- Obesity hypoventilation syndrome (OHS), first described as Pickwickian syndrome, is defined as a combination of obesity (body mass index≥30 kg/m2), chronic daytime elevated blood carbon dioxide levels (PaCO2>45 mmHg), and sleep-disordered breathing in the absence of other known causes of elevated carbon dioxide levels.
- Affluent and emerging societies alike are currently experiencing an alarming increase in the number of people who are clinically obese.
- The increase in obesity has been characterized by a marked increase in ‘severe’ or ‘morbid’ obesity (body mass index >40 kg/m2). From 2000 to 2005, the number of people who reported being obese (body mass index >30 kg/m2) increased by 24% in the USA. Over the same period, the number of people who reported having a body mass index >40/m2 and body mass index >50 kg/m2 increased two and three times faster, respectively. Significant social, economic and health burdens are associated with these levels of obesity.
- Patients with OHS typically present with symptoms of shortness of breath, daytime sleepiness and, in severe cases, heart failure. Despite the significant health care costs and excess mortality associated with untreated OHS, this disorder frequently goes unrecognized, even in hospitalized patients.
- Althogh OHS can be seen without sleep-related breathing problems, it is frequently seen in people who have obstructive sleep apnea (OSA). It is estimated that approximately 20% of patients referred to a sleep clinic for evaluation of OSA had the additional diagnosis of OHS. Given that 18 million adults in the U.S. are estimated to have OSA, this suggests approximately 3.6 million of these adults also suffer from OHS.
