How to Set the Pressure on Your CPAP Machine

A CPAP machine is one of the most commonly prescribed¹ treatments for those with sleep apnea. It delivers a continuous flow of air pressure to keep the airway from collapsing during sleep, ultimately keeping your oxygen levels steady throughout the night.¹ 

Your machine must deliver the right amount of pressure, specifically for you, or else it could be ineffective. In this article, we’ll discuss how you’ll determine your particular pressure setting, signs that your setting is too low or too high, different factors that can impact your pressure setting, side effects of using the wrong CPAP pressure setting, and auto-adjusting devices. 

If you’re using a CPAP machine for sleep apnea and feel like your settings are not working for you, be sure to contact your doctor as only medical professionals should change CPAP pressure settings. 

Determining the Correct Pressure Setting for Your CPAP Machine 

To determine your CPAP pressure settings, you’ll first need to undergo a CPAP titration study². This study is similar to an overnight sleep study to diagnose sleep apnea. However, in a titration study, you’ll be using a CPAP device. 

A sleep specialist will gradually increase the CPAP’s air pressure until they observe your breathing and oxygen levels becoming normal. They’ll stop at the lowest pressure setting that allows for normal breathing, record this number for your CPAP prescription, and then the pressure setting is programmed into your at-home CPAP machine. 

The settings are measured in centimeters of water pressure³ (cm H2O). Most people with sleep apnea fall between 5 to 10 cm H2O, though yours might be more or less than this.³ Your setting will depend on the severity of your sleep apnea, also known as your apnea-hypopnea index (AHI). 

AHI is the combined average number⁴ of apneas and hypopneas that occur each hour of your sleep. An “apnea” is when your breathing stops⁵ during sleep. A “hypopnea” is when breathing becomes shallow, which keeps you from taking in enough oxygen.⁵

According to the American Academy of Sleep Medicine⁶, those with mild sleep apnea have about 5 to 15 events per hour (including both apneas and hypopneas). Moderate sleep apnea is considered 15 to 30 events per hour, and those with severe sleep apnea have more than 30 events per hour.⁶ 

Generally, people with more severe sleep apnea will likely require higher pressure settings. Most modern CPAP machines will also keep track of your AHI, which can then let the doctor know whether or not your CPAP machine is doing its job or whether pressure settings need to be adjusted. 

Never adjust your CPAP’s pressure settings on your own. Though your pressure requirements may change over time (due to age, weight fluctuations, or even allergies), you’ll need to discuss this with your sleep specialist to get expert help changing your machine’s pressure settings. 

Signs Your CPAP Machine’s Pressure Needs Adjusting

As mentioned, most modern CPAP machines track the number of apneas and hypopneas you’re experiencing through the night. If your machine is calibrated correctly, this number should be less than five⁷ (but may not necessarily get to zero).

However, even without looking at your AHI, there are some signs you may notice if your machine’s pressure is too low or too high. 

Signs CPAP Pressure Is Too Low

If your pressure is set too low, you’ll likely still experience sleep apnea symptoms⁸ like fatigue, insomnia, dry mouth in the mornings, headaches, heavy snoring, choking or gasping for air in the night, or problems with blood pressure⁹. 

Signs CPAP Pressure Is Too High

CPAP machines with pressure settings that are too high¹⁰ may lead to difficulty exhaling, discomfort in the nose, mouth, or airway, nasal congestion, mask leaks, sore throat, or gas, bloating, or stomach pain. People whose pressure is too high might also end up removing the mask at some point during the night because of the discomfort.

How to Know CPAP Pressure Is Correct

Your pressure is probably okay if you notice an improvement in your sleep and a cessation of symptoms like snoring, gasping for breath, and next-day fatigue. You can also pay attention to the machine’s AHI monitor – if it is below five (or your ideal number given to you by your doctor), your setting is probably working for you.⁷ 

This doesn’t mean that it won’t take time to get used to your CPAP machine. Experts say that it could take several weeks¹¹ to get used to sleeping with your CPAP. To help in this transition, you can practice wearing it during the day when you’re not sleeping. 

Learn more: 9 Tips for Sleeping Better with CPAP

What Can Affect the Pressure Setting of Your CPAP Machine?

A patient’s CPAP pressure setting will depend on the severity of their sleep apnea. However, other factors, some of which might change over time, could also influence this. 

• Allergies – Allergies that cause nasal congestion or coughing can make using a CPAP more difficult. If this is the case, your doctor might want to tweak your pressure settings. If you find that the CPAP itself is causing you congestion, make sure that the mask is snug and not leaking any air. Also, machines with humidifiers could help alleviate congestion.¹¹ 

• Facial Structure – Certain facial characteristics¹² are linked to the severity of sleep apnea. For example, a wider and flatter mid to lower face, a shorter and smaller jaw, and more soft tissue or fat in the neck can help predict the severity of sleep apnea.¹² 

• Obesity – The more overweight a person is, the more severe¹³ their sleep apnea tends to be, which can correlate to higher pressure settings. However, researchers found significant AHI improvements¹⁴ in people with obstructive sleep apnea who experience loss of tongue fat following weight loss. 

• Deviated Septum – The septum¹⁵ is the bone and cartilage that runs down the center of the nose and nostrils, separating the nose into two sides. When the septum is “deviated,” it is crooked, and this can make breathing difficult. A higher CPAP pressure setting may be required for those with a deviated septum.

• Sleep position – Sleeping on your back can make sleep apnea worse¹⁶ because gravity allows the airway to further collapse and the tongue to fall backward. Those who sleep on their backs may need a higher pressure setting because of this.

Side Effects of Having the Wrong CPAP Pressure 

If your CPAP machine has the wrong pressure settings, the short-term side effects might include snoring, headaches, trouble sleeping, fatigue, difficulty breathing through your mask, congestion, sore throat, and stomach problems.^8,10

Long-term, though, a CPAP with the wrong pressure settings can result in more serious complications. This is because the machine will be less effective at actually treating your sleep apnea. Symptoms of untreated sleep apnea include a higher risk for vehicular and workplace accidents, high blood pressure and heart problems, type 2 diabetes, metabolic syndrome, liver issues, and complications with certain medications or surgeries.⁸ 

Auto-Adjusting Machines

There’s also the option of an APAP machine, which is an auto-adjusting¹⁷ positive airway pressure device. Unlike a CPAP, which delivers one continuous level of air pressure, an APAP measures your respiratory events during sleep and automatically adjusts its pressure accordingly.¹⁷ 

Some people find that an APAP is preferable because it automatically adjusts to factors such as weight fluctuations, having a cold, drinking alcoholic beverages, or sleeping in a different position.¹⁷.If your doctor determines APAP therapy is a viable option for you, they will provide a set pressure range for the device.

If you find that any positive airway pressure device negatively impacts your sleep, you might also discuss alternative CPAP treatment options with your doctor. However, never discontinue your CPAP therapy or start a new treatment without consulting your doctor.

Frequently Asked Questions