What is bilevel positive airway pressure (BPAP)?

Michael Allison, MD
27th Feb 2021

Bilevel positive airway pressure (BPAP) is the second of two cardinal modes of noninvasive ventilation (continuous positive airway pressure, or CPAP, is the other).

As the name suggests, BPAP provides two different pressures during the respiratory cycle.

Lungs with the different pressures on inspiration and expiration. Illustration.

Figure 1. Bilevel positive airway pressure (BPAP)—one of two cardinal modes of noninvasive ventilation—provides two different pressures throughout the respiratory cycle.

When a patient on BPAP breathes in, the ventilator will provide constant pressure during the inspiration. When the patient then breathes out, the ventilator will provide a different, lower pressure during expiration.

Graph with two different pressures on inspiration and expiration.

Figure 2. Bilevel positive airway pressure (BPAP) is one of two cardinal modes of noninvasive ventilation. It provides two different pressures throughout the respiratory cycle—the pressure is higher for inspiration than for expiration.

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Ventilator settings for BPAP

The ventilator settings for BPAP are as follows:

  • Inspiratory positive airway pressure (IPAP), measured in cmH2O
  • Expiratory positive airway pressure (EPAP), measured in cmH2O
  • The fraction of inhaled oxygen (FIO2), set between 21% and 100%

Iconic representation of bilevel pressure and fraction of inspired oxygen at 21 to 100 percent.

Figure 3. The ventilator settings for bilevel positive airway pressure (BPAP) as visual memory aide: bilevel pressure and the fraction of inspired oxygen (FIO2) set at 21–100%.

 

Common clinical use for BPAP

The main clinical use for BPAP is in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Patient with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Cartoon.

Figure 4. Visual representation of the main clinical use for bilevel positive airway pressure (BPAP): acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

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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