Reversion of atracurium and vecuronium residual nondepolarising neuromuscular blockade with low doses of neostigmine

Abstract

Objectives. To assess the effectiveness of low doses of neostigmine in the reversion of residual nonpolarising neuromuscular blockade (RNMB). Material and methods. The work involved one hundred and nineteen adult patients, ASA I-III, anaesthetised with fentanyl, thiopental, O2-N2O-isoflurane and atracurium (n=62) or vecuronium (n=57). RNMB was monitored with continuous electromyography of adductor pollicis with TOF stimulation. When TOF-Ratio (TR) < 75%, neostigmine 0.035, 0.03, 0.025 or 0.02 mg/kg (and atropine 0.0175, 0.015, 0.0125 or 0.01 mg/kg) were administrated based on the degree of NMB (0-1, 2, 3 or 4) to TOF stimulation respectively, registering the time to achieve TR > 75% and secondary effects. Results. Both groups were homogeneous. Twenty-five point eight percent (25.8%) (group A) and 21.1% (group V) presented TR>75% at the end of surgery, while 11.3% and 19.2% showed TR < 75% with 0-1 responses, 6.5% and 11.5% 2 responses, 4.8% and 7.6% 3 responses, and 51.6% and 50% 4 responses to TOF stimulation in groups A or V respectively. All patients who received neostigmine presented TR > 75% in 10.5±7 (group A) and 10.3±6.4 min. (group V). A predominance of secondary effects in the atracurium group was observed (p=0.027), basically due to excessive salivation, nausea and vomiting. There were no cases of RNMB. Conclusions. The reversion of the residual neuromuscular blockade of atracurium or vecuronium with low doses of neostigmine and atropine adjusted to the degree of RNMB is effective even in deep blockades, reducing the risk of secondary effects.