Central vs Obstructive Sleep Apnea

 Under the umbrella of sleep apnea conditions, there are two main disorders - central sleep apnea (CSA) and obstructive sleep apnea (OSA). While both of these conditions have similar symptoms and treatment processes, they are actually caused by two different bodily functions or dysfunctions.

Sleep apnea is a disorder in which breathing patterns are not regular and your breathing repeatedly stops and starts while sleeping. Episodes of not breathing have to be ten seconds or longer for it to be considered a sleep apnea event.

This guide will take you through the main similarities and differences between central vs obstructive sleep apnea and give you better insight into how your CPAP treatment can be altered to fit your individual symptoms.

What is central sleep apnea?

Central sleep apnea occurs because your brain's ability to send signals to the muscles that control breathing patterns does not function properly. While central sleep apnea is a less common sleep disorder than obstructive sleep apnea, it is still easily treatable through several different sleep apnea therapies.

Individuals that have central sleep apnea can wake up many times throughout the night with no memory as to why. Because the brain fails to send the signal for your body to keep breathing, someone with central sleep apnea will be woken up often gasping for air.

What is obstructive sleep apnea? 

Obstructive sleep apnea is more common than central sleep apnea and occurs from a physical dysfunction rather than a lack of brain signal. OSA occurs when the tissue in your throat blocks your airway when you begin to relax while sleeping. This creates an obstruction and there is not enough air to travel to your lungs.

Obstructive sleep apnea can often be recognised when an individual frequently snores and is woken up throughout the night gasping or choking for air. However, not every OSA sufferer does snore, so other indicators such as morning fatigue or headaches should also be monitored.

Symptoms of sleep apnea disorder

The general symptoms of sleep apnea disorders are as follows:

• Having abnormal breathing patterns and episodes of not breathing during sleep that are monitored by a sleep specialist
• Abrupt awakenings accompanied by shortness of breath
• Difficulty staying asleep (insomnia)
• Excessive daytime sleepiness (hypersomnia)
• Difficulty concentrating
• Mood changes
• Morning headaches
• Snoring

Central vs obstructive sleep apnea: what's the difference?

Overall, the difference between central vs obstructive sleep apnea is mainly how and why it occurs. While symptoms, risk factors and treatments are quite similar, the difference in the causes remains the largest disparity between the two medical conditions. 

The table below outlines the similarities and differences between central sleep apnea and obstructive sleep apnea:

Similarities and differences 

Causes of central sleep apnea

While obstructive sleep apnea is caused by a physical dysfunction in the throat when the body relaxes to sleep, central sleep apnea can be the outcome of many different causes, that are actually categorised as different types of sleep apnea:

• Drug-induced apnea: this can be caused by taking certain medications, especially within the opioid category- morphine, oxycodone or codeine. These medications can cause your normal breathing patterns to become irregular or temporarily stop completely.
• Cheyne-stokes breathing: this type of sleep apnea is commonly associated with congestive heart failure or a stroke. Cheyne-stokes is characterised by a gradual increase and decrease in your ability to produce normal flow in breathing. During your weakest breathing effort, central sleep apnea can occur.
• High altitude periodic breathing: central sleep apnea can occur if you are at a very high altitude, which can cause alternation of rapid breathing (hyperventilation) and under-breathing while sleeping.
• Medically induced central sleep apnea: this can occur from several different medical conditions, including a stroke and end-stage kidney failure.
• Idiopathic central sleep apnea: the occurrence or cause of this type of sleep apnea is still unknown.
• Treatment-emergent central sleep apnea: for those that have been diagnosed with OSA or obstructive sleep apnea, they may be treated with continuous positive airway pressure therapy. From this, they may develop central sleep apnea along with OSA, and treatment-emergent central sleep apnea is a complex sleep apnea syndrome that is a combination of OSA and CSA. This is sometimes referred to as mixed sleep apnea.

Risk Factors  

Certain risk factors can put you at a higher risk of developing any kind of sleep apnea disorder, including OSA and CSA. These risk factors are as follows:

• Sex: the development of sleep apnea is significantly more common in males than females.
• Age: sleep apnea is more typically diagnosed among older adults, specifically those older than the age of 65. This increased risk can be put down to both the ageing process, as well as the common development of other medical conditions that occur in older individuals.
• Heart disorders and medical conditions: individuals with irregular heartbeats or abnormal blood pressure are at much greater risk of developing sleep apnea. Other conditions such as kidney failure, atrial fibrillation (AF), excessive growth hormone production, spinal cord injuries and certain metabolic disorders can increase your risk as well.
• High altitude: this can lead to a type of central sleep apnea called high-altitude periodic breathing which is caused when the body is hyperventilating or under-breathing while sleeping due to lack of oxygen in the air.
• Opioids and other medications such as antidepressants and muscle relaxants.
• CPAP use for obstructive sleep apnea treatment

Diagnosis for sleep apnea 

Diagnosing sleep apnea is done primarily through undertaking a sleep study by a sleep specialist or doctor. A sleep study determines the type of sleep apnea, whether you have mild, moderate or severe sleep apnea and the best possible treatment.

Sleep studies or polysomnography usually take place at a sleep laboratory within a hospital or research centre. There are some instances where a simplified version may be participated in at home. This study will monitor your sleep habits, including any apneas or non-breathing episodes you have, how many and the duration of time these episodes occur.

A sleep specialist will then calculate your AHI or Apnea-Hypopnea Index level and determine the severity of your sleep apnea, and follow up with deciding the best course of action.

Treatment for sleep apnea 

The different treatments available for both central sleep apnea and obstructive sleep apnea are mostly the same and usually involve a device or apparatus that provides air flow or air pressure to regulate breathing effort and patterns.

For both central and obstructive sleep apnea treatment, the most common therapy is positive airway pressure treatment or PAP therapy. This involves a few different types of devices that aid in regulating breathing patterns, including continuous positive airway pressure (CPAP), bilateral positive airway pressure (BiPAP or BPAP) and auto-titrating positive airway pressure (APAP).

Other forms of treatment can include medication to simulate breathing, supplemental oxygen (primarily for CSA patients) and even just simple lifestyle changes such as losing weight, quitting smoking or altering your sleeping position.