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NIBP cuff size error — FRCA Primary MCQ

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ModeratePhysics and Clinical MeasurementNIBP cuff size errorFRCA Primary

In pre-assessment, a patient with a large upper arm has a standard adult NIBP cuff applied. Readings are unexpectedly high compared with an appropriately sized forearm cuff. What is the most likely explanation?

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

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Correct answer: D — Too small a cuff overestimates pressure

A cuff that is too small for the limb tends to overestimate blood pressure because more pressure is needed to occlude the artery. A cuff that is too large may underestimate pressure. Oscillometric devices infer arterial pressure from cuff oscillations, not venous pressure. Correct cuff sizing is a basic but important measurement safety issue.

Reference: Dorsch and Dorsch Understanding Anesthesia Equipment; Association of Anaesthetists monitoring standards