In Sleep Apnea: Is RA Connected? Part One, we discussed the percentage of RA patients who are at increased risk of developing sleep apnea. We also learned about the signs and symptoms of sleep apnea. In Part Two, we will discuss how sleep apnea is diagnosed and treated.
How is sleep apnea diagnosed?
Sleep studies are the most accurate tests for diagnosing sleep apnea and determining its severity. The most common sleep study is the polysomnogram (PSG) which uses sensors (applied to the scalp, face, chest, limbs, and a finger) to record brain activity, eye movements, leg movements, body position, respiratory rate, heart rate, blood pressure, and blood oxygen level while you sleep.
A sleep study report will detail the quantity of sleep (total sleep time), sleep efficiency (total sleep time divided by total testing time), sleep latency (how long it took to fall asleep), and sleep stages. Arousals (interruptions of sleep lasting 3 to 15 seconds) can occur spontaneously or as a result of sleep-disordered breathing. If the arousal lasts more than 15 seconds, it becomes an awakening. The higher the arousal index (frequency per hour), the more tired you are likely to feel during the day.
When airflow is reduced by at least 80 percent, an episode of apnea is noted. Hypopnea occurs when airflow is reduced by 50 to 80 percent, accompanied by a drop in blood oxygen level. The sleep study report will indicate the number of times each occurs in total and as an index. Apnea Hypopnea Index (AHI) = the number of apneas and hypopneas per hour of sleep. Respiratory Disturbance Index (RDI) = the number of apneas, hypopneas, and respiratory effort-related arousals (RERAs) per hour of sleep.
Sleep apnea is defined as an AHI of greater than 5 events per hour. An RDI of 5-15 indicates mild sleep apnea, 15-30 is moderate, and > 30 is severe.
During my sleep study, the overall AHI was 5.4 which included 13 apneas and 22 hypopneas. Of those 13 apneas, 2 were obstructive apneas and 11 were central apneas. There were 48 RERAs which resulted in a RDI of 12.9. The number of respiratory disturbances increased during REM sleep, giving me a RDI during REM sleep of 26.7. More disturbances also occurred when I was sleeping on my back rather than on my side.
How is sleep apnea treated?
The goal of treating sleep apnea is two-fold: to restore regular breathing during sleep and to relieve symptoms (such as loud snoring and daytime sleepiness). Lifestyle changes and/or a dental appliance may relieve mild sleep apnea, while people who have moderate or severe sleep apnea may need to use a CPAP machine or undergo surgery. Successful treatment may improve other medical problems linked to sleep apnea, such as high blood pressure, and reduce your risk for heart disease, stroke, and diabetes.
The following lifestyle changes may improve mild sleep apnea symptoms, according to the National Heart Lung and Blood Institute (NHLBI):