BIPAP or CPAP: How It Works, Which One is Better and More!

Brandi W. Cortright
If you’re considering a BIPAP or CPAP machine, you’ve been diagnosed with sleep apnea.

Obstructive sleep apnea and snoring occur when tissues of the upper airway, the tongue, and the throat relax during sleep. Relaxation of these tissues and muscles causes an obstruction and vibration of the airway, making breathing difficult and noisy.

This condition is referred to as snoring. Eventually, the tissues of the airway collapse, resulting in a breathing pause or apnea. As a result, you must work harder to breathe, and oxygen in the blood is reduced. This alerts the brain to awaken you, which temporarily disrupts your sleep.

This cycle repeats itself many times during sleep, causing you to wake up in the morning feeling sluggish, possibly with a morning headache, because of poor brain oxygenation during sleep. To treat this condition, your health care provided may suggest CPAP or BIPAP.

When considering BIPAP (Bilevel Positive Airway Pressure) and CPAP (Continuous Positive Airway Pressure) machines for treating sleep apnea, it's crucial to understand their distinct features. Both are non-invasive ventilation therapies that aim to enhance breathing during sleep, but they cater to different respiratory needs. Let's delve into the differences between these two devices:

Pressure Two levels: inhalation and exhalation Single, continuous level
Best for Severe respiratory distress, COPD, ARDS Obstructive sleep apnea
Cost Generally more expensive More affordable
Motion Good motion isolation Good motion isolation
Air Pressure Higher pressure during inhalation, lower pressure during exhalation Constant pressure during inhalation and exhalation
Use Cases Central Sleep Apnea, Complex Sleep Apnea Obstructive Sleep Apnea

BIPAP and CPAP are both non-invasive ventilation therapies used to treat sleep apnea, but they have some key differences. BIPAP delivers two levels of air pressure, one for inhalation and one for exhalation, while CPAP delivers a continuous, single level of air pressure throughout the breathing cycle 1.

Table Of Contents

BIPAP (Bilevel Positive Airway Pressure)

BIPAP devices offer a unique approach by delivering two distinct air pressure levels: higher pressure during inhalation and lower pressure during exhalation. This feature is particularly beneficial for individuals who find exhaling against the continuous pressure of CPAP challenging.

BIPAP machines are often prescribed for those with more severe respiratory conditions like COPD, as they offer a more accommodating therapy option. Due to their dual pressure settings, BIPAP devices ensure that exhaling feels natural and comfortable, enhancing overall therapy adherence.

Moreover, BIPAP machines have the capability to deliver supplemental oxygen if required, providing an added layer of flexibility in treatment. It's worth noting that BIPAP machines are generally more advanced and come at a higher cost compared to CPAP machines.

CPAP (Continuous Positive Airway Pressure)

CPAP machines, on the other hand, provide a consistent flow of air pressure throughout the breathing cycle. This constant pressure effectively maintains the openness of the airway during sleep, making it an effective treatment for obstructive sleep apnea. CPAP therapy is often the first line of treatment for sleep apnea due to its proven effectiveness and user-friendliness.

These machines are suitable for individuals with mild to moderate sleep apnea and are generally more affordable compared to BIPAP machines. CPAP devices play a crucial role in improving sleep quality, alleviating sleep apnea symptoms, and ensuring better overall health outcomes.

1,934 Reviews Analyzed

Why Do People Snore?

Normally, when you breathe in, air flows through your mouth and nose and down your throat to your lungs. With each breath, air pressure and the throat muscles respond to keep the airway open.

When the muscles relax too much, the tongue can fall back on to the soft palate, which can cause the airway to narrow. When the air passage narrows, the air pressure is increased and in turn causes the tissue at the back of the throat to vibrate and cause the snoring sound.

Bulky throat tissue that is overweight can cause snoring. This usually happens in children, but when their tonsils or adenoids get removed the problem normally subsides.

If you have a long soft palate or a long uvula, the opening between the nose and the throat can get obstructed. When they bump up against one another while your airway gets blocked and causes snoring.

Habitual snorers can be at risk of serious health problems, including obstructive sleep apnea and central sleep apnea.

What is Obstructive Sleep Apnea?

Sleep apnea is a disorder where the tongue falls back onto your soft palate, pressing it onto your throat causing the airway to become completely blocked. When this happens, the lack of air wakes you up gasping for air before falling back to sleep again.

Apart from causing a night of restless sleep, obstructive sleep apnea can have serious health implication. It meets the apnea criteria and is associated with continued or increased inspiratory effect throughout the entire period of absent airflow.

What is Central Sleep Apnea?

With central sleep apnea, the patient’s breathing repeatedly stops and starts during sleep because of a lack of respiratory effort. When this lack of respiratory effort occurs, the brain fails to transmit the proper signal to the breathing muscles.

Signs of this condition include: observed episodes of stopped or abnormal breathing patterns while sleeping. This is noticed by a sleep partner rather than the person with the sleep apnea.

Abrupt awakening with a shortness of breath, insomnia, excessive daytime sleepiness, problems with concentration, and loud snoring. People who experience some or all of these symptoms are recommended to seek medical attention.

What is a CPAP Machine?

Before understanding if BIPAP or CPAP is the best choice, you need to understand what a CPAP machine is.

Continuous Positive Airway Pressure (CPAP) is the most effective treatment for obstructive sleep apnea. This treatment involves wearing a mask over the nose, and sometimes over the mouth and the nose.

The mask is connected to a flow generator by six feet of corrugated tubing. The flow generator develops a predetermined air pressure that prevents the tissues of the airway from collapsing. The open air route prevents snoring and apnea.

The CPAP machine does not breathe for you, but rather keeps your airway open so that you are able to breathe freely. It is important to know that Continuous Positive Airway Pressure is regular room air and not the delivery of oxygen.

Sometimes oxygen is used in addition to CPAP for those with poor oxygen levels. Remember, this is a treatment for apnea and snoring and not a cure. You will need to use it all night every night to experience the benefits of this treatment.

In order to get a CPAP device, you would need a diagnosis from your health care provider. Then you will be sent to a sleep study. Therefore, there is a process. Being diagnosed doesn’t mean you will be able to make a purchase right away.

CPAP Benefits and Side Effects


When deciding BIPAP or CPAP, the side effects should be considered.

Continuous Positive Airway Pressure can reverse or prevent the effects of obstructive sleep apnea. This therapy can help protect your body against serious health risks, such as heart disease, stroke, diabetes, and automobile accidents.

Sleep apnea is associated with a number of heart problem, since it impairs or pauses your breathing every night. This results into significant changes in the blood pressure. As a result, it reduces blood oxygen levels, which puts a lot of straining on your heart.

Individuals who suffer from untreated sleep apnea do usually present higher cases of heart diseases compared to those with treated sleep apnea. Using this therapy over time will protect you from major heart problems.

The major heart problems that this therapy will protect you from are: irregular heartbeat, coronary artery disease, and congestive heart failure.

If you are suffering from apnoea, the use of Continuous Positive Airway Pressure can minimize the risk of stroke, which is one of the major causes of long-term disability and death. Stroke refers to a rapid loss in the brain function.

It is defined as an impairment of the blood flow supplying the brain that results in acute clinical syndrome lasting more than twenty-four hours. There is a clear neurological deficit and some degree of permanent brain damage.

Based on the blood vessel involved the symptoms are different and specific and often help pinpoint the exact location of the lesion in the central nervous system. There are different types of stroke, including ischemic and hemorrhagic.

Side Effects

Continuous Positive Airway Pressure is relatively safe for patients with obstructive sleep apnea. Nonetheless, some discomfort as well as rare complications have been noted following long-term use. The more common side effects include flow related, mask, and nasal problems. High CPAP can have a detrimental effect on the cardiovascular system. The effects include:

  • Increased pulmonary vascular resistance and increased extra pulmonary shunts.
  • Decrease oxygen available to tissues.
  • Decreased regional and peripheral blood flow.
  • Compression of right sided vessels, decreasing cardiac return, resulting in decreased cardiac output.

Decrease in cardiac output can significantly lead to reduced arterial blood pressure, tachycardia, and acidosis. The amount of CPAP that is too much will produce this effect depends on the lung compliance.

If the lung compliance is low, less intra airway pressure will be transmitted to the pleural space and cardiac compromise will be less.

Excessive CPAP may be detected by the development of acidosis, increased carbon dioxide retention, and decreased dynamic lung compliance. A trial of lower continuous positive airway pressure or increased intravenous fluids will resolve the problem.

Continuous positive airway pressure can lead to decrease in glomerular filtration rate, which reduces the urine output. The renal effects are directly proportional to compliance of the chest wall. Decreased renal blood flow results in increased ADH secretion and aldosterone.

Application of continuous positive airway pressure can increase intracranial pressure. This occurrence along with a decrease in arterial pressure, results in the decrease in cerebral perfusion pressure.

Increase in intracranial pressure is seen more with head box continuous positive airway pressure than with endotracheal CPAP or nasal prongs. High intracranial pressure is instrumental in the pathogenesis of intraventricular hemorrhage in low birth weight babies.

Abdominal distention can occur in babies on continuous positive airway pressure. It is compounded by the presence of immature gut in preterm as well as a decrease in blood flow to the gut. All these events may lead to CPAP belly syndrome.

What is a BIPAP Machine?

Considering BIPAP or CPAP requires you to know how the BIPAP machine works.

BIPAP stands for Bilevel Positive Airway Pressure. It is very similar in design and function to a CPAP (Continuous Positive Airway Pressure) machine. Similar to CPAP machine, a BIPAP machine is a non-invasive form of therapy for people with sleep apnea.

Positive Airway Pressure is a great mode to help patients breathe better. BIPAP provides two levels of pressure, which include: a lower expiratory positive airway pressure (EPAP), and inspiratory positive airway pressure (IPAP).

The first one is your IPAP setting, which determines how much volume the patient will receive. If you increase the IPAP, you increase the volume. The EPAP determines how much peep you are applying to the alveoli to keep it open during exhalation.

On blood gas, if the Co2 is high you can correct that by giving more volume. Also, if the PaO2 is low, you can correct that by increasing the EPAP.

Let us look at an example so as to understand how the two pressures work. Blood Gas:

  • HCO3 – 26.7mEq/L
  • PaO2 – 81mmHg
  • PaCO2 – 50mmHg
  • pH – 7.33

In the above blood gas, the main issue is ventilation. The IPAP setting creates a small volume. Therefore, to correct that you need to increase inspiratory positive airway pressure so that the volume increases.

This should help correct the Co2. Also, the more you increase the difference between IPAP and EPAP, the more volume the patient receives. Therefore, in the above example, oxygenation is low, but ventilation is normal.

The general recommendation would be to increase the lower expiratory positive airway pressure. This should help bring the oxygen back to normal.

However, you have to be careful when increasing the EPAP, because as you fix oxygenation, you may actually reduce the volume. You can compensate by increasing IPAP simultaneously with the EPAP.

BIPAP has a higher pressure on inspiration than on exhalation, but both pressures are above ambient. For example, a BIPAP setting of 10/5 cm H2O implies an IPAP of 10 cm H2O and an EPAP of 5 cm H2O.

BIPAP Benefits and Side Effects


When compared to continuous positive airway pressure, bilevel positive airway pressure has superior benefits. In fact, BIPAP therapy will be considered the better treatment option for sleep apnea in the near future. Keep this in mind when choosing between BIPAP or CPAP.

According to research, patients with sleep apnea present better compliance rates with bilevel positive airway pressure machines. This therapy is more effective in blood gas level improvement and in terms of clinical status.

BIPAP’s latest technology, expiratory pressure relief, tracks the airflow of a patient during expiration as well as minimizes the pressure with respect to a patient’s requirements. Usually, the pressure is increased to avoid airway collapse near the end of expiration.

People suffering from COPD stand to benefit from bilevel positive airway pressure therapy. This is not usually the case with CPAP machine, since the patient may find it difficult to exhale against the positive pressure.

Research also shows that central apnea related to cerebrovascular accident or cardiac failure can be treated with bilevel positive airway pressure.

Generally, the BIPAP device is very effective for cardiopulmonary disorders, including congestive heart failure. It is also a suitable therapy for people with neuromuscular disorders or those who require improved breathing assistance.

Side Effects

In some situations, titration of BIPAP may result into central sleep apnea. The cause is uncertain, but it is likely due to excessive lung capacity when air for inspiration is higher compared to expiration air.

The most common side effects of this therapy that you are likely to experience are: claustrophobia, general discomfort, rhinitis, nasal congestion, and dry nose.

Complications from this form of breathing therapy are rare. However, bilevel positive airway pressure may not be the ideal treatment option for everyone with respiratory issues. The most alarming side effects are associated with worsening lung injury or function.

Difference between CPAP and BIPAP

Number of Pressures One, CPAP Two, IPAP & EPAP
Price Cheaper Expensive
Popularity Most Commonly Used Less Commonly Used
Who Benefits Most People with Less Severe Cases of Obstructive Sleep Apnea People with Severe Obstructive Sleep Apnea, Congestive Heart Failure, Chronic Obstructive Pulmonary Disorder, and Central Sleep Apnea

Continuous positive airway pressure (CPAP) provides positive airway pressure at a constant level during inspiration and expiration. Bilevel positive airway pressure (BIPAP) provides a higher pressure during inspiration and a lower pressure during expiration.

The primary usefulness of BIPAP is in patients who experience difficulty exhaling while using CPAP. By lowering the expiratory pressure, patients are more comfortable breathing out against the positive airway pressure.

Patients often ask why they don’t just start with BIPAP if it is more comfortable. Simply, most patients do fine with CPAP or the BIPAP units, which are much more expensive than CPAP. Your physician should have significant input in the decision between BIPAP or CPAP.


The choice between BIPAP and CPAP machines hinges on several factors, including the severity of sleep apnea, individual comfort, and specific respiratory conditions. BIPAP machines excel in offering dual pressure levels for enhanced comfort during exhalation, making them ideal for individuals with specific breathing challenges. CPAP machines, on the other hand, provide consistent air pressure to maintain airway patency during sleep and are a great starting point for sleep apnea therapy. To make an informed decision, I recommend consulting a healthcare professional who can assess your needs and recommend the most suitable therapy for your individual case.

For more insights into sleep apnea treatment options and to determine the best fit for you, I recommend exploring further resources provided by reputable medical institutions and sleep health experts.

Featured Reviews

434,296 Reviews Analyzed
223,303 Reviews Analyzed
339,284 Reviews Analyzed
208,373 Reviews Analyzed
157,594 Reviews Analyzed
6,037 Reviews Analyzed
1,934 Reviews Analyzed
2,885 Reviews Analyzed

Related Posts

Zinus Vs Lucid Vs Signature Sleep Mattress

There are numerous mattress brands out there, which promise to deliver quality products. It could get really hectic trying to find the one that best s...