Pickwickian syndrome

Alternative names

Obesity hypoventilation syndrome (OHS)

Definition

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

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

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

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:
  o Swollen legs or feet
  o Shortness of breath or easy fatigue on minimal effort
  

Tests done to confirm the diagnosis include: