Blood Pressure in Arm/Legs

[GM911 0]

We've all been taught how to take pressure measurements in arms and legs, but I have never taken both on the same patient, and sitting at my desk right now, am too lazy to find someone to practice on. My question: should the pressures be the same in both the arms and the legs? I have heard of ankle BPs being extremely close to brachial measurements, and I have also heard that the thigh BP should be higher than the arm. Does anyone know if these findings are correct?? Thanks

[Guest]

Generally speaking, the closer you are to the heart, the higher the blood pressure. The actual BP in the distal leg is dependant on the patient's position (it will be lower if the patient is lying flat). This can be very useful when you need a quick "down and dirty" assessment of an unstable patient's BP. BP will decrease in the following order: Carotid, Femoral, Brachial, Radial, Tibial, and Pedal. So if a patient has a carotid pulse but no other pulse, you know that the BP is very low. At the same time, in a critical patient (say, one that was just resuscitated), a quick check to see if the patient has a radial pulse well let you know that the BP is high enough to perfuse the brain until you have time to check a BP. This is not a substitute for taking an actual BP, but it is an effective stop-gap measure when you have 27 things that all need to be done simultaneously.

[Guest partyrock]

A plapable pulse will decrease in those places as the blood pressure drops. Blood pressure differences between the radial and femoral arteries typically differ by about 5 mmHg.

A good rule of thumb for assesing hemodynamically unstable pts is plapable pulse in the radial, femoral, and carotid mean minnimum systolic pressures of 80, 70, and 60 respectively.

[Skooter92 7]

GM-

Thigh cuff or ankle pressures, or for that matter, forearm pressures, will be close enough to anything you might take on the upper arm so as to make no difference. The popliteal artery is a good second choice for auscultation for a BP.

[STAT213 332]

A plapable pulse will decrease in those places as the blood pressure drops.  Blood pressure differences between the radial and femoral arteries typically differ by about 5 mmHg.

A good rule of thumb for assesing hemodynamically unstable pts is plapable pulse in the radial, femoral, and carotid mean minnimum systolic pressures of 80, 70, and 60 respectively.

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Actually, this has been busted by the ACS and ATLS. I don't have the literature at hand, but here is the simple way to show its is just bad information that we all have been taught. How many of us have taken an upper arm blood pressure to find 50, 60 or 70 palp? I know I have. Applying what we (including me) were taught, this should not be so. Not having a radial pulse, or a femoral for that matter is good indication of severely impacted perfusion, and should be treated appropriately.

As for taking BP's on any extremity, I concur with what has been said by others here. You can take it anywhere and frequently on burn patients, you are forced to do just that.

However, palpation of carotid pressures is as of this point still discouraged.

Something that I remember to this day from paramagic class: 50 % of what I am gonna teach you numbskulls is wrong. I just don't know what 50 % yet. - Dick Cherry

[Guest partyrock]

I get more damn homework from this site than I got in school. The ability to obtain a BP by palp lower than 80 in the arm is due to back pressure that occurs when the BP cuff is applied. This results in a pulse that would not be palpable without the cuff in place.

[WAS967 97]

This thread has got me wondering: what affect does cuff size have on the results that we obtain from a B/P and what effect does taking a B/P through clothing have on the reading? I'd be interested in finding out. I believe cuffs aren't just supposed to wrap around an arm adequately to provide even pressure, but must also cover a certain surface area of the arm - was it 1/3 - 1/2?

Most Thigh cuffs I have seen are huge, and most services don't carry them, leaving us to resort to an ankle if we need to go lower extremety. It's not uncommon for me to take B/Ps with a small cuff on a wrist during winter to avoid having to relieve a patient of thier warm coat in the freezing cold.

[ckroll 101]

Excellent discussion. I'm guessing we care about BP because we intend to do something about it if we don't like the numbers.

I recall an MD at Hudson Valley making a compelling case at a CA that improperly sized cuffs can give aberrant readings and that treatment decisions need to be based on good numbers, especially with trauma and with those who are medicated to decrease cardiac work load.

We don't use what we don't have handy. I got a compact set of 4 cuffs with the quick connect syphgmomanometer and my experience is that BP numbers correspond better with patient appearance when I match the cuff to the patient.