How many types of sleep apnea are there?

Reading Time: 8 Minutes

What’s inside?:

• Obstructive Sleep Apnea (OSA)
• Central Sleep Apnea (CSA)
• Complex Sleep Apnea (CompSA)

 

So, you have sleep apnea.

Is that all you need to know?

Well, apparently not.

Firstly, there’s the question of which type of sleep apnea you have.

What?... there’s more than one??

Yep. So far we’ve uncovered 3. There’s every chance this isn’t the full-collection either. Science keeps sciencing and diggers keep digging, so who knows what’s next?

For now though, let’s take a look at the 3 we are aware of…

 

The Differences Between the Big Three

 

Obstructive Sleep Apnea (OSA)

Overview

Obstructive Sleep Apnea (OSA) is the most common type of sleep apnea, affecting millions of people worldwide. It occurs when the muscles in the throat relax excessively during sleep, leading to a partial or complete blockage of the airway. This blockage restricts airflow, causing breathing pauses that can last for several seconds.

 

Causes

The primary cause of OSA is the relaxation of the muscles in the throat, particularly the soft palate, uvula, and the tongue. When these muscles relax, the airway narrows or closes, making it difficult to breathe. Several factors can contribute to the likelihood of developing OSA:

• Obesity: Excess body weight, particularly around the neck, can increase the risk of airway obstruction during sleep. It is important to remember many people with sleep apnea are no where near obese, so while it is a major factor – it isn’t the only one.
• Anatomical Factors: Certain physical characteristics, such as a thick neck, narrow airway, large tonsils, or a receding chin, can raise the chances of developing OSA.
• Age: OSA is more common in older adults due to natural changes in muscle tone and tissue elasticity.
• Gender: Men are more likely to develop OSA than women, although the risk increases for women after menopause.
• Genetics: A family history of OSA can increase the risk of developing the condition.
• Lifestyle Factors: Smoking, alcohol consumption, and the use of sedatives can relax the muscles in the throat, increasing the likelihood of airway obstruction. Again, as with obesity, the potential reasons for anyone having sleep apnea are many. So, while adjusting your lifestyle COULD provide a major improvement in your sleep apnea, these are only a few tools in your toolbox.

 

Symptoms

The symptoms of OSA can vary in severity but typically include:

• Loud snoring
• Episodes of stopping breathing during sleep – most often observed by a bed partner
• Gasping or choking upon waking
• Excessive daytime sleepiness
• Morning headaches
• Difficulty concentrating
• Irritability or mood changes
• Dry mouth or sore throat upon waking

As with many things, such as the body language we pick-up from others every day, these symptoms cannot be taken in isolation. Just being a grumpy sod doesn’t necessarily mean you have sleep apnea!

 

Diagnosis

Diagnosing OSA usually involves a sleep study known as polysomnography, conducted in a sleep lab or at home using portable equipment. This study monitors various things, such as:

• Respiratory effort
• Airflow
• Blood oxygen levels
• Heart rate
• Brain activity (EEG)
• Eye movements (EOG)
• Muscle activity (EMG)

The data collected during the sleep study helps to determine the presence and severity of OSA, which is classified based on the number of apnea and hypopnea events per hour (the Apnea-Hypopnea Index or AHI):

• Mild OSA: AHI of 5-15 events per hour
• Moderate OSA: AHI of 15-30 events per hour
• Severe OSA: AHI of more than 30 events per hour

 

Treatment

The treatment of OSA focuses on keeping the airway open during sleep to prevent apneas. Treatment options include:

• Continuous Positive Airway Pressure (CPAP): The most common and effective treatment for OSA, CPAP involves wearing a mask over the nose and/or mouth connected to a machine that delivers a constant flow of air, keeping the airway open.

• Lifestyle Modifications:
• Weight Loss: Losing excess weight can reduce the severity of OSA or even eliminate it in some cases.
• Positional Therapy: Sleeping on the side instead of the back can reduce the likelihood of airway obstruction. Placing a pillow between your knees can also help you maintain that position comfortably.
• Avoiding Alcohol and Sedatives: These substances can relax throat muscles and should be avoided, especially before bedtime. Sleep doctor Matt Walker once made the true, but not advised, remark that the best time to drink alcohol and still get a good night’s sleep is around 10am. While his may be medically true, it doesn’t make it advisable.
• Oral Appliances: These are custom-fitted devices worn in the mouth that help to keep the airway open by repositioning the lower jaw and tongue.
• Surgery: In some cases, surgical interventions may be necessary to remove or reduce tissue in the throat or correct structural abnormalities contributing to airway obstruction. Common procedures include the extremely easy to say and understand…
• uvulopalatopharyngoplasty (UPPP)
• genioglossus advancement… and…
• maxillomandibular advancement.

Try getting them on a Scrabble board!

• Alternative Therapies: Newer treatments like hypoglossal nerve stimulation (HGNS) have shown promise for those who cannot tolerate CPAP or have not found relief through other methods.

 

Central Sleep Apnea (CSA)

Overview

Central Sleep Apnea (CSA) is less common than OSA and is caused by a failure of the brain to send the appropriate signals to the muscles that control breathing. Unlike OSA, where the problem lies in airway obstruction, CSA involves a neurological issue, where the brain's respiratory centres do not initiate breathing.

 

Causes

The underlying causes of CSA are typically related to neurological or cardiovascular conditions. Common causes include:

1. Heart Failure: CSA is often associated with heart failure, particularly in a condition known as Cheyne-Stokes respiration, where there are cyclic patterns of breathing with alternating periods of apnea and hyperpnea.
2. Stroke: Damage to the brainstem, which controls breathing, can lead to CSA.
3. High Altitude: Rapid ascent to high altitudes can cause a temporary form of CSA due to lower oxygen levels.
4. Opioid Use: Chronic use of opioid medications can depress the central respiratory drive, leading to CSA.
5. Brain-wiring Conditions: Disorders such as Parkinson's disease and multiple system atrophy can disrupt the brain's ability to regulate breathing.
6. Idiopathic CSA: In some cases, the cause of CSA is unknown, and it is referred to as idiopathic CSA… which simply means the doctors don’t know what is causing it. I guess if you give it a fancy name it must be something only doctors understand?!?!?

 

Symptoms

The symptoms of CSA are similar to those of OSA but may include additional signs related to the underlying brain or heart conditions:

• Disrupted sleep with frequent awakenings
• Shortness of breath upon waking
• Noisy or laboured breathing during sleep
• Fatigue and daytime sleepiness
• Difficulty concentrating
• Mood changes or depression

 

Diagnosis

Diagnosing CSA also involves a sleep study (polysomnography) that monitors the same physiological parameters as for OSA. However, the data will show a lack of respiratory effort during apneas, distinguishing CSA from OSA, where respiratory effort continues despite airway obstruction.

In addition to polysomnography, additional tests may be required to identify the underlying cause of CSA, such as echocardiograms or neurological evaluations.

 

Treatment

Treatment of CSA is more complex than OSA, as it often involves addressing the underlying condition contributing to the central apneas. Common treatment approaches include:

• Adaptive Servo-Ventilation (ASV): This is a type of positive airway pressure therapy that adjusts the amount of pressure based on the patient's needs, helping to stabilise breathing patterns.
• Bilevel Positive Airway Pressure (BiPAP): Where CPAP supplies a constant air pressure, a BiPAP machine delivers two levels of pressure – higher during inhalation and lower during exhalation – to support breathing efforts.
• Supplemental Oxygen: For patients with CSA related to heart failure or other conditions, supplemental oxygen during sleep can help reduce apneas.
• Medication: There are also a few medications occasionally used as part of CSA management too…
• Acetazolamide: A medication that helps to increase breathing drive and is sometimes used for CSA, particularly at high altitudes.
• Theophylline: Another medication that can stimulate breathing, though its use is less common due to potential side effects – such as messing with heartbeat rhythm, chest pain, increased peeing… just to mention a few.
• Treating Underlying Conditions: Managing the underlying cause, such as optimising heart failure treatment, can help reduce the severity of CSA.
• Lifestyle Modifications: Similar to OSA, avoiding alcohol and sedatives can help reduce CSA severity. However, as with OSA, there’s more to controlling CSA than just a few lifestyle changes. They can help though, so certainly worth discussing with your sleep specialist or doctor.

 

Complex Sleep Apnea (CompSA)

Complex Sleep Apnea (CompSA) is, as the name says, a bit more complex than the other two.

For that reason, and given I’ve gone on for too long already today, I’m going to take a deeper dive into CompSA next week.

For now though, and so you don’t feel completely in the dark, here’s a quick overview…

Also known as treatment-emergent central sleep apnea, complex sleep apnea is a condition where a patient diagnosed with OSA develops central apneas AFTER initiating therapy, particularly with CPAP. This condition is less understood and can be challenging to treat, as it involves elements of both obstructive and central sleep apnea.

 More on this next week.

 

For now though, I hope this dig into the Big 3 helps explain why having sleep apnea isn’t just having sleep apnea.

 

 

Cheers,
Alan

 

P.S. I have taken to creating various bits on sleep and sleep apnea. If you would enjoy hearing more and find out where else you can find stuff like this, you can get my weekly Triple Whammy email, which has 3 short topics each week. Some written or recorded by me and others I’ve found out there in the strange world we live in.

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