Nursing Tips for Heparin and Coumadin – Lab Monitoring

Nurses, I know how confusing Heparin and Coumadin lab monitoring can be. This guide will break them down, explain what they are, and help you understand it all.

This is informational only, always follow your hospital’s policies and procedures.

Nursing Tips for Heparin and Coumadin Lab Monitoring

Something that can be confusing at first for nursing students and brand new cardiac nurses is understanding Heparin, Coumadin, and the labs to draw to monitor them appropriately. Let’s go through some basic explanations to have this confusing topic make more sense.

Why Do Nurses Give Heparin and Coumadin Together?

First, let’s understand what they are separately, then you can understand how they work together.

What A Heparin Drip Does

A “heparin drip” means that heparin is going into the patient’s IV continuously. It’s not a one-time IV push med. It’s hooked up to an IV pump and continuously infused. When given in this form, the effects are immediate. This is a GOOD thing because we start these drips when patients have something serious going on, and we need to prevent the body from making more clots.

The amount given can be adjusted (titrated) to ensure the blood isn’t clotting enough or too much. The specific numbers of where depend on why they need their blood to be thin/not clot as easily in the first place. Reasons for this drip can be a pulmonary embolism (PE), deep vein thrombosis (DVT), myocardial infarction (MI/heart attack), post cardiac surgery, and more. Naturally, these are pretty serious.

It’s important to know that heparin will NOT break up existing clots. It will prevent more from forming and make the blood thinner so it can get around the existing clot(s) in the body.

So, if your patient has multiple PE’s, starting a heparin drip will thin the blood to allow it to get around those clots and perfuse the area beyond it much better, and it will also prevent more clots from forming. But, it will not break down the clot that has already formed.

Note: When heparin is given subcutaneously, it can take about 20-60 minutes for it to kick in. However, when given via this route, it’s typically to PREVENT a blood clot from forming, and not given as TREATMENT when one has already been identified.

Coumadin Works Much Slower

Heparin drips are immediate. Coumadin takes as long as 5 days to reach its full effect. 

Some patients are at such high risks for developing more clots and thinning the blood so it can get around existing ones that they can’t wait for the Coumadin to kick in. They need the effects, like, now. Right now.

Heparin Drip to Coumadin Bridge

The physician may decide to put the patient on a heparin drip to bridge Coumadin bridge. No, we’re not going to send them across a literal bridge, but what this means is that we’re going to first start a heparin drip to quickly get their blood to a safe place, and start Coumadin at the same time. We will draw labs to monitor them both to ensure the blood isn’t

The IV heparin drip will be continuously infusing, and you’ll administer a daily dose of oral Coumadin (in tablet form).

Labs will be drawn to monitor both, and once we see that the Coumadin has kicked in to a point where the physicians feel comfortable removing the heparin drip, that’s what is done. The patient will then continue to take the oral medication (which can be done at home!) for as long as necessary, and the drip will be discontinued.

How To Start a Heparin Drip

So, let’s say you’re taking care of your patient load and see an order to start a Heparin drip pop up.  This is one of those stop what you’re doing and do this ASAP kind of things.

IV Heparin is Different Than Subcutaneous Heparin

Remember, IV heparin is different than subcutaneous heparin.  Many patients have received subcutaneous Heparin in the past and assume it’s the same thing and has the same effect.  It’s a much higher dose and it goes straight into their blood stream, rather than first going into their subcutaneous tissue and then their blood stream.

Essentially, IV heparin works much faster, the dose isn’t high enough with the subcut shots, and we also need to be able to adjust the dosing faster than those allow.

So if the patient asks you if they can just do those little shots in their belly, you can tell them, “Absolutely and unequivocally no.”

(Did you say that in a Professor Slughorn voice? 10 points for Gryffindor if you did).

Setting the IV Heparin Rate

When a patient is on IV heparin, it is started at a set rate based on their weight and how aggressive the medical team would like it to be (again, completely situational) and it is continuously administered through their IV.  Occasionally, these order sets contain a weight-based heparin bolus as well.

Please double check your orders to make sure to administer the bolus if it is ordered when you’re initiating the drip.

How to Monitor the Safe Levels of the Blood

The way we monitor if the blood is at a safe level is with either a PTT or an Anti-Xa lab.  Typically, these are drawn every 6 hours until it is stable (making dosage adjustments based on how high/low their lab is) for a few lab draws, then it’s drawn every 12 hours, then every day.

Please note, this can vary from facility to facility.  Always refer to your policy, procedure, and appropriate order set regarding heparin drip initiation and maintenance.

Example of A Heparin Order

Not sure what a heparin order set is? Check out this example.

(Do NOT use this example for patient care, it is merely informational.)

Initiating Coumadin

The patient will then have an order to get Coumadin during the day and an INR will also be ordered daily to monitoring the level of the Coumadin in the blood.

Will giving Coumadin and Heparin together cause them to bleed out?

“Coumadin and Heparin at once?!  Isn’t that too much!?  They’re going to bleed out!” says the concerned family member.

You can tell them, no, the likelihood of that is very low.  The need to thin their blood is much greater than the bleeding risk of the medication at this point.  If a patient is being started on Coumadin for the first time, there should be quite a bit of lifestyle education occurring throughout their stay.  Many hospitals have specific educational handouts that must be discussed and documented.

Example of A Hospital Educational Booklet about Coumadin

Here’s an example of a hospital educational booklet about Coumadin. Again, do not use this to guide your care, it is simply an example.

Verify Orders to Check INR

If a patient is receiving Coumadin, please make sure there is an order to check their INR (most likely a daily lab, drawn in the morning so the rounding physician will see the result in the morning).

The patient’s doctor will specify a therapeutic range for them, which can be in a nursing order or in one of their notes.  It is important for you to know their goal and to communicate them to the patient.

The therapeutic range for their INR again depends on their clinical situation.  Patients also respond to Coumadin differently, so the same dose doesn’t work for everyone and the amount of time it takes to get to a therapeutic level varies.  This is why they start with a standard dose, check an INR and go from there.

Our goal is to get the INR within that range, near it, or consistently trending up towards it.  If the doctor rounds and an INR was not ordered and they weren’t alerted, you’ll probably hear about it.

Heparin and Coumadin Labs

Prior to starting a drip, your protocol likely requires baseline labs drawn. This probably includes coagulation studies and a complete blood count. They may re-draw these labs every 3-4 days. They’re necessary to watch, but a daily draw is probably not medically necessary.

To summarize:

(Again, this is informational and an example. Follow your hospital’s most up-to-date protocol.)

• Monitoring the effects of heparin = PTT’s or Anti-Xa labs
  • First draw would be 6 hours after the drip starts
  • If the lab result is “therapeutic” then, the next draw would be in 12 hours, then if that one is also within the desired range, they may switch to a daily (every 24 hours) draw
  • If the lab is way too high, you may need to pause the drip and re-check after 3-6 hours, and start at a new higher or lower rate
  • If the lab result is slightly out of range, the protocol will likely have you decrease or increase the drip a little bit and then re-check again in 6 hours
• Coumadin = INR labs
  • These labs are drawn daily, as that much time is needed to allow the effects of the med to be evident in the blood
  • If Coumadin is given around 4pm, then a lab draw every day around 0400 will likely be ordered

Some hospitals require the bedside nurse to draw labs, while others have phlebotomy do so.

Are all of these lab draws necessary?

Both labs are completely necessary and non-negotiable.  There’s no way around this; the labs must be drawn to know how to correctly dose the medications they so desperately need.

Something that is important with these labs is timing, which is why it can be frustrating to patients and family members and turn into a lot of lab draws.  We can do our best to combine them, but it doesn’t always work out.

Nurse Pro-Tip: Order Daily Labs at Same Time As INR

If your Heparin drip has been therapeutic and the PTT/Anti-Xa is now a daily lab, order it at the same time as your INR so they don’t have to get stuck twice.

Also, if your PTT/Anti-Xa needs to be drawn around the time some other non-time sensitive labs are due, re-time your labs to be when your PTT/Anti-Xa is due.  That’ll save the patient a stick, if possible.

And make sure you tell them you did that so you can get bonus points with them! Remember though, that PTT/Anti-Xa is TIMED.  It cannot be drawn whenever it is easiest.

Even if the patient was just stuck 2 hours ago for another timed lab, you cannot change the time.  You run the dangerous risk of their blood being too thick or too thin if you do this and adjusting medications inappropriately.

Why Nurses Prefer Coumadin

Please know that there are many other drugs on the market today to thin the blood appropriately in various situations, however many physicians still prefer Coumadin. Speaking as a nurse managing patients who have had various kinds of blood thinners, I honestly prefer it as well.

The reason is that we know the nature of the beast.  We know how to reverse it quickly and how to manage it very well.  Many of these newer drugs do not have an antidote to reverse it or even a lab to draw to see exactly how much is in the circulation.

When patients or families express frustration about all the lab draws, I educate them about this.  While it may be more of a pain and inconvenience, it highly studied and widely used over many years, and nurses and doctors are extremely familiar with all of the ins and outs of it.  This usually puts patients and families at ease.  Coumadin isn’t perfect for everyone, but it works well for many.

Learn more

Looking for more practical posts about cardiac nursing?

• Telemetry Basics Brush-Up
• 5-Lead ECG Interpretation, Electrocardiogram Tips for Nurses
• What is Telemetry and Telemetry Lead Placement?
• Nursing Management of Atrial Fibrillation