During laparoscopic cholecystectomy with the patient steeply head-up, the end-tidal carbon dioxide suddenly falls from 38 mmHg to 4 mmHg over seconds, accompanied by a sharp fall in blood pressure and a drop in oxygen saturation. The MOST likely diagnosis is:

• A Malignant hyperthermia
• B Venous air embolism ✓
• C Carbon dioxide embolism from insufflation into tissues
• D Disconnection of the sampling line

Explanation

Venous air entrained through open venous channels abruptly reduces pulmonary perfusion, so exhaled carbon dioxide collapses toward zero while the airway remains connected. A disconnection also abolishes the trace but does not cause sudden hypotension and desaturation. Carbon dioxide embolism raises end-tidal carbon dioxide acutely, and malignant hyperthermia produces a progressive rise with rising temperature. Management includes flooding the field with saline, left lateral head-down tilt and aspiration through a central line.

Reference: Miller's Anesthesia, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.