Definition of Obesity hypoventilation syndrome (OHS):

Obesity hypoventilation syndrome (OHS) is a in obese people in which poor breathing leads to lower oxygen and higher carbon dioxide levels in the blood.

Causes, incidence, and risk factors:

The exact cause of OHS is unknown. The condition is believed to result from both a defect in the brain's control over breathing, and excessive weight (due to obesity) against the chest wall. This makes it hard for a person to take a deep breath. As a result, the blood has too much carbon dioxide and not enough oxygen. People with OHS are often tired due to sleep loss, poor sleep quality, and chronic low blood oxygen levels (hypoxia).

Most patients with the syndrome have a form of sleep apnea. Obesity is the main risk factor.

See also: Respiratory acidosis