MedlinePlus Medical Encyclopedia: Obesity hypoventilation syndrome (OHS)

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Obesity hypoventilation syndrome (OHS)

Contents of this page:
Illustrations Alternative names Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Support Groups Expectations (prognosis) Complications Calling your health care provider Prevention

Illustrations

Respiratory system

Alternative names Return to top

Pickwickian syndrome

Definition Return to top

Obesity hypoventilation syndrome (OHS) is a condition related to (but can occur separately from) obstructive sleep apnea. In OHS, a very obese person does not breathe a sufficient amount of oxygen during sleep or while awake.

Causes, incidence, and risk factors Return to top

The cause of OHS in unknown, but it likely involves a combination of a disorder in the brain's control over breathing and the effects of obesity on the chest wall. With the excess weight of massive obesity, the muscles of the chest wall can have difficulty expanding the chest enough to exchange air efficiently.

This results in a decreased ability to oxygenate the blood, and the retention of carbon dioxide (see respiratory acidosis). Affected individuals suffer from chronic fatigue due to sleep loss, poor sleep quality, and chronic hypoxia (decreased blood oxygen).

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

Symptoms Return to top

The main symptoms of OHS are due to sleep deprivation, which results from sleep loss and poor sleep quality (see obstructive sleep apnea).

Excessive daytime sleepiness
Falling asleep at inappropriate times during the day
Increased risk for accidents or errors at work
Depression

In addition, symptoms of chronic hypoxia (low blood oxygen level) can also occur, such as shortness of breath or fatigue after minimal physical effort.

Signs and tests Return to top

Persons with OHS are usually very overweight. Physical signs that suggest OHS include:

Cyanosis (bluish coloration of the lips, fingers, toes, or skin)
Signs of right heart failure (cor pulmonale), including:
- Swollen legs or feet
- Shortness of breath or easy fatigue on minimal effort

Tests done to confirm the diagnosis include:

Arterial blood gas
Sleep study
Pulmonary function

Treatment Return to top

The treatment involves mechanical ventilation to help the person breath. Options include:

Non-invasive mechanical ventilation (BiPAP or other modes) through a mask that fits tightly over the nose or nose and mouth
Mechanical ventilation through a tracheostomy

Other therapies are aimed at weight loss, which may lead to reversal of the OHS.

Support Groups Return to top

Support groups may help patients with OHS, or their family members, adjust to the lifestyle changes that are required for successful treatment. In addition, support groups may provide information about new treatments that are developed.

Expectations (prognosis) Return to top

When treated, OHS has a good prognosis. Untreated, it can lead to serious cardiovascular complications, severe disability or death.

Complications Return to top

Complications of OHS include complications of excessive sleepiness, such as:

Increased risk for accidents
Depression, agitation, irritability
Sexual dysfunction

OHS may also include cardiovascular complications, such as

Hypertension
Cor pulmonale (right heart failure)

Calling your health care provider Return to top

Call your health care provider if you experience excessive daytime sleepiness, or any other symptoms that suggest OHS.

Prevention Return to top

Avoid obesity.

Update Date: 10/22/2003

Updated by: Allen J. Blaivas, D.O., Division of Pulmonary, Critical Care, and Sleep Medicine, University Hospital, Newark, NJ. Review provided by VeriMed Healthcare Network.

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