CPAP Still Leaks After Replacing Everything?

Replacing the mask, hose and headgear rules out worn parts, which is only one of the reasons a mask leaks. ResMed's fitting guidance lists wrong adjustment, wrong assembly and wrong size alongside a worn-out mask. If the leak is still there with new parts, look next at the size and style for your face, how the seal changes once you lie down and fall asleep, air escaping through your mouth, straps pulled too tight, and the parts of the machine itself.

This guide is for the reader who has already done the basics. If you have not yet tried the usual fixes (strap tension, a clean cushion, a cushion that is due for replacement), start with why your CPAP mask leaks and how to fix it, then come back here if the leak survives them.

Why a new copy of the same mask can leak the same way

A replacement cushion in the same size, on the same frame, fitted the same way, rebuilds the same seal. If that seal was leaking because of the size, the style, the way it sits on your face when you sleep, or the way it was put together, the new one inherits the problem. That is why the order matters. Before another round of parts, find out what kind of leak you have.

ResMed's glossary describes leak as air escaping from the mask "due to issues such as you having the wrong mask size or type, the mask not being assembled or fitted correctly, or the mask is worn out and needs to be replaced." New parts answer the last of those. The others need a different kind of check.

Find the pattern in your own data first

An AirSense 10's leak number is worked out, not read off a sensor at your face. ResMed's AirSense 10 clinical guide places its flow sensor inside the machine at the device inlet and lists leak under "Flow derived values", so the figure comes from the airflow the machine measures. That has two consequences worth knowing before you read your data.

It does not tell you where the air got out. The same guide has a "High leak detected, check your water tub, tub seal or side cover" message, which points at the machine itself, and a "High leak detected, connect your tubing" message, whose listed causes are air tubing not firmly connected or a mask fitted incorrectly. A leak at the machine end and a leak at your cheek can both raise the number.

One night near a line is not a clear verdict. ResMed states the AirSense 10's leak reading is accurate to within 12 L/min or 20% of the reading, whichever is greater, from 0 to 60 L/min, says it verified that using its own masks' nominal vent flows, and notes that accuracy may be reduced by the presence of leaks. That is a statement about accuracy, not about how much the reading moves from night to night. So a night that reads a few L/min either side of a line is not a clear verdict on your seal; a pattern across many nights tells you more.

On CPAP Clarity, here is where to look after you import your SD card.

• The sentences under the night's count. The leak sentence gives the night's typical leak ("Mask leak was ... L/min"). On most machines that is the median. On a summary-only machine the sentence gives the 95th percentile instead ("Mask leak stayed at or under ... L/min for 95% of the time it ran"). On a machine that records only an average, the sentence says so and the night is not graded against any line.
• "Tonight against your usual." The Mask leak bar puts tonight beside your usual range from your own recent nights, and the line under the section says how many nights that usual is drawn from. A night whose leak ran high is not compared against the range.
• "Every chart and number." Open this drawer at the bottom of the night. Under "Detailed charts", the Leak Rate row sits on the same clock as your events and pressure, so you can see when the leak happened. Under "The night's numbers", the Leak Rate row lists Min, Median, P95, P99.5 and Max for the night.
• History. "Compare Periods" lets you mark the date you changed your mask and shows Before and After side by side. Its Leak figure is the average of each night's typical leak, using the closest nights to that date, the same number on each side, and it shows n/a when either side holds a machine's own average. On ResMed machines, "When in the night your leak is highest" says whether your highest-leak minutes keep landing in the same part of the night, and the leak pattern finder explains how that read works.

What the leak lines on this site mean

ResMed sets its 24 L/min mask-seal line for the level a night's leak stays under 70% of the time; its AirSense 10 clinical guide calls the seal "Good" when the 70th percentile leak is less than 24 L/min. Your night view reads your typical (median) leak against that 24, which is this site's use of ResMed's line, not a reading ResMed gives. The 15 L/min edge below it is this site's own. On a night whose typical leak is under 24, when the leakiest 5% of the night (the 95th percentile, P95 in the table) runs above 36 L/min, the night view says your leak ran high for part of the night, and that 36 is also this site's own. If your machine is not a ResMed, reading it against these lines is this site's comparison, not your maker's.

Where to look first, by shape

• High from the moment the mask goes on. Look at size, assembly and how the mask is put on. This is the shape a mask check before bed can catch.
• Low at first, then high stretches later in the night. Look at sleep position and your mouth. ResMed says short periods of high leak "can sometimes occur when you roll over in bed or if you're opening your mouth while using a nasal or pillows mask."
• A low typical leak but a high P95. The seal held for most of the night and broke for part of it. ResMed says myAir looks at how leak is spread across the whole night, and that your overall seal can be good even when there were short periods of high leak.
• High all night, every night, through several mask changes. Look at the style of mask and the machine end, below.

Causes a new mask does not fix

The size or style is wrong for your face

ResMed's sizing advice says many people fit more than one size, that your size depends on the key measurements of your face, and that leak around the bridge of the nose is a reason to try adjustments or a different size. Its leak advice for one full face mask ends with "If leak continues, you may need a different size mask." A reorder of the size you already have cannot test that.

Switching to a full face mask is not automatically the answer either. A 2017 systematic review in the journal Chest found that, surprisingly, oronasal masks (full face masks that cover the nose and mouth) were associated with higher unintentional leaks, and that nasal obstruction, older age, higher BMI, central fat distribution and male sex might be associated with more leak. A different size or style is a question to work through with your equipment supplier, who can fit you in person. Our mask types guide explains the main styles.

The seal you set awake is not the seal you sleep in

Fisher & Paykel says your breathing style, sleep position and facial features can change the fit and seal of your mask, and its fitting steps end with "Lie in your preferred sleeping position to make final adjustments" and then testing the mask with the machine's pressure on. Philips's fitting guide for its FitLife mask checks for leaks at the prescribed pressure, lying on the bed and turning the head from side to side. A mask adjusted while sitting up on the edge of the bed has not been tested the way you will wear it.

On an AirSense 10, the Mask Fit function blows air so you can adjust the mask, cushion and headgear until it reads Good, and ResMed's guide says to talk to your care provider if you cannot get a good seal. Run it lying down, on the side you sleep on. Mask Fit still only checks you while you are awake. If your data shows the leak arriving in the middle of the night, a pillow that leaves room for the mask may be part of the answer; our guide to whether you need a CPAP pillow shows how to check that in your own leak data first.

Air is leaving through your mouth

With a nasal or pillows mask, an open mouth is a leak path no new cushion can close. ResMed's myAir guidance says that if you use a nasal or nasal pillows mask, it's important to manage air that can leak through your mouth, and that mouth leak can give you a dry mouth. Waking with a dry mouth after a night of high leak stretches is a pattern worth noting.

A small 2004 study in Sleep Medicine found that a chin strap reduced mouth leak in 15 people with mouth leak, from 42.9% to 23.8% of total sleep time on average, and that their arousal index fell too, but the authors still called the remaining figures unacceptably high. They also found that snoring time went up with the strap, and they warn that in rare cases a chin strap can worsen the respiratory disturbance index, a count of breathing events. Talk to your provider before adding a chin strap or mouth tape. Our guide to masks for mouth breathers covers the mask side of the choice.

The straps are too tight

When a leak will not stop, pulling the straps harder is the natural move, and the mask makers warn it can make the leak worse. Fisher & Paykel says a too-tight mask can distort the shape of components and cause leaks, and that a mask should be worn as loose as possible without excessive leaking. Philips's fitting guide says excessive tightening of the headgear may cause unnecessary discomfort and actually cause leaks, and adds that not all leaks need to be corrected. ResMed says that needing to over-tighten may be a sign that you have the wrong cushion size or an incorrectly adjusted forehead support.

Before tightening, try resealing. ResMed's advice for one full face mask is to pull the mask briefly away from your face with the machine on, let the cushion reinflate, and settle it again. Philips describes the same move. Our guide to a CPAP mask that is too tight covers the marks, sores and fitting steps in detail.

The cushion is clean but the care is wrong

ResMed says your skin releases oils that can reduce the quality and performance of your seal, and recommends washing the cushion every morning by hand with warm water and mild soap, avoiding harsh cleaning products, and drying it away from direct sunlight. Care steps also differ between cushion materials; ResMed's care advice for one of its memory foam cushions says not to submerge it in liquids. A brand-new cushion cleaned the wrong way can lose its seal early, so follow the care section of your own mask's user guide.

A part does not match or is not seated

Incorrect assembly is on ResMed's own list. With mixed parts from several orders, check three things against your mask's user guide. The cushion is the one made for your exact mask and frame, the size marked on the cushion matches the size you were fitted for, and every part is fully attached the way the guide shows. ResMed's AirSense 10 user guide also cautions to use only ResMed parts and accessories with the device, because non-ResMed parts may reduce the effectiveness of the treatment.

The vent is not the leak

Some air is meant to leave. ResMed explains that your mask has a vent that releases the air you breathe out, which you might feel as a light flow of air, and that air coming from the top, bottom or sides of the mask is leak. Fisher & Paykel says a certain amount of air leakage is normal to flush out the air you breathe out. Do not cover the vent to stop that flow; ResMed's guide says the mask vent holes must be kept clear and unblocked. The mask leak guide explains how the vent is handled in what your machine reports.

If you changed mask style, ask your provider whether the machine's Mask setting was changed to match. ResMed's AirSense 10 clinical guide lists a Mask setting (Full Face, Nasal or Pillows) to select the type of mask used.

Pressure

Pressure is your provider's decision. Fisher & Paykel's leak advice includes making sure you are using the right pressure and consulting your healthcare provider if you are unsure what that is. ResMed's clinical guide notes that under conditions of high leak with EPR enabled, AHI detection may not be optimal, which is one more reason to raise a persistent leak with your provider rather than read your event count on its own. Please do not change your pressure yourself. Our guide to CPAP pressure settings explains what the settings mean and what to ask.

Could it be the machine?

Sometimes, and the machine's own messages point the way. On an AirSense 10, "High leak detected, check your water tub, tub seal or side cover" lists a water tub or tub seal that is not inserted properly, and "High leak detected, connect your tubing" lists tubing not firmly connected at both ends or a mask fitted incorrectly. ResMed's care guidance says to check the water tub for wear and replace one that has cracked or become cloudy or pitted, and to examine the air tubing for small holes or tears, especially around the cuff, that could cause air leaks.

If none of that explains it, the next step is your equipment supplier or the machine maker, not a screwdriver. ResMed's AirSense 10 user guide says that if you are not able to fix the problem, contact your care provider or ResMed, and do not try to open the device. ResMed's Asia-Pacific care guidance suggests having the machine pressure tested at an accredited outlet every two years; ask your supplier what applies where you live.

When to talk to your provider

Bring it to your sleep physician or equipment supplier if any of these fit.

• Your typical leak stays at or above 24 L/min on most nights after you have worked through the checks above.
• You can only stop the leak by tightening until it leaves marks or hurts.
• Your leak and your event count rise together on the same nights.
• You wake with a dry mouth, or your partner hears air escaping, and you are thinking about a chin strap or tape.
• The machine shows a high-leak message you cannot clear.

Bring something to look at. A Compare Periods view around the date you changed your mask, the Detailed charts for a typical bad night, and your therapy report give your provider the timing that a single number cannot.

Import your SD card and see when your leak happens →

Common Questions

Why does my new mask leak as much as my old one?

New parts only rule out wear. ResMed's fitting guidance lists incorrect adjustment, incorrect assembly and incorrect size as other reasons a mask leaks, and a same-size replacement fitted the same way keeps the same seal. Check the shape of the leak in your data, then the size, the fit lying down, your mouth and the machine end.

Why does my mask seal when I am awake but leak once I fall asleep?

Fisher & Paykel says sleep position can change the fit and seal of your mask, and ResMed says short periods of high leak can happen when you roll over or open your mouth with a nasal or pillows mask. Make your final adjustments lying in your sleeping position with the pressure on, and look at when the leak happens on your Leak Rate chart.

Should I tighten the straps more?

Not as a first step. Fisher & Paykel says a too-tight mask can distort the shape of components and cause leaks, and Philips says excessive tightening may actually cause leaks. Try resealing the mask with the machine running first, and if you can only stop the leak by tightening until it hurts, ask your supplier about a different size or style. Our guide to a CPAP mask that is too tight has the fitting steps.

What leak number is too high?

ResMed sets its 24 L/min mask-seal line for the level a night's leak stays under 70% of the time. CPAP Clarity reads your typical (median) leak against that line, which is this site's use of it, and treats under 15 L/min as low, a line of its own. Other makers measure leak their own way.

Is my CPAP machine faulty if the leak will not go away?

It can be part of it. ResMed's AirSense 10 user guide lists a water tub or tub seal that is not seated, and tubing not firmly connected, as causes of its high-leak messages, so check those first. ResMed states the AirSense 10's leak reading is accurate to within 12 L/min or 20%, whichever is greater. So a night that reads a few L/min either side of a line is not a clear verdict on your seal; a pattern across many nights tells you more. If nothing explains it, contact your supplier and do not open the device.

Primary Sources

• ResMed. AirSense 10 Clinical Guide. The Mask Seal line (Good if the 70th percentile leak is less than 24 L/min), the Mask setting ("Select the type of mask used by the patient", Full Face / Nasal / Pillows), the flow sensor "Internally located at device inlet" with leak among the flow-derived values, and the note that under conditions of high leak with EPR enabled, AHI detection may not be optimal. ResMed AirSense 10 Clinical Guide (PDF) (opens in new tab)
• ResMed. AirSense 10 user guide. Mask Fit, the "High leak detected" messages and their causes, a leak accuracy of ±12 L/min or 20% of reading, whichever is greater, verified using nominal ResMed mask vent flows and possibly reduced by the presence of leaks, the vent-hole caution, and the caution to use only ResMed parts. ResMed AirSense 10 user guide (PDF) (opens in new tab)
• ResMed. Mask fitting (patient FAQ). Leak may indicate incorrect adjustment, incorrect assembly, incorrect size, or a worn-out mask; over-tightening may be a sign of the wrong cushion size or an incorrectly adjusted forehead support. ResMed mask fitting FAQ (opens in new tab)
• ResMed. Leak; leaking; leaking air or bad leak (glossary). ResMed glossary entry (opens in new tab)
• ResMed. Do your masks have different sizes? Many people fit more than one size, and size depends on the key measurements of your face. ResMed sizing FAQ (opens in new tab)
• ResMed. Managing leak with your AirFit F20. Resealing by pulling the mask away and letting the cushion reinflate, and "If leak continues, you may need a different size mask." ResMed AirFit F20 leak advice (opens in new tab)
• ResMed. When do I experience short periods of high mask leak? ResMed short leak periods FAQ (opens in new tab)
• ResMed. Why did I receive an email saying my mask is leaking? myAir looks at how leak values are spread across the whole night. ResMed myAir leak email FAQ (opens in new tab)
• ResMed. How is mask seal calculated? Managing mouth leak with a nasal or nasal pillows mask. ResMed mask seal FAQ (opens in new tab)
• ResMed. Why does my mask leak in front? The vent and the light flow of exhaled air. ResMed vent FAQ (opens in new tab)
• ResMed. How often should I be cleaning my CPAP equipment? Skin oils and the seal, daily cushion washing, the water tub and tubing checks, headgear elasticity, and the two-year pressure test (Asia-Pacific guidance). ResMed cleaning guidance (opens in new tab)
• ResMed. Can cushions with very small tears still be used? Care steps for a memory foam cushion, including not submerging it in liquids. ResMed cushion care FAQ (opens in new tab)
• Fisher & Paykel Healthcare. How do I fit my CPAP mask correctly? Sleep position and the seal, final adjustments lying in your sleeping position, and a too-tight mask distorting components. F&P mask fitting guide (opens in new tab)
• Fisher & Paykel Healthcare. How to prevent your CPAP mask from leaking air. Normal vent leakage, wearing the mask as loose as possible without excessive leaking, and the right pressure. F&P leak guide (opens in new tab)
• Philips. FitLife patient and clinician fitting guide. Checking for leaks lying on the bed at prescribed pressure, resealing, and excessive headgear tightening causing leaks. Philips FitLife fitting guide (PDF) (opens in new tab)
• Lebret M, Martinot JB, Arnol N, et al. Factors Contributing to Unintentional Leak During CPAP Treatment: A Systematic Review. Chest. 2017 Mar;151(3):707-719. PubMed 27986462 (opens in new tab)
• Bachour A, Hurmerinta K, Maasilta P. Mouth closing device (chinstrap) reduces mouth leak during nasal CPAP. Sleep Med. 2004 May;5(3):261-7. PubMed 15165532 (opens in new tab)