Thoracic influence on upper airway patency

Abstract

Patency of the upper airway (UA) is usually considered to be maintained by the activity of muscles in the head and neck. These include cervical muscles that provide caudal traction on the UA. The thorax also applies caudal traction to the UA. To observe whether this thoracic traction can also improve UA patency, we measured resistance of the UA (RUA) during breathing in the presence and absence of UA muscle activity. Fifteen anesthetized dogs breathed through tracheostomy tubes. RUA was calculated from the pressure drop of a constant flow through the isolated UA. RUA decreased 31 +/- 5% (SEM) during inspiration. After hyperventilating seven of these dogs to apnea, we maximally stimulated the phrenic nerves to produce paced diaphragmatic breathing. Despite absence of UA muscle activity, RUA fell 51 +/- 11% during inspiration. Graded changes were produced by reduced stimulation. In six other dogs we denervated all UA muscles. RUA still fell 25 +/- 7% with inspiration in these spontaneously breathing animals. When all caudal ventrolateral cervical structures mechanically linking the thorax to the UA were severed, RUA increased and respiratory fluctuations ceased. These findings indicate that tonic and phasic forces generated by the thorax can improve UA patency. Inspiratory increases in UA patency cannot be attributed solely to activity of UA muscles.

Obesity and Obstructive Sleep Apnea: Pathogenic Mechanisms and Therapeutic Approaches

“…These findings suggest that structural alterations predispose to upper airway obstruction during sleep when neuromuscular activity wanes (71). In further studies, investigators have demonstrated that structural defects may arise from soft tissues that compress the pharynx (72-75) and/or a loss of caudal traction on the upper airway from mediastinal, ribcage, and muscle attachments (63,74,76,77).…”

Expiratory Time Constant and Sleep Apnea Severity in the Overlap Syndrome

“…For instance, increased compliance and hyperinflation from COPD may reduce the severity of OSAS by increasing the traction on the upper airway and reducing its collapsibility. 3,4 In contrast, an increase in lower airway resistance may increase the negative inspiratory pressure and promote obstructive sleep apnea. We therefore sought to study patients with the overlap of COPD and OSAS to assess primarily the potential association and directionality of the association between the expiratory time constant (as obtained from the nasal pressure signal during polysomnography) and the AHI, and secondarily whether the time constant differs across sleep stages from variations of lung volumes and airway resistance.…”

Factors Effecting the Compliance of Positive Airway Pressure Therapy in Patients with Sleep Related Breathing Disorders

“…1 PAP tedavisi üst hava yolunu açarak 1 akciğer volümle-rini (fonksiyonel rezidüel kapasiteyi) artırıp, üst hava yolları kaslarının refleks dilatasyonu ve trakeal gerilmeyi sağlar, böylece üst solunum yollarındaki ödemi gidererek etkili olur. 2, 3 OUAS, erişkin popülasyonun %2-4'ünü etkilemektedir. Uyku ile ilişkili solunum bozuklukları hava yolunun tam veya kısmi oklüzyonu ile karakterizedir.…”