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Dr. Abhinav Singh

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Written by

Elise Chahine

    Hypopnea is a sleep breathing disorder that causes shallow breathing episodes, called hypopneas, while people sleep. This restricted breathing lowers blood oxygen levels and, untreated, can be a risk factor for conditions like cardiovascular disease and diabetes. Sleep apnea and hypopnea are closely related, and the two disorders share similar symptoms, risk factors, and outcomes. The main difference is that people stop breathing entirely during an apnea event rather than only breathing shallowly, like they do during a hypopnea.

    Although hypopnea is a serious chronic disorder, effective treatments are available. Learning more about the disorder’s causes, symptoms, and effects can make it easier to spot and help you understand what treatment option may work best for you.

    What Is Hypopnea?

    Hypopnea is both a symptom of and the common name for a type of sleep breathing disorder. The definition of a hypopnea is 10 seconds or more of shallow breathing where you lose 30% to 90% of your normal airflow, with a blood oxygen saturation drop of 3% to 4% or accompanied with sleep fragmentation. The longer the hypopnea event, the worse of an impact it has.

    If someone experiences five or more hypopnea events per hour of sleep, they likely have a hypopnea sleep disorder. In addition to symptoms like excessive daytime sleepiness and mood disturbances, untreated hypopnea can increase the risk of heart attack, stroke, cardiovascular disease, diabetes, and liver fibrosis.

    Types of Hypopnea

    Just like sleep apnea, there are three types of hypopnea. They share symptoms, but each has different causes and may require different treatment methods. However, it can be difficult for medical professionals to identify which type of hypopnea a person has.

    • Obstructive hypopnea, also known as obstructive sleep apnea hypopnea syndrome (OSAHS), occurs when hypopnea events are caused by the partial blockage of a patient’s airway. When we sleep, the muscles and tissue in our throat naturally relax. In someone with OSAHS, those relaxed tissues cause narrowing in the throat that restricts airflow.
    • Central hypopnea describes hypopnea events caused by reduced breathing rather than reduced airflow. Like central sleep apnea, central hypopnea can be caused by problems with the brainstem and some medications.
    • Mixed hypopnea occurs when hypopneas are due to both reduced airflow and breathing. Despite being categorized separately, mixed hypopnea is considered part of OSAHS and occurs most often in people with severe OSAHS.

    How Is Hypopnea Different from Sleep Apnea?

    Sleep apnea and hypopnea are from the same family of sleep breathing disorders. While a hypopnea is a period of shallow breathing, an apnea is a complete pause in breathing. If someone suffers from a sleep apnea disorder, they may also experience hypopneas. However, people with a hypopnea disorder experience a greater number of hypopneas.

    Beyond the difference in breathing, sleep apnea and hypopnea disorders are very similar. They share the same types, symptoms, and risk factors. While apneas are generally considered more severe than hypopneas, there is evidence that both carry similar risk factors for cardiovascular disease and other comorbidities.

    Symptoms of Hypopnea

    Hypopnea symptoms are very similar to those of sleep apnea and may include:

    People with hypopnea may disturb their partner’s sleep due to symptoms like snoring and choking. Anecdotal evidence suggests that sometimes, both sleep apnea and hypopnea are only diagnosed when the partner of a person who has the disorder complains about their snoring and prompts evaluation.

    Causes of Hypopnea

    Obstructive hypopnea occurs when the airway is partially blocked during sleep, so it is often caused by conditions that narrow the airway or cause throat tissue to become more prominent, such as hypothyroidism or obesity. It can also occur because the shape of your jaw or the size of your tonsils causes you to have a naturally narrow airway. When hypopnea occurs among children, it is usually due to the size of their tonsils or adenoids.

    While there is little research into the causes of central hypopnea, it is speculated that they may be similar to the causes of central sleep apnea. These include damage to the brain stem and the use of medications like opiates. Recent arrival at high altitudes can also cause temporary central hypopnea symptoms.

    Hypopnea Risk Factors

    There are a number of risk factors that can make someone more likely to suffer from hypopnea:

    • Obesity
    • Hypothyroidism
    • Acromegaly
    • Myotonic dystrophy
    • Ehlers-Danlos syndrome
    • Family history
    • Short upper or lower jaw
    • Male gender
    • Smoking

    Some of these factors, such as obesity or jaw shape, can cause hypopnea in and of themselves. However, factors like someone’s gender may increase their risk through other mechanisms.

    Hypopnea Diagnosis

    If you have the symptoms of hypopnea, your doctor will evaluate your risk factors, ask you and potentially your partner questions about your sleep and general health, and possibly examine you. However, your doctor is very unlikely to diagnose you with hypopnea without sending you for a sleep study. Also known as polysomnography, a sleep study is the gold standard for diagnosing both hypopnea and sleep apnea.

    Your sleep study tells your doctor or specialist how many apnea or hypopnea events occur, what stage of sleep they occur in, how long they last, and a range of other crucial information. Sleep studies also help differentiate between sleep apnea and hypopnea as disorders, something that is impossible to do otherwise. However, it is sometimes difficult for a sleep study to determine whether someone has obstructive or central hypopnea.

    Most sleep studies occur in specialized clinics, though some people use at-home sleep study monitors instead. The American Academy of Sleep Medicine suggests that at-home monitors only be used for people with suspected moderate to severe obstructive sleep apnea and no other health conditions. Since sleep apnea and hypopnea have similar symptoms, suspected hypopnea sufferers may qualify for an at-home sleep study.

    Hypopnea Treatment

    Doctors usually treat hypopnea with a combination of lifestyle changes and continuous positive airway pressure (CPAP) therapy. Lifestyle changes may include weight loss, reducing alcohol intake, changing your sleeping position, or stopping smoking. Weight loss is one of the most significant changes that can be made, as a weight reduction of 10% is associated with a 26% improvement in symptoms.

    CPAP therapy is the preferred treatment for obstructive hypopnea. CPAP machines deliver pressurized air via a hose and mask while you sleep, keeping your airway open and reducing hypopnea events or preventing them from occurring. Successful treatment with a CPAP machine can have a profound positive impact on quality of life, as well as reduce blood pressure levels and risk of cardiovascular disease.

    In addition to these standard treatments, hypopnea is sometimes also treated with a mandibular splint or surgery. Mandibular splints are devices that hold the tongue and jaw forward, opening up the airway. Several surgeries exist, but none are currently recommended for hypopnea treatment.

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