What is the Difference Between a CPAP and a BiPAP Machine?

bipap machine

BiPAP – or Bi-Level Positive Airway Pressure is a medical grade device similar to a CPAP. The function and the overall design are similar, and the BiPAP is also a non-invasive form of oxygen therapy. Both the CPAP and the BiPAP deliver pressurized air into the lungs of the patient, in order to maintain the airways open and prevent obstruction (or apnea). The pressurized air maintains the muscles and the throat open and prevents collapse. Both devices help patients enjoy a restful night of sleep by delivering required pressurized oxygen into the lungs.

The difference between a CPAP and BiPAP

CPAP treatment

Physicians prescribe the use of a CPAP machine for patients with OSA – Obstructive Sleep Apnea. The CPAP delivers a steady and continuous flow of pressurized air into the lungs. Patients will typically undergo a titration study which will help physicians determine the right level of pressure needed to successfully maintain the airways open.

The CPAP can be set to deliver one single level of pressure, which remains the same at both inhalation and exhalation phase. Some CPAP devices have the so-called “Ramp” feature which means that the treatment starts on a lower than prescribed pressure for a given period of time. Usually, Ramp feature helps patients fall asleep on a gentler pressure. When the RAMP time is up, the machine will return to delivering the higher, prescribed pressure of oxygen. This type of gentle pressure will basically make therapy more compliant, at least in the incipient phase. Many patients using CPAP for the first time will find the Ramp feature very useful and comfortable.

The BiPAP- who requires BiPAP machines?

Patients who require very high-pressure setting in order to get required therapy will find it difficult to exhale against the same type of higher intensity pressure. The higher level of pressure is needed upon inhalation to maintain the airways open. However, the CPAP will maintain the same pressure even at the exhalation phase. This is where the difference lies between a CPAP and BiPAP.
Just as its name suggests, Bi-Level means that the BiPAP can be set at two different pressures. Physicians can set the higher required pressure upon the inhalation phase and then set a much lower, more comfortable pressure for the exhale phase. This way, patients can enjoy the required therapy, while getting enough relief upon exhalation.

The BiPAP machine also has a breath timing feature. This feature helps in to measure the exact amount of breaths the patient should take. In case the time in-between breaths exceed this limit (there are too many pauses), then the device can actually increase air pressure on a temporary basis and this way somehow “force” the patient to breathe.

The two different types of pressure settings on a BiPAP are called iPAP and Epap. The ipap is the prescribed pressure level required for inhalation, and the epap is the pressure level for the exhalation phase. Thanks to these two different settings, patients can get the required oxygen to their lungs, and then exhale very comfortably against a gentle pressure, getting ready for the next shot of pressurized air.

Patients with very low blood oxygen levels are generally prescribed BiPAP therapy
BiPAP machines can also be prescribed for patients with higher than usual requirements regarding pressure levels
Congestive heart failure patients typically need a BiPAP instead of a CPAP
A physician can prescribe the use of a BiPAP for patients with neuromuscular disorders or lung complications

Can CPAP with C-Flex be used instead of a BiPAP?

BiPAP therapy

C-Flex is a special feature on some CPAP models. The C–Flex is regarded as a comfort feature, and its role is to offer some pressure relief. The C-Flex reduces the air pressure upon exhalation, but only with about 3cm. However, the pressure relief offered by a BiPAP starts at 4cm and going upwards. The CPAP device with C-Flex technology represents the ideal solution for those patients who require only minimal relief upon exhalation.

Also, the BiPAP maintains a steady and continuous pressure relief, depending on the setting. The C-Flex, on the other hand, offers pressure relief that is not constant (not fixed). The reductions in pressure can vary from one breath to the other when using the C-Flex feature. The BiPAP offers the same steady pressure drop all throughout therapy.

Before using BiPAP therapy

First, you need to go through the titration study so that your physician can determine the required pressure levels for optimal treatment. Next, your doctor will be able to tell if a BiPAP machine is recommended, or if a CPAP or CPAP with C-Flex feature should be used. In case you need to use a CPAP, and you have encountered problems when exhaling against a higher pressure, discuss with your doctor the possibility of getting a BiPAP instead.