Sleep Apnea Timeline: CPAP

CPAP (continuous positive airway pressure) is the most widely used treatment for obstructive sleep apnea. A mask connected to a quiet air pump holds the throat open with gentle air pressure, and it works on the nights and hours it is worn.

This page is one of seven treatment-track timelines for adult obstructive sleep apnea. The sleep study, how a track is chosen and how to read the outcomes row are covered on the sleep apnea treatment timelines page. How CPAP works, the types of machines and masks, and cleaning are described on the CPAP page.

Who follows this track

CPAP or a related positive airway pressure machine is the usual first treatment for moderate or severe sleep apnea, and for sleep apnea of any severity that causes symptoms such as daytime sleepiness. Machines that adjust the pressure automatically (auto-CPAP) and machines set to one pressure work equally well for most people. Bilevel machines, with a higher pressure breathing in than out, are used for special situations.

Getting started (weeks 1 to 3)

• Prescription and delivery: after the results visit, an equipment supplier delivers the machine, usually within 1 to 3 weeks. Some people start with an auto-adjusting machine at home; others spend a night in the sleep lab to set the pressure (sometimes during the second half of the diagnostic night, called a split-night study). Both approaches work.

• Setup visit: the mask is fitted (nasal pillows, a nasal mask or a full-face mask), the heated humidifier is set, and the person is shown how to use and clean the equipment. Full-face masks tend to leak more and dry the mouth more than nasal masks, so a nasal mask is often tried first when breathing through the nose is easy.

The first 90 days

• Week 1: many machines send usage, mask leak and the remaining breathing events (the "residual AHI") to the care team by cellular connection, so problems can be spotted early.

• Weeks 2 to 6: the most common adjustments are a different mask or size, pressure changes, more humidity, help with a stuffy nose, and gradual practice for people who feel closed in by the mask. A check-in about 4 to 6 weeks after starting is common.

• The insurance usage check: Medicare and most private plans continue paying for the machine only if it is used at least 4 hours a night on at least 70 percent of nights during any 30 days in a row within the first 90 days.

• Between day 31 and day 91: an in-person or video visit reviews the downloaded data and how symptoms have changed. If the usage rule has not been met, Medicare requires a new evaluation and an in-lab sleep study before another trial.

The 4-hour rule is a coverage rule, not a measure of benefit, and more hours of use generally bring more benefit. Remote monitoring with automated feedback, and coaching programs, help people keep using CPAP: in one trial, 73 percent met the usage rule with telemonitoring and education, compared with 54 percent with usual care.

Side effects and common problems

• Mask leak is the most common complaint (reported by about 3 in 4 users in one survey), and is usually fixed by refitting or changing the mask.

• Dry nose, up to about 2 in 3 people, and stuffy nose, about 1 in 4 to 2 in 3, usually respond to heated humidification and, when needed, treatment of nasal airflow problems or saline rinses.

• Swallowed air with bloating affects about 1 in 10.

• Feeling closed in, eye or skin irritation from leaks, and pressure marks on the nose are less common and often improve with a different mask.

Nasal surgery can make CPAP easier: after septum or turbinate surgery, the pressure needed was lower and most people who previously could not use CPAP were able to start.

Outcomes on this track

• Breathing (AHI): while CPAP is worn, the AHI returns to normal (under 5) in more than 9 in 10 people. In a study of people with moderate or severe sleep apnea (average AHI 26), the AHI on CPAP after a month was 4.5.

• Sleepiness: across 47 trials, the Epworth Sleepiness Scale averaged about 2.3 points lower with CPAP than without it. People who were sleepier to start with tend to improve more.

• Daily life: sleep-related functioning (FOSQ and similar questionnaires) improved modestly. In a trial of people with mild sleep apnea, energy and vitality scores were about 10 points higher after 3 months of CPAP than with usual care.

• Use over time: about 3 in 4 people who start CPAP meet the insurance usage rule at 90 days, averaging about 6 hours on most nights. Use is lower in younger adults and higher in older adults. At 1 year, about 45 percent use it well, 16 percent use it a little and 39 percent have stopped. People who use it well in the first month are much more likely to still use it 2 years later.

• Heart and blood vessels: in a large trial of people with heart or blood vessel disease, where average use was only about 3 hours a night, CPAP did not lower the number of heart attacks or strokes. CPAP clearly improves snoring, sleepiness, mood and quality of life; a heart benefit has not been proven in randomized trials.

These are averages from groups of people, not a prediction for any one person.

Check-ups and long-term care

• Common schedule: data reviewed from week 1, a visit between day 31 and day 91, then about 3, 6 and 12 months, then yearly.

• Masks, cushions, filters and tubing are replaced on a schedule because they wear out, and the machine itself about every 5 years.

• A repeat sleep study is common after a large change in weight or when snoring or sleepiness return.

• When CPAP cannot be used despite these steps, other tracks are available: an oral appliance, positional therapy, weight loss, the Inspire implant and surgery.