Causes Of Obstructive Sleep Apnea (OSA)

As air flow stops during a sleep apnea episode, the oxygen level in your blood drops. Your brain responds by briefly disturbing your sleep enough to kick start breathing, which often resumes with a gasp or a choking sound. If you have obstructive sleep apnea, you probably won’t remember these awakenings. Most of the time, you’ll stir just enough to tighten your throat muscles and open your windpipe. In central sleep apnea, you may be conscious of your awakenings.

Obstructive sleep apnea is caused by repetitive upper airway obstruction during sleep as a result of narrowing of the respiratory passages. Patients with the disorder are most often overweight, with associated peri-pharyngeal infiltration of fat and/or increased size of the soft palate and tongue. Some patients have airway obstruction because of a diminutive or receding jaw that results in insufficient room for the tongue. These anatomic abnormalities decrease the cross-sectional area of the upper airway. Decreased airway muscle tone during sleep and the pull of gravity in the supine position further decrease airway size, thereby impeding air-flow during respiration.

With a narrowed airway, the person continues his or her efforts to breathe, but air cannot easily flow into or out of the nose or mouth. Unknown to the person, this results in heavy snoring, periods of no breathing, and frequent arousals (causing abrupt changes from deep sleep to light sleep).

Airway obstruction can occur in many areas of the nasopharynx, oropharynx and hypopharynx. Although the contribution of nasal polyps and septal deviation to obstructive sleep apnea remains controversial, some investigators believe that partial or total nasal obstruction can lead to hypopnea and apnea.

Risk factors for obstructive sleep apnea include certain physical attributes, such as having a thick neck, deviated septum, receding chin, or enlarged tonsils or adenoids (the most common cause of sleep apnea in children). Your airway may be blocked or narrowed during sleep simply because your throat muscles tend to relax more than normal. Allergies or other medical conditions that cause nasal congestion and blockage can also contribute to sleep apnea.

Risk factors and contributing factors associated with obstructive sleep apnea:

  • Obesity
  • Over the age of 65
  • Black, Hispanic, or a Pacific Islander
  • Snoring (snoring can cause the soft palate to lengthen, which in turn can obstruct the airway)
  • Family history of OSA or snoring
  • Family history of sleep apnea – No specific genetic marker for sleep apnea has been discovered, but obstructive sleep apnea seems to run in families. This may be a result of anatomic abnormalities that run in the family
  • Small upper airway (large tongue, large uvula, recessed chin, excess tissue in the throat and/or soft palate)
  • Shape of head and neck may create a smaller than normal airway
  • Large tonsils or adenoids or other anatomical differences (A deviated septum, enlarged tongue or receding chin can also create difficulties breathing during sleep)
  • Throat muscles and tongue relax more than normal during sleep (This can be due to alcohol or sedative use before bedtime, but not necessarily)
  • Smoking or exposure to secondhand smoke
  • Nasal congestion, nasal blockages and nasal irritants
  • Other disorders and syndromes, such as Hypothyroidism, acromegaly, amyloidosis, vocal cord paralysis, post-polio syndrome, neuromuscular disorders, Marfan’s syndrome and Down Syndrome

Other physical conditions, such as immune system abnormalities, severe heartburn or acid reflux and high blood pressure. It isn’t clear whether the conditions are the cause or the result of sleep apnea

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