Assessment of residual curarization using low-current stimulation

Area of Science:

• Anesthesiology
• Pharmacology
• Critical Care Medicine

Background:

• Residual neuromuscular blockade (RNB) is a common complication following the administration of neuromuscular blocking agents (NMBAs) during general anesthesia.
• It can lead to adverse respiratory events and prolonged recovery in the Post Anesthesia Care Unit (PACU).
• Qualitative assessments of neuromuscular function intraoperatively may not accurately predict the absence of RNB.

Purpose of the Study:

• To determine the incidence and degree of residual neuromuscular blockade in PACU patients.
• To evaluate the effectiveness of train-of-four (TOF) stimulation at a low current (20 mA) in detecting RNB.
• To compare the incidence of RNB after administration of vecuronium versus pancuronium.

Main Methods:

• A prospective study involving 64 PACU patients randomly assigned to three groups: Control (no NMBA), Vecuronium (V), and Pancuronium (P).
• TOF stimulation at 20 mA was used to assess neuromuscular function 15 minutes after surgery.
• Patients were considered to have adequate neuromuscular function intraoperatively based on clinical signs and tactile/visual evaluation.

Main Results:

• A significant incidence of residual neuromuscular blockade was detected: 45% in the Pancuronium group (TOF ratio < 0.70) and 8% in the Vecuronium group.
• No residual blockade was observed in the control group.
• The findings were consistent with previous studies using supramaximal TOF stimulation.

Conclusions:

• Residual neuromuscular blockade is frequently encountered after the use of long-acting nondepolarizing muscle relaxants, despite intraoperative monitoring.
• TOF stimulation at a low current of 20 mA is effective in detecting residual curarization.
• Enhanced vigilance and quantitative monitoring are necessary to mitigate the risks associated with RNB.