Positive airway pressure (PAP) is a mode of respiratory ventilation used in the treatment of sleep apnea.

PAP ventilation is also commonly used for those who are critically ill in hospital with respiratory failure, in newborn infants (neonates), and for the prevention and treatment of atelectasis in patients with difficulty taking deep breaths.

In these patients, PAP ventilation can prevent the need for tracheal intubation, or allow earlier extubation.

CPAP is an acronym for "continuous positive airway pressure", which was developed by Dr. George Gregory and colleagues in the neonatal intensive care unit at the University of California, San Francisco.

[1] A variation of the PAP system was developed by Professor Colin Sullivan at Royal Prince Alfred Hospital in Sydney, Australia, in 1981.

The main indications for positive airway pressure are congestive heart failure and chronic obstructive pulmonary disease.

Usually PAP ventilation will be reserved for the subset of patients for whom oxygen delivered via a face mask is deemed insufficient or deleterious to health (see CO2 retention).

The "nasal pillow" mask maintains its seal by being inserted slightly into the nostrils and being held in place by various straps around the head.

Some full-face masks "float" on the face like a hover-craft, with thin, soft, flexible "curtains" ensuring less skin abrasion, and the possibility of coughing and yawning.

These factors lead to inability to continue treatment due to patient intolerance in about 20% of cases where it is initiated.

[7][8] Prospective PAP candidates are often reluctant to use this therapy, since the nose mask and hose to the machine look uncomfortable and clumsy.

These different machines may not be comfortable for all users, so proper selection of PAP models may be very important in furthering adherence to therapy.

However, facial irregularities of this nature frequently do not hinder the operation of the device or its positive airflow effects for sleep apnea patients.

The CPAP mask can act as an orthodontic headgear and move the teeth and the upper and/or lower jaw backward.

[13] A continuous positive airway pressure (CPAP) machine was initially used mainly by patients for the treatment of sleep apnea at home, but now is in widespread use across intensive care units as a form of ventilation.

The CPAP machine stops this phenomenon by delivering a stream of compressed air via a hose to a nasal pillow, nose mask, full-face mask, or hybrid, splinting the airway (keeping it open under air pressure) so that unobstructed breathing becomes possible, therefore reducing and/or preventing apneas and hypopneas.

This has the additional benefit of reducing or eliminating the extremely loud snoring that sometimes accompanies sleep apnea.

Given that sleep apnea is a chronic health issue which commonly doesn't go away, ongoing care is usually needed to maintain CPAP therapy.

The care and maintenance required for PAP machines varies with the type and conditions of use, and are typically spelled out in a detailed instruction manual specific to the make and model.

Second, the container may eventually show signs of "sludge" coming from dust and other particles which make their way through the air filter which must also be changed as it accumulates dirt.

To help clean the unit, some patients have used a very small amount of hydrogen peroxide mixed with the water in the container.

Machines may easily fit on a ventilator tray on the bottom or back of a power wheelchair with an external battery.

A limited study in Amsterdam in January 2016 using an induced sleep patient and when awake whilst on CPAP stretched the pectoralis major frontal chest muscles to bring back the shoulders and expand the chest and noted an increase in blood oxygen levels of over 6% during the manual therapy and 5% thereafter.

The conclusion by Palmer was that the manual stretching of the pectoralis major combined at the time of the maximum inflation of CPAP allowed the permanent increase in blood oxygen levels and reinflation of collapsed alveoli.