Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. People with OSA experience frequent, repeated pauses in breathing during sleep that can reduce the amount of oxygen they get while asleep. OSA affects roughly 10% to 30% of adults in the United States.
Some health care providers use a simple visual test called the Mallampati score to help predict a person's likelihood of having OSA. We explore what causes OSA, describe how medical professionals use the Mallampati score, and share information about other tools commonly used to diagnose the disorder.
What Is Obstructive Sleep Apnea?
Obstructive sleep apnea describes when a person's upper airway partially or completely collapses repeatedly during sleep, causing their breathing to briefly slow or stop.
Many factors contribute to a person developing OSA, including older age, obesity, and physical abnormalities in the jaw and throat. People assigned male at birth may also be at greater risk of developing OSA.
Bed partners of people who have OSA may notice their partners snoring, choking, or gasping for air while asleep. Common symptoms of sleep apnea include:
- Loud snoring
- Disrupted sleep
- Excessive daytime sleepiness
- Difficulty remembering things
- Poor concentration
- Headaches in the morning
- Waking at night to use the bathroom
- Nighttime restless
- Feeling unrefreshed upon waking
- Mood swings
Identifying and treating OSA is important because of the risks associated with the disorder. People with OSA are more likely to experience car crashes due to drowsy driving, attention and memory problems, high blood pressure, heart failure, type 2 diabetes, and other issues.
Researchers and medical professionals have several tools that can help predict the risk and severity of OSA, and the Mallampati score is one of those tools.
Understanding the Mallampati Score
Medical professionals determine a person's Mallampati score by looking at their mouth and throat while the mouth is fully opened and the tongue is sticking out.
An Indian doctor by the last name Mallampati and his colleagues first described the score in 1985. The scoring system was developed to quickly estimate how difficult it may be to insert a tube into the throat of a patient before surgery is performed.
Over time, the Mallampati score has been modified and become a useful tool to predict the risk and severity of obstructive sleep apnea in both children and adults. While the original Mallampati score used a scoring system ranging from class 1 to class 3, the modified version includes a class 4. Some experts also use a Mallampati scale with a class 0.
The Mallampati score assigned by a health care provider corresponds to which parts of the mouth and throat can be seen when looking into a person's open mouth while their tongue is sticking out.
- Class 0: The tonsils, uvula (tissue that dangles from the top of the throat), soft and hard palates (parts of the roof of the mouth), and epiglottis (a piece of cartilage just above the windpipe) are all visible.
- Class 1: The tonsils, uvula, and soft and hard palates are visible.
- Class 2: The soft palate and at least part of the uvula are visible.
- Class 3: The soft palate is visible.
- Class 4: Nothing beyond the tongue is visible.
Doctors generally conduct a Mallampati assessment while a person sits upright. A Mallampati score may be given to a person lying down if they are unable to sit upright, but some studies suggest doing so might result in a different score. Similarly, a person making sounds may artificially lower their Mallampati score, so the assessment is done while a person is silent.
Class 3 and class 4 Mallampati scores suggest a person has an airway that is narrower than usual. A higher Mallampati score corresponds to an increased chance of having obstructive sleep apnea. A higher Mallampati score also corresponds to increased OSA severity.
In adults, a person is twice as likely to have OSA with every point increase on the Mallampati assessment. In children, an increase of a single point in the Mallampati score means that a child has six times the chance of having OSA.
Diagnosing Obstructive Sleep Apnea
Although the Mallampati score may help predict a person's likelihood of having OSA, it's not a tool used to make an official OSA diagnosis. Instead, doctors and sleep specialists diagnose OSA using a sleep study, called polysomnography, or home sleep apnea testing (HSAT).
Before ordering one of these tests, doctors generally ask questions to determine whether or not they think a person likely has OSA. They may ask questions about symptoms, such as snoring, daytime sleepiness, or morning headaches. They may also take into consideration a person's body weight, age, and biological sex at birth.
A sleep study involves spending the night in a sleep lab or hospital, while home sleep apnea testing can be conducted while a person sleeps at home. Doctors order a sleep study when a person has or is suspected of having other health problems, like lung disease or another sleep disorder. HSAT is used when it seems likely a person is primarily dealing with OSA.
Both a sleep study and HSAT record multiple measurements as a person sleeps, including respiratory effort, airflow, snoring, heart rate, and blood oxygen levels. A sleep study involves recording more measures, however. For example, sleep studies also monitor brain waves during sleep and involve a video recording of the sleeper.
Both types of studies record how many episodes of shallow breathing a person has while sleeping and the number of times they temporarily stop breathing. Both episodes of shallow breathing and stopped breathing are considered respiratory events. People who have more than an average of five respiratory events per hour as they sleep are given a diagnosis of OSA.
Obstructive Sleep Apnea Severity Classification
Sleep experts commonly use a measure called the apnea-hypopnea index (AHI) to help diagnose OSA and determine its severity. The AHI involves making a calculation based on the number of respiratory events a person experiences while asleep.
When a person stops breathing for at least 10 seconds, it is called an apnea. An episode of shallow breathing lasting more than 10 seconds is called a hypopnea. A person's AHI may be calculated by adding up the number of apnea and hypopnea respiratory events they experience during a sleep study or HSAT, then dividing that by the total number of hours they were asleep.
The AHI is used to classify obstructive sleep apnea as mild, moderate, or severe.
- Mild (5 to 14 events per hour): In mild cases of OSA, a person might not notice symptoms, or they may experience daytime sleepiness when they are not stimulated. People may notice they feel more alert after their mild OSA is treated, however. Mild OSA is associated with high blood pressure.
- Moderate (15 to 30 events per hour): People with moderate OSA are usually aware that they feel tired during the day. As a result, they may choose to take naps or avoid driving for long periods to manage their tiredness. Car crashes and high blood pressure are more common in people with moderate OSA.
- Severe (more than 30 events per hour): Severe OSA can prompt tiredness that interferes with a person's daily life, causing them to fall asleep throughout the day. Severe OSA also increases the risk of high blood pressure, heart problems, and other health issues.
Related Obstructive Sleep Apnea Tools
In addition to the Mallampati score and AHI, there are multiple other tools and measurements sleep experts commonly use with people who are suspected to have OSA.
- Body mass index (BMI): Doctors may determine a person's body mass index, because a higher BMI suggests an increased risk of having OSA. BMI can be calculated by taking a person's body weight in kilograms divided by their height in meters squared. A BMI over 30 indicates obesity.
- Waist or neck circumference: Doctors may measure a person's waist or neck when they suspect OSA, since having a larger waist or neck is more closely correlated with having OSA than obesity in general. In particular, a neck size over 16 inches in women and 17 inches in men signals increased OSA risk.
- Epworth sleepiness scale: This scale is a one-page list of questions that a doctor may ask to better understand how easily a person falls asleep during the day. The questionnaire helps determine if a person is experiencing low energy or excessive daytime sleepiness.
- Berlin questionnaire: The Berlin questionnaire includes questions about snoring, daytime tiredness, and high blood pressure. Higher scores on this scale indicate a higher risk of OSA, so doctors may use the measure to help determine who should undergo a sleep study or home sleep apnea testing.
- STOP-Bang questionnaire: A higher score on this questionnaire indicates a person faces a higher risk of having OSA. Questions relate to known OSA risk factors like snoring, tiredness, high blood pressure, BMI, age, and more.
- Oxygen saturation: Both sleep studies and home sleep apnea testing often measure blood oxygen levels, also called oxygen saturation. Some research studies suggest oxygen saturation can predict the severity of a person's sleep-related breathing disorder, like OSA, better than AHI.
- Oxygen desaturation index (ODI): Like oxygen saturation, the ODI is collected during some sleep studies and home sleep apnea testing. This measurement represents how many times during each hour of sleep, on average, blood oxygen level drops by a certain amount.
When to See a Doctor
If you are experiencing symptoms of obstructive sleep apnea, make an appointment with your doctor. For example, see your doctor if you regularly feel unrefreshed when you wake up or have a tendency to fall asleep or become very tired during the day, such as while watching TV or driving.
Sometimes, the bed partner of a person who has OSA is the first to notice the symptoms of the disorder. See your doctor if your sleep partner notices that you snore loudly, gasp, or stop breathing while asleep. If necessary, your doctor can conduct relevant tests and order studies to determine if you have OSA.
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