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Does the “Buzzy” Affect the INR?

This is from George’s friend and colleague, Dennis Ernst, of the Center for Phlebotomy Education: A good friend of mine is a pediatric emergency physician, needle-pain expert, and entrepreneur. Dr. Amy Baxter has developed a device you may have already heard of. It’s called the Buzzy. (She was my newsletter’s Mover & Shaker in March.) It attaches to the arm prior to a venipuncture or shot and provides a cold and vibration sensation simultaneously. The combination effectively blocks the pain of the needle. It’s proven to be effective and is widely used.

She recently asked a question I can’t answer, and I was hoping you could. Do you think a vibration device attached above a venipuncture site would affect the INR? I know vibration of blood in a pneumatic tube system activates platelets, but I wouldn’t think vibration on the upper arm would affect the blood being withdrawn, especially since it originates distal to the puncture site, and the Buzzy is strapped on proximal.

George’s response: To venture into the slippery world of “expert opinion,” I am comfortable in concluding that Buzzy will have no effect on hemostasis parameters. I base this on my understanding of venous blood flow velocity. Presuming Buzzy could mechanically activate circulating platelets, the platelets would rapidly disperse and their activation be reversed by the antiplatelet properties of the intima. I’m equally comfortable in suggesting that Buzzy would not activate extrinsic or intrinsic pathway coagulation factors for similar reasons, and would have no effect on the PT/INR. Of course, the usual standards for length of tourniquet application apply.

I invite comments from our participants, particularly if anyone has direct experiece with Buzzy while collecting hemostasis specimens.

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