What is Complex Sleep Apnea?

Reading Time: 14 Minutes

What’s inside?

• A high-level snippet…
• What is complex sleep apnea?
• Causes and how the bits fit together… or don’t…
• How common is it?
• What’s the risk?
• How different is managing CompSA versus OSA or CSA?
• How long have I got, Doctor?
• What’s on the horizon?

 

A high-level snippit…

Complex sleep apnea (CompSA), also known as treatment-emergent central sleep apnea, is a strange beast that falls under the same sleep-disordered breathing remit as obstructive sleep apnea (OSA) and central sleep apnea (CSA). While OSA and CSA –  which covers most of us sleep apnea peeps – are relatively well-understood, complex sleep apnea presents a unique challenge due to its dual nature and the difficulties it poses in both diagnosis and treatment.

 

What is complex sleep apnoea?

Complex sleep apnea is essentially when central sleep apnea starts developing during the treatment of obstructive sleep apnea with positive airway pressure (PAP) therapy.

So, I start off with obstructive sleep apnea (like most of us), get a CPAP machine to force air down my pipes while sleeping and – for strange and obscure reasons – the brain signals telling me when to breath during sleep start getting messed about with. These are the same brain signals that worked perfectly fine before I started on CPAP therapy.

Where obstructive sleep apnea causes me to stop breathing due to a blockage in the airway, such as airway muscles relaxing… with central sleep apnea my brain has stopped sending some of the ‘You need to breath now!’ signals.

The result?...

I now have my original obstructive sleep apnea AND a brand-new friend in central sleep apnea. I’m not sure how often either of them will come out to play or even if they’ll both turn-up at the same time.

Now… that’s complex.

And because they are a bit sporadic in their approach, getting a CompSA diagnosis isn’t easy. If I DO get the diagnosis… I still have to jump through even more hoops as my sleep doctors and I try to agree a workable treatment.

 

Causes and how the bits fit together… or don’t…

The exact cause of complex sleep apnea is not entirely understood, but it is believed to be associated with an interplay of various things including the underlying physical setup causing the original OSA, the body and brain’s response to PAP therapy, and random individual patient characteristics.

• An Unfair Start: Many patients with OSA have an underlying tendency toward unstable breathing control, which may not manifest as central apneas until PAP therapy is initiated. PAP therapy, particularly continuous positive airway pressure (CPAP), stabilises the upper airway but can alter the body’s normal regulation of breathing. In some patients, this can lead to faster breathing followed by periods of central apnea as the body tries to correct carbon dioxide levels.

Some research in BiPAP machine with users who develop complex sleep apnea has pointed towards the brain signals perhaps getting used to the machine taking over the decision-making process of when to breath and how much pressure to send. So much so they question whether the brain has simply allowed the machine to run the show during sleep.

• Chemoreceptor Sensitivity: Okay, we were never going to get through this without some sciency words creeping in. I apologise.

Chemoreceptors are the bits in my brain that work-out how much carbon dioxide I have in my blood. If they think I have too much they’ll send a signal telling me to breath more so I can up my oxygen levels and lower those pesky carbon dioxide ones.

If the sensitivity of my chemoreceptors starts messing-up I could experience exaggerated responses to small changes in carbon dioxide levels, leading to screwy breathing patterns and central apneas. This is especially true during sleep when breathing regulation is naturally more vulnerable.

• Heart Issues: Complex sleep apnea is also often seen in patients with heart failure or other forms of cardiac dysfunction. I could have an underlying form of central sleep apnea known as Cheyne-Stokes respiration, which is characterised by regular fluctuations in breathing patterns. The introduction of PAP therapy can make these fluctuations worse, leading to complex sleep apnea.
• Build Quality: I could simply just be built in a way that means I am more likely to develop complex sleep apnea than others. This could be caused by underlying neurological conditions or changes in how my central nervous system controls my breathing. This could includes issues with my brainstem, where the primary hub for breathing control is located.

 

How common is it?

When compared to obstructive and straight-forward central sleep apnea flavours, complex sleep apnea is relatively less common but is a significant condition due to its complex management. The spread of complex sleep apnea among patients treated with CPAP for OSA varies widely, with some studies estimating that 5% to 15% of patients may experience treatment-emergent central sleep apnea – aka complex. In reality, there doesn’t appear to be enough research to give a definitive number though.

 

What’s the risk?

Many of the risk factors for complex sleep apnea appear to be similar to those for obstructive and central. It isn’t clear though if this is simply a case of ‘You need to have OSA before you can have CompSA’ or whether these are genuine factors relating to complex sleep apnea in it’s own right. That said, here’s what would make me more a risk:

• Male Gender: Men are more commonly affected by complex sleep apnea, which is consistent with more men in general having OSA and CSA.
• Advanced Age: Older adults are more likely to develop complex sleep apnea. Again, age is understood to be a factor for sleep apnea in general, but that isn’t to say I couldn’t be diagnosed with OSA while in my 20s and develop CompSA by the time I hit 50.
• Cardiac Conditions: Patients with heart failure or other cardiovascular conditions are at higher risk. This does appear to be a separate factor from OSA, however heart conditions have been considered a higher risk for me developing central sleep apnea without any history of obstructive.
• Higher Wake-up Threshold: If I were to have a higher tendency of waking from sleep due to breathing disturbances then I may also be more prone to developing central apneas during PAP therapy.
• High Loop Gain: Linked to our earlier point on how the brain recognises how much carbon dioxide is in our blood, loop gain refers to the sensitivity of the feedback control of breathing. A high loop gain means that the breathing control system is highly sensitive to disturbances. If I have a high loop gain then my brain is more likely to react poorly to the disruption and potentially react by allowing the situation to get worse instead of better. In other words; a vicious circle.

 

What makes me ask for help?

Often, it appears patients turn-up at their doctors or sleep clinic having never heard of complex sleep apnea. Even if I have obstructive sleep apnea and am on PAP therapy, I may still have no idea CompSA is even a thing.

The symptoms I have, such as daytime sleepiness, poor sleep, frequent awakenings and morning headaches may seem identical to OSA symptoms. So, it is understandable if a doctor can’t see anything else to base a diagnosis on or reason to refer me back to a sleep specialist.

There is one other symptom that may be enough to sway things enough to get another sleep test ordered though… poor ability to keep up with PAP therapy - regardless of CPAP or BiPAP. The discomfort caused by central apneas can be enough to tip the balance… so long as the medical bod I am speaking with is open to investigation.

The good news for those already on PAP therapy is we can often (but not always) bypass the general practitioner doctor as we already have a relationship with a sleep clinic. So long as their local processes allow it, I may be able to convince them to put me in line for another sleep test.

Diagnosis

Just because I’m already on CPAP or BiPAP doesn’t mean I can’t have another sleep test done.

If my original test showed I stopped breathing and there was evidence of obstruction then an OSA diagnosis would seem fair.

If that has changed and my next sleep test shows I stop breathing with no evidence of obstruction then the peeps in white coats have more information to work with.

Depending on where you live, you may not even need to ask. Some sleep clinics, especially in areas where health insurance pays the bills, actively pull PAP patients in for follow-up sleep tests. If this is the case, I could find out I have CompSA without ever thinking anything had changed.

How different is managing CompSA versus OSA or CSA?

While some of the suggestions are similar to those for obstructive or complex sleep apnea, such as maintaining a healthy weight and being careful how much alcohol I drink (and when I drink it) some of the other options are quite different…

• Adaptive Servo-Ventilation (ASV): Where my troubles using a Continuous PAP machine may see the sleep clinic move me to a Bi-level or AutoPAP one, ASV is reserved for times when those are still failing me and I need something a bit more bespoke.

It works by adjusting the pressure levels in response to my breathing pattern. In practice, this should result in me getting more pressure when experiencing central apneas and less when I’m breathing normally.

The intended goal is for the machine to learn when I will need that extra boost and deliver it exactly when I need it. A clever piece of kit, if it works.

• Optimising Current PAP Therapy: If the docs don’t think I’m ready for ASV yet, they may try tweaking my current treatment, such as reducing the pressure settings on my CPAP/BiPAP machine – to reduce the risk of central apneas – or, if I’m on CPAP, they may think BiPAP is worth a try as a middle-ground.
• Addressing Underlying Conditions: Where standard obstructive sleep apnea gets the ‘look at your lifestyle’ advice, central & complex assessments tend to take a closer look at heart conditions or neurological disorders. This makes sense when you consider it’s the brain’s signalling system that controls how we are supposed to breath naturally.
• Oxygen Therapy: Remember the chemoreceptors that assess my blood’s carbon dioxide levels? Well, sometimes adding supplemental oxygen can help stabilise oxygen levels and reduce the number of central apneas. This could particularly help if I don’t respond well to PAP therapy alone.
• Medications: In some cases, medications could be used to manage some of the things that could cause central sleep apnea. For example, acetazolamide (normally used to help reduce water retention) can reduce the sensitivity of chemoreceptors to carbon dioxide, thereby helping to stabilise breathing patterns.

 

How long have I got, Doctor?

Doctors will always give you a caveat of… ‘Well, that depends on how well you react to the treatment and blah blah’, but research has shown many patients who stick with the programme experience significant improvements in their symptoms and quality of life.

However, in some cases, the condition can be more challenging to control, requiring ongoing adjustments to therapy.

• Heart Risks: Like other forms of sleep apnea, complex sleep apnea is associated with an increased risk of heart complications, including hypertension, heart failure, and arrhythmias. Effective treatment can help mitigate these risks.
• Quality of Life: Untreated or poorly managed complex sleep apnea can lead to significant impairments in quality of life due to persistent sleep disturbances, daytime sleepiness, and the psychological burden of living with a chronic condition.

On the other hand, successful management, can result in marked improvements in sleep quality and daytime functioning.

• Sticking with the Programme: Adherence to therapy, particularly PAP therapy, is crucial. However, we’ve already seen how it can often be pretty difficult to do just that.

The more unusual the diagnosis and treatment, the more important to keep the relationship with the sleep clinic – and any other professionals – on good terms.

 

What’s on the horizon?

Research into complex sleep apnea is ongoing, with efforts focused on better understanding its physical and neuro make-up. Improving ways of getting to an accurate diagnostic and developing more effective treatments are all high on the agenda. Some key areas of research include:

• Mechanisms of Central Apneas: Getting a strong understanding how central apneas are triggered and sustained, particularly in the context of PAP therapy, is a key area of research. All going well, this could lead to the development of targeted therapies to address the root causes of central sleep apnea. And getting to the cause before the effect can only be a good thing.
• Advanced Diagnostic Tools: There is ongoing research into developing more sophisticated diagnostic tools that can better differentiate between different types of sleep breathing disorders. Modern machines and assessment tools are pretty good at capturing real-time data. Using that data to improve treatment for the current patient and preventing the issue for future patients is a huge, but realistic, goal.
• Personalised Medicine: As with many other areas of medicine, there is a growing interest in personalised approaches to treating complex sleep apnea. This could involve tailoring therapies based on an individual’s specific physiological and genetic profile, as well as their response to treatment.
• New Treatment Modalities: Researchers are consistently exploring new treatment methods, including novel PAP devices, pharmacological treatments, and even neurostimulation techniques that could offer alternatives to current therapies.
• Long-Term Outcomes: Complex sleep apnea is still relatively poorly understood. Studies following patients with complex sleep apnea over the long term are needed to better understand the natural development of the condition and the long-term effects of different treatment strategies.

 

So, there you have it.

A bit longer than my normal articles, but I did say it was complex.

Ways to diagnose and manage complex sleep apnea will continue to improve but can only do so if our researchers and sleep apnea communities continue to share knowledge & experiences and keep an eye on what is currently unknown.

 

More than ever… Keep Breathing.

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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