# Obtaining BP in both arms



## Achilles (Apr 14, 2013)

This question may be more suited for the ALS discussion, however, I'm going to ask it here. I was recently reading on a forum about a difference in blood pressures in either arm. So my question is; should an EMT bother obtaining a blood pressure in both arms? Can an EMT do anything for the what is causing the difference. If a difference can be seen in the upper extremities can the difference be seen in lower extremities as well? Perhaps it's a foolish question but i'm curious to know. 

Thank you.


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## NomadicMedic (Apr 14, 2013)

As a routine screening its not a bad idea to take a BP in both arms. A study has shown that a 15 point difference arm to arm is an indicator of possible PVD . It's also an indicator, albeit not definitive, of a dissecting aortic aneurysm. It's not something an EMT (or medic) can fix, but if you have time, a BP on both arms isn't a bad idea. 

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)61926-0/fulltext


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## Achilles (Apr 15, 2013)

You have to sign in to read that.
Can you email me the text or pm me?


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## Handsome Robb (Apr 15, 2013)

Like DE said, it can indicate a few different things. 

With that said, personally I don't check bilateral BPs unless I'm suspecting a dissecting aneurysm or its on my differentials and I'm "ruling out" things but again, like DE said, it's not a "ZOMG THEY'VE GOT DIFFERENT PRESSURES IN EACH ARM THEY'RE DISSECTING!"

I'll ask you a question, what would you expect the difference in BPs in the presence of a dissecting aneurysm? (Which would be higher and which would be lower?)


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## Achilles (Apr 15, 2013)

Robb said:


> I'll ask you a question, what would you expect the difference in BPs in the presence of a dissecting aneurysm? (Which would be higher and which would be lower?)


I don't know. I don't want to guess because I don't know why I wound be right or wrong.


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## chaz90 (Apr 15, 2013)

Robb said:


> I'll ask you a question, what would you expect the difference in BPs in the presence of a dissecting aneurysm? (Which would be higher and which would be lower?)



I'm thinking it depends on the DeBakey classification. Where the dissection occurs determines which arterial branches off the aortic arch are involved and which blood supply may be impaired. I think you'd get major EMS points if you brought in a pt. with a suspected TAD and gave which DeBakey classification you thought most probable. Only if you were right of course.


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## Carlos Danger (Apr 15, 2013)

Achilles said:


> This question may be more suited for the ALS discussion, however, I'm going to ask it here. I was recently reading on a forum about a difference in blood pressures in either arm. So my question is; should an EMT bother obtaining a blood pressure in both arms? Can an EMT do anything for the what is causing the difference. If a difference can be seen in the upper extremities can the difference be seen in lower extremities as well? Perhaps it's a foolish question but i'm curious to know.
> 
> Thank you.



The only time I would check a BP in both arms is perhaps if I strongly suspected an AA. Even then I probably wouldn't do it, though. Because if I strongly suspect an AA, the findings of this test aren't going to convince me that one doesn't exist.

The problem is that this test is not sensitive enough or specific enough to be of any diagnostic value:


If you suspect an AA and there is a difference in BP's, then this test hasn't told you anything that you didn't already know, which is that your patient _may_ have an AA. 


If you suspect an AA and there is no difference in BP's, you should still suspect an AA, because this test certainly isn't sensitive enough to rule one out. 


If you have no suspicion of an AA and check BP's in both arms of every patient simply as a screening measure, you will encounter enough false positives and perturbations that you will waste time and effort and expose your patients to more discomfort than necessary as you re-check BP's to confirm what you think you just discovered.


And in any case, whether your findings support your suspicion or not, this test isn't going to affect your plan of care at all.


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## chaz90 (Apr 15, 2013)

Halothane said:


> [*]And in any case, whether your findings support your suspicion or not, this test isn't going to affect your plan of care at all.
> [/LIST]



This is true, but I still can see the value in raising your index of suspicion. I wouldn't ever use a negative test to rule it out, but a positive result that correlates with other clinical findings would just be additional icing on the cake. In this case, the more reasoning you have, the better it is to put an additional hop in the ED doc's step and/or call a trauma alert.


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## Summit (Apr 16, 2013)

chaz90 said:


> This is true, but I still can see the value in raising your index of suspicion. I wouldn't ever use a negative test to rule it out, but a positive result that correlates with other clinical findings would just be additional icing on the cake. In this case, the more reasoning you have, the better it is to put an additional hop in the ED doc's step and/or call a trauma alert.



If you suspect an AA enough to do bilat BPs, you should be on the way to ED already. If you have to do it on the way in, knock yourself out.


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## KellyBracket (Apr 16, 2013)

According to one study, about 20% of adult patients, who were not being evaluated for dissection, who came to an ED had a difference in systolic or diastolic blood pressure between their arms of ≥ 20 mm Hg. (http://www.ncbi.nlm.nih.gov/pubmed/8823153/).

I think the original observation was that patients with an aortic dissection were found to occasionally lack a missing pulse in an upper or lower extremity. Somehow this got translated into "Look for a blood pressure difference of x mm Hg," but no one can seem to agree on the best cut-off.


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## Brandon O (Apr 18, 2013)

Summit said:


> If you suspect an AA enough to do bilat BPs, you should be on the way to ED already. If you have to do it on the way in, knock yourself out.



I think this is about right. If you're worried about something, you look for support. For an acute pathology that can nevertheless present somewhat vaguely, it's nice when you have a well-known flag to wave around, to get the attention of the doc or triage nurse and get them all thinking the same thing. Doesn't matter that it's not a particularly specific sign... it's a code word. "And doc... he says... it feels _just like when he had his last heart attack, but worse._" (cue dramatic music)


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## VFlutter (Apr 18, 2013)

Brandon Oto said:


> I think this is about right. If you're worried about something, you look for support. For an acute pathology that can nevertheless present somewhat vaguely, it's nice when you have a well-known flag to wave around, to get the attention of the doc or triage nurse and get them all thinking the same thing. Doesn't matter that it's not a particularly specific sign... it's a code word. "And doc... he says... it feels _just like when he had his last heart attack, but worse._" (cue dramatic music)



With some aortic dissections, usually type A, patients will develop acute aortic insufficiency resulting in a new diastolic murmur. However many of these patients already have a preexisting murmur so it can be hard to differentiate.


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## Brandon O (Apr 18, 2013)

Chase said:


> With some aortic dissections, usually type A, patients will develop acute aortic insufficiency resulting in a new diastolic murmur. However many of these patients already have a preexisting murmur so it can be hard to differentiate.



Tricky to hear over the diesel too


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## NPO (May 10, 2013)

DEmedic said:


> As a routine screening its not a bad idea to take a BP in both arms. A study has shown that a 15 point difference arm to arm is an indicator of possible PVD . It's also an indicator, albeit not definitive, of a dissecting aortic aneurysm. It's not something an EMT (or medic) can fix, but if you have time, a BP on both arms isn't a bad idea.
> 
> http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)61926-0/fulltext



That is very interesting. We transported a dissecting AA the other day. As my CCT-RN stated her AA "Was from the arch all the way to her big toe." So I did the EMT thing and treated with diesel.

I did notice however that enroute they kept getting bad BP readings. Initially low 90s/60s then 160s/100s. They kept moving the cuff to get what they thought was a more accurate reading, but I wonder if it was just what you are talking about. We will never know, but fun to think about.


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## medic741 (Jun 1, 2013)

Ripping/tearing abd/back pain not a bad idea to do this.


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## TheLocalMedic (Jun 4, 2013)

Not worth doing BPs on both arms.  On the few thoracic and abdominal aneurysms I've seen either an arm or leg has been pulseless, dusky or cool. 

Pretty clear a lot of times when there's an aneurysm going on, and I don't really think a BP on both arms will give a definitive way to diagnose anything.  And as others have stated, sometimes people will have a different pressure in their arms for no discernible reason and the finding isn't clinically significant.


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## sir.shocksalot (Jun 4, 2013)

TheLocalMedic said:


> Not worth doing BPs on both arms.  On the few thoracic and abdominal aneurysms I've seen either an arm or leg has been pulseless, dusky or cool.
> 
> Pretty clear a lot of times when there's an aneurysm going on, and I don't really think a BP on both arms will give a definitive way to diagnose anything.  And as others have stated, sometimes people will have a different pressure in their arms for no discernible reason and the finding isn't clinically significant.



I disagree. I think if you have time bilateral blood pressures and pulses are prudent if you suspect dissection, aneurism or other pathology that can cause unequal circulation. Using cool, dusky, or pulselessness to evaluate unequal circulation is just begging to miss something. That sort of assessment can quickly be complicated by ambient temperature, skin color, and provider error/patient anomaly (one pulse is easier to discern than the other or provider technique when palpating).

Aneurysms and dissections do not always have clear presentations even in extremis. I do fully agree that unequal blood pressure is by no means pathopnomonic for dissection/aneurism. Subclavian steal syndrome can cause it, I think I've read that coarctation of the aorta and cardiac tamponade can cause it (maybe really bad pneumothoraces?). Regardless, a significant difference in blood pressures shouldn't be considered normal; within 15mm/Hg is a normal variance but any greater should be further evaluated. Just because an exam finding doesn't give us a definitive diagnosis doesn't mean we shouldn't do it, if that were the case I'd never touch an abdomen. If you find unequal blood pressures it should be documented and you should consider the capabilities of the hospital you are transporting to in case the pt does need further treatment/evaluation even if it isn't the root cause of your 911 call.

That all said, I wouldn't do them routinely unless I suspected something based on chief complaint or exam findings. And if you are doing that nonsense on a patient in overt shock, or is otherwise sick as poo, you either have a long transport, too many people in the ambulance, or seriously misplaced priorities. Bilateral BPs have their place in an assessment, the trick is taking the finding and applying it to the patient in front of you. The absence of unequal blood pressures means nothing (except that the patient has both arms), it's presence means something but it's up to the provider to determine the value and applicability of it.


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## sir.shocksalot (Jun 4, 2013)

KellyBracket said:


> According to one study, about 20% of adult patients, who were not being evaluated for dissection, who came to an ED had a difference in systolic or diastolic blood pressure between their arms of ≥ 20 mm Hg.



That's an interesting study, I wish I could read the whole thing. It definitely shows that there are normal variations in blood pressure and that it's not all that specific for aortic dissection. Although, it sort of makes me wonder how well the data was obtained. A convenience sample of ambulatory ED patients sounds an awful lot like a triage nurse or tech was stuck taking blood pressures on both arms. If that's how the data was collected it makes you wonder how well controlled the data collection was. I could definitely see a tired/busy triage nurse/tech falsifying a second set if they forgot, blood pressures hastily obtained over clothing, or physical activity between blood pressure readings. It just makes me question the value of the specific numbers being put out there.

http://www.ncbi.nlm.nih.gov/pubmed/11041906

That is a study that shows that a blood pressure or pulse difference along with tearing/ripping chest pain is pretty predictive of a dissection. I just kind of wish they could throw out some numbers for how much of a difference we should look for? If 10mm/hg is normal for 50% of people then does the specificity for dissection increase the higher above 10mm/hg you go? Or is any amount of difference enough when there is ripping/tearing pain? For now I'm just going to assume that above 15-20mm/hg is suggestive of dissection in patients with other signs/symptoms. Like one poster said it might be the key words to put the ED in gear. If you are wrong and the difference was just a normal variation what's the worst you have done?



sir.shocksalot said:


> Using cool, dusky, or pulselessness to evaluate unequal circulation is just begging to miss something. That sort of assessment can quickly be complicated by ambient temperature, skin color, and provider error/patient anomaly (one pulse is easier to discern than the other or provider technique when palpating).



Sorry LocalMedic, I realized this sounded rude after rereading this, I didn't intend to be rude, I was trying to respectfully disagree about not doing bilateral BPs, not label your assessments as inadequate. I also didn't mean to say this like cool/dusky/pulseless were meaningless findings. I think these findings are pretty significant and valuable. What I meant to say was that just because the limb isn't cool/dusky/pulseless doesn't mean there isn't a circulatory deficit. Bilateral blood pressure might be a more useful tool to assess a deficit when you suspect that the presenting complaint might produce one.


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## Melclin (Jun 5, 2013)

> Different BP >20 mmHg in arms, or missing pulse (15-30%; LR+ 5.7).



http://lifeinthefastlane.com/2010/11/ebm-aortic-dissection/


Doesn't seem insignificant. 

Personally, I do radial pulses as screening on pretty much pretty much any abdo, chest or back pain. 

Neurovascular obs in all limbs and BPs on both arms if I have any higher suspicion. 

I'm still fond of some of these not so specific or sensitive techniques for the way they push me to develop ideas and question information. 

*Take a chest pain radiating to the R shoulder I did a while back. *A few language difficulties were getting in the way. It was looking for reproducible pain that lead to information about his shoulder issues coming to light and other relevant hx that had not come out in the normal hx taking. Previous to that I could have simply felt, well there is CP with radiation, this is a no brainer ACS job, nothing else I find out will change that because reproducible pain isn't diagnostic. I find that sort of thing happens all the time with some of these exam techniques that aren't necessarily diagnostic in themselves.  

Also, I think there is more to it than simply saying, oh sign X doesn't prove anything per this study. I know reproducible pain doesn't prove a lack of ACS of PE. That said though, there is, I think a difference between Nanna screaming in pain, guarding and withdrawing, when you palpate her epigastrum and her vaguely stating that it 'sort of changes the pain'. 


Also from a purely selfish documentation and handover point of view, QA/QI look for it and it makes you _look like_ you were doing and thinking the right things and that the triage nurse will probably ask for the info anyway, so I may as well have it.


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## KellyBracket (Jun 5, 2013)

Melclin said:


> http://lifeinthefastlane.com/2010/11/ebm-aortic-dissection/
> 
> 
> Doesn't seem insignificant.



(First of all, dissection ≠ aneurysm. A dissection can look somewhat "aneurysmal," but they are distinct entities, different epidemiology, different pathophys, clinical presentation, treatment, etc. )

A LR(+) of *5.7* is helpful, but let me talk a little bit more about where that number came from.

The linked website (LITFL) grabbed it from a review article published in JAMA in 2002 (Does This Patient Have an Acute Thoracic Aortic Dissection?) 

In that meta-analysis, they compile the results of three studies looking at pulse deficits (not blood pressure differential). 2 of the studies do not have statistically significant results for the LR(+). The positive study is Von Kodolitsch et al, 2000

Now we're getting somewhere! This study enrolled 250 patients who had presented with chest or back pain, who were "considered clinically suspicious of acute aortic dissection by 2 experienced emergency department physicians," and who had negative work-ups for ACS, pneumothorax, or any other clear alternative diagnosis. This group, in other words, was at very high risk for aortic dissection, and the results bear that out - *128* of the *250* patients had a confirmed dissection. That's a _really_ high positive rate!

So, in this wicked high risk group, they found that 38% of the dissections had a pulse deficit *or* BP differential, while only 1% of the non-dissections did. Their language leads me to believe that the BP differential wasn't actually as helpful as the simple presence/absence of a pulse, but they don't just come out and say it.

Soooo, if you have someone with severe chest/back pain who doesn't have ACS, PNA, PTX, PE, cholecystitis, etc., then a pulse deficit might be very helpful.


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