Doxacurium chloride for neuromuscular blockade before tracheal intubation and surgery during nitrous oxide-oxygen-narcotic-enflurane anesthesia.

The neuromuscular effects of doxacurium (BW A938U) were studied in 36 patients, divided into four groups of 9 patients each, given doxacurium either 50 micrograms/kg (2 x ED95) 5 or 4 minutes or 80 micrograms/kg (3 x ED95) 4 or 3 minutes before tracheal intubation. Adequate neuromuscular relaxation permitted successful intubation at 5 minutes for doxacurium 50 micrograms/kg and at 4 minutes for 80 micrograms/kg. Time to 90% blockade was 5.4 +/- 1.5 minutes for doxacurium 50 micrograms/kg and 3.5 +/- 1.2 minutes for 80 micrograms/kg. Time to 25% spontaneous recovery was 84.7 +/- 54.3 minutes for doxacurium 50 micrograms/kg and 164.4 +/- 85.2 minutes for 80 micrograms/kg. Either neostigmine 45 micrograms/kg, neostigmine 60 micrograms/kg, or edrophonium 1000 micrograms/kg was given for reversal when T1 had spontaneously recovered to 25% of baseline level, T1 being the first response to repetitive train-of-four (TOF) stimuli (2 Hz for 2 seconds at 10-second intervals) expressed as percent of baseline level. The T4:T1 ratio is the amplitude of the fourth twitch relative to the first twitch in a TOF stimulus expressed as a ratio. T1 rapidly achieved 90% of baseline in 5-10 minutes after reversal of neuromuscular blockade. In contrast, the T4:T1 ratio lagged, recovering to a mean of 0.6 at 20 minutes when T1 was over 90% of baseline. Recovery patterns were not statistically significantly different (unpaired t-test) among the three reversal regimens. Therefore, the reversal data were pooled. No clinically significant hemodynamic effects occurred in any group.(ABSTRACT TRUNCATED AT 250 WORDS)