Overview

Obesity hypoventilation syndrome (OHS), or Pickwichian syndrome, is a breathing disorder that affects some people with obesity. This condition causes too much carbon dioxide and significantly less oxygen in the blood. Usually, humans exhale carbon dioxide and inhale oxygen. But when you breathe slowly, you are not allowing enough air in and out of your lungs; this condition is called hypoventilation. This is different from hyperventilation.

Patients with OHS often suffer excessive body weight, particularly in the chest and abdomen areas, which can interfere with chest expansion and cause breathing problems. 

Apart from hypoventilation, patients can also experience sleep-disordered breathing due to obstructive sleep apnea (OSA).¹ Without treatment, OHS can lead to severe and even life-threatening health problems. ⁸ Patients with untreated OHS have an increased risk of developing cardiovascular and respiratory morbidity and mortality.¹⁰

Relationship between breathing, obesity and hypoventilation

Being overweight or suffering from obesity may increase the risk of developing OHS. Most people who have obesity hypoventilation also suffer from sleep apnea.

OHS affects some people who have obesity but not others. Extra fat on your neck, chest, and across the abdomen can slow down the oxygen flow and may produce hormones that affect your body’s breathing pattern. This can also restrict lung functions, cause an inability to expand and rest, and cause persistent shallow breathing patterns.

OHS may cause individuals to experience a problem with the way the brain controls breathing.⁵ Breathing shortness related to obesity might not be just because of a lack of fitness, but could also indicate some underlying conditions associated with lung inflammation and changes to lung functions. 

Obesity can also cause the narrowing of the airways, which can, in some cases, lead to their complete closure.¹¹

Factors contributing to the development of OHS

Studies do not show the exact cause of OHS, but it may result from a defect in the brain that affects breathing control. 

The responsible causes of OHS are multifactorial.  The leading causes are obesity and obstructive sleeping disorder. Excess fat around the chest wall makes it harder for the muscles to draw in a deep breath quickly. This worsens the brain’s breathing control systems. As a result, the blood contains too much carbon dioxide and carries less oxygen.⁶

The following factors can contribute to the development of OHS:

• Obesity: People with a BMI of more than 30 kg/m² are at higher risk of developing OHS.
• Sleep Apnea: Disturbing sleep patterns can increase the risk of OHS.
• Hypothyroidism: Hyperactive thyroid is a contributing factor in the development of OHS. 
• Hypoxia: Hypoxia or low blood oxygen level can increase the chances of developing OHS. 
• Medication: Certain medications, such as opioids, are closely linked to developing OHS.⁷ 

Signs and symptoms of OHS

Obesity hypoventilation syndrome typically occurs due to lack of sleep and low blood oxygen level (hypoxemia). The most common symptoms include morning headaches and daytime sleepiness.⁸  Some of the common symptoms are:

• Shortness of breath
• Lack of energy
• Fatigue 
• Dizziness 
• Depression

While you are sleeping, others may notice the following symptoms:

• Loud snoring 
• Gasping 
• Pauses in your breathing 

Note that everyone with shortness of breath and obesity has OHS. Obesity can cause shortness of breath even if it doesn’t meet the OHS diagnostic criteria.¹

How is it Diagnosed?

If your healthcare provider suspects that you have obesity hypoventilation syndrome, they will conduct the following tests:

• Measure your weight and height 
• Perform a physical check 
• Calculate your body mass index (BMI)
• Measure your weight and neck circumstances 
• Lung volume test 
• Spirometry 

Additional tests may include a lung test to measure your oxygen level and how well your lungs work. Consider taking a sleep study if they think you may have sleep apnea. ⁵ These procedures may include:

• Radiographs
• CT Scan
• MRI
• Bronchoscopy

To ensure a correct diagnosis, your healthcare provider may suggest further tests, including:

• Complete blood Count (CBC)
• Sleep study 
• Cardiac study 
• When obesity has been confirmed, no other conditions are linked to your symptoms, and your arterial gal levels are at a certain point, only then can OHS be diagnosed. ⁴

Although obesity is a significant risk factor for OHS, only some obese patients will develop this condition. Before making the diagnosis, it is essential to rule out other possible disorders that might lead to hyperventilation.¹¹  

Treatment and management for OHS

OHS is associated with a significantly higher rate of mobility and mortality. Several therapeutic options have been tried, including positive airway pressure therapy, weight reduction surgery, and pharmacotherapy.

• Airway pressure therapy (PAP): Continuous Positive airway pressure (CPAP) is typically the first-line therapy for OHS. This treatment uses a stream of compressed air to support the airways.² For patients with OHS, maintaining airway patency with CPAP may prevent the accumulation of CO2 during complete or partial airway obstruction.⁹
• With CPAP therapy, you wear a mask during sleep. A portable machine gently blows pressurised room air into the upper airway through a tube connected to the mask. This significantly reduces the nocturnal build-up and improves sleeping during the daytime. The positive airflow keeps the airways open, preventing collapse during apnea and allowing normal breathing.³
• Weight Reduction: Maintaining an average body weight is helpful for treatment. Although many patients may lose weight initially, they appear to be non-adherent to dietary restrictions in the long term. Weight loss reduced CO₂ production and decreased the severity of sleep apnea. It also enhances pulmonary artery hyperventilation and left ventricular dysfunction.²

Tracheostomy: This treatment is reserved for patients with OHS who are unable to tolerate positive airway pressure treatment and who are at risk of developing life-threatening complications, such as acute respiratory failure or cor pulmonale. By relieving upper airway obstruction, tracheostomy may result in improved daytime hypercapnia. However, hyperventilation persists in some patients.¹¹

Prognosis

Obesity hypoventilation syndrome is associated with low quality of life, prolonged admission rates and time in intensive care. For patients with other medical conditions, such as asthma and diabetes, the mortality rates are significantly high, with 23% over 18 months and 46% over 50 months. 

Early use of CPAP can reduce the associated mortality rate by 10%. However, older patients with restrictive ventilatory defects may not respond to CPAP treatment. The prognosis is poor, with a shortened life expectancy for patients with OHS who do not lose weight.²

FAQs

What are the complications associated with OHS?

OHS can cause complications related to sleep if left untreated for a long time. Some of the complications may include:

• Depression
• Agitation
• Increased risk of accidents

OHS can also cause heart problems, such as

• High blood pressure (hypertension) 
• Right-sided heart failure
• High blood pressure in the lung (pulmonary hypertension ¹

When can I seek medical advice?

You should see health care provide if you experience the following symptoms:

• You have obesity along with other symptoms of OHS
• You experience breathing pauses while sleeping
• You are overly tired during day¹

How can I reduce the risk of developing OHS?

You can reduce the risk of developing OHS by maintaining weight and healthy lifestyles. If your doctor prescribed CPAP, continue the treatment as directed.

Stay active, make healthy lifestyle choices and eat a balanced diet.¹ This condition is both preventable and treatable. If left undiagnosed, obesity hypoventilation can also lead to severe health problems.

Can losing weight help with shortness of breath?

Multiple studies suggested that losing weight can significantly improve the symptoms of OHS. As weight is reduced, the carbon dioxide level decreases, and lung function improves.

When shortness of breath is due to excess weight, losing weight is the primary way to improve the symptoms of OHS.

If you are dedicated to losing weight, your dietician or doctor can help to create a safe plan that reduces weight at a safe rate.⁷

Summary

Despite recent advances in the study of OHS, much remains unknown, and more research is needed. Obesity and shortness of breath can be closely linked. Excess weight can alter lung performance and contribute to the physical process of inflammation, further hindering the problem. Weight loss can be achieved through dietary management. Bariatric surgery is an option for those in more extreme and life-threatening circumstances in order to help with substantial weight loss.

When sleep disorder is related to obesity reaching a certain level, it can be diagnosed as obesity hypoventilation syndrome. This condition often requires medical attention and treatment, including weight management strategies and non-invasive ventilation therapies, such as CPAP. 

Overall, CPAP therapy is a safe and effective treatment. Weight loss can take time; during that time, CPAP therapy can help you breathe easier.