Mechanism of Obstructive Sleep Apnea (OSA)
With each arousal event, the muscle tone of the tongue, and the airway tissues, increases. Each time this happens, the obstruction is relieved putting an end to the apneic event. As soon as the patient drifts to sleep, the tongue and soft tissues assumes a relaxed position. This could yet again trigger a partial or complete obstruction in the airway accompanied by snoring.
More commonly, airway obstruction occurs in the common space where the food pipe and air pipe intermix at the back of throat called the oropharynx. Oropharynx includes the soft palate, the base of the tongue, and the tonsils. The factors causing the obstruction are usually multiple, depending on the severity of the condition; they include-
- The increased deposit of fat around the airway
- An elongated soft palate
- An enlarged uvula
- Decreased muscle tone during sleep
- The effect of gravity in supine position
- Some patients have airway obstruction because of a diminutive or receding jaw that results in insufficient space for the tongue.