Complex Sleep Apnea (CompSA), also known as Treatment-Emergent Central Sleep Apnea (TECSA), is a hybrid disorder that develops when central sleep apnea emerges during treatment of obstructive sleep apnoea (OSA) with Continuous Positive Airway Pressure (CPAP) therapy.
Central sleep apnea is characterised by a lack of respiratory effort due to disturbed ventilatory control, which comes from CPAP therapy. In contrast, obstructive sleep apnoea involves repeated episodes of upper airway collapse leading to airflow obstruction, oxygen desaturation, and sleep fragmentation.
While CPAP successfully resolves the physical problems of obstructive sleep apnea, sometimes the resulting changes in carbon dioxide levels destabilise the brain’s breathing control system, leading to complex sleep apnea. Repeated central apneas are a hallmark of complex sleep apnea, often persisting or emerging even after obstructive events are eliminated. CompSA is therefore a dynamic diagnosis that requires ongoing monitoring and treatment adjustment.
Complex Sleep Apnea develops when the removal of airway obstruction by CPAP causes an instability in the brain’s breathing control system, leading to the emergence of central breathing pauses.
Specific interventions, such as surgery, oral appliances, or inappropriate PAP therapy pressures, can trigger central sleep apnea in susceptible individuals. This underlying tendency toward ventilatory instability, sometimes called ‘high loop gain’, is revealed when the obstruction is removed, which is why it is termed ‘treatment-emergent’.
Barrie Tan ENT Head & Neck Surgery provides comprehensive care for snoring and all types of sleep apnea.
If you believe you or a loved one has sleep apnea, contact us today so that we can start working on a plan towards better sleep.
Common symptoms of complex sleep apnea include:
Persistent Sleep Disruption
Waking up all the time, even though you’re using your CPAP, not getting a good night’s sleep.
Daytime Sleepiness
Feeling fatigued and drowsy all day long, not getting the rest needed, despite CPAP treatment
Breathing Pauses while on CPAP
Stop breathing for a bit while you’re on the CPAP machine
Morning Headaches
Pounding headache every morning due to fluctuating oxygen levels and sleep that just doesn’t feel right
Ongoing Brain Fog
Trouble focusing, remembering things, and just generally feeling clear-headed
Mood Swings
Irritable, anxious, or even feeling down despite getting the right amount of sleep
Restless Sleep
Tossing and turning all night and not feeling rested in the morning
Dry Mouth or Sore Throat
Breathing is inconsistent, and breathing through your mouth all night results in a sore throat and a dry mouth
Nocturia
Getting up all night to urinate, even when using your CPAP machine
Complex sleep apnea arises when CPAP therapy for obstructive sleep apnea unmasks or triggers central breathing instability. The precise mechanisms are not fully understood, but several factors contribute to its development:
CPAP-Induced Ventilatory Instability
The application of positive pressure can temporarily destabilise the respiratory control system, leading to central apneas that were not present before treatment.
Underlying Respiratory Control Sensitivity
Some individuals have heightened sensitivity in their brainstem respiratory centres, making them more prone to developing central events once obstruction is relieved.
Carbon Dioxide Fluctuations
Rapid correction of obstructive events can cause shifts in carbon dioxide levels, which may confuse the brain’s breathing regulation and trigger central pauses.
Pre-Existing Cardiovascular Conditions
Heart failure, arrhythmias or other cardiac issues can predispose patients to breathing instability, and the introduction of CPAP may reveal previously hidden central tendencies.
Opioid or Sedative Use
Medications that depress the central nervous system can contribute to central apneas, and their effects may become more apparent once CPAP eliminates obstructive events.
Mixed Sleep Apnea Pattern
Some patients have both obstructive and central components from the outset, but the central events become prominent only after CPAP addresses the obstructive component.
Recognising the risk factors for developing complex sleep apnea is essential for both patients and healthcare providers, especially when starting or adjusting CPAP therapy for obstructive sleep apnea. Here are the key risk factors to be aware of:
Severe Obstructive Sleep Apnea
Individuals with a high apnea-hypopnea index (AHI), or more severe obstructive sleep apnea, are at greater risk of developing complex sleep apnea during CPAP therapy. The more severe the baseline sleep-disordered breathing, the higher the likelihood that central apnea events will emerge as the airway obstruction is relieved.
Pre-existing Central Apnea Events
If a diagnostic sleep study reveals central apnea events before starting CPAP, this suggests an underlying instability in ventilatory control.
Male Gender
Men are more likely than women to experience complex sleep apnea, possibly due to differences in ventilatory response and upper airway anatomy that influence how the brain and breathing muscles respond to CPAP therapy.
Low Carbon Dioxide Levels (Hypocapnia)
Overventilation from CPAP or bilevel positive airway pressure (BiPAP) can sometimes lower blood carbon dioxide below the brain’s apneic threshold, causing the brain to temporarily stop sending signals to breathe – resulting in central sleep apnea.
High CPAP Pressures
Using higher levels of positive airway pressure can, in some cases, provoke central apneas by activating lung stretch receptors and inhibiting the normal drive to breathe, a phenomenon known as the Hering-Breuer reflex.
Bilevel Positive Airway Pressure (BiPAP) Therapy
While BiPAP is often used to treat more severe sleep apnea or complex sleep disordered breathing, excessively high inspiratory pressures or improper settings can sometimes trigger central apnea events, especially in patients with fragmented sleep.
Heart Failure and Other Medical Conditions
Patients with congestive heart failure, atrial fibrillation, or other cardiac and neurological conditions that affect ventilatory control are at increased risk for developing central sleep apnea during CPAP therapy.
Weight and Obesity Hypoventilation Syndrome
Obesity not only increases the risk of obstructive sleep apnea but can also complicate the response to positive airway pressure therapy.
Excessive Daytime Sleepiness
Persistent excessive daytime sleepiness, even after starting CPAP, may signal complex sleep apnea, as untreated central events continue to fragment sleep and reduce restorative sleep.
Upper Airway Anatomy and Function
Variations in the structure or function of the upper airway and throat muscles can influence how well CPAP therapy works and may contribute to the emergence of central apneas if the airway is not fully stabilised.
Diagnosis of Complex Sleep Apnea is confirmed via a formal in-lab polysomnogram (sleep study) that captures the patient’s breathing pattern while they are using their Positive Airway Pressure (PAP) device. Split-night sleep studies are often utilised to efficiently diagnose both obstructive and central sleep-related breathing disorders within a single night.
Establishing a primary diagnosis is crucial for guiding appropriate treatment decisions and ensuring insurance coverage for therapy. This differs from an initial OSA diagnosis because the central events must be documented under pressure therapy.
Our ENT specialists in Singapore will review the sleep study report for a high Central Apnea Index relative to the Obstructive Apnea Index. The diagnosis is confirmed when the Central Apnea Index exceeds 5 events per hour and accounts for more than 50 percent of the total Apnea-Hypopnea Index recorded during PAP use. The respiratory arousal index is also considered a key parameter for assessing therapy effectiveness and monitoring sleep-related respiratory disturbances.
Furthermore, a complete physical examination of the nose and throat is essential to rule out any residual structural obstructions that could complicate mask tolerance and successful breathing stabilisation.
When to See an ENT Specialist
Seek a consultation if you have persistent sleepiness, witnessed pauses in breathing, or co-existing heart or neurological conditions with declining sleep quality. An ENT will determine if obstruction contributes to your symptoms and ensure your positive airway pressure therapy is practical, comfortable and effective
Treatment for Complex Sleep Apnea primarily involves switching the patient’s breathing apparatus from standard CPAP or BiPAP to an Adaptive Servo-Ventilation (ASV) device, which is specifically designed to stabilise the brain’s respiratory control loop.
In many cases, central events that emerge during the first weeks of CPAP therapy resolve spontaneously as the body adapts. Your specialist may recommend continuing CPAP at optimised settings while closely monitoring symptoms and device data over several weeks.
Bilevel Positive Airway Pressure (BiPAP) with Backup Rate is often used as a practical intermediate step. BiPAP addresses central pauses by guaranteeing a minimum breath rate while maintaining upper airway patency through adjustable expiratory pressure (EPAP).
Adaptive Servo-Ventilation (ASV) is a top-of-the-line therapy that recognises breathing patterns and adjusts pressure to maintain stable ventilation. It’s very effective for the most severe cases of sleep apnea. Something to keep in mind, though, is that ASV is usually not a good idea for people with severe CHF who have a heart that’s just not pumping that well ( left ventricular ejection fraction of 45% or below ).
Low-Flow Supplemental Oxygen
Adding a bit of oxygen to the mix helps keep breathing stable and reduce central apneas, especially in people with heart disease.
Sorting Out Your Medications
If you’re taking opioids or sedatives that can affect your breathing, adjusting the dose with your doctor might make a big difference in how stable your breathing is.
Tackling the Root Cause
Getting your underlying conditions under control makes it a whole lot easier to manage the sleep apnea. That means treating heart failure, monitoring your fluid levels, and addressing kidney or nervous system issues.
Surgery is not a cure-all for complex sleep apnea, as it can’t fix the brain part that’s not correctly transmitting the breathing signals. Surgery can help with physical obstructions that get in the way.
Surgery is like a supporting actor in the complicated play of sleep apnea. It helps with the physical parts that are getting in the way, making it easier to breathe, but it can’t fix the part of the brain that’s causing the problem.
Septoplasty and Turbinoplasty
If your nasal passages are completely blocked, surgery can clear them. That makes it much easier to use a breathing machine, because there’s less resistance to overcome.
Palate and Pharyngeal Surgery
If your airways are collapsing during sleep, surgery can help fix that, too. It’s all about finding ways to keep the air flowing and make the breathing machine more effective.
Maxillomandibular Advancement (MMA)
For some people, the problem is that their jaws are too small and they’re not getting enough air. Surgery can help fix that, but it’s a big operation and not for everyone.
At Barrie Tan ENT Head & Neck Surgery in Gleneagles Hospital, we take a very personalised approach to treating complex sleep apnea. We treat a wide range of sleep disorders, including conditions affecting breathing during sleep.
We’ll work with you to get a diagnosis, then tailor a treatment plan for you featuring options such as:
Managing complex sleep apnea is all about working together, adapting to new information, and being patient. Our goal is to help you get stable, restful sleep that protects your heart and your quality of life.
If you’ve been dealing with obstructive sleep apnea and are having trouble with your breathing machine, or if new breathing problems have popped up since you started treatment, we’ll work with you to find a solution that works best for you.
Complex sleep apnea can sneak up on you, but there are some lifestyle changes and proactive monitoring that can help you stay on top of things:
Be open and honest with your sleep team about any symptoms you’re experiencing, whether they’re comfort issues or medication changes. By staying on top of your care and living a generally healthy lifestyle, you can improve your chances of managing this long term and keeping your overall health in good shape.
MBBS, MRCS (Edinburgh), MMed (Otorhinolaryngology), FAMS
Dr Barrie Tan is an ENT specialist at Gleneagles Hospital, Singapore, with more than 20 years of clinical and surgical experience. He previously served as Head of ENT and Director of the Centre for Hearing and Ear Implants at Singapore General Hospital. The information provided is not intended as medical advice. More about our medical experts.
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