Which finding is characteristic of a gas embolus during laparoscopy?

• A. Mill-wheel murmur on auscultation
• B. Hyperkalemia
• C. Increased urinary output
• D. Elevated end-tidal CO2 with stable oxygen saturation

Answer: (A)

Gas embolism during laparoscopy happens when gas from the working space enters torn veins and travels to the right side of the heart. The most telling sign on physical examination is a mill-wheel murmur, a faint, splashing sound heard over the precordium as gas bubbles swirl in the right atrium and ventricle. This murmur is produced by the turbulent movement of intravascular gas and is a classic clue to the presence of a gas embolus.

Why this is the best choice: the mill-wheel murmur directly reflects gas within the heart, a hallmark of this complication. The other options don’t fit the typical pattern. Hyperkalemia is not an acute, characteristic finding of gas embolism. Decreased renal perfusion from hemodynamic compromise would more likely reduce urine output, not increase it. End-tidal CO2 behavior is variable, but a common response to significant embolism is a drop in ETCO2 from reduced pulmonary perfusion, not a reliable rise with stable oxygen saturation.