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Quantifying the effect of succinylcholine on vocal cord opening using electromyographic single twitch for facilitated mask ventilation: a prospective observational study

Year: 2025

Type: article

Abstract: Background Neuromuscular blocking drugs open the vocal cords and facilitate mask ventilation but may impede the return to spontaneous breathing. Current German S1 airway management guidelines recommend short-acting neuromuscular blocking drugs such as succinylcholine for at-risk patients without defining doses or methods to monitor vocal cord opening. This study investigates the relationship between electromyography-based single twitch response amplitude and vocal cord opening. Secondary endpoint was the quantification of succinylcholine’s neuromuscular blocking effect after administration of 0.1 and 0.9 mg/kg IBW. Methods Thirty patients aged ≥18 years scheduled for surgery with tracheal intubation using succinylcholine were enrolled. Induction of anaesthesia included remifentanil and propofol. The depth of anaesthesia was measured with an electroencephalogram monitor. The baseline neuromuscular block was determined electromyographically with single twitch stimulation of the ulnar nerve at the abductor digiti minimi muscle. The vocal cord area was videorecorded to determine baseline conditions. Then, the patient received 0.1 mg/kg IBW succinylcholine and additional 0.9 mg/kg IBW after two minutes. After four minutes the trachea was intubated. Results Pearson’s correlation coefficient between the variables of the primary endpoint was -0.54±0.09 ( P <0.001). The non-linear regression including interactions with a sedation-depth-index estimated accurately the vocal cord opening (R 2 68.3%, P <0.001). Succinylcholine 0.1 mg kg -1 opened the vocal cords 78% (IQR 65-86%). Conclusions After succinylcholine administration, the electromyographic single twitch stimulation combined with sedation-depth monitoring reliable estimates vocal cord aperture. The considerable vocal cord opening achieved after 0.1 mg kg -1 succinylcholine supports using lower doses for assuring mask ventilation. Clinical trial registration DRKS00021433

Source: Trends in Anaesthesia and Critical Care

DOI: 10.1016/j.tacc.2025.101564