Priming with vecuronium in obstetrics

The priming technique for rapid sequence induction with vecuronium is used safely in nonpregnant patients. We describe two instances where this technique was associated with respiratory depression due to muscle weakness that required immediate tracheal intubation. The first patient was a 28-year-old white female who weighed 73 kg; she was scheduled for Caesarean section. Vecuronium I mg (13.7 pgjkg) was administered intravenously as a priming dose after preoxygenation for 5 minutes. Two minutes later the patient developed difficulty in breathing. The tidal volume decreased from 800 to 200 ml and she could neither open her eyes nor protrude her tongue. She became intensely restless, moved her extremities violently and was unable to breathe. The priming technique was abandoned and rapid sequence induction with thiamylobarbitone and suxamethonium was performed. The baby was delivered safely and had Apgar scores of 8 and 9, respectively. at I and 5 minutes after delivery. The second patient was a 27-year-old white female also scheduled for Caesarean section. In this instance vecuronium 10 pg/kg was administered intravenously as a priming dose. Four minutes after administration of vecuronium, while preparing to inject thiamylobarbitone and the intubating dose of vecuronium, the patient complained of difficulty in breathing and then vomited. Her mouth and pharynx were immediately cleared with suction and the trachea was intubated expeditiously after thiamylobarbitone and suxamethonium. The baby was delivered with Apgar scores of 8 and 10 at 1 and 5 minutes after delivery. Both patients demonstrated respiratory distress after a priming dose of vecuronium that is considered acceptable in nonobstetric Neither patient was on any medication (magnesium sulphate, diuretics or antibiotics) which could possibly potentiate the muscle relaxation produced by nondepolarising muscle relaxants. These two cases illustrate the sensitivity of parturients to small doses of vecuronium (1C15 pg/kg) which are considered acceptable and safe in the nonpregnant population. It would be reasonable to avoid the use of the priming technique in these cases or to reduce the muscle relaxant dose significantly in order to avoid this complication.