Obesity hypoventilation syndrome (OHS)

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Respiratory system

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

Pickwickian syndrome

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

OHS 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, 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.

Review Date: 08/10/2005
Reviewed By: David A. Kaufman, M.D., Assistant Professor, Division of Pulmonary, Critical Care & Sleep Medicine, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.