Researchers at the University of Cambridge have uncovered the underlying reason why the most common form of blood pressure measurement — the cuff-based auscultatory method — may often produce inaccurate readings. Their findings, published in the journal PNAS Nexus, offer a clearer understanding of the physics behind these inaccuracies and suggest simple adjustments to current protocols could significantly improve health outcomes.
To investigate, researchers built a simplified physical model that mimicked the conditions of blood flow and artery behavior during cuff inflation and deflation. Unlike previous studies that used rubber tubes (which do not replicate how arteries behave when blood flow is stopped), the Cambridge model used tubes that fully collapse under pressure — more accurately representing human arteries.
The study revealed that when the cuff cuts off blood flow to the lower arm, the downstream pressure drops significantly. This causes the artery to remain closed longer as the cuff deflates, delaying the return of blood flow sounds and leading to an underestimation of systolic blood pressure. “We are currently not adjusting for this error when diagnosing or prescribing treatments, which has been estimated to lead to as many as 30% of cases of systolic hypertension being missed,” said co-author Kate Bassil.
Crucially, the researchers suggest that a simple change — such as raising the arm before measurement — could standardize downstream pressure and improve accuracy without requiring new equipment. “You might not even need new devices, just changing how the measurement is done could make it more accurate,” added Professor Anurag Agarwal.
The team now aims to secure funding for clinical trials and collaborate with clinicians and industry partners to refine and validate their findings across broader populations.
Reference: Kate Bassil, Anurag Agarwal. Underestimation of systolic pressure in cuff-based blood pressure measurement. PNAS Nexus, 2025; 4 (8) DOI: 10.1093/pnasnexus/pgaf222
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