Which factors can affect the accuracy of cuff-based blood pressure measurements?

• A. Cuff size matters, but accuracy is generally robust to other factors
• B. Positioning alone determines accuracy
• C. Recent activity and caffeine intake determine accuracy
• D. Cuff size, body position, recent activity, caffeine, and arrhythmias can influence accuracy

Answer: (B)

The accuracy of cuff-based blood pressure readings depends on several interacting factors, not just one. Cuff size matters a lot: a cuff that’s too small will push the reading higher, while a cuff that’s too large can yield a falsely low value. The position of the arm and cuff relative to the heart is also crucial—the arm should be supported and the cuff at heart level; deviations up or down can skew the result. Recent activity and caffeine intake can transiently raise blood pressure, so measurements should be taken after a period of rest and without recent stimulant use. Arrhythmias pose another challenge, especially for automated devices, because irregular heartbeats can produce unreliable readings and may require manual auscultation or multiple measurements.

Because all of these factors can influence the result, the most reliable practice is to ensure proper cuff size, correct arm positioning at heart level, a rest period before measuring, avoidance of recent caffeine or stimulants, and awareness of any rhythm irregularities.