Is the sleep study required for the diagnosis?
http://thorax.bmj.com/content/early/2013/08/28/thoraxjnl-2013-204298.extract
Sleep study is not required to diagnose Obesity hypoventilation syndrome.
a body mass index greater than or equal to 30kg/m2 with awake chronic hypercapnia (PaCO2 >45 mm Hg), and sleep-disordered breathing. many have resting hypoxemia. Other disorders that may cause hypoventilation i.e COPD or neuromuscular diseases should be ruled out with spirometry. Approximately 90% of patients with OHS also have obstructive sleep apnea (OSA) and 10% have further worsening of hypoventilation especially during rapid eye movement (REM) sleep.
So I have 2 situations:
1. Hypercapnia in acute illness then normal stable CO2. Has OSA.
2. Obese but no OSA, with high bicarbonate, hypoxia, CO2 upper limit of normal.
I agree with Khaled Saad's definition. Even the ones given earlier by others too.
Maybe not, but it sure helps. I've had a couple of patients where I strongly suspected OHS, but the PSG led me to think otherwise. Turns out they really had neuromuscular disease, and just happened to be obese.
- Badges
- Science topic