, neutral globe position within 30 s following administration which lasted for 20-30 min. All patients in the standard dose group experienced uneventful anesthetic episodes with physiological parameters well within the normal ranges. Within 5 min after administration, all patients in the low-dose group developed a pronounced respiratory acidosis (mean arterial pH = 7.07 +/- 0.08; mean PaCO2 = 79.8 +/- 10.7 mmHg), which exceeded a set of predetermined safety limits, and subsequently these dogs received ventilatory support. We conclude that 0.022 mg kg-1 pancuronium rapidly produces an unacceptable level of respiratory acidosis and, as a result, patients receiving neuromuscular blocking agents should routinely receive ventilatory support.