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Underdamped arterial line — FRCA Primary MCQ

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HardPhysics and Clinical MeasurementUnderdamped arterial lineFRCA Primary

An arterial line trace has exaggerated systolic peaks, low diastolic values and ringing after a fast flush test. The cuff pressure is lower than the displayed systolic pressure. What is the most likely problem?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Underdamped measurement system

An underdamped arterial system overshoots systolic pressure, underestimates diastolic pressure and shows ringing. Overdamping blunts the waveform and underestimates systolic pressure. A transducer below the axis would falsely elevate the whole pressure, not cause ringing. Fast flush testing helps assess damping and natural frequency.

Reference: Dorsch and Dorsch Understanding Anesthesia Equipment; Primary FRCA physics texts