Is A BiPAP Machine Right For Your Sleep Apnea?
IPAP plus EPAP
CPAP users have probably heard the term Bi-level, VPAP or BiPAP but are unclear about what it is and how it differs from a regular CPAP machine. Without getting too technical, there are a few key differences between a normal CPAP machine and the more complex BiPAP machine. As CPAP users are aware, a regular CPAP machine essentially prevents apneas by delivering a constant stream of air through a tube and into a face mask. This constant pressure helps keep the airway open and allows the user to breathe normally.
Although BiPAP machines function similar to a regular CPAP for inhalation pressure (IPAP), it differs on the exhalation pressure (EPAP). On exhalation, the BiPAP machine delivers a pressure relief or drop to allow for patients to breathe more closely to their normal breathing pattern. This exhalatory pressure relief is especially noticeable for patients with prescribed pressures of 15cm or higher as it allows them to exhale without fighting against a strong constant pressure. The difference between the IPAP and EPAP or pressure support must be determined by a sleep study and has no limits. In fact, the EPAP pressure of a BiPAP can reduce to the machines lowest setting of 4cm. This function provides for a more comfortable CPAP experience and, thus, a higher compliance rate.
A more advanced device, a BiPAP ST machine, provides Spontaneous/Timed (S/T) therapy. This machine allows for the patient to breathe at their normal, pre-set respiratory rate. If the patient experiences an apnea or their breathing falls below the set rate, the device maintains the patient's ventilation with a timed breath. The Bipap ST device will actually initiate a breath during therapy which allows for the patient to receive a minimum number of breaths per minute Even more complex machines actually calculate ventilation and BiPAP pressure automatically.
All major CPAP machine manufacturers have BiPAP machines, but they vary slightly in their algorithm and operation while still providing the basic pressure relief function. Also, as with all CPAP machines, any type of CPAP nasal, full face or nasal pillow mask will function with a BiPAP machine. Nevertheless, it is always important to discuss with your sleep specialist which type of machine or mask style is most appropriate. CPAP compliance is directly associated with comfort levels, so it is important to make sure both machine and mask are suitable and properly fitted for your particular situation.
A new Auto BiPAP we at The CPAP Shop are impressed with is the Resmed S9 VPAP Auto. The main objective of this compact, travel friendly machine is to deliver effective therapy as naturally and comfortably as possible. This Bi-Level featuring Easy-Breathe, ResMed's comfort technology, offers nearly silent therapy and greater pressure stability so patients sleep comfortably throughout the night. The Easy-Breathe technology synchronizes with the patient's normal respiration so breathing feels natural and comfortable. This device also uses AutoSet technology which automatically adjusts to a patient's pressure needs as they vary throughout the night. With ResMed's clinically proven AutoSet algorithm, the S9 VPAP is able to detect flow limitation and act preemptively to prevent apneas and snoring events. The unit also has an optional ClimateLine tube which delivers a constant, comfortable temperature at the mask and also helps substantially reduce rainoutwhich. An optional humidifier attaches to the side of the S9 VPAP to provide heated humidification. The device automatically detects the presence of the humidifier and no other accessories are required for its use.
Respironics has also designed a Bi-Level machine which automatically adjusts to the patient's breathing cycles. The Respironics PR System One Auto BiPAP features a proactive, multi-level algorithm that analyzes several parameters to monitor and respond to a patient's breathing. This BiPAP combines auto adjusting pressure delivery with the breath-by-breath pressure relief of Bi-Flex. Bi-Flex softens airflow at inhalation and exhalation and allows for patients to further refine their IPAP and EPAP pressures making for an extremely natural and stress-free experience for patients. In Bi-Flex mode, patient adjustable pressure relief is provided at the critical stages of EPAP, IPAP, and exhalation. The Auto BiPAP also allows for fixed IPAP and EPAP and a function which transitions the machine to automatic during the night. It also has a wide pressure range (4-25cm). As with all Respironics PR System One BiPAP machines, it has an optional heated humidifier. Because dry mouth and nasal irritation are common reasons for non-compliance, the PR System One Heated Humidifier features an easy-turn dial that is easily set to five different humidification levels.
Hopefully, this article has provided a clear, concise picture between the differing functions of a CPAP and a BiPAP machine. If there are further questions or need for further information, please call our experts at The CPAP Shop.
The CPAP Shop is pleased to offer the following machines:
- Resmed S9 Auto VPAP
- Resmed S8 VPAP Auto 25
- Resmed VPAP Adapt SV Enhanced
- Respironics PR System One Bipap Auto
- Respironics PR System One Bipap Pro
- Respironics PR System One Bipap ST
Written by: Chris Vasta of The CPAP Shop.
Family owned and operated since 2003, we are CPAP specialists and our first priority is our customer and their satisfaction. Our goal is to educate and provide knowledge to help people who suffer from sleep apnea make informed decisions. Please visit us at https://www.thecpapshop.com/and become one of our thousands of satisfied customers.
Copyright (c) 2009 Chris Vasta
This post was updated with the latest information in November 2025.
If you are new to sleep therapy, the terms CPAP and BiPAP (or Bi-Level) can be confusing. While a standard CPAP machine is the primary treatment for most cases of Obstructive Sleep Apnea (OSA), a BiPAP machine is a specialized device prescribed when CPAP is either ineffective or uncomfortable.
BiPAP therapy offers a significant comfort advantage, but its use is determined by specific medical necessity.
Here is a concise guide to understanding the key differences and determining if Bi-Level pressure therapy is the right choice for you.
The Core Difference: Two Pressures
A CPAP (Continuous Positive Airway Pressure) machine delivers a single, fixed pressure during both inhalation and exhalation. While modern CPAP devices offer comfort features like EPR (Expiratory Pressure Relief) to slightly drop pressure upon exhale, the relief is minor and temporary.
A BiPAP machine (Bi-Level Positive Airway Pressure) delivers two distinct pressure settings:
-
IPAP (Inspiratory Positive Airway Pressure): A higher pressure delivered when you breathe in. This keeps your airway open.
-
EPAP (Expiratory Positive Airway Pressure): A lower pressure delivered when you breathe out. This significantly reduces the resistance you feel during exhalation.
The difference between these two pressures (known as Pressure Support) is what makes BiPAP therapy far more comfortable and effective for certain patients.
When is BiPAP Therapy Necessary?
BiPAP machines are not a "better" version of a CPAP; they are an essential tool for patients with complex breathing needs. They are prescribed when a patient requires a high level of pressure or has specific underlying respiratory conditions.
| Condition | Why BiPAP is Used |
| High Pressure Intolerance | If your sleep study determined you need a high CPAP pressure (>15 cmH20), the resistance can make breathing out feel like a struggle. BiPAP relieves this resistance, increasing compliance. |
| Central Sleep Apnea (CSA) | Unlike OSA (a blockage), CSA occurs when the brain fails to signal the muscles to breathe. Advanced BiPAP machines (BiPAP-S/T models) can monitor breathing and initiate a timed breath if the patient misses one. |
| Co-Existing Respiratory Conditions | Patients with conditions like COPD (Chronic Obstructive Pulmonary Disease) or specific types of Hypoventilation often need BiPAP to assist with ventilation and the removal of excess carbon dioxide. |
| Complex Sleep Apnea (CompSA) | CompSA is a form of OSA that turns into CSA when fixed CPAP pressure is applied. Bi-Level therapy, often in an Auto-BiPAP mode, can better manage these fluctuating pressure needs. |
Modern BiPAP Technology and Features
Today’s BiPAP machines are highly advanced and significantly quieter and smaller than their predecessors (such as the Respironics PR System One models).
-
ResMed AirCurve Series: The modern standard, featuring the enhanced AirCurve 10 VAuto (Auto BiPAP) and the more complex AirCurve 10 ASV (Adaptive Servo-Ventilation) for severe CSA and CompSA patients.
-
Integrated Comfort: Like CPAP, all BiPAP machines include integrated heated humidification and should be used with Heated Tubing to ensure warm, moist air delivery and maximum comfort.
-
Advanced Modes: Look for modes like VAuto (Resmed), which intelligently adjust the pressure support to make breathing even smoother and more responsive to natural breathing cycles.
Who is BiPAP Therapy Not For?
If you have routine Obstructive Sleep Apnea and are comfortable with a low-to-moderate pressure setting (e.g., 4-10 cm H20), there is generally no medical reason to switch to a BiPAP machine. BiPAP therapy is more specialized and often more expensive, meaning it is reserved for those who require its specific clinical advantages.
The final determination of whether a BiPAP machine is right for you must be made by a sleep specialist or pulmonologist. If you feel your current CPAP pressure is too high, discuss a change in settings or a potential upgrade to BiPAP with your physician. For more information, our customer care team at The CPAP Shop would be happy to help you! Contact us by calling 866-414-9700.
