II. Definitions
- Obesity-Hypoventilation Syndrome (OHS, Pickwickian syndrome)
- Central Sleep Apnea in morbidly obese patients
- Results from Chemoreceptor hyporesponsiveness
- Charactized by chronic hypercarbia, Hypoxia and polycythemia, as well as Hypersomnolence
III. Epidemiology
- Prevalence: 0.4% of adults in U.S.
- Age of diagnosis (typically delayed): 40 to 60 years old
IV. Findings
- Morbid Obesity (BMI >40 kg/m2)
- Sleep disordered breathing
- Daytime arterial hypercapnia (PaCO2>=45 mmHg)
- Commonly presents with adute on chronic hypercapni Respiratory Failure
-
Sleep Study with apnea/hypopnea index
- Moderate Obstructive Sleep Apnea (>=5 events/hour): 90% of OHS patients
- Severe Obstructive Sleep Apnea (>=15 events/hour): 70% of OHS patients
V. Associated Conditions
-
Obstructive Sleep Apnea
- Obstructive Sleep Apnea (OSA) is comorbid in 90% of Obesity-Hypoventilation Syndrome patients (severe in 70%)
- However, only 10 to 20% of patients with OSA have Obesity-Hypoventilation Syndrome
- Cardiopulmonary Disease (see complications below)
VI. Management
- Positive Airways Pressure (CPAP or BiPAP)
- Use BiPap for patients with Central Sleep Apnea (by Sleep Study)
- Paradoxically, nighttime Central Sleep Apnea is less common in OHS
- Most OHS patients are treated with CPAP for Obstructive Sleep Apnea
- Weight loss
- Bariatric Surgery is often indicated
VII. Complications
- Heart Failure
- Pulmonary Hypertension
- Increased mortality