Vit K: information on decreasing INR's in emergent situations

[stoic]

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What's up everyone -

Please excuse what is probably a simple question... i've still got a few years of training left....

Anyways, so not long ago I saw was a patient while shadowing in the ED who was on warfarin therapy and presented with a pretty severe SAH. Before we shipped the patient to a tertiay care facility, he was given a dose of Vit K (5mg, as i recall). I know this is done to speed the clotting cascade, but I'm wondering how much of an effect a single dose will have and how quickly this effect can be observed via INR levels.

This guy had a pretty normal INR for someone on warfarin (right around 3.0); so how long after a single dose of 5mg Vit K would the maximum decrease in INR be achived? How large would the expected decrease be? And for what period of time would the INR be reduced?

thanks for the info everyone,
s

 

[tofurious]

who was on warfarin therapy and presented with a pretty severe SAH. Before we shipped the patient to a tertiay care facility, he was given a dose of Vit K (5mg, as i recall).

Vitamin K takes a little longer to act, since it is aimed at the synthesis rather than immediate replenishment of Vitamin-K dependent clotting factors. In this instance (elevated INR, patient bleeding), FFP is definitely indicated if bleeding is severe. Depending on the patient's hemodynamic at the time however, fluid overload may also not benefit the patient (although a unit of FFP is usually not too large in volume).

 

[docB]

Ditto tofurious. I've talked to critical care docs who advocate FFP only in certain situations such as GI bleed in someone with a real need for the anticoagulation such as a St. Jude valve. Their point is that you want to use FFP and direct intervention (such as endoscopy) to stop the bleed but then you have to reanticoagulate them and if they got a big hit of Vit K that will be tough to do for days (and it makes it more likely to overshoot) or they will have to be maintained on heparin for an extended period of time.

 

[anonymousEM]

just had to look this up in the ICU actually for a guy who was being transferred with a big SDH after multiple falls on coumadin (DID YOU SEND ME THAT GUY IN THE MIDDLE OF THE NIGHT???) But turns out that the onset for parenteral Vit K is 8-12 hours (sc/IV/IM...with IV/IM much more likely for anaphylaxis so rarely indicated) and PO is 12-24 hours. Give, like for my guy, when they're not going to be anticoagulated again...lifethreatening bleeding, fall risk precluding anticoag for afib...

 

[DocWagner]

The route makes very little difference !V/SQ/IM, and the dosage can vary widely from .5mg to 10mg. The general thoughts are to give a dose (say in emergent situation) 5mg IV wait 6hrs, if the INR is trending down, then repeat in 6hrs...if in 12 hours the INR has not trended down to your liking, then you may redose. There has been no shown benefit of vit k doses greater than 10 (at a single dose). The time to onset may be 6-12 hrs and the effect may last anywhere to days to 2 weeks.

 

[Scrubbs]

Anyone using the vitamin K dose calculator reported in Chest 2001? My program director (a tox guy) talks about it, but I've always been afraid to try it out... especially since the patients aren't following up with me.

Anyhoo... the formula is: Vit K dose (PO) = 16 - [17(INR Goal/INR Actual)]

Supposed to be helpful for those PMD referrals for super therapeutic coumadin patients who aren't bleeding. I believe it supposedly gives you the correct dose of Vitamin K to bring the patient to a goal INR without dropping lower than that in 24 hours. Also, they skip 1 dose of Coumadin and then restart their regular dose (not completely sure about that part).

Just curious 😀