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Blood pressure readings can vary drastically depending on where it's taken

Different parts of the body could yield different blood pressure results

Photo (c) laflor - Getty Images
With many consumers struggling with high blood pressure, a new study conducted by researchers from UT Southwestern Medical Center explored how medical professionals could have a hard time getting an accurate blood pressure reading. 

The study revealed that taking patients’ blood pressure at different parts of the body can create different readings. This is problematic for health care professionals, as the reading can determine the course of treatment for patients. 

“For our patients in the [neuroscience intensive care unit, NSICU], blood pressure often needs to be maintained in a very narrow range,” said researcher Kathrina B. Siaron, RN. “Moving it one way or another could potentially harm the patient.” 

Understanding different blood pressure readings

The researchers, all of whom were nurses, evaluated 80 patients admitted into the NSICU between three months last year. 

Participants had their blood pressure taken in both arms, their wrists, and (for a small portion of patients) directly from their arteries. When taking the pressure in the arms or wrists, the researchers set up different machines on either arm or wrist and activated the machines at the same time. 

The researchers learned that blood pressure readings varied greatly between the different testing sites of the patients. Though the readings were taken at the same time, they came up quite differently. 

On average, systolic blood pressure changed by a value of 13 between the arm reading and the wrist reading, while the diastolic reading changed by a value of five between those spots. Similarly, the systolic reading had a difference of eight between the two arms, and the diastolic reading was different by as much as six points. 

The researchers are unsure as to why these changes are so drastic on the same patient, so they plan to continue their work in this area to better understand this trend. Because a blood pressure reading can determine what kind of treatment a doctor chooses for a patient, these variations in the readings can make a huge difference when it comes to health outcomes. 

“If we take pressure in one arm, a patient seems fine, but in the other arm, they’re in crisis,” said researcher DaiWai M. Olson, PhD. “The values we collected were really all over the place. There was no consistency between the same arm or wrist between different patients.” 

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