Upper airway negative-pressure effects on respiratory activity of upper airway muscles

Abstract

Influence of upper airway negative-pressure change on the respiratory activity of various upper airway muscles was investigated in 13 anesthetized rabbits. Phasic inspiratory activity increased or appeared during virtually all negative-pressure trials in nasolabial, cricothyroid, and posterior cricoarytenoid muscles. No phasic inspiratory activity was seen in the sternothyroid (ST) and sternohyoid (SH) muscles before negative-pressure applications but appeared during 80% of trials in ST and 62% of trials in SH. During maintained negative pressure, a gradual decline in activity was often observed in the nasolabial and laryngeal muscles, whereas a rapid decline in activity was seen in the cervical strap muscles. Reflex effects of negative pressure was markedly reduced or abolished by sectioning the internal branch of the superior laryngeal nerve bilaterally. Reflex augmentation of upper airway muscle activity reported here may have functional significance in the maintenance of upper airway patency. It could prevent upper airway collapse when negative pressure swings in the upper airway increase or facilitate recovery when large negative pressure swings are produced by obstructed inspiratory efforts.

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].…”

“…Upper airway muscle EMG activity increases when negative pressure is applied to the isolated upper airway of tracheotomized rabbits [144,145,147], probably through reflexes involving mechanoreceptors located above the trachea, and via several afferent pathways. Small but consistent changes in respiratory frequency were also seen in many of the animals, suggesting some involvement of the respiratory centre in these changes [144].…”

Early Onset of Ventilatory and Airway Response to Hypercapnia is Mediated by Medullary 5-HT_1A Receptors in Infant Rats

“…Upper airway muscle activity is increased by increasing upper airway negative pressure 16 . Additionally, negative pressure of the upper airway decreases the RR depending on the magnitude of the pressure change 17 .…”