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Fick's Law of Diffusion — FRCA Primary MCQ

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HardPhysiology - RespiratoryFick's Law of DiffusionFRCA Primary

A radial arterial waveform becomes smooth with loss of the dicrotic notch. The fast-flush test returns slowly to baseline without oscillation. Which change is most likely to improve fidelity?

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

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Correct answer: B — Remove air bubbles and shorten the tubing

The best answer is “Remove air bubbles and shorten the tubing”. Air bubbles, compliant components, long tubing, clots and kinks lower natural frequency and increase damping. Removing bubbles and unnecessary tubing therefore improves transmission. Lowering the transducer creates a hydrostatic offset, while excessive pressure-bag inflation does not correct the dynamic response and risks equipment failure.

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/