What is the definition of Obesity Hypoventilation Syndrome?

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.

What are the alternative names for Obesity Hypoventilation Syndrome?

Pickwickian syndrome

What are the causes for Obesity Hypoventilation Syndrome?

The exact cause of OHS is not known. Researchers 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. This worsens the brain's breathing control. As a result, the blood contains too much carbon dioxide and not enough oxygen.

What are the symptoms for Obesity Hypoventilation Syndrome?

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

  • Poor sleep quality
  • Sleep apnea
  • Daytime sleepiness
  • Depression
  • Headaches
  • Tiredness

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

What are the current treatments for Obesity Hypoventilation Syndrome?

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

  • Noninvasive mechanical ventilation such as continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) through a mask that fits tightly over the nose or nose and mouth (mainly for sleep)
  • Oxygen therapy
  • Breathing help through an opening in the neck (tracheostomy) for severe cases

Treatment is started in the hospital or as an outpatient.

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

What is the outlook (prognosis) for Obesity Hypoventilation Syndrome?

Untreated, OHS can lead to serious heart and blood vessel problems, severe disability, or death.

What are the possible complications for Obesity Hypoventilation Syndrome?

OHS complications related to a lack of sleep may include:

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

OHS can also cause heart problems, such as:

  • High blood pressure (hypertension)
  • Right-sided heart failure (cor pulmonale)
  • High blood pressure in the lungs (pulmonary hypertension)

When should I contact a medical professional for Obesity Hypoventilation Syndrome?

Call your provider if you are very tired during the day or have any other symptoms that suggest OHS.

How do I prevent Obesity Hypoventilation Syndrome?

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

Respiratory system


Malhotra A, Powell F. Disorders of ventilatory control. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 80.

Mokhlesi B. Obesity-hypoventilation syndrome. In: Kryger M, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 120.

Mokhlesi B, Masa JF, Brozek JL, et al. Evaluation and management of obesity hypoventilation syndrome. An official American Thoracic Society clinical practice guideline. Am J Respir Crit Care Med. 2019;200(3):e6-e24. PMID: 31368798 www.ncbi.nlm.nih.gov/pubmed/31368798.

Clinical Trial
  • Status: Active, not recruiting
  • Phase: N/A
  • Intervention Type: Diagnostic Test
  • Participants: 105
  • Start Date: November 11, 2018
The Debated Role of Sleep Studies in Patients Under Established Home Mechanical Ventilation
Clinical Trial
  • Status: Active, not recruiting
  • Phase: N/A
  • Intervention Type: Device, Other
  • Participants: 32
  • Start Date: May 1, 2021
Remote Monitoring to Improve Low Adherence in Non-invasive Ventilation: READ-NIV Trial