Inferior pharyngeal constrictor electromyographic activity during permeability pulmonary edema in lambs

• Published in: Journal of applied physiology (1985) 1996-10, Vol.81 (4), p.1598-1604
• Main Authors: Diaz, Veronique, Kianicka, Irenej, Letourneau, Patrick, Praud, Jean-Paul
• Format: Article
• Language: English
• Subjects: Anesthetics, General - pharmacology; Animals; Animals, Newborn; Biological and medical sciences; Blood Gas Analysis; Electromyography; Glottis - physiopathology; Halothane - pharmacology; Lung Volume Measurements; Medical sciences; Muscle Contraction - physiology; Organ Size - physiology; Permeability; Pharyngeal Muscles - physiopathology; Pneumology; Pulmonary Edema - physiopathology; Pulmonary hypertension. Acute cor pulmonale. Pulmonary embolism. Pulmonary vascular diseases; Respiratory Mechanics - physiology; Sheep
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1996.81.4.1598

Véronique Diaz, Irenej Kianicka, Patrick Letourneau, Jean-Paul Praud (With the Technical Assistance of Bruno Gagne) Department of Pediatrics and Pulmonary Research Unit, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada Received 13 October 1995; accepted in final form 23 May 1996. Diaz, Véronique, Irenej Kianicka, Patrick Letourneau, and Jean-Paul Praud. Inferior pharyngeal constrictor electromyographic activity during permeability pulmonary edema in lambs. J. Appl. Physiol. 81(4): 1598-1604, 1996. Newborn mammals exhibit an active expiratory upper airway closure during the first hours of extrauterine life. We have recently shown that permeability pulmonary edema led to active expiratory glottic closure in awake newborn lambs while hypoxia (inspired O 2 fraction 8%; 15 min) did not. In the present study, we tested the hypothesis that expiratory glottic closure was accompanied by an increase in pharyngeal constrictor muscle expiratory electromyographic (EMG) activity. We studied seven awake nonsedated lambs aged 8-20 days. Airflow (facial mask + pneumotachograph), blood gases (arterial catheter), and EMG activity of both the thyroarytenoid muscle (a glottic adductor) and the inferior pharyngeal constrictor muscle were recorded before and after intravenous injection of halothane (0.05 ml/kg) to induce a permeability pulmonary edema. A central apnea (duration 15 s to 5 min) with continuous thyroarytenoid and inferior pharyngeal constrictor activity was observed within seconds after halothane injection. One lamb died despite rescuing maneuvers. An expiratory phasic thyroarytenoid and inferior pharyngeal constrictor muscle activity with simultaneous zero airflow gradually took place and, by 30 min after halothane injection, was present at each expiration in the six remaining lambs. Expiratory glottic and pharyngeal constrictor muscle EMG activity was subsequently present during the whole study period (1.5-5 h), even after correction of the initial hypoxia. Permeability lung edema was present at postmortem examination in all seven lambs. We conclude that a permeability pulmonary edema induced by intravenous halothane in nonsedated lambs enhances both glottic and pharyngeal constrictor muscle expiratory EMG. We hypothesize that expiratory contraction of the inferior pharyngeal constrictor muscle could participate in the active expiratory upper airway closure; this, in turn, might improve alveolocapillary gas exchange by increasing