Sleep apnea: Clinical sciences

Sleep apnea is a condition characterized by episodes of either the reduction or cessation of inspiratory airflow during sleep, commonly resulting in recurrent nighttime hypoxemia. Untreated sleep apnea over time may lead to the development of complications, such as hypertension, heart disease, atrial fibrillation, stroke, diabetes, and sudden death.

Sleep apnea can be classified as obstructive sleep apnea or OSA, and central sleep apnea or CSA.

In OSA, respiratory effort is present but apnea occurs due to collapse of the patient’s upper airway, which is especially common in obesity, conditions associated with oropharyngeal crowding, and nasal allergies.

On the other hand, in CSA, apneic episodes occur due to a lack of spontaneous respiratory effort, associated with alterations in central respiratory drive. This is typically seen in patients with heart failure, neurologic diseases, and sedating medications.

Finally, if no underlying condition is associated with central sleep apnea, we are talking about primary, or idiopathic central sleep apnea.

If your patient presents with a chief concern suggesting sleep apnea, the first step is to obtain a focused history and physical exam. Your patient may report either excessive daytime sleepiness or fatigue.

They may also report loud snoring and morning headaches, as well as nighttime breathing disturbances, such as frequent awakenings, pauses in breathing, choking, or gasping. Also, history findings might include some underlying chronic conditions, like hypertension, or heart failure.

On the flip side, physical examination typically reveals a neck circumference of greater than 16 inches in biologically female individuals and 17 inches in biologically male individuals. Other important physical exam findings include central obesity and enlarged oropharyngeal structures, such as the tonsils, uvula, or tongue.

If your patient presents with these signs and symptoms, you should suspect sleep apnea, so your next step is to order polysomnography, or PSG for short. Polysomnography, also known as a sleep study, measures a patient’s stages of sleep; oxygen saturation; respiratory effort; and the apnea-hypopnea index, or AHI for short, which is the average number of apneas plus hypopneas per hour of sleep.