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People with obstructive sleep apnea (OSA) stop breathing for brief intervals during sleep due to blocked or collapsed airways. Continuous positive airway pressure (CPAP) machines are commonly prescribed to treat the condition following the results of a sleep apnea test. The devices deliver pressurized air to help normalize breathing. The right amount of pressure is critical to effective CPAP therapy, as pressure that is too low or too high can create adverse side effects.

We’ll discuss how CPAP pressure is measured and the various factors that determine pressure needs. We’ll highlight signs and symptoms that suggest your pressure level might need adjusting, in which case it’s important to contact your doctor. Pressure settings should only be changed under the guidance of a medical professional.

How to Determine the Proper Pressure Setting for a CPAP Machine

Pressure in a CPAP machine is measured in centimeters of water pressure (cm H2O). Settings vary based on the device, but most CPAP machines have a pressure range of 4 cm H2O to 20 cm H2O. Some machines go as high as 30 cm H2O, but this is less common. The average pressure setting Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference for people with OSA is around 10 cm H2O.

A CPAP titration study is the most common method used to determine an appropriate pressure level. Similar to a sleep study, the assessment is usually done overnight at a sleep center or hospital. Sensors are attached to your body to monitor oxygen levels, breathing, heart rate, brain waves, and body movements. A physician or sleep specialist calibrates CPAP pressure levels until the lowest amount of pressure needed to keep airways open is determined.

The apnea-hypopnea index (AHI) assesses how many times a person stops breathing or breathes shallowly while asleep, which helps medical professionals determine CPAP pressure settings. Most modern CPAP machines keep track of your AHI, which lets you and your doctor know if your pressure level needs to be modified.

You will also be fitted for a CPAP mask during the study, which is crucial for effective treatment. CPAP masks come in a variety of styles, including full-face masks, nasal masks, and nasal pillows.

After the study, your doctor will discuss your optimal pressure range. They can also make recommendations about how to use a CPAP machine based on your results.
 

 

Factors That Affect the Pressure Setting of a CPAP Device

A number of factors determine the severity of OSA Trusted Source MSD Manuals First published in 1899 as a small reference book for physicians and pharmacists, the Manual grew in size and scope to become one of the most widely used comprehensive medical resources for professionals and consumers. See Full Reference and a person’s appropriate CPAP pressure setting. Some are anatomical, while others relate to lifestyle and sleep habits.

  • Anatomical factors: People with craniofacial or upper airway abnormalities such as a small lower jaw, a large tongue or tonsils, or a neck circumference greater than 17 inches may be at greater risk of developing OSA and may require higher CPAP pressure levels.
  • Deviated septum: A deviated septum Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference limits airflow through the nose, so a higher amount of pressure may be needed to keep the upper airway open.
  • Body mass index (BMI): Overweight people are more likely to have extra throat tissue that restricts airflow to the lungs. Pressure requirements tend to increase with a person’s weight Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference , so people who lose a significant amount of weight usually need to lower their pressure setting.
  • Nasal allergies: Allergies and nasal congestion Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference can make breathing more difficult, thereby reducing oxygen intake. In addition to calibrating pressure settings, a CPAP machine with a humidifier can sometimes help people with allergies. Regularly cleaning filters can also reduce allergen triggers.
  • Sleep position: Back sleeping is generally believed to be the worst position for sleep apnea Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference because the pull of gravity puts pressure on the airways. Back sleepers therefore usually require higher pressure settings. Experts recommend side sleeping Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. See Full Reference for people with OSA because it puts less weight on the upper airways.

The Benefits of Having CPAP Pressure Properly Set

Proper CPAP pressure levels help alleviate conditions associated with sleep apnea, such as snoring and sleep disturbances. If you’re not experiencing better sleep quality after CPAP therapy, you will probably need to consult with your doctor about adjusting your pressure settings. Here are telltale signs that your pressure is either too low or too high:

  • Your CPAP pressure is too low: If you still wake up feeling groggy or unrefreshed after using a CPAP machine, your airways might not be getting enough oxygen to stay open. Heavy snoring, feeling like you’re choking, or a lack of improvement in high blood pressure Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference may be signs that your CPAP pressure is too low. If your AHI does not improve once you have fully integrated CPAP therapy into your sleep routine, it may also be an indication that the settings should be adjusted.
  • Your CPAP pressure is too high: Discomfort is the strongest clue that your pressure setting Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. See Full Reference is too high. Struggling to exhale, nose and mouth dryness, or a burning sensation in the throat are common symptoms of excessive pressure. Some people also experience mask leaks, fluid in the ears, and gas or belching from swallowing air.

APAP Machines

If you continue to have issues with pressure settings on your device, your doctor might prescribe an automatic positive airway pressure (APAP) machine. This device automatically changes pressure levels based on a user’s breathing patterns. The machine starts at a low setting and then increases according to changes in breathing and airway resistance.

Even though APAP machines automatically adjust pressure levels, a physician still needs to prescribe an ideal pressure range suited to your needs. If the range is off, you may experience adverse side effects.

Frequently Asked Questions

How do I know if my CPAP pressure needs adjusting?

If you consistently experience discomfort during CPAP therapy, or you are not noticing any improvements in your sleep or health, then you probably need to adjust the pressure settings. Persistent fatigue, loud snoring, mask leaks, and difficulty exhaling all indicate suboptimal pressure levels. An above-average AHI level suggests that your pressure setting may be too low.

What pressure should my CPAP be set at?

A physician determines proper pressure settings based on your CPAP titration study and AHI. Your pressure might need to be adjusted later if you lose or gain significant weight, change your sleep position, or start taking certain medications. Always speak with your doctor if you suspect your pressure level needs fine-tuning.

How do I adjust my CPAP pressure?

If you think your pressure level needs adjusting, contact your doctor’s office and bring your CPAP machine to the appointment. Your doctor will evaluate data from the device and make changes as needed. Pressure settings should only be changed under medical supervision.

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