Question about taking BP in lower extremities and forearms

prowlingMA · Feb 8, 2009

For double mastectomy pt at where I work we have to do calf BP. I experimented a few times on other staff and found the calf vs forearmvs Ac can be slightly different 5-10. Have you tried getting a calf BP and a forearm on her?

Spatialized · Feb 8, 2009

Hey everybody. When I was giving report to the oncoming nurse the other day, I was telling her how the BP's have been taken in the pt's forearm b/c her upper arms are way too large for the size cuffs we have. We were taking the pressures Q2hrs b/c the pt was having 80's/50's sometimes, and she is quite a large lady. So I mentioned how much more worried I was that we were getting that low of a pressure that far away from the heart (forearms instead of biceps.) My A&P instructor and a nursing instructor once taught me that the further away from the heart you go, the higher the pressure will be in the vessels due to the vessels being smaller/narrower the further you get from the heart. The oncoming nurse had never heard of that, so it made me question what I was taught. I have seen that there is a difference. I've taken a BP in a friend's arms and then calves and had the pressure turn up higher in the calves, but that was only one incident. My teacher had said that the difference in pressure from the upper arms to the lower legs can be as much as 10-20 systolic and 5-10 diastolic, with the lower extremity being the higher resulting pressure. Okay, now I'm rambling. I've not even been a nurse for a year yet, so I don't have much experience to draw from. Please someone enlighten me?
:bowingpur

The further you get away from the heart, the lower the pressure is going to be, but pressure in the arteries should be fairly consistent through the body. Think about it this way: there's no extra pump downstream to increase the pressure. Unless you have an obstruction that squeezes the lumen of the vessel, think putting your thumb over the opening of a hose, the pressure should be lower in the distal extremities, not higher. Your lower extremities should have slightly high pressure than the arms as they have a higher blood flow, bigger pipes (femoral versus brachial for example).

In cases like this, especially with patients with odd anatomy (that's PC huh?) you have to rely on more than numbers as the validity of the numbers may be a bit suspect. Things to ask/think about:

1. What's the trend? Is this lower pressure new or has she been hanging out there the whole admission?

2. Any drugs on-board that could affect BP? We know the typical culprits, b-blockers, ACEIs, even pain meds (morphine's histamine effect).

3. Are they symptomatic? Our CHF patients can run in this range normally, it's where they live. Maybe this is where your patient lives BP-wise. Look for confusion, light-headedness, dizziness, etc.

4. Are they peeing?

5. what's their mean arterial pressure? Even with 80/50 their MAP is still 60mmHg, which is decent enough to be perfusing the end-organs. Sure it's not great, but see #3...it could be where they live.

One of the hardest things to learn as a new nurse is when to treat the numbers and when to treat the patient. You'll learn. Just keep asking questions and adding to your knowledge base. :up:

Cheers,

Tom

Whispera, MSN, RN · Feb 8, 2009

Do you have access to a large and or/a thigh sphygmomanometer? If not, I'd suggest getting one to your boss.

Bumashes, MSN, APRN, NP · Feb 8, 2009

Thanks for the replies.

This BP is NOT the trend. She came in with pneumonia. Had 130's/80's. The third day, she began to have BP's in the 80's/50's. She is asymptomatic so far, though. No active bleeding has been determined. She's been bolused x6 liters in 2 days. She IS peeing with good output. She is on no BP meds or pain meds (well, she has ultracet available, but never asks for it). BUT, she has gained 17 pounds since she's been there! I know with that much fluid, you're bound to gain weight, but she's put out almost just as much as has gone in. No bad lung or heart sounds yet, though. No bad blips on the tele monitor either. No hx of heart/renal or anything significant so far in her life. Although I find it hard to believe that someone in their fifties at 356 pounds doesn't have anything other than some arthritis and depression in their medical hx. I'm thinking that maybe she has an undiagnosed disease that will probably come to light during this admission... Anyway, one of my coworkers ventured that she has heard that infection can cause a ruckus with BP, but didn't know how. Anyway, thanks for answering my original message. I hate when I get taught things that either aren't true or are skewed. Oh well, experience will come eventually... :dzed:

Bumashes, MSN, APRN, NP · Feb 8, 2009

Do you have access to a large and or/a thigh sphygmomanometer? If not, I'd suggest getting one to your boss.

No, we don't have one. Will mention to my manager, though.

Jenifer819 · Feb 9, 2009

I work in the Peds ED and was taking BP's on an 18 yo female a few days ago in her calves d/t IV's in both AC's. Her BP in her calf was significantly higher. I mentioned this to the ER attending and he said that is normal. After I took out one of her IV's I checked in upper extremity, it was normal. Her BP in RLE was 155/89ish and 114/65ish in LUE. She said her BP is normally is in the lower range.

kmoonshine, RN · Feb 9, 2009

What's her lactate?

Sepsis can drop your BP due to vasodilation, thus requiring massive volume replacement.

Someone needs to figure out a way to get an accurate BP on this lady. Are these BP's taken manually? Is she tachy?

Bumashes, MSN, APRN, NP · Feb 9, 2009

What's her lactate?
Sepsis can drop your BP due to vasodilation, thus requiring massive volume replacement.
Someone needs to figure out a way to get an accurate BP on this lady. Are these BP's taken manually? Is she tachy?

No, they've just been taking the BP with the VS machines. Our manual cuffs only come in regular adult size, and we have to use the large/long size on her with the machines. And yes, she is tachy at around 100-105 consistently.

bluemalibu · Feb 9, 2009

The further you get away from the heart, the lower the pressure is going to be
Tom

This is not completely accurate... while of course it is indeed necessary for there to be a decrease in pressure between the two ends of the vessels to facilitate flow, (the pressure gradient), in the short throw between say the upper arm and forearm, this drop is overshadowed by the reduction in vessel diameter between these to relatively close points. Here, the restriction results in an increase in pressure. (When diameter decreases, then pressure or velocity (or both) must increase)

Here is a citation of several studies conducted:

http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijanp/vol9n1/bp.xml

Bumashes, your instructor was teaching you correct principles.

~Blue

malaski · Jun 11, 2009

blood pressure in the lower extremities is higher than the upper - what your teacher said was correct

Here is an article in Medscape stating the same fact

"Normally, the systolic blood pressure in the legs is usually 10% to 20% higher than the brachial artery pressure. Blood pressure readings that are lower in the legs as compared with the upper arms are considered abnormal and should prompt a work-up for peripheral vascular disease. All hypertensive patients should have comparisons of arm and leg blood pressures as well as volume and timing of the radial and femoral pulses at least once to rule out coarctation of the aorta.[1] " - MEDSCAPE (see link below)

http://www.medscape.com/viewarticle/471829

LuLu2008 · Jun 25, 2009

In taking a BP on an obese patient, when the only cuff available will not fit on her forearm, I use the adult cuff on her forearm. I put the stethoscope on her wrist. However, when supervising a C.N.A. recently, and the C.N.A. put the stethoscope on the antecubital space with the cuff on the forearm, I corrected the C.N.A. who replied that another R.N. told her to use this method. Any comments?