E66.2

HCC Category Mapping

What This Code Means

This condition describes severe obesity that is so significant it causes the person to have shallow breathing and inadequate oxygen intake, often called Pickwickian syndrome. The excess weight physically restricts the lungs' ability to expand fully, leading to respiratory problems.

Coding Tips

• •Always verify that both the morbid obesity AND alveolar hypoventilation are documented by the physician before assigning this code; do not assume one causes the other without explicit documentation
• •This code includes the obesity component, so do not assign an additional obesity code (E66.0 or E66.1); however, you may need to add a separate respiratory code (such as R06.02 for shortness of breath) if the hypoventilation is documented as a distinct clinical finding

Clinical Significance

Morbid obesity with alveolar hypoventilation, also known as Obesity Hypoventilation Syndrome or Pickwickian Syndrome, is a serious condition where extreme obesity mechanically restricts lung expansion, leading to chronic hypoventilation with daytime hypercapnia and hypoxemia. This condition carries high mortality risk from respiratory failure, pulmonary hypertension, and cor pulmonale, and often requires nocturnal positive airway pressure therapy or invasive ventilation.

Documentation Requirements

• ✓Documentation must include both the morbid obesity diagnosis (with body mass index) and objective evidence of alveolar hypoventilation including arterial blood gas showing daytime hypercapnia (partial pressure of carbon dioxide above 45 mmHg), exclusion of other causes of hypoventilation, and pulmonary function testing.
• ✓Sleep study results, oxygen saturation data, and echocardiographic findings for pulmonary hypertension should be documented.
• ✓Treatment with noninvasive ventilation or other respiratory support should be noted.

Commonly Confused Codes