CPAP machines deliver pressurized air to sleepers' mouths. They help patients with obstructive sleep apnea (OSA) breathe through the night. These patients suffer from narrowing or collapse of their air passages during sleep, causing breathing to stop (apnea) or become markedly reduced periodically (hypopnea). Invented in 1980 by Colin Sullivan, CPAP machines now help millions. Quality of sleep and quality of daytime waking can be vastly improved when a CPAP is used. Indeed, use of CPAP has been shown to help reduce hypetension in patients.
There are two types of CPAP machines: Nasal and Bilevel (or BiPAP) Nasal CPAPs (NCPAPs) blow air into the upper airway continuously; they are basically fans blowing into a tube. (Despite their simplicity they can be effective.)
BiPAP machines try to more closely match normal breathing rhythms by allowing different pressure during expiration from inspiration.
How do you wear them at night?
The machine pumps air, which is delivered usually through snugly fitting masks over their nose. The masks may also cover the mouth, and parts of the face and forehead, depending on the design.. They are held securely in place by headbands or tapes, throughout the duration of sleep. "Nasal pillows" are one variation in design, where air is delivered directly inside the nostrils through small cushions, without anything on the face.
CPAP machines can be uncofortable, which is a factor in a substantial portion of patients quitting use within a few weeks.
How much pressure or flow can they generate?
CPAP machines can generate a range of pressures above atmospheric pressure, typically between 4 and 20 centimeters of water. The average patient however requires between 6 and 14 centimeters of water pressure, and individual pressure requirements are calculated for patients after a sleep study in a laboratory. High-end CPAP machines can also incorporate programmed patterns of varying pressure depending on air flow (auto-CPAP).
Air flow rates can also be varied between 20 to 60 liters of air per minute on most machines. The user adjusts the rate to fit the individual airway resistance and tidal volume (average volume of air inhaled or exhaled per breath). The airflow rate that is appropriate for you is one that allows the oxygen levels in your blood to remain at normal levels. Again, your sleep laboratory or physician can help you in this regard.
Do you need your doctor’s approval to get one?
Yes. CPAP machines cannot be sold without your doctor’s prescription. More importantly, sleep apnea is linked to several serious health problems, and it is very important that you are under medical supervision if you suffer from it.
Do they work?
Yes, they work very well. Of course, different people have different stories, but hundreds of thousands of people use CPAPs regularly. Further, they can improve sleep quality during the first night and allow the sleeper to spend more time in slow-wave sleep.
Do people stop using them?
A high percentage of patients quit using them soon after starting. The discomfort and restricted mobility are the main complaints. Only a very small number of patients find it impossible to use CPAP machines – if you find it difficult to use at the beginning, check with your doctor or sleep lab, small adjustments can easily solve the problem in most instances.
How much does they cost?
CPAP machines come in a wide price range – from around $150 up to $5000 or more. The more expensive models usually incorporate alarms, medical data recording, and adjustable ventilator setting suitable for a wide range of disorders. Check with your doctor or laboratory about the features you need, before you choose which models to buy. There is an element of moral hazard in this market, as most CPAPs are purchased by insurance companies, and thus priced higher than they otherwise would be. The same pricing dynamic occurs in the wheelchair market. It is estimated that the CPAP market in the US is $4 billion per year (source: Reuters).
Can I get portable CPAP machines which I can carry with me?
Yes. CPAP machines come in a variety of shapes and sizes, and most are portable. In addition, small compact machines are available, specifically created for easy travelling, with rechargeable battery packs and chargers. Adapters for power sockets on most commercial flights are readily available – but check with the airline representative before you go.
Are there any other important things I need to know?
Humidifiers are essential for some CPAP users, who get uncomfortably dry noses and throats. Your face mask can easily be modified to use one, or you can but a face mask with built-in humidification.
People sometimes suffer apnea only when they are obese and when their weight declines the apnea disappers. Although CPAP machines help people mitigate the effects of apnea, their use may actually keep the patient overweight. A study found that CPAP use is associated with slight increases in body mass index. Helthcare professionals should stress the importance of weight loss to help solve apnea problems in obese patients, and not assume the CPAP machine will take care of problems.
Because of discomfort, inconvenience, or other reasons, apnea patients often stop using their CPAPs. Some doctors have suggested that non-compliance with CPAP therapy is worse for the patient than smoking, although this idea has drawn criticism.
It is estimated that fewer than 10% of people who could benefit from CPAP machines use them. This low adoption rate has many causes: insufficient diagnosis of apnea, patient preference of oral appliances, high cost of CPAP machines, discomfort experienced during CPAP use, and the bother the machines poses to others in the household. Considering the effectieness of any therapy is a combination of efficacy and compliance, the effectiveness of CPAP therapy is fairly low in general.
An engineer at Stanford University has developed a small alternative to the CPAP. Called the Provent, it is basically a valve that fits on the nostrils and influences its pressure in the airways. Exhaling is a little harder, so there is discomfort with this device, but some feel it is a big improvement over the CPAP machine. The FDA approved the Provent in 2008 and it has slowly been gaining market share for apnea patients. More on the Provent.
Provent sells for about $120 for 30 days' supply. That's expensive, but no more than most prescription drugs that are under patent protection. The price seems to be slowly declining. You need a prescription to get Provent.
"O Sleep, rest of all things, mildest of the gods, balm of the soul..."
(Iris to Hypnos. Ovid, Metamorphoses)