What is the mechanism of action of Bilevel Positive Airway Pressure (BiPAP)?

From the Guidelines

Bilevel Positive Airway Pressure (BiPAP) works by delivering two different air pressure levels to help a person breathe: a higher pressure when inhaling and a lower pressure when exhaling, as described in the study by 1 and further detailed in 1. Here's how it functions:

• The machine draws in room air and pressurizes it.
• When the user inhales, the machine delivers air at a higher pressure (IPAP - Inspiratory Positive Airway Pressure) to keep airways open and assist with breathing in.
• When the user exhales, the machine reduces the air pressure (EPAP - Expiratory Positive Airway Pressure) to make it easier to breathe out while still maintaining enough pressure to keep airways open.
• This cycle repeats continuously, synchronizing with the user's breathing pattern. The IPAP and EPAP levels are adjusted to maintain upper airway patency, and the pressure support (PS = IPAP-EPAP) augments ventilation, as noted in 1. Typical pressure settings range from 4 to 25 cm H2O for IPAP and 2 to 10 cm H2O for EPAP, but these are adjusted based on individual needs, and the specific settings may vary depending on the patient's condition and response to treatment, as discussed in 1. BiPAP is often used for conditions like sleep apnea, COPD, or neuromuscular disorders, and it's more comfortable than CPAP for many users because it mimics natural breathing patterns more closely, as mentioned in 1. The machine requires a mask (nasal, full-face, or nasal pillows) and regular cleaning to function properly and prevent infections. The alternating pressures help reduce work of breathing, improve gas exchange, and maintain airway patency, making it easier for users to breathe and get restful sleep, which is critical for improving morbidity, mortality, and quality of life outcomes, as implied by the principles of respiratory support discussed in 1 and 1.

From the Research

Mechanism of Action of Bilevel Positive Airway Pressure (BiPAP)

The mechanism of action of BiPAP involves the delivery of two different levels of air pressure, namely Inspiratory Positive Airway Pressure (IPAP) and Expiratory Positive Airway Pressure (EPAP), to help improve breathing patterns in patients with respiratory disorders.

• BiPAP combines pressure-controlled ventilation with unrestricted spontaneous breathing, allowing patients to breathe spontaneously at any moment of the ventilatory cycle 2, 3.
• The device switches between a high (IPAP) and a low (EPAP) airway pressure level in an adjustable time sequence, with the patient able to breathe spontaneously in a continuous positive airway pressure system (CPAP) at both pressure levels 2.
• The volume displacement caused by the difference between IPAP and EPAP, and the BiPAP frequency, contribute to the mechanical ventilation of total ventilation 2.
• BiPAP can be subdivided into different modes, including controlled mechanical ventilation (CMV-BIPAP), intermittent mandatory ventilation (IMV-BIPAP), and assisted spontaneous breathing at both CPAP levels (genuine BIPAP) 3.
• The use of BiPAP has been shown to effectively increase static pressure, improve airway patency, and reduce the risk of airway collapse in patients with Central and Obstructive Sleep Apnea (CSA and OSA) 4.
• Lower EPAP settings can help reduce the work of breathing during exhalation, which is particularly useful for patients who have difficulty exhaling against higher pressures or need to exhale CO2 more effectively 4.
• BiPAP has also been used to support patients with Chronic Obstructive Pulmonary Disease (COPD), although it may carry the risk of increased work of breathing in spontaneously breathing COPD patients 5.

Key Features of BiPAP

• Adjustable IPAP and EPAP settings to meet the specific needs of patients with various respiratory dysfunctions 4, 2, 3.
• Ability to switch between different modes of ventilation, including controlled and assisted spontaneous breathing 3.
• Portable and non-invasive, making it suitable for use in both hospital and home settings 6.
• Effective in improving respiratory mechanics and reducing the risk of airway collapse in patients with CSA, OSA, and other respiratory disorders 4, 5.