Previous studies have shown that there is a difference between the blood pressure that you'll get using an automated cuff on the forearm versus the upper arm. However, in some of your patients, their arms are just too large to fit your cuff and you might need to use the forearm as a measuring area.
Understand that there will be a difference in pressure between the forearm and the upper arm. In general, the blood pressure you get from the forearm will be higher than the blood pressure you get from the upper arm. A study by Schell, et al. showed additional differences that can affect forearm blood pressure values; the most important being head-of-bed elevation. The greatest differences between forearm values and upper arm values occurred when the head of the bed was elevated by 30 degrees. In addition, patients with a large body mass and patients on vasoactive medications were also more likely to have big differences between the forearm and the upper arm values.
The take-home point here is that the forearm is an acceptable method of monitoring blood pressure. Understand that the pressure from the forearm is probably higher than it would be from the upper arm. If you're dealing with a patient who is borderline hypotensive with a forearm blood pressure measurement of 90 mmHg systolic, that patient could actually be in shock since blood pressure measurements typically are going to be higher in the forearm. This is more likely if the head of the bed is elevated by more than 30 degrees, the patient has large body mass index, or the patient is on a vasoactive medication.
From:
Schell, K, et al. (2008). Comparison of forearm and upper arm non-invasive oscillometric blood pressures in critically ill adults. American Journal of Critical Care 17(3): 282-3.
Best wishes,
David W. Woodruff, MSN, RN-BC, CNS, CEN
President, Ed4Nurses, Inc.
Empowering Nurses to Become Extraordinary
www.Ed4Nurses.com
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