Obesity Hypoventilation Syndrome

What is Obesity Hypoventilation Syndrome?

Obesity hypoventilation syndrome (OHS) also known as Pickwickian syndrome is a breathing disorder in obese people that leads to low oxygen levels and too much carbon dioxide in the blood during wakefulness in the absence of an alternative neuromuscular, mechanical or metabolic explanation for hypoventilation. Daytime hypoventilation is developed because of the inefficient moving of air in and out of the lungs. OHS is a progressive disease that can put a strain on the heart resulting in heart failure which is associated with significant morbidity and mortality.

What are the three main features of Obesity Hypoventilation Syndrome?

  • Obesity; (BMI) ≥30 kg/m2
  • Daytime hypercapnia: arterial carbon dioxide tension (PaCO2) ≥45 mmHg at sea level
  • Sleep-disordered breathing (such as obstructive sleep apnea)

What are the symptoms of Obesity Hypoventilation Syndrome?

The symptoms of OHS are due to lack of sleep and a lower oxygen level in the blood. It includes: 

  • Poor sleep quality
  • Loud and frequent snoring during sleep and/or breathing pauses 
  • Daytime sleepiness
  • Depression
  • Headaches

How to diagnose Obesity Hypoventilation Syndrome

The diagnosis of OHS includes detailed medical history including patient’s symptoms and physical examination. Physical examination is focused on signs of right-sided heart failure such as swollen lower extremities or oxygen deprivation evidenced by cyanosis (Bluish color in the lips, fingers, toes, or skin). Other tests used in the diagnosis of OHS include:

  • Arterial blood gas
  • Chest x-ray or CT scan to rule out other possible causes
  • pulmonary function tests (PFT)
  • Sleep study 
  • Echocardiogram 

How to treat Obesity Hypoventilation Syndrome?

  • Weight loss: The best long-term treatment for patients with OHS is weight loss. Weight loss improves lung function, sleep-disordered breathing, and ultimately in improvement in daytime hypoventilation. Lifestyle modification including diet and exercise can be effective in weight loss, but bariatric surgery remains the most effective way to produce and maintain substantial weight loss.
  • Positive pressure ventilation:  Continuous positive airway pressure (CPAP) can eliminate daytime hypercapnia when OHS is associated with sleep-disordered breathing
  • Tracheostomy: Tracheostomy helps to relieve the upper airway obstruction and it is reserved for patients with OHS who are developing life-threatening complications or who are unable to tolerate positive airway pressure.

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