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TECHNOLOGY, COMPUTING, AND SIMULATION

Simultaneous Determination of Neuromuscular Blockade at the Adducting and Abducting Laryngeal Muscles Using Phonomyography

Neuromuscular Research Group (NRG), Department of Anesthesiology, Centre Hospitalier de l’Université de Montréal (CHUM) Hôtel-Dieu, Université de Montréal, Canada

Address correspondence and reprint requests to T.M. Hemmerling, MD, DEAA, Department of Anesthesiology, Université de Montréal, Hôtel-Dieu, 3580 Rue St. Urbain, Montréal (Québec) H2W 1T8, Canada. Address e-mail to thomashemmerling{at}hotmail.com

Phonomyography (PMG) is a new method for measuring neuromuscular blockade (NMB) at the larynx. In this study, we used PMG to compare NMB at the posterior cricoarytenoid (PCA) and the lateral cricoarytenoid muscle (LCA) in humans. Twelve patients were included in this study. Endotracheal intubation was performed without aid of neuromuscular blocking drugs. One small condenser microphone was inserted beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic responses of the LCA (vocal cord adduction), and a second microphone was placed behind the larynx to measure NMB of the PCA (vocal cord abduction). Stimulation of the recurrent laryngeal nerve was performed using superficial electrodes placed at the neck (midline between jugular notch and cricoid cartilage) using train-of-four (TOF) stimulation every 12 s. After supramaximal stimulation, mivacurium 0.1 mg/kg was injected and onset, peak effect, and offset of NMB measured and compared using t-test (P < 0.05). The data are presented as mean (SD). Peak effect, onset time, and early recovery to 25% of control twitch height were not significantly different between PCA and LCA at 86% (13) versus 78% (16), 2.3 min (0.45) versus 2.3 min (1.0), and 9.55 min (3.05) versus 8.5 min (4.7), respectively. However, recovery to 75%, 90% of control twitch height, and recovery to a TOF ratio of 0.8 were significantly longer at the PCA than at the LCA at 14 min (4) versus 11 min (5), 17 min (5) versus 11.8 min (5.6), and 17.5 min (5.6) versus 12.3 min (5.5), respectively. The authors conclude that recovery of NMB at the PCA takes longer than at the LCA in humans after mivacurium.

IMPLICATIONS: After neuromuscular blockade in humans, the recovery of the ability to open the vocal cords takes longer than the ability to close the vocal cords.

This article has been cited by other articles:

				T. M. Hemmerling, G. Michaud, S. Deschamps, and G. Trager An External Monitoring Site at the Neck Cannot Be Used to Measure Neuromuscular Blockade of the Larynx Anesth. Analg., June 1, 2005; 100(6): 1718 - 1722. [Abstract] [Full Text] [PDF]

				A. Michalek-Sauberer, H. Gilly, T. M. Hemmerling, G. Michaud, S. Deschamps, and G. Trager Neuromuscular Blockade at Laryngeal Muscles * Response Anesth. Analg., January 1, 2005; 100(1): 297 - 298. [Full Text] [PDF]