ASATT NCE Exam Practice 2026 – Comprehensive Preparation Resource

A gas embolism disrupts pulmonary blood flow, so less blood reaches the lungs to offload CO2. This means CO2 isn’t carried to the alveoli as efficiently, and the amount exhaled at the end of expiration falls. On capnography, this appears as a sudden drop in end-tidal CO2, which is the most immediate and measurable sign of a gas embolism during a procedure. While more severe outcomes like hypotension, hypoxemia, or, in extreme cases, cardiac arrest can occur with a substantial embolism, the characteristic intraoperative indicator clinicians look for is the rapid decrease in end-tidal CO2.