Differences in Bilateral BP's

[Rhonda V]

Hi! I would like to know how far apart BP's can be on each arm. I often take BP's on each arm especially when I get a high reading on one arm or if it's hard to hear on one side. I sometimes get totally different readings...like 10-20 points difference. Can this be normal? I've heard that wide variations in BP on each arm can be an indicator of an occlusion. Also, is it true that BP's are usually higher on the left arm or does it matter? Thank you for all replies.

[nursej22, MSN, RN]

I was taught in nursing school (a million years ago, :) ) that BP is usually higher on the right, due to less of an arch in the subclavian artery as it branches off from the aorta. Of course, this may be an old wives' tale, as many of the things seem to be the longer I am in nursing.

Any how, the BP should not differ more than 10 -20 mmHg. But sometimes you don't always have a choice as to which arm to use, ie presence of a dialysis fistula, PICC line, cast or other kind of wound. Yes, occlusion, usually of the subclavian artery can cause a substantial difference in BP as well as an anuerysm. Occlusions might occur in someone with other signs of athersclerosis such as coronary artery disease or peripheral vascular disease. Other risk factors, smoking, high blood pressure, diabetes mellitus, hypercholsterolemia.

Where I work an ankle-brachial index is used to diagnose peripheral arterial disease, that is comparing the systolic BP of the ankle, by doppler to that in the arm. Normal is

[SEOBowhntr]

Major differences in BP from one arm to the other can often times indicate a Subclavian Artery Stenosis. I have a couple really good pictures on my bulletin board of a large Subclavian Steal Syndrome arteriogram before and after angioplasty. The improvement is amazing!!! You can actually see the flow is improved up the carotid, down the LIMA, and further out the SC artery. This patient had pressures in the 80's on the left side, and in the 150's on the right. Post procedure, there was still a difference, but more like 20mm of Hg, not 70!!

[EricTAMUCC-BSN, BSN, RN]

good question, It is pretty normal to find alot of patients with a lower pressure in one arm than the other in an acute care setting, particularly patients with mild heart failure (majority of patients in the hospital). This maybe improved with positioning, light exercise, fluids, anticoagulants, cardiovascular medications, oxygen, PS or PEEP, and pumps.

Secondly your concern over occlusion is valid and more than likely this patient should be on an anticoagulant. However this is more normal physiology rather than an emergent situation. Speaking from personal experience I can tell you emboli are best manifested by direct patient symptoms.

I've seen a patient who had an emboli to her left radial artery where she had extremely severe pain to her left wrist exacerbated by movement. Her hand was ice cold and white like winter snow and of course no pulse on doppler. Her remedy was a simple cath procedure and heparin drip.