Incidence of Postoperative Residual Curarization, a Prospective Observational Study

Neuromuscular blocking agents are commonly used in clinical anesthetic practice to facilitate tracheal intubation and allow muscle relaxation during surgical interventions.

Anesthesiologist's subjective qualitative assessment of the patient's recovery of muscle strength before extubation is not predictive of adequate neuromuscular recovery even if many surveys conducted at an international level [1,2,3] demonstrate how this modality of evaluation is often used above all due to the not always widespread availability of tools for quantitative monitoring of neuromuscular blockade3.

An incomplete recovery of neuromuscular function at the end of surgery (Postoperative residual curarization - PORC) exposes the patient to potential adverse respiratory events and a Consensus Statement [4] of experts in 2018 suggested a quantitative and objective evaluation of neuromuscular function using the train acceleromyographic method -of-four ratio (TOFR) at the level of the adductor muscle of the thumb represents the best way to minimize this risk after administration of non-depolarizing neuromuscular agents.

In case of TOFR ≤ 0.9, reversal of the neuromuscular block is normally performed with drugs belonging to the class of acetylcholinesterase inhibitors (e.g. neostigmine 0.03-0.05 mg/kg, associated with an antimuscarinic agent such as atropine to counteract the cholinergic effects) or by sugammadex (2 or 4 mg/Kg), a selective antagonist of rocuronium and vecuronium which acts by encapsulating the neuromuscular blocking molecule making it ineffective.

Recurrence of neuromuscular blockade may, however, occur primarily due to mechanisms of redistribution of the muscle relaxant or if insufficient doses of the reversal drug are administered.