Biphasic Positive Airway Pressure (BiPAP) is a non-invasive ventilation therapy that delivers pressurized air through a facial mask to keep a person’s airways open. It supports respiration for individuals who can breathe on their own but struggle to maintain adequate oxygen levels or expel enough carbon dioxide.
The BiPAP Mechanism
The core of BiPAP therapy is its “biphasic” or two-level pressure system. The machine delivers air at two distinct pressures that synchronize with the breathing cycle: Inspiratory Positive Airway Pressure (IPAP) and Expiratory Positive Airway Pressure (EPAP). The IPAP setting provides a higher pressure as a person inhales, helping them take a full breath with less effort.
When the user exhales, the machine switches to the lower EPAP setting, making breathing out more comfortable. The machine senses the user’s breathing rhythm, allowing it to alternate between the IPAP and EPAP levels at the correct moments. This process supports more effective gas exchange in the lungs.
Conditions Treated with BiPAP
BiPAP therapy is prescribed for medical conditions involving respiratory muscle fatigue or failure. A primary use is for managing Chronic Obstructive Pulmonary Disease (COPD), especially during acute exacerbations. The dual-pressure support lessens the physical effort to breathe and aids in clearing excess carbon dioxide from the body.
The therapy is also used for central sleep apnea, a condition where the brain does not consistently send signals to the breathing muscles. In such cases, a timed feature on the BiPAP machine can trigger breaths. It is also applied to treat certain neuromuscular diseases, like amyotrophic lateral sclerosis (ALS), or chest wall deformities that weaken respiratory muscles.
Key Differences from CPAP Therapy
The fundamental difference between BiPAP and Continuous Positive Airway Pressure (CPAP) therapy is how air pressure is delivered. A CPAP machine provides a single, continuous level of pressure throughout both inhalation and exhalation. This constant pressure works to keep the airway open and is effective for many with obstructive sleep apnea.
BiPAP provides a variable pressure system, with a higher pressure for inhalation and lower pressure for exhalation. This lower expiratory pressure can make the therapy more tolerable for people who require higher pressure settings. BiPAP is reserved for those who find it difficult to exhale against CPAP’s constant pressure or for individuals with more complex respiratory conditions.
The BiPAP System and Its Components
A BiPAP system consists of several components. The generator is a small machine that takes in room air, pressurizes it, and delivers it to the user. Most modern BiPAP machines include a heated humidifier, which adds moisture to the pressurized air to prevent dryness in the nasal passages, mouth, and throat.
Pressurized air travels from the generator through a flexible tube to the mask. Users wear a mask that creates a seal over their nose or both their nose and mouth. Common styles include nasal pillows that seal at the nostrils, nasal masks that cover the nose, and full-face masks that cover both the nose and mouth. A proper mask fit is important to prevent air leaks and ensure the prescribed pressure is delivered correctly.
Adjusting to BiPAP Therapy
Mask discomfort and air leaks are common issues, often resolved by trying different mask styles or sizes to find a better fit. Skin irritation from the mask or straps can be managed with mask liners or pads, which provide a soft barrier between the equipment and the skin.
Nasal congestion and dryness are frequent side effects, but using the heated humidifier consistently provides significant relief. A saline nasal spray used before bed may also help keep nasal passages moist. Some individuals find the sensation of the pressurized air unusual at first, but many machines have a “ramp” feature that starts the pressure at a low level and gradually increases it to the prescribed setting.