Interstitial emphysema

Interstitial emphysema refers to the presence of air within the connective tissue of the lung, outside of the normal airspaces. This condition typically arises from alveolar rupture, allowing air to dissect into the pulmonary interstitium, often extending along bronchovascular sheaths. It can lead to complications such as pneumomediastinum or pneumothorax.

This code is appropriate for documenting cases where imaging studies (e.g., CT scan, chest X-ray) confirm the presence of air within the lung parenchyma but outside the alveoli. It is commonly seen in patients on mechanical ventilation, those with severe asthma, or following trauma. Documentation should clearly state "interstitial emphysema" or describe air within the lung's connective tissue.

• Differentiate from emphysema NOS (J43.9) which refers to chronic obstructive pulmonary emphysema.
• Do not use for subcutaneous emphysema (T81.82 or T79.7), which involves air under the skin.
• Consider sequencing this code as a secondary diagnosis if the underlying cause (e.g., mechanical ventilation complication, trauma) is the primary reason for the encounter.