Obesity hypoventilation syndrome

Question 1

What is obesity hypoventilation syndrome?

Answer 1

Breathing disorder that only affects morbidly obese individuals; frequently accompanied by OSA, it is characterized by diurnal hypercapnia

Question 2

What is the pathophysiology in obese hypoventilation syndrome?

Answer 2

Obesity reduces inspiratory muscle strength and restricts respiratory excursions → alveolar hypoventilation, sleep-disordered breathing (e.g., OSA), and failure of ventilatory compensatory mechanisms → decreased PaO2 and increased PaCO2 during sleep (PaCO2 retention extends to the waking hours)

Question 3

What are the symptoms of obesity hypoventilation syndrome?

Answer 3

Same as obstructive sleep apnea

Question 4

How is obese hypoventilation diagnosed?

Answer 4

BMI ≥ 30 kg/m2
Arterial blood gasses showing diurnal* hypercapnia (PaCO2 > 45 mm Hg) with no other cause
Polysomnography shows hypoventilation
*during the day

Question 5

What is the treatment from obese hypoventilation?

Answer 5

Weight loss

Nasal intermittent positive pressure ventilation