Table of ContentsView AllTable of ContentsSleep Apnea SeverityDetermining Required CPAP PressureFactors That Affect the Pressure SettingComplications of Incorrect Settings
Table of ContentsView All
View All
Table of Contents
Sleep Apnea Severity
Determining Required CPAP Pressure
Factors That Affect the Pressure Setting
Complications of Incorrect Settings
If you’ve been prescribedcontinuous positive airway pressure (CPAP)therapy to treat obstructivesleepapnea, your prescribed CPAP setting is related to several factors—the severity of your sleep apnea, as well as the anatomy of your throat muscles, your sleep position, and the timing of your sleep stages throughout the night.
This article explains the key factors that your sleep physician uses to determine the correct setting, as well as how the device can automatically adjust the settings based on your needs.
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Obstructive sleep apnea (OSA) is diagnosed with an overnightsleep studyor home sleep apnea test that assesses the number of times per hour the upper airway collapses, resulting in a drop in blood oxygen levels or awakenings from sleep.
If the airway completely collapses, it’s called apnea. If it partially collapses, it’s calledhypopnea. The total number of these events per hour of sleep is known as theapnea-hypopnea index (AHI).
You might think that severe OSA requires a higher CPAP pressure setting to treat it. In actuality, this is not always the case as there are multiple factors involved in determining the required setting. Typically, the treatment starts at a low setting and is gradually increased to resolve all apnea and hypopnea events, as well as snoring.
Learn AHI RatingsThe AHI values and corresponding ratings are:Less than 5 (<5): Normal, meaning no sleep apnea5 to 15: Mild sleep apnea15 to 30: Moderate sleep apneaMore than 30 (>30): Severe sleep apnea
Learn AHI Ratings
The AHI values and corresponding ratings are:Less than 5 (<5): Normal, meaning no sleep apnea5 to 15: Mild sleep apnea15 to 30: Moderate sleep apneaMore than 30 (>30): Severe sleep apnea
The AHI values and corresponding ratings are:
The lowest setting on CPAP machines may be 4 to 5 centimeters of water pressure (abbreviated as cm of H2O or CWP). Most people require more pressure than this low setting. The maximum setting varies with the type of machine, but it could be as high as 25 or 30 CWP. The average setting often lies between these two extremes. Levels above 15-20 CWP may require a change tobilevel therapy,(BPAP).
If the CPAP setting is determined as part of an overnight titration study in a sleep lab, apolysomnographytechnologist will observe your breathing patterns and adjust the setting upwards while you sleep. This is done remotely from another room so that you are not disturbed.
The goal is to eliminate snoring, sleep apnea, and hypopnea episodes, and for deep sleep, including rapid eye movement (REM) sleep, to be observed in your sleep study. This setting should also be optimized while sleeping supine (on your back) when sleep apnea often worsens.
Self Adjusting Machines
Some people are sent home with a self-adjusting CPAP machine, sometimes calledAutoCPAP or APAP. With this, the prescribing physician recommends a range of pressures. The machine will start low and adjust upwards as needed in response to measured airway resistance. Airway resistance suggests persistent collapses of the soft tissues, like the base of the tongue or soft palate into the throat.
The CPAP delivers intermittent pulses of extra air pressure to evaluate for resistance, which indicates that the upper airway is collapsing.If the airway stays open at the CPAP setting delivered, the setting is maintained.
People with more severe sleep apnea might need higher pressure on CPAP or BPAP, which offers varying degrees of pressure.Childrenmay require similar pressure levels to adults, despite their smaller overall size and the smaller dimension of their airways.
Settings Can Defy AssumptionsThe required CPAP pressure does not always directly correlate with the severity of sleep apnea. Some people with mild OSA need high pressures and some people with severe OSA need relatively modest pressure.
Settings Can Defy Assumptions
The required CPAP pressure does not always directly correlate with the severity of sleep apnea. Some people with mild OSA need high pressures and some people with severe OSA need relatively modest pressure.
The anatomy of the upper airway and the nature of the airway obstruction play the biggest role in determining the required CPAP pressure setting. Factors that affect the pressure setting include:
Anatomy Influences SettingsThe biggest influences on CPAP settings are the anatomy of the upper airway and the nature of the airway obstruction.
Anatomy Influences Settings
The biggest influences on CPAP settings are the anatomy of the upper airway and the nature of the airway obstruction.
Given these factors, it’s not always easy to determine how much CPAP pressure you may need to treat your sleep apnea. It may also vary somewhat during the night, depending on your sleep position and sleep stage.
Remember the MaskA CPAP mask can deliver air through the nose or the mouth. The choice of which type of mask to use is up to you (whether you’re a nose breather or a mouth breather), but the mask must fit well. There are no differences in efficacy among the different mask types. The best mask is the one you find comfortable and will wear regularly.
Remember the Mask
A CPAP mask can deliver air through the nose or the mouth. The choice of which type of mask to use is up to you (whether you’re a nose breather or a mouth breather), but the mask must fit well. There are no differences in efficacy among the different mask types. The best mask is the one you find comfortable and will wear regularly.
Summary
It can take some time to get a diagnosis and to find the right settings, but most people feel that the effort pays off substantially.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Division of Sleep Medicine at Harvard Medical School.Understanding the results.Sleep Foundation.CPAP pressure settings.Al-Otaibi HM, Alahmari MD, Al-Maqati TN, Ghazwani A.Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants.Can J Respir Ther. 2020 Jul 23;56:21-24. doi:10.29390/cjrt-2020-005Division of Sleep Medicine at Harvard Medical School.Understanding PAP.
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Division of Sleep Medicine at Harvard Medical School.Understanding the results.Sleep Foundation.CPAP pressure settings.Al-Otaibi HM, Alahmari MD, Al-Maqati TN, Ghazwani A.Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants.Can J Respir Ther. 2020 Jul 23;56:21-24. doi:10.29390/cjrt-2020-005Division of Sleep Medicine at Harvard Medical School.Understanding PAP.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Division of Sleep Medicine at Harvard Medical School.Understanding the results.Sleep Foundation.CPAP pressure settings.Al-Otaibi HM, Alahmari MD, Al-Maqati TN, Ghazwani A.Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants.Can J Respir Ther. 2020 Jul 23;56:21-24. doi:10.29390/cjrt-2020-005Division of Sleep Medicine at Harvard Medical School.Understanding PAP.
Division of Sleep Medicine at Harvard Medical School.Understanding the results.
Sleep Foundation.CPAP pressure settings.
Al-Otaibi HM, Alahmari MD, Al-Maqati TN, Ghazwani A.Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants.Can J Respir Ther. 2020 Jul 23;56:21-24. doi:10.29390/cjrt-2020-005
Division of Sleep Medicine at Harvard Medical School.Understanding PAP.
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