Obesity hypoventilation syndrome (OHS)

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

  • Alternative Names
    • Pickwickian syndrome

  • Causes
    • The exact cause of OHS is not known. Doctors believe OHS results from a defect in the brain's control over breathing. Excess weight against the chest wall also makes it harder for the muscles to draw in a deep breath and to breathe quickly enough. As a result, the blood contains too much carbon dioxide and not enough oxygen.

  • Symptoms
    • The main symptoms of OHS are due to lack of sleep and include:

      Symptoms of low blood oxygen level (chronic hypoxia) can also occur. Symptoms include shortness of breath or feeling tired after very little effort.

  • Exams and Tests
    • People with OHS are usually very overweight. A physical exam may reveal:

      • Bluish color in the lips, fingers, toes, or skin (cyanosis)
      • Reddish skin
      • Signs of right-sided heart failure (cor pulmonale), such as swollen legs or feet, shortness of breath, or feeling tired after little effort
      • Signs of excessive sleepiness

      Tests used to help diagnose and confirm OHS include:

      Doctors can tell OHS from obstructive sleep apnea because a person with OHS has a high carbon dioxide level in their blood when awake.

  • Treatment
    • Treatment involves breathing assistance using special machines (mechanical ventilation). Options include:

      Treatment is started in the hospital or as an outpatient.

      Other treatments are aimed at weight loss, which can reverse OHS.

  • Outlook (Prognosis)
    • Untreated, OHS can lead to serious heart and blood vessel problems, severe disability, or death.

  • Possible Complications
    • OHS complications related to a lack of sleep may include:

      • Depression, agitation, irritability
      • Increased risk of accidents or mistakes at work
      • Problems with intimacy and sex

      OHS can also cause heart problems, such as:

  • When to Contact a Medical Professional
    • Call your health care provider if you are very tired during the day or have any other symptoms that suggest OHS.

  • Prevention
    • Maintain a healthy weight and avoid obesity. Use your CPAP or BiPAP treatment as your provider prescribed.

  • References
    • Balachandran JS, Masa JF, Mokhlesi B. Obesity hypoventilation syndrome epidemiology and diagnosis. Sleep Med Clin. 2014;9:341–347. PMC4210766

      Malhotra A, Powell F. Disorders of ventilatory control. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 86.