What does the respiratory physician interested in sleep need to know about bariatric surgery?

Educational aims

1. To understand the relationship between obstructive sleep apnoea/hypopnoea syndrome, obesity and bariatric surgery.

2. To learn the mechanisms, techniques and non-respiratory benefits of bariatric surgery.

Summary Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is reported to affect 4% of middle-aged males and 2% of middle-aged females in the UK [1], with one of the most widely recognised major risk factors being obesity [2]. The prevalence of obesity in many countries is rising – in England, 24% of males and 24% of females were classified as obese in 2007 (body mass index (BMI) ≥30 kg per m²), compared with 13.2% of males and 16.4% of females in 1993 [3]. The prevalence of OSAHS within the obese population is widely reported to range between 55–90% in people with a BMI of >40 kg per m² [4], and many studies have found a reduction in the apnoea/hypopnoea index (AHI) and symptoms of OSAHS with weight loss [5], although it is widely recognised that weight loss by medical methods does not yield good results in the long term. The mainstay of treatment for OSAHS is nocturnal continuous positive airway pressure (CPAP) therapy. This has been shown to have a discontinuation rate of 18–24% [2], which adds to the need for alternative therapy for OSAHS associated with obesity.

Bariatric surgery is the field of weight-loss surgery, from the Greek words ‘baros’ meaning ‘weight’ and ‘iatrike’ meaning ‘medicine’, and is widely accepted as the most effective, long-term treatment for obesity, especially in those with a BMI of >40 kg per m². The Swedish Obese Subjects Trial, the largest trial studying surgical versus medical treatment of weight loss, showed an average weight loss of approximately 25.6% 2 yrs after surgery and 18.3% after 10 yrs, compared with a weight change of ±2% in the medically managed group [6].