What is continuous positive airway pressure (CPAP)?

Master the basics of continuous positive airway pressure (CPAP). Check out this short article to learn from our expert!
Michael Allison, MD
Michael Allison, MD
2m read
Editors:Shelley Jacobs, PhD
Peer reviewers:Franz Wiesbauer, MD MPH Internist
Last update7th Jan 2021

Continuous positive airway pressure (CPAP) is one of two cardinal modes of noninvasive ventilation (bilevel positive airway pressure, or BPAP, is the other).

As the name suggests, CPAP provides continuous pressure throughout the respiratory cycle.

Figure 1. Continuous positive airway pressure (CPAP)—one of two cardinal modes of noninvasive ventilation—provides continuous pressure throughout the respiratory cycle.

When a patient on CPAP breathes in, the ventilator machine will provide one constant pressure during the inspiration. When the patient then breathes out, the ventilator will continue that inward pressure during the entire expiration.

Figure 2. Continuous positive airway pressure (CPAP) is one of two cardinal modes of noninvasive ventilation. It provides one continuous pressure throughout the respiratory cycle—the pressure is set to the same level for inspiration and expiration.

Become a great clinician with our video courses and workshops

Start learning for free

Ventilator settings for CPAP

The ventilator settings for CPAP are the following:

  • One single pressure, measured in cm of water (cmH2O)
  • The fraction of inhaled oxygen (FIO2), set between 21% and 100%
Figure 3. The ventilator settings for continuous positive airway pressure (CPAP) as visual memory aide: continuous pressure and fraction of inspired oxygen (FIO2) set at 21–100%.

Common clinical uses for CPAP

CPAP is commonly used for patients with the following respiratory disorders:

  • Acute pulmonary edema
  • Obstructive sleep apnea
  • Obesity hypoventilation syndrome (Pickwickian syndrome)
Figure 4. Visual representation of the common clinical uses for continuous positive airway pressure (CPAP): acute pulmonary edema, obstructive sleep apnea, and obesity hypoventilation syndrome (Pickwickian syndrome).

That’s it for now. If you want to improve your understanding of key concepts in medicine and improve your clinical skills, make sure to register for a free trial account, which will give you access to free videos and downloads. We’ll help you make the right decisions for yourself and your patients.

Recommended reading

  • Garpestad, E, Brennan, J, and Hill, NS. 2007. Noninvasive ventilation. Chest. 132: 711–720. PMID: 17699147
  • Hillberg, RE and Johnson, DC. 1997. Noninvasive ventilation. N Engl J Med. 337: 1746–1752. PMID: 9392701

About the author

Michael Allison, MD
Michael is Chief of Critical Care Medicine at the University of Maryland St. Joseph Medical Center, USA.
Author Profile

Become an expert

Noninvasive Ventilation Masterclass

Pulmonary
By Michael Allison, MD
3 CME
Noninvasive Ventilation Masterclass

Mechanical Ventilation Essentials

Pulmonary
By Josh Cosa, MA RRT-ACCS RRT-NPS RCP
3 CME
Mechanical Ventilation Essentials

Mechanical Ventilation Essentials Workshop

Pulmonary
By Josh Cosa, MA RRT-ACCS RRT-NPS RCP
1 CME
Mechanical Ventilation Essentials Workshop
BMA Highly recommendedComenius EduMedia Siegel 2017
Highly commended by the British Medical Association
Awarded in the “digital” category of the BMA Book Awards - London 2017
See all courses