CHAOS sequence
The cascade of abnormalities resulting from congenital high airway obstruction syndrome affecting multiple organ systems.
Full Definition
CHAOS sequence refers to the constellation of abnormalities that develop secondary to congenital high airway obstruction syndrome. The sequence includes massively enlarged, hyperechoic lungs due to retained lung fluid, flattened or inverted diaphragms, dilated airways distal to the obstruction, fetal ascites, and potential development of hydrops fetalis. The enlarged lungs compress the heart and great vessels, leading to decreased venous return and cardiac output. Understanding this sequence is crucial for prenatal counseling and planning the EXIT procedure to establish a secure airway immediately at delivery.
Usage
Usage note: Use 'sequence' rather than 'syndrome' to emphasize the cascade nature of the abnormalities.
In Context
- "The CHAOS sequence was evident with bilateral lung enlargement, inverted diaphragms, and early hydrops changes." — Ultrasound interpretation
- "Recognition of the CHAOS sequence prompted immediate consultation with the fetal surgery team for EXIT planning." — Referral documentation