Transporting tPA


If you run on a program that does interfacility transports, you have likely heard of a drug called tPA. This medication is classified as a fibrinolytic (thrombolytic) and works to dissolve clots in the setting of ischemic stroke or acute coronary syndrome.


There has been a lot of controversy over tPA, CT ambulances, and some guy named Eddy Lang within the past three years. However, regardless of whether or not you believe tPA is the devil's drug, we typically are NOT the ones making that call and need to know how to safely transport a patient who has received or is currently on a tPA infusion. This blog will serve as a logistical guide. Think of it like Indiana Jone's guide to avoiding boobie traps in transport.

Blood Pressure Goals

The first thing we need to talk about is blood pressure goals. The biggest fear after giving tPA for an ischemic stroke is the conversion from ischemic to hemorrhagic. The blood vessels become very weak when ischemic and hypertensive episodes can potentially cause intracranial bleeding. There is both a pre and post-tPA blood pressure goal that is recommended by the manufacturer.




I have always thought these goals seemed very specific and decided to dig into some of the literature suggesting the current blood pressure parameters following tPA. I found a study from the American Heart Association in 2009 that evaluated the effect of violating these blood pressure protocols resulted in a 159% increase in the risk of symptomatic intracranial hemorrhage (sICH).

In addition to hypertension, there are some other interesting risk factors that put a patient at risk for sICH. While not all significant, the invariable analysis of risk factors included in this study may give providers some intuition about which patients are at a higher risk.


So how do we treat the blood pressure? I made a list of some of the more common anti-hypertensive agents and their dosing. As always, follow your shop's guidelines.




The Bolus

tPA is given as a bolus and then infusion. The standard dosing is 0.9 mg/kg with a max dose of 90mg. The patient will get 10% of that total dose as a bolus, and the remainder will be infused over the course of an hour.

It is very possible you might arrive at the hospital while the patient is still in the CT scanner (determining whether ischemic or hemorrhagic), and the decision to give tPA has not been made yet. While program-specific, the initial bolus should be given by the hospital and not handed to the EMS crew to give during the transport. It is very likely that the EMS providers were not the ones going through the tPA candidate checklist, and therefore the responsibility of giving the initial bolus makes sense to be carried out by the referring provider and accompanying nurses. Check your guidelines to see your program's specific recommendations.


The Infusion

As mentioned above, the remainder of the tPA will be given as an infusion over 60 minutes. There are a few nuances for this infusion that require some planning.


Was the waste removed?

Not every patient is going to get the max dose of 90mg. Imagine a 70kg patient who only gets a total of 63mg (0.9 x 70). This means they will get a bolus of 6.3mg and then 56.7 mg over the next hour.


Typically tPA comes in a concentration of 100mg in 100ml. Since we only needed 63mg, most facilities will remove the remaining 37mg from the glass bottle. This means after the bolus, the patient would just get whatever is remaining in the bottle over the course of an hour. While this is best practice, not every facility will remember to do this, and it is important to ask to avoid the risk of a medication error.


Don't Waste

By this point, you can see how carefully this drug is calculated and dosed. Another area of planning is determining how to switch the infusion to your IV pump without losing any of the medication. My method of doing this largely depends on how much drug is left in the bottle when I arrive at the bedside. Where I work we have full-sets and half-sets. A full-set has a spike on the medication end and a luer-lock on the other end that connects to the patient's IV. The half-set has a luer-lock on both ends and can be used in between the hospital's IV tubing and the patient.


If the patient has < 50 ml's remaining in the infusion, I will disconnect the infusion from the patient and draw up the remaining drug into a 60 ml syringe. This syringe is then connected to a half-set and placed on my IV pump.


If there is >50ml's remaining, I will just connect my extension tubing to the patient's current (hospital tubing) and skip the syringe part. You end up with quite a bit of tubing, but this is about the only option if you don't have the same IV pump as the hospital or can't take the hospital's IV pump with you.


Once the infusion is complete, it is important to flush the tubing with whatever isotonic crystalloid you have. This will assure the patient received the entire dose. This flush can just keep running at whatever rate the tPA was running at.

Well, that about wraps it up, but I would love to hear any tips or tricks you have found helpful when transporting tPA. One of the new kids on the block that will likely soon be replacing tPA is Tenecteplase. This fibrinolytic is given as a single bolus and no infusion, which makes it ideal for transport.

References

Southerland, A. M., Johnston, K. C., Molina, C. A., Selim, M. H., Kamal, N., & Goyal, M. (2016). Suspected Large Vessel Occlusion: Should Emergency Medical Services Transport to the Nearest Primary Stroke Center or Bypass to a Comprehensive Stroke Center With Endovascular Capabilities?. Stroke, 47(7), 1965–1967. https://doi.org/10.1161/STROKEAHA.115.011149NLM


Tsivgoulis G, Frey JL, Flaster M, Sharma VK, Lao AY, Hoover SL, Liu W, Stamboulis E, Alexandrov AW, Malkoff MD, Alexandrov AV. Pre-tissue plasminogen activator blood pressure levels and risk of symptomatic intracerebral hemorrhage. Stroke. 2009 Nov;40(11):3631-4. doi: 10.1161/STROKEAHA.109.564096. Epub 2009 Sep 17. PMID: 19762689.


Warach SJ, Dula AN, Milling TJ Jr. Tenecteplase Thrombolysis for Acute Ischemic Stroke. Stroke. 2020 Nov;51(11):3440-3451. doi: 10.1161/STROKEAHA.120.029749. Epub 2020 Oct 13. PMID: 33045929; PMCID: PMC7606819.


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