Obstructive Sleep Apnea

David L. Steward

History

A 57-year-old man is complaining of snoring and daytime sleepiness. His wife reports witnessed apnea. His symptoms have worsened over the past few years, and he has gained weight during this period. His father snored. He denies nasal obstruction. He falls asleep immediately on lying down and sleeps 8 hours nightly but awakes feeling unrefreshed, sometimes with headache or muscle aches. He has nodded off while driving but has never had a motor vehicle accident as a result. He has systemic hypertension requiring antihypertensive therapy. He denies coronary artery disease but is on statin therapy for hyperlipidemia.

Physical examination reveals an obese man (body mass index [BMI] 35 kg/m²) with a short, thick neck (18 inches in circumference). Oropharyngeal examination reveals a large tongue obscuring the pharynx and soft palate (modified Mallampati class or Friedman tongue position III) with dental indentations laterally. Use of a tongue depressor reveals a thickened uvula with small 1+ tonsil. Nasal examination and the remainder of his examination are unremarkable.

Differential Diagnosis—Key Points

The patient complains of snoring but has signs and symptoms of obstructive sleep apnea syndrome (OSAS). Obstructive sleep apnea (OSA) results from pharyngeal airway collapse during sleep. Confirmatory sleep testing (polysomnography) is needed to establish the presence of obstructive sleep apnea, but the diagnosis of OSAS includes the presence of symptoms of daytime sleepiness.

Symptoms of OSAS are related to sleep fragmentation from the repeated arousals necessary to reestablish airway patency. Many patients with severe OSAS never achieve the restorative deeper stages of sleep associated with REM sleep and dreaming. His greatest risk from untreated OSAS may be from motor vehicle accidents, which are increased sevenfold in these patients, and his history of falling asleep while driving is of concern.

Test Interpretation

Flexible fiberoptic nasopharyngoscopy in the supine position may identify areas of potential pharyngeal collapse during sleep, predominantly both retropalatal and retroglossal in most (80%) adult OSA patients. The Mueller maneuver, having the patient suck in against a closed nose and mouth, may further reveal lateral pharyngeal wall collapse. Sleep nasendoscopy has been reported to be more specific than awake fiberoptic examination, but it generally requires sedation in an endoscopy suite or operating room and is not routinely performed. The Epworth Sleepiness Questionnaire can determine the degree of daytime sleepiness present, with a score above 10 considered excessive.

Polysomnography is the gold standard for diagnosis of OSA (see snoring case). The frequency of obstructive events is related to the severity of the syndrome, reported as an apnea–hypopnea index (AHI), with 5 to 15 considered mild, 16 to 30 moderate, and greater than 30 to 40 severe. Oxyhemoglobin desaturation is reported as the proportion of time below 90% and lowest saturation recorded and is another measure of OSA. Polysomnography may identify other co-existent sleep disorders such as periodic limb movement.