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Non-invasive ventilation (NIV) supports your breathing through a mask over the nose, or nose and mouth, rather than a tube — so it is "non-invasive". CPAP delivers one steady pressure that holds the airway open; BiPAP delivers two pressures — a higher one as you breathe in and a lower one as you breathe out — to help move air in and out. They treat different problems, and your specialist decides which (if any) is right for you.
How CPAP and BiPAP are prescribed
CPAP
CPAP is normally prescribed after a sleep study (home-based or in hospital) has confirmed obstructive sleep apnoea.1 By holding the upper airway open with one steady pressure, CPAP stops the repeated airway collapses and drops in oxygen that fragment sleep — which typically improves daytime sleepiness, concentration, blood pressure and quality of life. If you think you may have sleep apnoea, start with our Sleep Apnoea Check. A referral for a home sleep study is arranged through your GP; locally these are typically undertaken at CQ Respiratory and Sleep Clinic under the care of Dr Sudhakar Koduri.
BiPAP (bilevel)
BiPAP is prescribed by a sleep or thoracic (respiratory) medicine department — for example the Royal Brisbane and Women's Hospital — usually for conditions where the breathing muscles need support or carbon dioxide builds up (some COPD, neuromuscular and chest-wall conditions)2,3, rather than for straightforward sleep apnoea.
CPAP and BiPAP — what is the difference
| CPAP | BiPAP (bilevel) | |
|---|---|---|
| Pressure | One constant pressure | Higher pressure breathing in, lower breathing out |
| Main job | Splints (holds) the upper airway open | Also assists the work of breathing and clears carbon dioxide |
| Commonly used for | Obstructive sleep apnoea | Conditions where breathing muscles need support, or carbon dioxide builds up (e.g. some COPD, neuromuscular and chest-wall conditions) |
What to expect
You wear a soft mask connected by tubing to a quiet bedside machine, usually overnight. It can feel strange at first — most people adjust within a week or two. Modern machines ramp the pressure up gently, warm and humidify the air, and record how well the therapy is working so your team can fine-tune it.
Getting comfortable
- Persist through the early adjustment — most discomfort settles with small changes to mask or pressure.
- Tell your team about a dry nose, sore bridge of the nose, or a leaky mask — all are usually fixable.
- Keep using your other treatments; NIV supports them, it does not replace them.
Breathing support can stop working as well as it should — because of mask leak, a change in your condition, or pressures that no longer suit you. The signs come on gradually:
- Waking with a headache, or headaches that are worse first thing in the morning
- Still unusually sleepy during the day despite using the machine every night
- Confusion or muddled thinking, or more breathlessness than usual
- Using the machine less than you should, or taking the mask off in the night without meaning to
Do not change your own pressure settings, and if BiPAP was prescribed because carbon dioxide builds up, do not stop using it without advice — contact your sleep or thoracic service, who can review the data and adjust it. If you or someone with you becomes very drowsy or hard to rouse, call 000.
Driving and sleepiness
Untreated sleep apnoea makes falling asleep at the wheel more likely, so this matters legally as well as medically. In Australia fitness to drive is assessed against the national Assessing Fitness to Drive standards (Austroads).
- Never drive when you feel sleepy, whether or not you have a diagnosis. Pull over somewhere safe.
- Tell your doctor if you have been falling asleep during the day, or have had a near miss caused by sleepiness. They will advise whether you should stop driving while you are assessed and treated.
- Treated apnoea is usually compatible with driving. Once CPAP is used regularly and the sleepiness has settled, eligibility is normally restored — your doctor confirms this.
- If you hold a commercial licence the standards are stricter, so raise it with your doctor early.
Our Obstructive Sleep Apnoea guide sets out the driving and occupational detail in full.
How Inspire Clinic can help
Once therapy has been prescribed, the Inspire Clinic team supports the practical side of CPAP and BiPAP:
- Installation and set-up of both CPAP and BiPAP devices.
- Ongoing monitoring of how well your therapy is working, using the machine's data.
- Mask checks and fittings for a comfortable, well-sealed fit.
- Quotes on new devices and help choosing equipment.
References & evidence base
- Australasian Sleep Association. Positive airway pressure therapy: consumer information. Sydney: ASA, 2023.
- McDonald CF, Whyte K, Jenkins S, et al. Clinical practice guideline on adult domiciliary non-invasive ventilation. Respirology 2020;25(11):1206–1213.
- Murphy PB, Hart N. Home non-invasive ventilation for COPD. Thorax 2016;71(6):495–496.
References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.
More than one of our services applies here, and which combination suits you depends on what your assessment shows.
Corrections: If something on this page is wrong, out of date or unclear, we want to know. Email reception@inspireclinic.au with the page name and what you believe is incorrect. Substantive corrections are made promptly, and the guide’s version and last-updated date are changed to reflect it.