Continuous positive airway pressure

Continuous positive airway pressure (CPAP) is a form of positive airway pressure (PAP) ventilation in which a constant level of pressure above atmospheric pressure is continuously applied to the upper airway. The application of positive pressure may be intended to prevent upper airway collapse, as occurs in obstructive sleep apnea, or to reduce the work of breathing in conditions such as acute decompensated heart failure. CPAP therapy is highly effective for managing obstructive sleep apnea. 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.[1]

"CPAP" redirects here. For other uses, see CPAP (disambiguation).
Continuous positive airway pressure
CPAP therapy: flow generator, hose, full face mask

Medical uses

Severe to moderate obstructive sleep apnea

CPAP is the most effective treatment for moderate to severe obstructive sleep apnea, in which the mild pressure from the CPAP prevents the airway from collapsing or becoming blocked.[1][2] CPAP has been shown to be 100% effective at eliminating obstructive sleep apneas in the majority of people who use the therapy according to their doctors recommendations.[1]

Pre-term infants

CPAP also may be used to treat pre-term infants whose lungs have not yet fully developed. For example, physicians may use CPAP in infants with respiratory distress syndrome. It is associated with a decrease in the incidence of bronchopulmonary 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 primary pulmonary disease, researchers have found that nurses can initiate and manage care with once or twice daily physician rounds.[3]

COVID-19

In March 2020 the USFDA suggested that CPAP devices may be used to support patients affected by COVID-19;[4] however, they recommended additional filtration as non-invasive ventilation may increase the risk of infectious transmission.[5]

Other uses

CPAP has also been suggested for treating acute hypoxaemic respiratory failure in children, however the effectiveness and safety of this approach to providing respiratory support is not clear due to a limited number of clinical studies.[6]

Contraindications

CPAP cannot be used in the following situations/conditions:[7]

  • A person is not breathing on their own
  • A person is uncooperative or anxious
  • A person cannot protect their own airway (i.e., is unconscious)
  • A person is not stable due to respiratory arrest
  • A person has experienced facial trauma or facial burns
  • Previous facial, esophageal, or gastric surgeries may also make it difficult or not a suitable treatment option

Adverse effects

Some people experience difficulty adjusting to CPAP therapy and report general discomfort, nasal congestion, bloating of the abdomen, sensations of claustrophobia, mask leak problems, and convenience-related complaints.[1]

Mechanism

CPAP therapy uses machines specifically designed to deliver a flow of air at a constant pressure. This constant stream of air opens and keeps the upper airway unobstructed during inhalation and exhalation.[1] Some CPAP machines have other features as well, such as heated humidifiers.

It is an alternative to positive end-expiratory pressure (PEEP). Both modalities stent the lungs' alveoli open and thus recruit more of the lung's surface area for ventilation, but, while PEEP refers to devices that impose positive pressure only at the end of the exhalation, CPAP devices apply continuous positive airway pressure throughout the breathing cycle. Thus, the ventilator itself does not cycle during CPAP, no additional pressure above the level of CPAP is provided, and patients must initiate all of their breaths.[8]

An example of a nasal mask for CPAP

Nasal CPAP

Nasal prongs or nasal mask is the most common modality of treatment.[7] Nasal CPAP is frequently used in infants, though its use is controversial. Studies have shown nasal CPAP reduces ventilator time but an increased occurrence of pneumothorax was also prevalent.[9] Nasal prongs are placed directly in the person's nostrils. A nasal mask is a small mask that covers the nose.

Nasopharyngeal CPAP

Nasopharyngeal CPAP is administered by a tube that is placed through the person's nose and ends in the nasopharynx.[7] This tube bypasses the nasal cavity in order to deliver the CPAP further down.

Face mask

A full face mask over the mouth and nose is another approach for people who breathe out of their mouths when they sleep.[7] Oral masks and naso-oral masks are often used when nasal congestion or obstruction is an issue. Devices that combine nasal pressure with mandibular advancement devices (MAD) also exist.

Example of a full face masks CPAP

Compliance

A large portion of people do not adhere to the recommended usage of CPAP therapy, with over 50% of people discontinuing use in the first year.[1] A significant change in behaviour is required in order to commit to long-term use of CPAP therapy, and this can be difficult for many people.[1] In addition, people with moderate to severe obstructive sleep apnea have a higher risk of symptoms such as anxiety and depression, which can make it more difficult to change their sleep habits and use CPAP on a regular basis.[1] Educational and supportive approaches have been shown to help motivate people that need CPAP therapy use their devices more often.[1]

History

Colin Sullivan, an Australian physician and professor, invented CPAP in 1980 at Royal Prince Alfred Hospital in Sydney.[10]

See also

References
  1. Askland, Kathleen; Wright, Lauren; Wozniak, Dariusz R.; Emmanuel, Talia; Caston, Jessica; Smith, Ian (April 2020). "Educational, supportive and behavioural interventions to improve usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea". The Cochrane Database of Systematic Reviews. 4: CD007736. doi:10.1002/14651858.cd007736.pub3. ISSN 1469-493X. PMC 7137251. PMID 32255210.
  2. Werman, Howard A.; Karren, K; Mistovich, Joseph (2014). "Continuous Positive Airway Pressure(CPAP)". In Werman A. Howard; Mistovich J; Karren K (eds.). Prehospital Emergency Care, 10e. Pearson Education, Inc. p. 242.
  3. Patrick, Wilson; Moresky, Rachel; Baiden, Frank; Brooks, Joshua; Morris, Marilyn; Giessler, Katie; Punguyire, Damien; Apio, Gavin; Agyeman-Ampromfi, Akua; Lopez-Pintado, Sara; Sylverken, Justice; Nyarko-Jectey, Kwadwo; Tagbor, Harry (June 2017). "Continuous positive airway pressure for children with undifferentiated respiratory distress in Ghana: an open-label, cluster, crossover trial". Lancet Global Health. 5 (6): e615–e623. doi:10.1016/S2214-109X(17)30145-6. PMID 28495265.
  4. "Ventilator Supply Mitigation Strategies: Letter to Health Care Providers". U.S. Food and Drug Administration. FDA. Retrieved 30 March 2020.
  5. "COVID-19 resources for anesthesiologists". asahq.org. American Society of Anesthesiologists (ASA). Retrieved 30 March 2020.
  6. Shah, Prakeshkumar S.; Ohlsson, Arne; Shah, Jyotsna P. (2013-11-04). "Continuous negative extrathoracic pressure or continuous positive airway pressure compared to conventional ventilation for acute hypoxaemic respiratory failure in children". The Cochrane Database of Systematic Reviews (11): CD003699. doi:10.1002/14651858.CD003699.pub4. ISSN 1469-493X. PMC 6464907. PMID 24186774.
  7. Pinto, Venessa L.; Sharma, Sandeep (2020), "Continuous Positive Airway Pressure (CPAP)", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29489216, retrieved 2020-09-02
  8. Werman, Howard A.; Karren, K; Mistovich, Joseph (2014). "Continuous Positive Airway Pressure(CPAP)". In Werman A. Howard; Mistovich J; Karren K (eds.). Prehospital Emergency Care, 10e. Pearson Education, Inc.
  9. Morley, C. J.; Davis, P. G.; Doyle, L. W.; Brion, L. P.; Hascoet, J. M.; Carlin, J. B.; Coin Trial, I. (2008). "Nasal CPAP or Intubation at Birth for Very Preterm Infants" (PDF). New England Journal of Medicine. 358 (7): 700–708. doi:10.1056/NEJMoa072788. PMID 18272893.
  10. https://www.sleepfoundation.org/articles/past-present-and-future-cpap
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