Treating Acute DVT in obese patients with enoxaparin

[WVUPharm2007]

So...morbidly obese patients....specifically over 150 kg. Acute platelet killin' DTV treatment. The usual thought with enoxaparin is 1mg/kg....maybe 1.5 per. The kinetics literature shows that it accumulates in free water (i.e. in lean mass). I've also read about obese patients being more susceptible to bruising with conventional dosing.

So what are your thoughts? Should dosing, perhaps, be capped at the highest dose tested by the manufacturer (150mg) and make patients over 150kg go to 17,500 of heparin? Should we just continue to dose at 1mg/kg, even in the most extremely obese? Does anyone know of a good algorithm, protocol, or strategy for dose adjustments for the obese?

Talk to me....

---

Members don't see this ad.

 

[Glycerin]

I found a reference and I was trying to access the article for you, but I can't from home. Here's the info, though:

Duplaga BA, Rivers CW, Nutescu E. Dosing and monitoring of low-molecular-weight heparins in special populations. Pharmacotherapy. 2001;21:218-34.

From the latest CHEST guidelines in reference to prophylaxis: "The existing data, however, suggest that weight-based prophylactic dosing is preferable to fixed dosing for obese patients," and "2.2.4 In obese patients given LMWH prophylaxis or treatment, we suggest weight-based dosing (Grade 2C)."

In the meantime, what about non-pharmacological measures such as foot pumps? I recently saw a morbidly obese patient who was not a candidate for Lovenox due to Xeloda-induced enteritis/GI bleeding receive treatment with foot pumps.

 

[WVUPharm2007]

2001 is kinda old....a lot of studies have come out since then, no?

And DVT prophylaxis guidelines are rather solid, like the ones you posted...I'm more interested in actual acute DVTs, however. The doses have the potential to be humongous if the patient is big enough. DVT boots work, too...but not as well as chemical warfare. I'm not really sure a good consensus really exists to this specific question, to be honest....if it does though, I'd like to hear it.....

 

[Glycerin]

2001 is kinda old....a lot of studies have come out since then, no?

And DVT prophylaxis guidelines are rather solid, like the ones you posted...I'm more interested in actual acute DVTs, however. The doses have the potential to be humongous if the patient is big enough. DVT boots work, too...but not as well as chemical warfare. I'm not really sure a good consensus really exists to this specific question, to be honest....if it does though, I'd like to hear it.....

It is old, but it's the first one I came across. You'll see, too, that in the last part of the exerpt I posted from CHEST, it says "prophylaxis or treatment." However, I personally would probably feel more comfortable going with 1 mg/kg dosing with morbidly obese patients only after having ruled out other options from a literature search.

Regarding the foot pumps, I think it's a start and better than nothing, at least for the meantime until a treatment regimen can be found. In my patient the foot pumps were used ~5 days or so until the bleeding stopped, and then enoxaparin 40mg SC QD was initiated, so foot pumps are only a temporary partial solution.

I'll be interested to see what anyone else has seen in practice related to this as well.

 

[twester]

2001 IS kind of old, but CHEST hasn't updated the guideline for obese patients since then. All I found in the literature was that anti-Xa levels in obese patients should be monitored until the correct dose is found. Levels should be checked four hours after dosing and target <1 IU/ml.

 

[WVUPharm2007]

Ok...so what would YOU do. I started this thread pretty much knowing there weren't any officialish guidelines out there...I was more wondering if there were some good protocols people use out in practice that accurately predicted doses kinda well giving consideration to LBW over ABW.

At my hospital, the clinical director is hella conservative. She just last week decided to cap the dose at 150mg and put everyone else on Hep boli for their em-boli.

 

[twester]

When is the heparin bolus given - when they throw another clot? What's the monitoring parameter? Is she trying to bridge with heparin bolus and warfarin? Why not just give a heparin drip and bridge to warfarin?

A post-marketing trial for enoxaparin has been completed at the University of Utah that evaluates the use of 1/2 dosing for obese patients. I don't think it's been published yet.

 

[WVUPharm2007]

When is the heparin bolus given - when they throw another clot? What's the monitoring parameter? Is she trying to bridge with heparin bolus and warfarin? Why not just give a heparin drip and bridge to warfarin?

Well...a bolus is a large dose of something...maybe I should said "dose" instead. I forgot that bolus has changed meaning to become "the first huge dose given to avoid having to wait for steady state" nowadays.

Anyway, it would be given scheduled 1-2x a day at roughly 35,000 units/day. 17,500 BID seems to be popular. And you would monitor aPTT trying to get it prolonged to whatever the lab's assay correlates to...usually like 150-250% of baseline or so. You know....old school...

As for bolus v infusion, we haven't decided which....or if we will leave it to the physicians to choose. You can either do the SubQ dosing or the infusion. I have no idea if one has been shown to be better than the other. It's what we're doing, anyway....as of last week. I've honestly never heard of actually capping enoxaparin at 150mg as policy. Not sure what to make of it, honestly...and I'm just looking for opinions...

I've also wondered if anti-Xa labs are feasible for enoxaparin and maybe dosing the obese that way. All of the other LMWHs and Arixtra are all based upon weight dosing, too, so that's not an easy fix. It's just all rather odd to me...

A post-marketing trial for enoxaparin has been completed at the University of Utah that evaluates the use of 1/2 dosing for obese patients. I don't think it's been published yet.

Um. Yeah. So you know where to find the preliminary results? The trial description on Clinical Trial Feeds sounds interesting.

 

[Priapism321]

Up to 200 kilograms, I would employ enoxaparin 1 mg/kg twice daily. Some of the clinical work has evaluated patients up to 190 kg, and they do just as well when it comes to effectiveness and bleeding as individuals who weigh less. I would monitor anti-Xa activity aiming for 0.6 - 1.0 four hours post dose in patients with a BMI greater than 40.

If the patient is renally compromised, I would use unfractionated heparin.

 

[njac]

I think I would be more comfortable with plain ole' heparin.

clots suck and so does bleeding.

(that's my profound thought for the day)

 

[WVUPharm2007]

Thanks to a certain mystery private messager, I've stumbled upon this study....which, after reading the full version...is quite nice...and includes this info:

Of which the second bullet point justifies my concern. I'ma gonna have to bring this one in on Tuesday after the weekend. WTF...me of all people doing this ****...the apocalypse is nigh....

If anyone wants a copy of the full article, PM me...

 

[ItsOverZyvox]

dayum.. a worthy post... finally...

 

[GatorRxGirl]

Tell them to lose some freakin weight and put the cupcakes down. Then dose them like a normal person.