Obstructive Sleep Apnea (OSA) is an extremely common health problem present in two to four percent of the general population. It has been linked to development of hypertension and is a risk factor for incidental development of stroke, coronary artery disease, congestive heart failure and atrial fibrillation (a common irregular heart rhythm).
The Link Between Obesity and Sleep Apnea
About 70 percent of people with OSA are obese. For every 20 pound increment in weight, the risk for OSA increases by more than twofold. This is due to increased fat deposits in the upper airway that cause soft tissue enlargement and contribute to critical narrowing of the airways.
Detecting and Treating Sleep Apnea
The two main reasons to detect and treat OSA are to improve symptoms and decrease cardiovascular risks. There are good data to show that treatment of OSA improves symptoms and quality of life.
The gold standard for diagnosing OSA is through a sleep study called polysomnography. In this test, the severity of OSA is given a rating based on the Apnea Hypopnea Index (AHI). A test will show the hourly rate of apneas (cessations in breathing) and hypopneas (upper airway blockages or obstructions) averaged over the total sleep time.
- Normal: 4 per hour or less
- Mild: 5 to 14 per hour
- Moderate: 15 to 29 per hour
- Severe: 30 per hour or higher
Therapeutic options for snoring and sleep apnea include reducing nasal congestion or obstruction, positional therapy, nasal continuous positive airway pressure (CPAP/BiPAP), oral appliances, the nasal expiratory positive airway pressure device, oral pressure therapy or surgery. CPAP/BiPAP remains the most effective therapy for OSA. The other options are viable in specific circumstances.
The Impact of Weight Loss on Sleep Apnea
Weight loss in those who are obese reduces the severity of OSA. In fact, about 30 to 40 percent of people who are able to achieve substantial weight loss may become cured of their OSA.
Weight loss may reduce soft tissue in the neck, making the oropharynx less compressible. The improvement in lung volumes accompanied by weight loss also favor enhancement of longitudinal traction on the upper airway, the so-called “tracheal tug.” Careful follow-up is needed because remissions in certain patients may not be permanent. Alcohol and other substances that reduce upper-airway tone or cause sedation or reduced responsiveness worsen OSA and should be prudently avoided.
The most important therapy for OSA in those who are obese is weight loss. Weight loss changes pharyngeal anatomy and decreases airway collapsibility by increasing the pharyngeal closing pressure. Several studies have reported a significant association between the extent of weight loss and reduction in the severity of OSA. And, the most impressive results of AHI improvement are from those who underwent bariatric surgery.
If someone chooses to undergo bariatric surgery, it is recommended to monitor sleep quality and usage of CPAP/BiPAP after surgery and as weight loss progresses. Many people prematurely discontinue the use of CPAP/BiPAP within the first three months after surgery because they experience a dramatic improvement in their symptoms, and sometimes because of intolerance to “high” pressure settings. Therefore, I recommend a consultation after surgery to reevaluate the condition and reduction in CPAP/BiPAP settings, if required. Information acquired from the device often proves useful in clinical decision-making.
Randip Singh, MD, is a board-certified neurologist and sleep physician. He is actively involved in screening and managing sleep apnea in bariatric surgical patients (with his colleague, bariatric surgeon, Thien Nguyen, MD) and other patients with wide array of sleep disorders.