What is Obstructive Sleep Apnea?
Obstructive sleep apnea (OSA) is a respiratory disorder closely associated with morbid obesity, in which breathing is made more difficult by excessive body fat around the neck or on the chest. This excess body fat constricts the air-passageways and sometimes the lungs, causing short interruptions in breathing during the night. Patients with sleep apnea may experience sudden daytime sleepiness, difficulty concentrating, and on rare occasions heart failure. The health consequences of sleep apnea can be life-threatening, especially among patients suffering from morbid or malignant obesity.
High Risk of Obstructive Sleep Apnea in Morbidly Obese
Obesity, particularly abdominal and upper body obesity, is the most significant risk factor for obstructive sleep apnea. The prevalence of sleep apnea among patients with morbid obesity is a 12-30 times higher compared to the general population. Surveys show that more than two thirds of patients with obstructive sleep apnea are obese. This respiratory disorder is associated with obesity hypoventilation syndrome.
Effect of Weight Loss on Obstructive Sleep Apnea
Clinical tests demonstrate that weight reduction leads to a significant improvement in symptoms of sleep apnea. For example, in one 3-month clinical trial (1998), a group of obese patients were put on a 600-800 calorie diet, losing about 22 pounds each. Using the Valsalva test, the deep-breathing test and assessment of heart rate variability at rest, as well as sleep studies, the oxygen desaturation index (ODI4) and autonomic function tests, patients exhibited significantly lower blood pressure, and a 50 percent increase in baroreflex sensitivity.
Effect of Bariatric Surgery on Obstructive Sleep Apnea
Gastric surgery like Lap Band or Roux-en-Y stomach bypass is highly beneficial for obstructive sleep apnea. On average, it is cured in about 75 percent of patients after bariatric surgery.
Central Sleep Apnea
Obstructive sleep apnea – which is greatly affected by obesity – should not be confused with the respiratory disorder called “central sleep apnea.” The latter condition is unconnected with excess weight: instead, it is caused by malfunction in the brain and nerves, as a result of (eg) brain damage or stroke.