Pickwickian syndrome, aka obesity hypoventilation syndrome (OHS), is a breathing disorder that can affect people with obesity. It can cause low oxygen and high carbon dioxide in the blood, potentially leading to serious complications.

Some people with obesity can experience breathing difficulties. This can affect the exchange of oxygen and carbon dioxide from the blood to the lungs, an essential process in human functioning.

Pickwickian syndrome, clinically known as obesity hypoventilation syndrome (OHS), describes a condition in which blood carbon dioxide levels are too high due to obesity-related breathing challenges. While OHS is associated with several daily symptoms, it can also contribute to long-term changes in your body’s health.

The exchange of gases in your body primarily takes place in the alveoli (air sacs) in your lungs. Surrounding the 300 million alveoli in the lungs are capillaries, tiny blood vessels arranged in networks.

The oxygen you breathe into your lungs moves from the alveoli into the blood in your capillaries. Carbon dioxide moves from the blood in your capillaries into the alveoli for you to breathe out. This is gas exchange, and it’s essential for keeping a healthy balance of oxygen and carbon dioxide in your blood.

People with OHS may have difficulty with exhalation, causing too much carbon dioxide to build up (hypercapnia). This makes it harder for the blood to pick up oxygen, which then lowers oxygen levels (hypoxemia).

Why is it called “Pickwickian syndrome”?

While clinically known as OHS, Pickwickian syndrome is named after the character Joe from the 1836 Charles Dickens novel “The Pickwick Papers.”

Joe had many of the symptoms later described by clinicians when they discovered this condition, including obesity and sleep apnea (not breathing for extended periods during sleep).

Many OHS symptoms are related to the lack of oxygen in your blood. This can affect your body while you’re awake and while you sleep. During sleep, your breathing can become shallow and may even stop for minutes at a time or longer.

  • feeling out of breath
  • having a lack of energy
  • feeling sleepy or fatigued during the day
  • dizziness
  • headaches, especially in the morning
  • impaired concentration and memory

About 9 in 10 people with OHS also often experience obstructive sleep apnea, which is when you have periods of not breathing while you sleep. You or a partner may notice increased snoring, choking, or breathing difficulties while you sleep.

There are also more serious OHS symptoms. Talk with a doctor as soon as possible if you experience:

These may be symptoms of cor pulmonale, a type of right sided heart failure that’s a potential complication of untreated OHS.

OHS development appears to involve multiple factors, including:

  • changes to your respiratory system due to obesity, such as extra weight around your chest, which makes it harder for your lungs to breathe out carbon dioxide
  • sleep-disordered breathing
  • your brain’s inability to properly control your breathing or respond to stimuli that trigger breathing
  • elevated levels of leptin, a hormone that can help regulate your breathing frequency

OHS develops in people with obesity, meaning they have a body mass index (BMI) of 30 or higher. However, most people with OHS have a BMI above 35. However, OHS may occur in people of East Asian background at lower BMIs.

It’s not clear why some people with obesity develop OHS, and others don’t. Other risk factors may include extra fat on your neck, chest, or abdomen, as these can affect breathing.

While sleep apnea is more common in males, OHS seems to affect males and females equally.

A note about BMI

BMI is a calculation of someone’s body fat based on their height and weight. However, studies show that it’s a poor indicator of body fat percentage. It can be misleading because it doesn’t account for overall body composition.

Factors the BMI measurement overlooks include bone density, muscle mass, and other considerations.

For additional information, talk with a doctor about other body fat assessment methods.

An OHS diagnosis requires three criteria:

  • a BMI of 30 or higher
  • arterial carbon dioxide tension (a measure of how much is in your blood) of 45 mmHg or higher while awake
  • hypoventilation not due to another cause

Doctors will run several tests to determine the potential causes of your symptoms, including:

While early diagnosis is essential, most people don’t receive a diagnosis until late in the course of their disease. Consider seeing a doctor as soon as possible if you have risk factors for OHS and notice symptoms.

Many treatment plans exist to help you manage the symptoms of Pickwickian syndrome.

Weight loss

Weight loss is a standard component of an OHS treatment plan. Losing excess weight can help take the stress off your body and restore regular breathing. A comprehensive weight loss plan will include regular physical activity and informed dietary choices.

PAP (CPAP) therapy

The typical first-line treatment for OHS is positive airway pressure (PAP) therapy. A doctor may recommend this type of treatment in the form of a continuous PAP (or CPAP) machine. This machine provides oxygen from a motor into a tube connected to a mask you wear over your nose and mouth.

While people with sleep apnea may use a CPAP machine when they sleep, people with OHS may use the machine at times when they are awake as well.

Ventilator machine

A doctor may also recommend using a ventilator to ensure consistent breathing. A ventilator moves oxygen in and out of your lungs and can help balance the oxygen and carbon dioxide in your lungs.

Tracheostomy

If these treatments don’t work and your condition worsens, your doctor may suggest a tracheostomy. In this procedure, a doctor cuts a hole open in your trachea, or windpipe, and inserts a tube to allow consistent breathing.

Bariatric surgery

A doctor may also recommend bariatric surgery to help you manage your weight. Common options include gastric bypass and laparoscopic adjustable gastric banding. Both surgeries limit the amount of food you can hold in your stomach.

You may need to make some significant lifestyle changes if you choose either of these surgeries. Talk with a doctor about the benefits and costs of these surgeries before you make a decision.

If you are at risk of OHS, managing your weight is the best way to prevent it from developing. Eat a healthy, balanced diet and exercise at least 30 minutes a day. This will help you take in the right nutrients for your body and avoid building up fat and gaining extra weight.

If you have sleep apnea, seeking treatment may help prevent OHS. Talk with a doctor about choosing a CPAP machine that works best for you. A medical equipment provider can help you set up and operate your machine.

OHS can lower your quality of life. People with this condition tend to have more frequent and longer hospital stays. They’re also at higher risk of complications like

A 2022 study also suggests that OHS may cause secondary polycythemia, which can increase the risk of stroke. But more research is needed.

But early diagnosis and treatment can improve your outlook with OHS. Starting CPAP treatment early can reduce death rates by 10%.

Obesity is increasingly common in the United States and around the world. It can contribute to several health conditions, including OHS (aka Pickwickian syndrome), a breathing disorder characterized by high carbon dioxide levels in the blood.

Many people don’t receive an OHS diagnosis until symptoms have progressed considerably. But early treatment with CPAP or other breathing-assistive devices, combined with weight loss strategies, can help improve outcomes.

See a doctor as soon as possible if you have risk factors for OHS, like obesity or sleep apnea, and experience symptoms like slow, labored breathing or morning headaches.