The continuous positive airway pressure (CPAP) mask, originally invented to provide continuous airflow to prevent the upper airway from collapsing in sufferers of obstructive sleep apnea, is now an important therapeutic device used in the treatment of congestive heart failure.

Congestive heart failure (CHF) is a condition in which the demands of the body for oxygen exceed the heart's ability to provide it. This often occurs because the heart has been weakened or damaged by secondary disease. In order to compensate for the heart's inability to adequately oxygenate the body, the lungs must work harder, often to the point of exhaustion. A common side effect of a weak heart is pulmonary edema, a collection of fluid in the lungs, which makes this job even more difficult.

CPAP masks, which are hooked up to an external machine which provides the continuous positive pressure, improve the respiratory system's ability to adequately add oxygen and remove carbon dioxide from the blood supply. Because CPAP machines essentially force air into the patient's lungs, the work involved with breathing in and out is significantly reduced because the alveoli and bronchioles are prevented from collapsing after breathing out. In addition, the circulation of air within the patient's respiratory system is improved, reducing the amount of stale pockets of air in the lungs. This in turn decreases the work of breathing for the CHF patient; breathing is slowed down and becomes less labored, and because more oxygen is present in the blood, the work load on the patient's heart is also reduced.

Despite the utility of CPAP machines, many patients, especially those prone to anxiety or claustrophobia, may find the sensation of having air blown into their lungs displeasing. In addition, many patients, especially those who use a CPAP mask for obstructive sleep apnea, may find the mask a nuisance as it requires a complete seal around the mouth in order to deliver air into the respiratory track. If the mask is not completely sealed, leaks will occur which reduce the effectiveness of the mask.

Beards, moustaches, and other facial hair can prevent the mask from sealing properly. In some users, long term CPAP use can lead to temporomandibular joint disorders because of the structural changes the constant air pressure causes in the jaw and upper airway. Other commonly reported side effects of CPAP use include dizziness, bronchitis, dry mucosal tissue, and ear pain. All of these side effects can be reduced or eliminated by adjusting the amount of pressure exerted by the CPAP machine or by trying different masks.