Obesity Hypoventilation Syndrome

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What is Obesity Hypoventilation Syndrome(OHS)

Obesity hypoventilation syndrome is a disorder that occurs in obese patients due to

  • Obesity
  • Sleep disordered breathing (OSA or Non obstructive sleep hypoventilation)
  • Daytime hypercapnia (high levels of Co2 in blood)

Obesity causes decreased space for the lungs to expand, leading to short shallow breaths. This acts as a chronic process and leads to an increase in the carbon dioxide levels in your blood and the oxygen levels to become low.

The oxygen is exchanged with carbon dioxide by the air sacs in the lungs and is called gas exchange. This oxygen is then carried to the rest of the body and organs through blood stream. When this gas exchange is disrupted it leads to hypo-ventilation. Almost all patients that have OSA can develop OHS and poses as a high risk.

Some of the other comorbidities that are associated with OHS are metabolic syndrome, cardiovascular diseases, heart failure, cor pulmonale and pulmonary hypertension. Hence patient’s with OHS have a high risk of mortality

What causes OHS besides obesity?

The cause of OHS is not still known. OHS may be caused due to a combination of reasons.

  • The brain is unable to manage shallow breathing pattern 
  • Hormones that produce excess fat, which makes breathing ineffective
  • The extra weight that presses against your chest makes it more difficult to breathe normally.

It is usually only diagnosed in the absence of other causes of other obstructive and restrictive airway diseases.

Clinical characterization of Obesity hypo-ventilation syndrome

People with OHS are diagnosed with in acuity of an event like respiratory failure. A few clinical characterization for OHS are listed below.


People with a body mass index (BMI) above 30 are generally considered obese. People with OHS are severely obese with a BMI of 40.

Obese person

Being overweight and obese are the major causes of pulmonary complications, which can result in a respiratory failure from occurring.  However other factors such as infection, post operative status can also bring about OHS

Daytime hypercapnia

This is the inability of adequate oxygenation of tissues and organs due to decreased amount of respiratory function that occurs as a result of obesity. This causes the build of carbon di oxide in the lungs to occur which leads to daytime hypercapnia.

Sleepdisordered breathing

Sleep disorder breathing or sleep apnea is a recognized clinical characterisation for people with OHS.

The upper airway closes when pharyngeal dilating forces cannot overcome the collapsing effect of the negative inspiratory pressure and the tissue weight.

Negative inspiratory pressure is the maximum pressure generated against an occluded airway.

Excessive fat deposition causes the soft tissue that surrounds the upper airways to enlarge and this causes the airways to close during sleep.

The reduced lung volume in obesity hypoventilation syndrome patients reduces the inspiratory-related caudal tracheal traction that helps to stabilise the upper airways.

Apart from these anatomical predispositions, the fluid shifts from the legs to the neck during sleep lead to the pathogenesis of sleep apnea.

Symptoms of OHS

  • Lack of energy
  • Sleepiness during daytime
  • Headache
  • Breathlessness
  • Snoring
  • Disturbed sleep
  • Breathing disturbed or choking while sleeping
  • Swelling of limbs
  • Bluish discoloration of extremities
  • Depression


  • Sleep study (Polysomonography
  • ABG

Treatments of OHS

People with obesity hypoventilation syndrome will need help mentally and physically.

As the condition progresses the symptoms may worsen and will require medical treatments to mitigate the effects of the disorder.

Weight loss

Being overweight is the cause of this disorder. Take small steps to change lifestyle, Do not overburden and start one at a time.

Go for a small walks and increase the time to walk slowly by building tolerance. Eat healthy and balanced foods.

Consult the doctor before taking any heavy workouts. Do not go for any intense workouts as they may aggravate breathlessness.

In the gym, talk about your condition to your trainer. They might suggest workouts that are not intense.

Drink water to keep hydrated and this also helps to eat less. Stick to a sleeping time and make sure you adhere to it.

Weight loss is not eating less but eating right. Many people have a misconception that if they eat less, they will lose calories. There is a healthy proportion for the calorie deficit that needs to be followed that can differ from person to person.

Visiting a nutritionist or dietitian for a proper diet plan can be helpful. Foods that may seem healthy sometimes may have more calories. Keeping a food diary can help in recounting what is being eaten in a day.

Breathing support

Breathlessness is a major disadvantage in obesity hypoventilation syndrome. The treatment will be given in such a way that it reduces breathlessness.

There are devices and therapy that will help to reduce breathing problems.

  • Oxygen therapy
  • CPAP

Continuous Positive Airways Pressure (CPAP)

Continuous Positive Airways Pressure

Continuous positive airway pressure (CPAP) is a non-invasive method to help you with your sleep condition. Continuous positive airway pressure is a non-invasive mechanical ventilation treatment to help with hypoventilation. When people are diagnosed with sleep apnea CPAP is recommended.

The CPAP machine helps people with sleep apnea to maintain a breathing pattern during sleep. The pressurised air will be pumped in constantly to keep your airway open and prevent it from collapsing.

CPAP is a device that pumps air with mild pressure to keep your airways open while you sleep. The machine will have a mask that fits over your nose and mouth.

The machine also includes a tube that connects the mask to the machine’s motor and a motor that blows air into the tube.

For the treatment to work, you should use your CPAP machine every time you sleep, even when you take naps.

The air pressure is determined by studying your sleep pattern. There is also an autotitration program available that sets the pressure needed for your airways to open.

You should also take your CPAP machine with you when you travel. It will take some time and patience to get used to your CPAP machine.

Oxygen therapy

Oxygen therapy is also used to treat sleep-related problems. When you are diagnosed with sleep apnea your doctor will ask for a sleep study. The sleep study is a laboratory where the sleep cycle is monitored and also where the oxygen level drops.

The condition where oxygen levels drop when you sleep is called hypoxia. Oxygen therapy is used when other therapies are not effective.

Oxygen therapy is also used to treat obstructive sleep apnea (OSA). In this condition, CPAP and oxygen therapy are recommended.

Risk Factors of OHS

  • Obesity
  • OSA


OSA is obstructive sleep apnea, typically seen in patients with obesity. There will be episodes of sleep where the breathing stops and again starts. This happens due to the sudden blockage of upper airways.

Muscles of respiration should put an extra effort to open the upper airway and pull the air into the lungs.

When this does not happen spontaneously, the breathing pattern becomes shallow and breathing  stops for a brief time while sleeping. As a result, the sleep gets disrupted and patients do not get a good quality sleep.

Common symptoms of obstructive sleep apnea are

  • Headache when you wake up in the morning.
  • Dry mouth or sore throat in the morning.
  • Sleepiness during the day.
  • Snoring
  • Problems in sex life.
  • Waking up because of sudden gasps.

Preventions of OHS

Obesity hypoventilation syndrome can be prevented by concentrating on physical health. Keep the weight in check.

Eat right with all types of nutrients instead of consuming extra calories. These nutrients will help cut down those extra calories and make one feel full for a long time.

Make it a habit to exercise 30 minutes every day. Go for short walks,  limit sugar intake and alcohol consumption. Eat foods that help to boost metabolism.

Learn meditation from an expert and practice it daily. Meditation can keep all breathing problems at bay, lungs also work efficiently and all organs can get enough oxygen.


Obesity is the main cause of many diseases like diabetes, cardiovascular diseases and other pulmonary problems.

Weight loss can reduce many health-related problems and help keep fit. Weight loss also promotes mental health. It improves sleeping pattern and your body will get enough oxygen.


1.Is there a cure for OHS?

There are treatments to help you with the condition like obesity hypoventilation syndrome. CPAP and oxygen therapy are commonly used treatments. Currently, there is no specific cure for the treatment.

2.How do you treat obesity hypoventilation syndrome?

The goal of the treatment will be to provide oxygen support as obesity hypoventilation syndrome causes breathlessness. Continuous positive airway pressure (CPAP) is administered for patients with aggravated hypoventilation symptoms. Oxygen therapy is also administered when CPAP is not effective.

3.Can obesity hypoventilation syndrome be reversed?

Obesity hypoventilation syndrome is an exacerbated condition, yet it can be treated. It can be reversed with weight loss and proper clinical assistance.

4.Why does obesity cause hypoventilation?

The excess fat called adipose tissue gets accumulated and presses against your lungs. It also blocks the upper airways which makes people difficult to breathe. The gas exchange also gets limited and the oxygen is lowered in your body and carbon dioxide gets accumulated. These factors lead to hypoventilation.

5.What are the dangers of hypoventilation?

Hypoventilation or breathlessness reduces the oxygen levels in your body. The carbon dioxide level also shoots up. Your organs and cells won’t receive enough oxygen. As a result, the efficiency of your body functions decreases. You also have disturbed sleeping patterns, and you tend to feel sleepy throughout the day.


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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