As a recap, in my previous post, I talked about various sleep
disorders, including sleep apnea. There are two types: central and obstructive.
In this post, I will be talking about obstructive sleep apnea.
OSA is caused by the collapsing of the airway. When we inhale,
the diaphragm moves downwards. This creates more room in the chest cavity for
the lungs to expand. There are many things that can contribute to OSA. Some patients
have a small oropharyngeal airway. The oropharynx is the part of the throat
located at the back of the mouth. It includes the tonsils, the soft palate, and
the base of the tongue. It also appears that in many OSA patients, muscle
hypotonia, or a decreased muscle tone, combined with airway obstruction causes
apnea.
The consequences of sleep apnea can be divided into two
categories: medical effects and effects on sleep. This cessation of airflow
results in a decrease in oxygen saturation of the blood. Oxygen desaturation is
most severe when the apneic event is really long.
Additionally, during an apneic event, the pressure in the systemic
artery, arteries that carry oxygenated blood away from the heart, and pulmonary
artery, the artery that carries deoxygenated blood from the right ventricle of
the heart to the lungs, increases (systemic and pulmonary circuits are shown in
the picture below) Repetitive apneic events can cause a stepwise increase in
both pressures. This means that OSA may cause problems like chronic systemic
hypertension and cardiac dysrhythmias.
Sleep apnea also affects sleep itself. When an OSA patient
experiences an apneic episode, to terminate that event, he must be partially
aroused. Thus, the sleep is fragmented and consists of short periods of light
sleep and frequent arousals. Additionally, these arousals are accompanied by
increased sympathetic nervous system activity and skeletal muscle activity. This
causes more body movements, or “restless” sleep.
Together, sleep fragmentation and restless sleep most likely
contribute to excessive daytime sleepiness the patient experiences.
Source: Reite, Martin, Michael P. Weissberg, and John Ruddy. Clinical manual for the evaluation and treatment of sleep disorders. Washington, DC: American Psychiatric Pub., 2009. Print.
Source: Reite, Martin, Michael P. Weissberg, and John Ruddy. Clinical manual for the evaluation and treatment of sleep disorders. Washington, DC: American Psychiatric Pub., 2009. Print.
This is really fascinating because I never knew that the entire airway collapses. How do patients discover they have sleep apnea? Do they wake up when they realize they can't breathe, or is this something that parents notice early on in their children?
ReplyDeleteWhen the patient stops breathing, they wake up with a snort or gasp. This is when they enter a stage of light sleep. A common sign of sleep apnea is snoring. However, this is a very vague symptom. For this reason, not many people seek diagnosis and treatment for sleep apnea. This is why this disorder is often underdiagnosed. It is diagnosed using polysomnography, which I will discuss in upcoming posts.
ReplyDeleteDo you know if doctors typically look for sleep apnea when they have patients with chronic systemic hypertension and cardiac dysrhythmias or is it typically overlooked?
ReplyDeleteHello Ms. Q. That is a great question! Often when a patient comes in with a heart problem such as a stroke, the doctor will order a sleep study. This is so that they can potentially rule out sleep apnea being the cause of a cardiovascular problem.
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