Obesity hypoventilation syndrome (OHS)

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Respiratory system

Obesity hypoventilation syndrome (OHS)

Definition:

Obesity hypoventilation syndrome (OHS) occurs when a very obese person does not breathe enough oxygen while sleeping.

Alternative Names:
Pickwickian syndrome
Causes, incidence, and risk factors:

The exact cause of OHS in unknown. Most (but not all) patients with the syndrome have a form of sleep apnea.

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OHS is believed to result from both adefect in the brain's control over breathing and excessive weight (due to obesity) against the chest wall, which 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. (See respiratory acidosis). Patients with OHS have chronic fatigue due to sleep loss, poor sleep quality, and chronic hypoxia.

Morbid (massive or excessive) obesity is the main risk factor.

References:

Murray J, Nadel J. Textbook of Respiratory Medicine. 3^rd ed. Philadelphia, Pa: W.B. Saunders Company; 2000:2326-2328.

Moore DP, Jefferson JW. Handbook of Medical Psychiatry. 2nd ed. St. Louis, Mo: Mosby, Inc; 2004:221-223.