What is the minimum quantity of intracardiac air detectable by a precordial Doppler?

What is the minimum quantity of intracardiac air detectable by a precordial Doppler?

• A. 0.25 mL
• B. 5.0 mL
• C. 10 mL
• D. 25 mL

Answer: (A)

Precordial Doppler detects intracardiac air by picking up the acoustic signal changes produced by gas bubbles as they pass through the heart. Air bubbles create a distinct Doppler signal because their acoustic properties differ markedly from surrounding blood, so even tiny bubbles generate measurable signals. Because of this sensitivity, the smallest amount of intracardiac air that can be detected reliably is about a quarter of a milliliter (0.25 mL). Anything smaller tends to be indistinguishable from background noise, while larger volumes produce clearer signals. This makes 0.25 mL the practical lower limit of detection for a precordial Doppler in monitoring for air embolism.

Precordial Doppler detects intracardiac air by picking up the acoustic signal changes produced by gas bubbles as they pass through the heart. Air bubbles create a distinct Doppler signal because their acoustic properties differ markedly from surrounding blood, so even tiny bubbles generate measurable signals. Because of this sensitivity, the smallest amount of intracardiac air that can be detected reliably is about a quarter of a milliliter (0.25 mL). Anything smaller tends to be indistinguishable from background noise, while larger volumes produce clearer signals. This makes 0.25 mL the practical lower limit of detection for a precordial Doppler in monitoring for air embolism.