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Starling's Law — FRCA Primary MCQ

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HardPhysiology - CardiovascularStarling's LawFRCA Primary

An arterial trace has an exaggerated systolic peak, a low diastolic pressure and several oscillations after a fast-flush test; mean arterial pressure is relatively unchanged. Which defect best explains the trace?

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Correct answer: D — Underdamping of the catheter–transducer system

The best answer is “Underdamping of the catheter–transducer system”. An underdamped system resonates and exaggerates high-frequency components, producing systolic overshoot, diastolic undershoot and a widened pulse pressure; a fast-flush test shows multiple oscillations. Overdamping blunts the trace. Incorrect levelling shifts systolic and diastolic pressures in the same direction rather than selectively widening pulse pressure.

Reference: Saugel et al., How to measure blood pressure using an arterial catheter: a systematic 5-step approach: https://pmc.ncbi.nlm.nih.gov/articles/PMC7183114/