What is OHS?

OHS is defined as chronic daytime hypercapnia (PaCOof 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).

More OHS

Equipment replacement
Educate patients on the importance of timely equipment replacement and how critical it is to the success of their sleep apnea therapy.
Patient outcomes
Learn about the positive outcomes for OHS patients being treated with NIV.
Getting the most out of ventilation therapy for OHS patients
Adhering to therapy is critical for patients receiving noninvasive ventilation.


  1. Olson AL, Zwillich C. The obesity hypoventilation syndrome. Am J Med. 2005 Sep 118(9): 948-56 

  2. 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