Sleep Apnea: Is it A risk Factor for COVID Morbity and Mortality?

By sleep apnea, I mean untreated sleep apnea. Which, in the United States, means 80% of sleep apnea, since at any one time 80% of people affected by the disorder do not know that they have it. Obstructive sleep apnea (OSA) is the most commonly undiagnosed common medical condition in this country, affecting up to 10% of the general adult population. Why is it so hard to diagnose? One, people cannot possibly see themselves sleep so they do not know if they snore or stop breathing unless someone else recognizes these are signs of sleep apnea and tells them. Two, doctors are trained to screen the morbidly obese for sleep apnea and ignore it in anyone else. Three, the testing is complicated--an overnight stay in a sleep lab is the gold standard. Imagine if the test for diabetes involved an overnight stay in a lab? How many people would know that they have diabetes?

Why sleep apnea? Look at the known demographic factors that are associated with increased morbidity and mortality. Male gender--men are affected by sleep apnea twice as often as women. African-American race--Blacks have twice the risk. Advancing age is associated with greater risk. Hypertension is also a risk factor since untreated sleep apnea is associated with difficult to control hypertension---3 or 4 medications and the blood pressure still is not controlled, but since it easy to check a blood pressure and difficult to get a sleep study, the secondary hypertension is diagnosed and the underlying sleep disorder i missed. Diabetes---OSA is associated with metabolic syndrome or insulin resistance. And finally, obesity, which is a risk factor but not the only risk factor.

Why might untreated sleep apnea increase the risk of complications from COVID?

1. Low oxygen spells at night might exacerbate the hypoxic effects of the virus on the lungs. Low oxygen can damage the lungs.

2. Sleep apnea is associated with relatively more sympathetic autonomic activity and decreased parasympathetic activity. Some doctors (like me) suspect that the virus may attack the vagus nerve. The vagus nerve plays an important role in limiting inflammation and the cytokine storm that seems to be killing some people. Severing the vagus nerve in lab animals causes the lungs to quickly fill up with fluid leading to a rapid death. Now, obviously the vagus nerve is not severed in COVID--if it was it would affect the ability to speak. However, degrees of injury might be important in determining how severe a bout of COVID will be. And if you start off with a relatively suppressed parasympathetic nervous system because you have untreated OSA, this might make a significant difference in how sick you get.

3. Another risk factor for sleep apnea is reflux disease. The body stops breathing in order to protect the airway. Those who have reflux are at increased risk of aspiration pneumonia which can worsen their pulmonary disease. They are also at increased risk for sleep apnea.

This hypothesis should be easy to test. When people are diagnosed with COVID ask their family members "Does he/she snore or stop breathing at night?" Ask the patient if he has ever been diagnosed with sleep apnea and is he compliant
with treatment (a great many people cannot tolerate CPAP currently the gold standard treatment for OSA).

https://www.ncbi.nlm.nih.gov/pubmed/23729937 Link about increased sympathetic and decreased parasympathetic tone in sleep apnea.