08/02/2026
Obstructive Sleep Apnea (OSA)
OSA is a mechanical issue where your airway physically collapses or becomes blocked during sleep. This causes "apneas" (pauses in breathing).
Crucially, people with OSA usually have normal oxygen and carbon dioxide levels when they are awake.
Obesity Hypoventilation Syndrome (OHS)
Formerly known as Pickwickian Syndrome, OHS is a ventilation issue. It is defined by a combination of obesity (BMI > 30), and high carbon dioxide (PCO2 >45mmhg) levels in the blood during the day.
In OHS, the body simply doesn't breathe deeply or frequently enough to clear out CO2, even when you are wide awake.