| Continuous positive airway pressure | |
|---|---|
 Equipment for CPAP therapy: flow generator, hose, mask | |
| Pronunciation | The abbreviation CPAP is commonly pronounced "see-pap" |
| Uses | Treatment of obstructive sleep apnea and/or acute decompensated heart failure and/or COVID-19 |
Continuous positive airway pressure (CPAP) is a form ofpositive airway pressure (PAP)ventilation in which a flow of air withpressure greater thanatmospheric pressure is continuously applied to theupper respiratory tract of a person. This flow is generated by a device to which a flexible hose is connected that in turn feeds air into a mask. The application of positiverelative pressure may be intended to prevent upper airway collapse, as occurs inobstructive sleep apnea (OSA), or to reduce thework of breathing in conditions such asacute decompensated heart failure. CPAP therapy is highly effective for managing obstructive sleep apnea.[1] Compliance and acceptance of use of CPAP therapy can be a limiting factor, with 8% of people stopping use after the first night and 50% within the first year.[2] For treatment of chronic conditions such as obstructive sleep apnea, CPAP needs to be used for all sleep, including naps and travel away from home.
CPAP is the most effective treatment for moderate to severeobstructive sleep apnea, in which the mild pressure from the CPAP prevents the airway from collapsing or becoming blocked.[2][3] CPAP has been shown to be 100% effective at eliminating obstructive sleep apneas in the majority of people who use the therapy according to the recommendations of their physician.[2] There is weak evidence that CPAP therapy may reduce erectile dysfunction symptoms in people with obstructive sleep apnea.[4]
Use of CPAP for people with sleep apnea reduces the overall risk of death fromcardiovascular causes.[5]
Upper airway resistance syndrome (UARS) is another form of sleep-disordered breathing with symptoms that are similar to obstructive sleep apnea, but not severe enough to be considered OSA. CPAP can be used to treat UARS as the condition progresses, in order to prevent it from developing into obstructive sleep apnea.[1][6][7][8]
CPAP also may be used to treat pre-term infants whose lungs are not yet fully developed. For example, physicians may use CPAP in infants withrespiratory distress syndrome. It is associated with a decrease in the incidence ofbronchopulmonary dysplasia. In some preterm infants whose lungs have not fully developed, CPAP improves survival and decreases the need for steroid treatment for their lungs. In resource-limited settings where CPAP improves respiratory rate and survival in children with primarypulmonary disease, researchers have found that nurses can initiate and manage care with once- or twice-daily physician rounds.[9]
CPAP can be used for the treatment ofobstructive pulmonary diseases includingasthma.[10][11]
In March 2020, theUSFDA suggested that CPAP devices may be used to support patients affected byCOVID-19;[12] however, they recommended additional filtration since non-invasive ventilation may increase the risk of infectious transmission.[13]
CPAP also has been suggested for treating acute hypoxaemic respiratory failure in children. However, due to a limited number of clinical studies, the effectiveness and safety of this approach to providing respiratory support is not clear.[14]
CPAP cannot be used in the following situations or conditions:[15]
Some people experience difficulty adjusting to CPAP therapy and report general discomfort, nasal congestion, abdominal bloating (including increased flatulence), sensations ofclaustrophobia, mask leak problems, and convenience-related complaints.[2] Oral leak problems, in which air from the machine is expelled back out of the mouth instead of holding the respiratory tract open, also interfere with CPAP effectiveness.[16]
CPAP therapy uses machines specifically designed to deliver a flow of air at a constant pressure. CPAP machines possess a motor that pressurizes room temperature air and delivers it through a hose connected to a mask or tube worn by the patient. This constant stream of air opens and keeps the upper airway unobstructed during inhalation and exhalation.[2] Some CPAP machines have other features as well, such as heated humidifiers,[17] and connectivity to allow data from during sleep to be viewed with a smartphone app.[18]
The therapy is an alternative topositive end-expiratory pressure (PEEP). Both modalities stent open thealveoli in the lungs and thus recruit more of the lung surface area for ventilation. However, while PEEP refers to devices that impose positive pressure only at the end of theexhalation, CPAP devices applycontinuous positive airway pressure throughout the breathing cycle. Thus, the ventilator does not cycle during CPAP, no additional pressure greater than the level of CPAP is provided, and patients must initiate their breaths.[19]
Nasal prongs or a nasal mask is the most common modality of treatment.[15] Nasal prongs are placed directly in the person's nostrils. A nasal mask is a small mask that covers the nose. There are also nasal pillow masks which have a cushion at the base of the nostrils, and are considered the least invasive option.[20] Frequently, nasal CPAP is used for infants, although this use is controversial. Studies have shown nasal CPAP reduces ventilator time, but an increased occurrence ofpneumothorax also was prevalent.[21]
Nasopharyngeal CPAP is administered by a tube that is placed through the person's nose and ends in the nasopharynx.[15] This tube bypasses the nasal cavity in order to deliver the CPAP farther down in the upper respiratory system.
A full face mask over the mouth and nose is another approach for people who breathe out of their mouths when they sleep, as this can deal with oral air leaks that reduce effectiveness of CPAP.[15] Often, oral masks and naso-oral masks are used when nasal congestion or obstruction is an issue.[22] There are also devices that combine nasal pressure withmandibular advancement devices (MAD).
The use of specializedsurgical tape appropriate for placement over the mouth with lips closed, and/or a flexible cloth chin strap to hold the jaws together, are other options to prevent air leaks while sleeping.
A large portion of people do not adhere to the recommended method of CPAP therapy, with more than 50% of people discontinuing use in the first year.[2] A significant change in behavior is required in order to commit to long-term use of CPAP therapy and this can be difficult for many people,[2] since CPAP equipment should be used consistently for all sleep (including naps and overnight trips away from home) and needs to be regularly maintained and replaced over time. In addition, people with moderate to severe obstructive sleep apnea have a higher risk of concomitant symptoms such as anxiety and depression, which can make it more difficult to change their sleep habits and to use CPAP on a regular basis.[2] Educational and supportive approaches have been shown to help motivate people who need CPAP therapy to use their devices more often.[2]
CPAP was developed by Dr. George Gregory and colleagues in the neonatal intensive care unit at the University of California, San Francisco.[23]Dr. Colin Sullivan, an Australian physician and professor, invented a machine in 1980 applying CPAP for use on adult patients with sleep apnoea atRoyal Prince Alfred Hospital inSydney.[24]Gerald McGinnis, founder ofRespironics, began selling one of the first commercially available CPAP machines for adults with sleep apnea in 1985.[25]
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