Influence of upper airway pressure changes on genioglossus muscle respiratory activity

Abstract

The effects of change in pharyngeal airway pressure on electromyographic (EMG) activity of a pharyngeal dilating muscle (genioglossus) were investigated in 20 anesthetized rabbits. In vagotomized animals, upper airway loading maneuvers (nasal occlusion) increased the peak inspiratory activity of the genioglossus (GG) muscle on the first occluded breath. In contrast, "unloading" maneuvers (switching from nose to tracheostomy breathing) decreased GG activity. To further characterize the GG response, sustained pressure changes were produced within the isolated upper airway. Negative pressure increased GG activity; positive pressure decreased it. A poststimulus effect consisting of increased GG activity compared with control was seen following both negative- and positive-pressure stimuli. Cyclical pressure changes applied to the isolated upper airway increased the GG activity. These observations indicate the presence of reflex pathways that regulate GG muscle activity in response to upper airway pressure loads. This reflex system appears to play a role in regulating GG activity during tidal breathing and could be important in ensuring pharyngeal airway patency.

Obesity and Obstructive Sleep Apnea: Pathogenic Mechanisms and Therapeutic Approaches

“…More recently, methods have been developed for quantifying active neuromuscular responses in sleeping subjects, and a defect in these active responses has been demonstrated in patients with sleep apnea compared with normal subjects. This defect in neuromuscular control was independent of age, obesity, and sex (86), and may be caused by sleep-related reductions in dilator activity during sleep compared with wakefulness (87,88) or by a loss of compensatory responses during sleep (87)(88)(89)(90)(91)(92)(93)(94)(95)(96)(97)(98)(99). Thus, current evidence indicates that sleep apnea is associated with fundamental disturbances in upper airway mechanical (68,100,101) and neuromuscular control (80,(102)(103)(104)(105)(106)) (see Figure 1, left), and suggests that a combined defect is required to produce sleep apnea (86).…”

Pathophysiology of obstructive sleep apnoea

“…Several reports indicate a role for upper airway reflex mechanisms in the maintenance of patency [111,112,[143][144][145][146][147][148][149]. Evidence suggests that these reflex mechanisms are pressure sensitive [112,[144][145][146], and interference with them could lead to an imbalance between intrapharyngeal pressure and the contraction of upper airway dilating muscles, resulting in obstructive apnoeas [3].…”

Alae Nasi Activation in Preterm Infants during Oral Feeding

“…Three potential stimuli could activate the alae nasi during feeding: hypercarbia (8), hypoxemia (1 9), and mechanoreceptor response within the airway itself (20). One paradox of feeding is that the decrease in VE that occurs is not accompanied by a large increase in C 0 2 tension in the blood.…”

“…Mechanoreceptors that respond to subatmospheric pressure within the upper airway may also activate upper airway dilating muscles and inhibit the rate of diaphragmatic contraction (20,22,23). It is conceivable that the subatmospheric pressure generated in the pharynx during the breaths that occur between swallows could trigger this reflex response, resulting in inhibition of the diaphragm and activation of the alae nasi.…”