cardiac care/lab values

Editorial Team / Admin · Nov 20, 2005

Moved to the cardiac nursing forum.

jmgrn65, RN · Nov 20, 2005

Hello all!
I have a quick question...If a patient is experiencing cardiac problems (either ongoing or potential), what lab values would I need to look at and why. I hope that makes sense. Any feedback would be greatly appreciated. Thanks for your help!
L:heartbeat

BNP tells you if the patient is in chf usually a 3 digit or higher number the worse the chf is

cpk and troponin demonstrates ischemia (MI) cpk however can go up with any type of muscle damage. troponin is more cardiac specific.

electrolytes high or low k+ can cause arrthymias,

cbc low hgb/hct can cause some cardiac patient some difficulty also

abg is sometimes useful too

hope this is helpful

papawjohn · Nov 20, 2005

Hey Icazgirl

Those labs that jmgrn pointed out are a good set of things to pay attention to. Let me pull up a chair and take a couple of minutes to 'splain why.

You say your Pt is experiencing cardiac problems or potential problems. Nurses ever since Florence have been asking--'what's the worst that can happen' as a place to start our thinking, so let me begin there. The worst thing that your Pt can be having is an MI. So what you should look for are indicators of the death of cardiac muscle cells: The best indicator is Troponin. This is an enzyme used INSIDE the cardiac cell to make the ACTIN and MYOSIN do their thing. It's s'posed to be very specific for cardiac cells (which is good--obviously) and it stays in the body for several days so we can detect an MI several days after it happened. (Sometimes Pts come to the ER with breathing trouble and it turns out they're in CHF--how'd that happen? Well, gosh, we check the troponin and discover they had an MI a couple of days ago. Seems strange if you're new--but it happens all the time.)

Other lab numbers that indicate your Pt had an MI are CPK and CPK-MB. The CPK enzyme is elevated by ANY muscular injury. Years ago there was a big deal made out of avoiding IM injections if your Pt was getting his cardiac enzymes checked because the needle would damage muscle cells and cause a false positive elevation in the CPK. (Of course, we also did silly stuff like NEVER giving him iced fluids--they were all room temperature--'cause cooling his esophogus would possibly cool the heart and increase cardiac ischemia. Then we'd do a cardiac output with the SwanGanz and inject 10cc of iced saline right into his heart!!! Go figure! But we thought we were pretty clever.)

The CPK-MB was found to be more specific to cardiac tissue--so you'll still see it checked and it still shows MIs when elevated. Two problems: It is gone from the blood very quickly (

You'll still see the LDH enzyme checked. It's not very specific to heart damage but it stays in the system a long time and was useful before we learned to check Troponin.

Now if your Pt has Congestive Heart Failure you'll see the MDs order a BNP. This is a protein secreted by the Atrium of the heart as it is being stretched and distressed by the pressures created by a failing ventricle. It is of interest to MDs to confirm CHF as opposed to similar signs and symptoms (?Pneumonia) and treatment (?Xigris, ?Lasix). Your Pt in CHF will be requiring you to do lots of work to support his breathing--so to you it is mainly something to call the MD about and expect medications for the heart as opposed to antibiotics and nebulizer treatments.

Your CHF Pt will have ABGs drawn. You should check for adequate pO2 and pH.

Your cardiac Pt's heart needs certain electrolytes to help avoid arrhythmias. The first to think about is Potassium and the 2nd is Magnesium. If these are low his heart is losing ground in what's called 'fibrillation threshold'.

I guess that covers it.

Yer ol'

Papaw John

nursej22, MSN, RN · Nov 20, 2005

I can think of a few others, mainly for those with known cardiac problems. If there is a potential that a patient may go to the cath lab,we check the BUN/creatinine for kidney function. A patient with atrial fib may be on dig and/or warfarin and may need that value checked. We are seeing C-reactive protein levels checked that might indicate inflammation such as an unstable atherosclerotic placque with a potential to rupture. Almost all of our cardiac patients get fasting lipid levels.

papawjohn · Nov 20, 2005

Hey

I ditto Nursej22. For Cath Lab visit--renal function very significant. (Altho I understand not quite as much nephro-toxicity as there used to be.)

Papaw John

zambezi, BSN, RN · Nov 21, 2005

fantastic replies, as usual...

I will also add PT/INR and CBC (which have both been mentioned peripherally). We recently had a guy come in who had a slow gi bleed...his h/h got so low, caused his heart too much stress, and he infarcted- a real quandry because we couldn't take him to cath lab due to his decreased H/H (somewhere in the realm of 5/16) but he was having a huge MI! Also it is good to check the platelet levels, particularly after cath lab if reopro or aggrastat is used (and probably intregrlin too, but we don't carry that so I would have to look it up!). I have seen someone go from normal platelets to 3 after a bolus of aggrastat...

As the others have mentioned we usually draw:

CMP (to look for electrolyte imbalances- particularly look at K and renal function pre-cath).

Magnesium level

Digoxin level (we don't always draw this, but we do if patient is on dig)

CBC

BNP- for those with CHF in question

PT/INR

SCP (Screening Cardiac Panel: myoglobin, cpk, troponin) we usually do serial draws of this: either Q8x3 or 4, 12, 24 hours after admit.

FLP (Fasting Lipid Panel)- usually done on admit/after NPO.

ABG if indicated

We don't routinely draw C-Reactive Protien levels but I hear that they are being used more routinely in offices to help "predict" heart disease problems...but the time the patient is in my unit, we already know they have cardiac issues.

Other acute tests you will see:

12 lead EKG

Echo

Cardiac Catheterization

CXR

lcazgirl · Nov 21, 2005

I wish I could reach out and give you all a great big hug! :icon_hug:

THANK YOU SO MUCH for all the dynamite information. It's exactly what I'm looking for.

If there's anything else to add, I'm all ears....

L :flowersfo

ark-two · Feb 25, 2006

We usually check a d-dimer for blood clot. Mild pulmonary embolism can cause chest pain. IF d-dimer elevated v/q scan and/or ct of chest ordered and fragmin subq or heparin iv started.

Nightrn16 · Feb 25, 2006

What everyone else said ... I normally look at their CK-MB's, Troponin I, (Troponin T can be affected by renal status) K+ level, Mag level, and also Calcium level. Those are the things I gander at first. Once I see that those are normal, then I'll look at their dig level, and ect.

When someone starts having a lot of PVC's {more than is normal for them}, I'll normally call one of the Cardiac PA's on call (we have some in the hospital so we don't have to wake up evil doctors for simple things.) and ask if we can get a mag, K+, and calcium level with the pt's AM labs. 9/10 it's a low mag level.

Hope this helped some. :)

SEOBowhntr · Mar 10, 2006

A little more to add......

Ck and Ck-MB are really the best indicator in indicating an acute MI, Troponin-I is good in finding those small Non Q MI's or a person with a potentially diseased heart, but it will rise considerably later and peak later than the Ck-MB. Troponin can register elevated up to 14 days after an MI, therefore esp. in a re-admit pt. Ck-MB is often times a better indicator in acute phase management of Chest Pain.

Electrolytes are important, but probably the 2 most important are K+ and Mag++. These are the first two that can potentially kill a paitent.

BNP is a tricky test, which is often misused and misinterpretted because renal failure patients and patients often times have a baseline BNP that is elevated to what would be considered a critical level because it is not metabolized well.

PT/INR/PTT are all useful esp. when dealing with patients on Coumadin or Heparin, to be sure that the target therapeutic level is achieved.

CBC is important, and most Cardiologists I've known prefer to keep the Hgb > 10.

Renal Function is also very important, esp. when dealing with heart failure, because they will not respond to diurets as well. Putting them at an increased risk for Pulmonary Edema.

tridil2000, MSN, RN · Mar 18, 2006

i'll add to this great list - thyroid function tests! many tachydysrhythmias can be caused by a hyperactive thyroids and be early 'storm.'

another thought for chest pain is to consider the old gall bladder! an amylase and lipase test would help to rule him out.