CPAP Therapy for OSA: Treatment, Use and Options

CPAP therapy for OSA is the leading treatment for obstructive sleep apnoea, recommended by NHS sleep services and supported by NICE guidance (NG202) as the first-line option for moderate to severe disease. By delivering a continuous stream of pressurised air through a mask, CPAP keeps the upper airway open during sleep, preventing the repeated breathing interruptions that fragment rest and strain the cardiovascular system. This article explains how CPAP works, who qualifies for it on the NHS, how to adapt to using it, what side effects to expect, and how it compares to other available treatments for OSA.

What is CPAP therapy and how does it treat sleep apnoea?

CPAP delivers a steady stream of pressurised air through a mask to act as a pneumatic splint, keeping the upper airway open and preventing the repeated collapses that cause obstructive sleep apnoea. It is a purely mechanical, medication-free treatment recommended as first-line therapy by NHS sleep services.

CPAP (continuous positive airway pressure) therapy treats obstructive sleep apnoea (OSA) by delivering a steady stream of pressurised air through a mask, keeping the upper airway open during sleep and preventing the repeated collapses that cause apnoeas. OSA occurs when the muscles of the throat relax during sleep, causing the airway to narrow or close entirely, leading to brief but repeated interruptions in breathing. These episodes reduce blood oxygen levels, fragment sleep and place strain on the cardiovascular system.

Sleep services in the UK classify OSA severity using the apnoea-hypopnoea index (AHI) or the oxygen desaturation index (ODI), which is commonly used in home sleep studies. Broadly, an AHI or ODI of 5 to 14 events per hour is considered mild, 15 to 30 moderate, and above 30 severe. These bands inform treatment decisions.

A CPAP machine consists of a small bedside unit, a length of flexible tubing and a mask that fits over the nose, the mouth, or both. The device is set to a prescribed pressure, determined either by a sleep study or by an auto-adjusting (APAP) machine that varies pressure in response to breathing patterns. By acting as a pneumatic splint, the airflow holds the soft tissues of the throat apart throughout the night.

The mechanism is purely mechanical: CPAP does not involve any medication and carries no pharmacological interactions. It is considered the first-line treatment for moderate to severe OSA by NHS sleep services and is supported by NICE guidance (NG202).^[2][3] When used consistently, it markedly reduces apnoeas, improves sleep quality and relieves the daytime sleepiness, poor concentration and morning headaches that characterise untreated OSA. The degree of benefit depends on correct mask fit, adherence and disease severity.

It is worth noting that CPAP manages OSA rather than curing it. Stopping therapy typically causes symptoms to return, so most people with moderate to severe OSA use their machine every night on a long-term basis.

Who is offered CPAP on the NHS for OSA?

NHS sleep services offer CPAP to adults with moderate to severe OSA (AHI or ODI of 15 or more events per hour) and to those with milder OSA who have significant daytime symptoms or cardiovascular comorbidities. Referral is made by a GP to a local sleep clinic or respiratory service.

NHS sleep services offer CPAP to adults with moderate to severe OSA, generally defined as an AHI or ODI of 15 or more events per hour, and to those with milder OSA who have significant daytime symptoms or cardiovascular comorbidities. NICE guidance (NG202) supports CPAP as the primary treatment for symptomatic OSA across these groups, and referral is typically made by a GP to a local sleep clinic or respiratory service.

Diagnosis is usually confirmed by a home sleep study (limited channel polygraphy), which measures ODI alongside other parameters, or, where more complex sleep disorders are suspected, by an in-laboratory polysomnography. The sleep service interprets the results alongside the clinical history before recommending treatment.

Commissioning of sleep services differs across the UK. In England, Integrated Care Boards (ICBs) commission local sleep services. In Scotland and Wales, Health Boards hold this responsibility, and in Northern Ireland it falls to Health and Social Care (HSC) Trusts. There can be variation in waiting times and service models across all four nations.

Once CPAP is recommended, the NHS sleep service typically provides the machine, mask and consumables, along with initial education and follow-up support. Patients are usually reviewed after a few weeks of use to check adherence data downloaded from the device and to address any difficulties with comfort or pressure.

People with mild OSA who do not have significant symptoms or comorbidities may be offered lifestyle advice, positional therapy or a mandibular advancement device instead of CPAP. Weight loss, where relevant, is encouraged alongside any treatment, as excess weight around the neck is a significant risk factor for OSA.

An important safety point concerns driving. Excessive daytime sleepiness is a recognised risk for road traffic collisions. Anyone with symptomatic OSA who feels excessively sleepy should stop driving until their symptoms are adequately controlled. Some people are required to notify the DVLA (or DVA in Northern Ireland); the relevant guidance is available on GOV.UK under "Assessing fitness to drive." A GP is the appropriate first point of contact for anyone who suspects they have OSA.

How do you get used to sleeping with a CPAP machine?

Adapting to CPAP typically takes several weeks; wearing the mask while awake, using the ramp feature and adding a heated humidifier are among the most effective strategies. Contact your sleep service rather than abandoning therapy if difficulties persist, as most problems have practical solutions.

Most people find that adapting to CPAP takes several weeks of consistent use, and the first few nights are often the most challenging. The sensation of pressurised air and the physical presence of a mask can feel unfamiliar, but tolerance generally improves steadily with practice and the right equipment choices.

Several strategies help with the adjustment period:

• Start gradually: Wear the mask while awake during the day, for example while reading or watching television, to become comfortable with the fit before trying to sleep in it.

• Choose the right mask: Nasal masks, nasal pillow masks and full-face masks each suit different breathing patterns and facial structures. The sleep service can help with fitting, and trying more than one style is reasonable if the first is uncomfortable.

• Use the ramp feature: Most machines allow the pressure to start low and rise slowly over a set period (the duration varies by device and setting), making it easier to fall asleep before full pressure is reached. Your sleep service can advise on the appropriate ramp duration for your machine.

• Address mouth breathing: If air escapes through the mouth, a chin strap or a switch to a full-face mask can help. Mouth taping is not a recommended approach; the alternatives listed here are safer and more effective.

• Humidification: A heated humidifier attached to the machine reduces nasal dryness and congestion, which are among the most common reasons people stop using CPAP.

Hygiene and maintenance are important for both safety and adherence. Follow the manufacturer's Instructions for Use and your sleep service's guidance on how often to clean the mask cushion, tubing and humidifier chamber. Filters and mask cushions need replacing at intervals specified by the manufacturer. Use distilled or cooled boiled water in the humidifier unless your device's instructions state otherwise.

Do not adjust therapeutic pressure settings yourself; any changes should be guided by your sleep service. Consistency matters more than perfection in the early weeks. Sleep services can download adherence data from the machine and use it to identify patterns, such as mask leaks or pressure intolerance, that can be corrected. If difficulties persist, contacting the sleep service rather than abandoning therapy is strongly advised, as most problems have practical solutions.

What side effects can CPAP cause and when should you seek help?

Common CPAP side effects include nasal congestion, dry mouth, mask leak and mild aerophagia, most of which resolve with equipment adjustments or humidification. Contact your GP for chest pain, new breathlessness or skin infection, and call NHS 111 if you are unsure whether a symptom needs prompt attention.

CPAP is generally well tolerated, but side effects are common in the early weeks and most are manageable with simple adjustments. Nasal congestion, a dry mouth or throat, skin marks from the mask, and mild bloating from swallowed air (aerophagia) are among the most frequently reported issues. These rarely require stopping therapy and usually resolve with equipment changes or the addition of a humidifier.

More specific issues to be aware of include:

• Mask leak: Air escaping around the seal can cause eye irritation and reduce therapy effectiveness. Adjusting the headgear or trying a different mask size usually resolves this. Persistent eye irritation warrants a mask refit with your sleep service.

• Ear or sinus pressure: Some people notice discomfort in the ears or sinuses, particularly if they have nasal congestion. Treating the underlying congestion and ensuring the mask fits correctly can help; if it persists, ask your sleep service to review your settings.

• Pressure discomfort: A feeling of difficulty breathing out against the airflow can be addressed by enabling the expiratory pressure relief setting on the machine (labelled EPR, C-Flex or similar depending on the manufacturer), or by switching to a bilevel PAP (BPAP) device if recommended by the sleep service.

• Skin irritation or pressure sores: Rotating mask positions slightly and using mask liners can help. Persistent skin breakdown should be reviewed by the sleep service.

• Claustrophobia: A nasal pillow mask, which has minimal facial contact, is often better tolerated by those who feel confined.

If you continue to feel excessively sleepy despite using CPAP, do not drive and contact your sleep service, as pressure settings or mask fit may need review. Follow DVLA (or DVA in Northern Ireland) guidance on driving and OSA, available on GOV.UK.

Contact your GP if you develop chest pain, new or worsening breathlessness, or signs of a skin infection around the mask contact points. Call NHS 111 for urgent advice if you are unsure whether a symptom needs prompt attention. Any suspected adverse effects from CPAP equipment or accessories can be reported to the MHRA via the Yellow Card scheme at yellowcard.^[10]mhra.gov.uk.

How effective is CPAP compared to other OSA treatments?

CPAP is the most effective treatment for moderate to severe OSA, reducing apnoea frequency and relieving daytime sleepiness more reliably than alternatives such as mandibular advancement devices or positional therapy. Mandibular advancement devices are recommended by NICE for mild to moderate OSA or for those who cannot tolerate CPAP.

CPAP is the most effective treatment available for moderate to severe OSA, consistently reducing apnoea frequency, improving oxygen saturation during sleep and relieving daytime sleepiness more reliably than alternative approaches. Evidence reviewed by NICE (NG202) supports its use as first-line therapy for this group. Greater hours of use each night are associated with greater benefit; NICE advises using the device whenever asleep rather than aiming for a fixed minimum. Blood pressure reductions have been observed in some studies, though the effect is generally modest and varies between individuals.^[12][13]

Other treatments for OSA include:

• Mandibular advancement devices (MADs): Custom-fitted, clinician-titrated oral appliances that hold the lower jaw forward, keeping the airway open. NICE recommends MADs as an alternative for people with mild to moderate OSA or for those who cannot tolerate CPAP.^[2][4] Over-the-counter devices are not equivalent to custom-made, titratable appliances. MADs are less effective than CPAP in severe disease but may achieve better real-world adherence in some individuals.^[4][14]

• Positional therapy: For people whose OSA occurs predominantly when sleeping on their back (supine-dependent OSA), devices or techniques that encourage side sleeping can reduce apnoea frequency meaningfully.

• Weight management: Significant weight loss can reduce OSA severity substantially and, in some cases, resolve it. It is recommended alongside CPAP rather than as a replacement in most clinical settings.

• Surgery: Procedures such as uvulopalatopharyngoplasty (UPPP) are considered in selected patients, typically after CPAP has been tried. Surgical outcomes vary and are assessed on an individual basis by specialist teams.

• Upper airway stimulation (hypoglossal nerve stimulation): This is available in the UK but access is limited to selected specialist centres. NICE has published interventional procedures guidance on this technique; eligibility and availability should be discussed with a specialist team.

• Lifestyle measures: Reducing alcohol intake, avoiding sedatives and treating nasal congestion can complement any primary therapy.

Effective treatment of OSA, particularly relief of excessive daytime sleepiness, is also associated with a reduced risk of road traffic collisions, which is one reason DVLA guidance places importance on symptom control before returning to driving.^[8][9]

The choice between treatments depends on OSA severity, individual anatomy, comorbidities and patient preference, and is best made in discussion with a sleep specialist or GP.

Scientific References

1. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202) – Terms used in this guideline.
2. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202) – Chapter 1: Obstructive sleep apnoea/hypopnoea syndrome.
3. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202).
4. NG202 Rationale and impact – mandibular advancement splints.
5. Automated home testing devices for diagnosing obstructive sleep apnoea – topic description (HTG735).
6. Sleep apnoea.
7. Find your local integrated care board (ICB).
8. Excessive sleepiness and driving.
9. Miscellaneous conditions: assessing fitness to drive.
10. Every report to MHRA's Yellow Card scheme helps improve the safety of medicines and medical devices for all.
11. Hypoglossal nerve stimulation for moderate to severe obstructive sleep apnoea (IPG598).
12. Effect of CPAP therapy on blood pressure in patients with OSA: IPD meta-analysis. Pengo MF et al..
13. Effect of CPAP on Blood Pressure in Patients With OSA. Martínez-García MA et al..
14. Comparative Efficacy of Continuous Positive Airway Pressure vs Mandibular Advancement Devices. Dipalma G et al..
15. Effect of an Interdisciplinary Weight Loss and Lifestyle Intervention on Obstructive Sleep Apnea. Carneiro-Barrera A et al..

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