Causes / Risk Factors for Obstructive Sleep Apnea
Obesity, Obesity, Obesity
Increasing age
Male gender
Structural abnormalties
Tonsillar hypertrophy, nasal pathology
Alcohol, smoking and family history

Up to 90% of adult patients with OSA are obese

Obstructive Sleep Apnea is defined as a cessation of airflow for more than 10 seconds despite continuing ventilatory effort, 5 or more times per hour of sleep and a decrease of more than 4% in SaO2.

What Happens with Normal Sleep?
4 to 6 cycles of N-REM sleep followed by REM sleep
4 stages of N-REM with progressive slowing of EEG
Stage 3 and 4 N-REM and REM are very deep levels of sleep
Progressive generalized loss of muscle tone
Restorative periods of sleep
Progressive decrease in muscle activity and resultant increase in upper airway resistance.

Airway Collapse
Occurs with loss of muscle activity
Increased subatmospheric pharyngeal pressure
MRI reveal anterior and lateral wall collapse

Obesity Effects Airway Anatomy Adversely
Inverse relationship between obesity and pharyngeal area
Fat deposits in the uvula, tongue, tonsillor pillars, aryepiglottic folds and lateral pharyngeal walls.


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