While the three main types of sleep apnea are obstructive, central, and complex, there is another important condition that often overlaps with sleep apnea: Obesity Hypoventilation Syndrome (OHS).
What is OHS?
OHS occurs in people with obesity when breathing is too shallow or ineffective, leading to high carbon dioxide (CO₂) levels and low oxygen levels during the day. Unlike sleep apnea, which mainly affects breathing at night, OHS continues to impact breathing even while awake.
How OHS relates to sleep apnea:
- Most patients with OHS also have Obstructive Sleep Apnea (OSA).
- The difference is that OHS adds daytime breathing problems on top of sleep‑disordered breathing.
- Doctors diagnose OHS when blood tests show elevated CO₂ levels (PaCO₂ > 45 mm Hg) in addition to obesity and sleep apnea.
Symptoms of OHS:
- Morning headaches
- Daytime fatigue and sleepiness
- Shortness of breath
- Swelling in the legs (from fluid retention)
Why OHS matters:
OHS is more serious than OSA alone because it can lead to complications such as pulmonary hypertension, heart strain, and chronic respiratory failure if untreated. Recognizing OHS in patients with sleep apnea is crucial for proper care.
Treatment:
- Non‑invasive ventilation (like BiPAP machines)
- Oxygen therapy when needed
- Weight loss strategies
- Management of coexisting OSA with CPAP or other therapies