What Is Hypopnea, and Is It Serious?
Hypopnea is defined as a decrease in respiratory airflow of 30% or more. It must also cause partial awakening during sleep or a decrease in oxygen saturation of at least 3%. This is according to the American Academy of Sleep Medicine (AASM).
Oxygen saturation refers to the percentage of hemoglobin molecules in your blood that are bound to an oxygen molecule. It is a measure of how well your lungs are functioning.
A quick way of measuring oxygen saturation is to use pulse oximetry. Doctors take this measurement by placing an infrared sensor on your finger.
According to the American Lung Association, a healthy oxygen saturation level is anything higher than 90–92%.
Both hypopnea and apnea are conditions in which breathing is decreased during sleep.
The AASM defines apnea as a 90% or more decrease in airflow for at least 10 seconds. Apnea can involve complete pauses in breathing.
Hypopnea is a reduction in airflow rather than a pause. However, the definition of hypopnea is controversial. In fact, researchers may refer to both hypopnea and apnea as “sleep-disordered breathing.”
Researchers have not identified specific causes of hypopnea separate from those of apnea. As a form of sleep-disordered breathing, hypopnea can be classified as central, obstructive, or both.
Central sleep apnea is much less common than obstructive sleep apnea. In a study of 5,804 adults, researchers found that about 1 in 100 participants had central sleep apnea. By contrast, almost half of participants had obstructive sleep apnea.
Central apnea-hypopnea is caused by improper signaling from the brain. Nerve signals may be disrupted between the brain and the diaphragm, the muscle that allows you to breathe. This disruption of breathing muscle function is a defining characteristic of central apnea-hypopnea.
Risk factors for central apnea-hypopnea include:
- drugs such as opioids, which depress breathing function
- high altitude
- neurological conditions such as:
You may be more at risk for obstructive apnea-hypopnea if you:
- have obesity or are overweight
- are middle-aged
- are male
- have high blood pressure
- have a thyroid or other endocrine disorder
- have large tonsils or a thick neck
- experience airway anomalies such as deviated septum
- have a family history of obstructive sleep apnea
Hypopnea affects your quality of sleep by causing you to partially awaken several times during the night. Symptoms of hypopnea can be related to poor sleep as well as decreased oxygen in your blood. They can be similar to those of sleep apnea and may include:
- daytime sleepiness
- morning headaches
- decreased libido
- frequent need to urinate at night
A sleep or living partner may also notice symptoms such as:
- pauses in your breathing
- gasping for air
When to contact a doctor
Contact your physician if you experience symptoms of hypopnea or a sleep partner notices symptoms such as snoring or gasping.
To diagnose hypopnea, your doctor may perform a physical and ask for a complete medical history. This can include any family history of sleep-related respiratory disorders.
Your doctor will assess your general health and identify possible risk factors. They may then order a sleep study or ask you to keep a sleep diary.
Although there are some sleep studies you can do at home, your physician may recommend a study done at a sleep center.
A study at a sleep center may involve taking a polysomnograph test. This test takes different measurements using sensors attached to your body. These sensors will monitor your:
- breathing effort and rate
- brain waves, using an EEG
- heart rate
- blood oxygen saturation
- muscle activity
The apnea-hypopnea index
The apnea-hypopnea index (AHI) is a way of quantifying apnea and hypopnea events. It can help physicians determine the severity of these events and recommend appropriate treatments.
Your AHI is calculated using a wearable monitor. The monitor records the total number of apnea-hypopnea events you experience during a night of sleep. It then divides this by the number of hours you slept.
- normal: less than 5 events per hour
- mild: 5–14 events per hour
- moderate: 15–29 events per hour
- severe: more than 30 events per hour
Treatment for hypopnea will depend on your symptoms and their severity. Treatment options may include:
- Continuous positive airway pressure (CPAP) therapy: This helps maintain pressure in the trachea during sleep.
- Oral appliances: These reposition the jaw or tongue to prevent blockage of the airway.
- eXciteOSA: This is a device approved by the Food and Drug Administration (FDA) to help strengthen the tongue and decrease apnea-hypopnea events.
- Orofacial therapy: This strengthens the tongue and upper airway muscles.
- Surgeries: These can include:
Left untreated, sleep apnea and hypopnea can have serious consequences. According to the NHLBI, low oxygen saturation during sleep can increase your risk for certain conditions, including:
- heart and blood vessel conditions including:
- metabolic syndrome and type 2 diabetes
- pregnancy complications
- certain cancers including renal and pancreatic cancers
- chronic kidney disease
- eye conditions such as glaucoma
- respiratory complications during surgery
Contact your doctor if you have symptoms of hypopnea. They can help you design a treatment plan to manage your hypopnea and lower your risk for more serious conditions.
The following frequently asked questions were reviewed by Thomas Johnson, PA-C.
Does CPAP help with hypopnea?
With correct and consistent use, a CPAP machine can help reduce symptoms of hypopnea.
Contact your physician or a respiratory therapist if your mask fit changes or you experience symptoms while using your CPAP machine. Your settings may need an adjustment.
How many hypopnea episodes per hour is considered normal?
Clinicians consider anything less than 5 apnea-hypopnea episodes per hour to be normal breathing.
Hypopnea and apnea are potentially serious conditions. They disrupt sleep and reduce the amount of oxygen in your blood.
Left untreated, hypopnea and apnea can increase your risk for heart, vascular, and respiratory diseases.
Hypopnea is treatable with a physician’s assistance. Treatment may include lifestyle changes, breathing or oral appliances, and surgery. Correctly following your treatment plan may help to lower your risk for complications.