What is OHS?

OHS is defined as chronic daytime hypercapnia (PaCO₂of over 45 mmHg) in obese patients (those with a BMI of > 30kg/m²) after ruling out any other causes of hypoventilation.¹

As a result of poor breathing, those with OHS suffer from excess carbon dioxide (hypoventilation) and insufficient oxygen in their blood (hypoxemia).

OHS symptoms include:

Dyspnoea²
Excessive daytime sleepiness (EDS)²
Morning headache²
Depression

As many as 90% of patients with OHS also suffer from obstructive sleep apnoea (OSA).

References

Olson AL, Zwillich C. The obesity hypoventilation syndrome. Am J Med. 2005 Sep 118(9): 948-56
Mokhlesi B, Kryger MH, Grunstein RR. (2008) Assessment and management of patients with obesity hypoventilation syndrome. Proc Am Thorac Soc 5:218–225

3: Kessler R, Chaouat A, Schinkewitch P, Faller M, Casel S, Krieger J, Weitzenblum E. (2001) The obesity-hypoventilation syndrome revisited: A prospective study of 34 consecutive cases. Chest 120:369–376