The Second in a Series Providing Busy Physicians With a Helpful Overview of This Serious Sleep Disorder
Sleep apnea is a common medical condition, affecting millions of people in this country and around the world. Yet, it is often difficult to diagnose simply because people who have the condition aren’t aware of it.
That’s why it’s critical for healthcare professionals to diagnose sleep apnea so that appropriate treatment can be started, and to help prevent serious complications from developing.
Common Symptoms of Sleep Apnea
The first step to diagnosing sleep apnea is to understand its many different symptoms. The three types of sleep apnea—obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed sleep apnea (MSA)—can have similar symptoms. These include:
- Difficulty staying asleep (insomnia)
- Gasping for air while sleeping
- Night sweats
- Morning headaches
- Dizziness upon awakening (due to low oxygen levels)
Additional symptoms of obstructive sleep apnea include:
- Chronic snoring, which is the most common symptom. It usually involves choking, snorting, or gasping and often causes the person to briefly wake up. But snoring doesn’t necessarily mean a person has sleep apnea.
- (Snoring isn’t even a frequent symptom with CSA.)
- Morning sore throat or dry mouth
- Frequent need to wake up to urinate
Evaluating a Patient You Suspect May Have Sleep Apnea
Probe patients to learn more about their condition by asking such questions as:
- What is your typical sleep schedule?
- Do you take any medications to help you sleep?
- How long does it take for you to fall asleep?
- How much sleep do you think you get each night?
- Has anyone told you that you snore?
- Have you ever been jolted awake or felt “panicky” when you awake?
- How do you feel when you wake up?
- Has anyone in your family had a sleep disorder?
Ordering a Sleep Study to Confirm the Diagnosis of Sleep Apnea
The most accurate way to diagnose sleep apnea is with a sleep study, also called a polysomnogram (PSG). Two types of PSGs are available:
In-lab Sleep Study
An in-lab sleep study diagnoses sleep apnea, as well as a wide range of other sleep disorders. It is considered the gold standard of diagnostic testing for sleep apnea.
An in-lab sleep study generally takes place overnight in a sleep center, lab, clinic, or hospital. It is a multiple-component test that electronically measures and records specific physical activities during sleep:
- Electroencephalogram (EEG) monitors brain wave activity
- Electroculogram (EOG) measures eye and chin movements that signal the different stages of sleep
- Electrocardiogram (EKG) records and measure heart rate and rhythm
- Electromyogram (EMG) records muscle activity – face twitches, teeth grinding, and leg movements – and detects REM stage sleep
- Chest bands measure respiration
- Nasal airflow sensor records airflow
- Snore microphone records snoring activity
- Additional monitors sense oxygen and carbon dioxide levels in the blood and record leg movement
In-lab sleep studies are more suitable for people with additional health conditions, such as heart and lung diseases.
Depending on the patient, a “split-night study” may be appropriate. The first hours are devoted to sleep apnea diagnosis. If OSA is found, the patient is awakened and fitted with a positive airway pressure (PAP) device. The rest of the patient‘s sleep is then monitored to determine how well he or she responds to PAP therapy.
In-lab Sleep Study Results
An enormous amount of data is generated by a sleep study, but the most crucial is the apnea-hypopnea index (AHI). An apnea, apneic episode, is defined as a complete cessation of breathing for 10 seconds or longer. A hypopnea is constricted breathing lasting 10 seconds or longer. The AHI is the number of apneic episodes and hypopneas the patient experiences each hour.
- People who don’t have sleep apnea or have a mild form usually experience fewer than five apneic episodes per hour
- People with severe sleep apnea may have more than 30 sleep apneas per hour
AHI data also offers insights into additional sleep patterns:
- How long the patient spends in each sleep stage
- How often the patient wakes up
- Whether the patient snores
- Unusual brain activity patterns
- Body position and limb movements
Home Sleep Study
A home sleep study is a simplified version of an in-lab sleep study to diagnose sleep apnea in the comfort of the patient’s home. It uses portable monitoring devices to measure heart rate, blood oxygen level, airflow, and breathing patterns.
Unlike an in-lab sleep study, an at-home test doesn’t measure sleep cycles, body position, or limb movements during the night.
Home sleep studies are less costly and more convenient than in-lab sleep studies; however, they aren’t as definitive. They also aren’t appropriate for people with significant medical problems; such as, cardiac disease, heart failure, neuromuscular disease, or pulmonary disease. Or for people who have other sleep disorders (central sleep apnea, narcolepsy, insomnia, restless legs syndrome, circadian rhythm disorders, parasomnias).
Home sleep study results are sent to healthcare providers to discuss with their patients and use as a basis to recommend next steps.