What is Obstructive sleep apnea (OSA)?
Snoring leading to blockage of air passage and subsequent cessation of breathing during sleep is called as OSA. Snoring is caused due to narrow air passage, mainly in obese people, but people with narrow upper airways may too suffer from OSA. (Figure 1)
Figure 1: What happens in obstructive sleep apnea?
What are the symptoms of OSA?
Following symptoms have been noted in patients with OSA: Waking up with the feeling of unrefreshed sleep, increased daytime sleep, snoring while sleeping, history given by sleep partner about episodes of snoring followed by apnea and awakening, daytime irritability and loss of memory.
The patient of OSA may present directly with complications of OSA as well. Complications include uncontrolled diabetes mellitus, high blood pressure (BP), stroke, heart attack and accidents.
How to diagnose OSA?
A detailed history with regards to snoring and daytime sleepiness gives a clue to the diagnosis of OSA. Epworth sleepiness scale score of more than 10 is highly suggestive of OSA and sleep study is recommended in such cases. (Figure 2)
Figure 2: Epworth sleepiness scale
Polysomnography or sleep study is the most helpful test to diagnose this disease. Sleep study may be conducted at home by a technician or alternatively the patient may have to stay overnight in the hospital for the test. Test conducted at the hospital is better because more readings including EEG can be generated in a hospital based set up.
Other supportive tests to rule out co-morbid conditions or complications are: chest X ray, spirometry, blood sugar levels, serum lipid profile and 2D echocardiography.
Advise prior to the sleep study
- Patient getting their sleep study done need to eat dinner and take their regular medicines such as those for BP, diabetes and cardiac drugs
- Sedative need to be avoided, unless the patient cannot sleep without the same
- Hair need to be washed the same day and oil should not be applied
- Men should shave their beard the same day
How to judge the severity of OSA with the help of a sleep study?
In the sleep study report there is a value termed as apnea hypopnea index (AHI) which indicates the number of times in an hour the patient stops breathing during sleep.
- None/Minimal: AHI < 5 per hour
- Mild: AHI ≥ 5, but < 15 per hour
- Moderate: AHI ≥ 15, but < 30 per hour
- Severe: AHI ≥ 30 per hour
How to treat OSA?
- Lifestyle modifications such as weight reduction, dietary changes and exercise are the primary requirements for treating OSA
- Thyroid levels should be checked, as low thyroid levels may cause weight gain and OSA
- In patients with severe OSA with AHI>30, a CPAP machine is advisable
What is a CPAP machine?
Continuous positive airway pressure (CPAP) is applied by the patient while sleeping. The machine provides a constant pressure throughout the night, which keeps the airways open. (Figure 3)
Figure 3: Patient sleeping with the application of CPAP mask