Bilevel ventilation is a non-invasive respiratory therapy that helps people breathe by delivering pressurized air through a mask. This support keeps the airway open and aids the movement of air into and out of the lungs without requiring a tube inserted into the throat. While often known by the brand name BiPAP, the correct term is bilevel positive airway pressure (BPAP). It is prescribed for individuals who can breathe independently but need help maintaining oxygen levels or removing carbon dioxide.
How Bilevel Ventilation Works
Bilevel ventilation delivers two distinct air pressures synchronized with a person’s breathing cycle. A higher pressure, Inspiratory Positive Airway Pressure (IPAP), is delivered during inhalation. This increased pressure reduces the effort needed to take a full breath, ensuring the lungs receive enough air and oxygen. This action supports breathing muscles that can become fatigued in certain respiratory conditions.
Conversely, a lower pressure called Expiratory Positive Airway Pressure (EPAP) is delivered during exhalation. This reduced pressure makes it easier to breathe out against the machine’s airflow. This dual-pressure system improves the efficiency of gas exchange, boosting oxygen intake and the removal of carbon dioxide. The machine’s sensors detect the user’s breathing pattern, allowing it to switch between IPAP and EPAP at the correct moments.
Conditions Treated with Bilevel Ventilation
Bilevel ventilation treats several medical conditions that affect breathing, especially during sleep. Common conditions include:
- Certain types of sleep apnea, including cases requiring high pressure settings or central sleep apnea, where the brain fails to send proper breathing signals.
- Chronic Obstructive Pulmonary Disease (COPD) exacerbations, where it helps rest fatigued respiratory muscles and remove excess carbon dioxide.
- Neuromuscular disorders, such as amyotrophic lateral sclerosis (ALS) or muscular dystrophy, which cause breathing muscles to weaken.
- Obesity hypoventilation syndrome, where excess weight impairs the ability to breathe deeply, leading to low oxygen and high carbon dioxide levels.
Bilevel Ventilation Versus CPAP
A primary distinction exists between bilevel ventilation and Continuous Positive Airway Pressure (CPAP) therapy. CPAP delivers a single, constant stream of pressurized air during both inhalation and exhalation. This continuous pressure is effective at keeping the airway open, making it useful for treating obstructive sleep apnea.
Bilevel therapy provides a variable pressure system. The dual settings of a higher inhalation pressure (IPAP) and a lower exhalation pressure (EPAP) are more tolerable for some users. Patients who find it difficult to exhale against the constant pressure of a CPAP machine find relief with the lower EPAP setting. This makes bilevel ventilation a suitable alternative for those unsuccessful with CPAP or who require very high pressures, as exhaling against high constant pressure can be uncomfortable.
Using Bilevel Ventilation
Using bilevel ventilation involves a machine connected by a tube to a mask that fits over the nose, mouth, or both. A proper mask seal is important for effectiveness and comfort. A respiratory therapist helps with the initial setup, ensuring the mask fits correctly and the physician-prescribed pressure settings are programmed into the device. This calibration occurs in a hospital or sleep lab.
Users may notice the sensation of pressurized air when first starting therapy, which can take time to get used to. Many machines include a humidifier to add moisture to the air, preventing dryness in the nose, throat, and mouth. Consistent use of the device, especially during sleep, improves sleep quality and reduces daytime sleepiness. Regular cleaning of the mask and tubing is also required to maintain hygiene and proper function.