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Fetal Hb Left Shift ODC — FRCA Primary MCQ

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HardPhysiology - RespiratoryFetal Hb Left Shift ODCFRCA Primary

A pressure-transducer kit has a natural frequency of 12 Hz. Adding a needle-free connector reduces it to 7 Hz without materially altering damping. What is the principal monitoring consequence?

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Correct answer: C — Greater distortion from resonance with arterial harmonics

The best answer is “Greater distortion from resonance with arterial harmonics”. Reducing natural frequency moves the system closer to frequencies contained in the arterial waveform, increasing resonance and waveform distortion. Levelling and zeroing errors create fixed pressure offsets; they are distinct from dynamic-response errors. Gauge-to-absolute conversion and hydrostatic signal loss are not produced by a connector.

Reference: Fujiwara et al., Effect of Planecta and ROSE on the frequency characteristics of blood pressure-transducer kits: https://pmc.ncbi.nlm.nih.gov/articles/PMC4621715/