CPAP works in the following way:
- The device itself is a machine weighing about 5 pounds that fits on a bedside table.
- A mask containing a tube connects to the device and fits over just the nose.
- The machine supplies a steady stream of air through a tube and applies sufficient air pressure to prevent the tissues from collapsing during sleep
Effects on Sleep and Wakefulness: A major 2003 analysis confirmed the benefits of CPAP on both objective and subjective measures of sleep. After using CPAP regularly many patients report the following benefits:
- Restoration of normal sleep patterns.
- Greater alertness and less daytime sleepiness.
- Less anxiety and depression and better mood.
- Improvements in work productivity.
- Better concentration and memory. Some adults with symptoms of attention deficit hyperactivity disorder have improved after CPAP treatments for apnea. In two studies, however, equal improvements were also observed in people on sham CPAP, suggesting that the actual cognitive benefits from CPAP may be modest.
- Patients' bed partners also report improvement in their own sleep when their mates use CPAP, even though objective sleep tests showed no real difference in the partners' sleep quality.
If patients comply with the CPAP regimen but do not feel less sleepy after a period of time, or their sleep apnea symptoms don't improvement, the airflow pressure may not be high enough. Patients may need to be retested. Likewise, if patients have started using an oral appliance or had a surgical procedure, their doctor problably needs to reevaluate them. Many patients report feeling more alert after CPAP treatments even if objective laboratory tests fail to show significant differences in the number of apneas and wake-up periods.
Side Effects and Getting Used to the Device
CPAP works well for both adults and children, but many patients have problems getting used to the device. Unfortunately, CPAP devices are often cumbersome, which can lead to patients becoming discouraged and stopping treatment. All patients should be warned that the first few nights of CPAP therapy are unnerving. The mask may cause some patients to feel anxious. Starting out with low pressure to get used to the mask may help. Patients may actually sleep less, or have different sleep quality, at the start of treatment.
Nearly all patients complain of at least one side effect. Nearly half of complaints are related to the mask. Many of these problems can be minimized with a well-chosen mask that is comfortable and reduces leakage as much as possible. Thorough education and ongoing support are essential for successful treatment with CPAP.
Common complaints include:
Irritation in the nose and throat: The most common complaints are nasal congestion and sore or dry mouth, which are caused by leakage that dries the airway. (This may be severe in elderly people or patients who have had uvulopalatopharyngoplasty, a surgical treatment for sleep apnea. Such patients are more likely to stop using CPAP.) Chin straps, nasal salt water sprays, or humidifiers may prevent these side effects. Heated humidification devices are also now available for CPAP users.
Excessive application of pressure making exhalation difficult.
A feeling of claustrophobia is a major factor in noncompliance. This can be improved by a lightweight and transparent mask or with masks known as nasal pillows, which are used only around the nostrils.
- Up to 30% of patients have irritation and sores over the bridge of the nose. Getting a properly fitted and cushioned mask can help reduce this problem.
- Eye irritation or conjunctivitis.
- Upper respiratory infections. It is very important to keep the unit clean.
- Patients may also feel temporary chest muscle discomfort, which is caused by an increase in lung volume.
- Severe side effects are very rare but may include heart rhythm disorders (arrhythmias), severe nose bleeding, and air pockets in the skull.
In addition to initial difficulties with its use, the fixed CPAP needs to be periodically readjusted. Patients can be trained to adjust the CPAP at home, thereby avoiding trips to the sleep professional for machine adjustments and making the process more convenient.
Studies have reported that long-term compliance with CPAP systems is low, with about one-third of patients giving up the treatment. Compliance may be improving, however, probably due to better technologies and better education. Factors that may help include:
- Patient education and support groups
- Adedicated nurse to ensure close follow-up of patients (particularly in the first 2 weeks of therapy)
- Access to doctors to make adjustments as needed have all been shown to greatly improve compliance
(However, sleeping pills do not appear to help patients adapt to the device.) Not surprisingly, patients whose symptoms are noticeably relieved by the procedure early on are more likely to continue the therapy.
Because many patients find CPAP uncomfortable and difficult, they tend not to use it for the duration of the entire night. However, while some patients daytime sleepiness may improve after 4 - 6 hours of CPAP use each night, maximum benefits in quality of life require at least 7.5 hours of nightly CPAP use. It appears that longer nightly duration of CPAP use is best for achieving normal daytime functioning.
CPAP sleep apnea
