Heparin BEFORE spiral CT?

[Rendar5]

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Had a recent patient with a PE. Non-smoker, 3wks out from hip replacement, b/l ankle swelling, at nursing home was suddenly in the 80%'s SpO2 correcting with NRB, (non-tachy, though), no base crackles (negative physical exam), no CP, decreased exercise tolerance. Neg Doppler at rehab home prior to coming in. Despite the vitals, she appeared relatively stable. But she stopped breathing temporarily (did not require resusc) while on the CT machine. This was approximately 1-2 hours after I saw her and ordered the test. She had fairly extensive b/l PE's

Now my question is, does anyone consider starting heparin BEFORE you can confirm it in a medium or high-risk patient, and then canceling if it comes back negative? I realize starting heparin is not without risk, but I wonder what the risk:benefit ratio is when PE is already number 1 on your differential?

 

[DrMom]

If I am really thinking someone has a clinically significant PE, I will give 1 mg/kg lovenox prior to CT.

 

[WilcoWorld]

If I have a high suspicion and the patient is on the border of being unstable and there aren't contraindications to anticoagulation then I think you should start the heparin while awaiting CT. I would be less inclined to start LMWH sub Q since you can't shut that off as quickly.

 

[Hamhock]

Had a recent patient with a PE. Non-smoker, 3wks out from hip replacement, b/l ankle swelling, at nursing home was suddenly in the 80%'s SpO2 correcting with NRB, (non-tachy, though), no base crackles (negative physical exam), no CP, decreased exercise tolerance. Neg Doppler at rehab home prior to coming in. Despite the vitals, she appeared relatively stable. But she stopped breathing temporarily (did not require resusc) while on the CT machine. This was approximately 1-2 hours after I saw her and ordered the test. She had fairly extensive b/l PE's

Now my question is, does anyone consider starting heparin BEFORE you can confirm it in a medium or high-risk patient, and then canceling if it comes back negative? I realize starting heparin is not without risk, but I wonder what the risk:benefit ratio is when PE is already number 1 on your differential?

There are plenty of folks who would not only start heparin (most likely LMWH) before the CT but would continue it even after a neg CT if the pt was high-risk before the CT and PE was #1 on the differential and no other explaining pathology was identified.

HH

 

[Aloha Kid]

This case sounds okay to start it.

Nonetheless, careful you don't start it on a possible dissection.

 

[Hernandez]

Now my question is, does anyone consider starting heparin BEFORE you can confirm it in a medium or high-risk patient, and then canceling if it comes back negative? I realize starting heparin is not without risk, but I wonder what the risk:benefit ratio is when PE is already number 1 on your differential?

Yes, I'll start prior to CT on a pt my pre-test probability is high on a pt. If you go through the wells pre-prediction numbers, a high probability pt has just shy of 80% likelihood of having a PE. For Moderate risk pts, their pre-test probability is 28%, so I don't start heparin on them.

Now a personal preference is I do not do that even on a high probability pt if I can not justify answering yes to the are other diagnosis less likely than pe, if I can't say yes there, then I won't start it, but a high pre-test pt that I feel has a PE, I'll start heparin before CTA. I personally don’t start lovenox without a bun/cr in my hands as I’ve seen some nasty retroperotenial hematomas on people with borderline creatinine clearence.

 

[DrMom]

I personally don't start lovenox without a bun/cr in my hands as I've seen some nasty retroperotenial hematomas on people with borderline creatinine clearence.

I'll do a single full dose without a creatinine if I they don't have any hx of renal insufficiency and nothing to make me think renal failure currently. Right or wrong? I'm not sure.

I had one of these cases recently while moonlighting: elderly, hypoxic, chest pain (sudden onset), dyspneic, non-ischemic EKG, stable vitals with O2 NC. A few weeks post op (non-ortho) and hx past PE post-ortho surgery. High suspicion, but definitely could have been cardiac/aortic etiology.

Got EKG, CXR, labs percolating. Off to the scanner. I made a point to look at the study while still in radiology. Large PEs so the lovenox was waiting upon return from CT.

 

[Hernandez]

I'll do a single full dose without a creatinine if I they don't have any hx of renal insufficiency and nothing to make me think renal failure currently. Right or wrong? I'm not sure.

I've done lit searches, and there is no consensus, or even any way to predict. Israel has some data that showed mostly elderly with CrCl less than 45 were the group who had slitghly higher likelihood of adverse reactions to lovenox, but when you get a rash of people with bad side effects from a drug in a row, it definitely influences your prescribing habits. All 3 of the pts I saw back to back to back had CrCl between 45-70, so I’ve been hesitant to use Lovenox in any pt with CKD. I’ve not diagnoses enough HIT-2 much less HIT with severe thrombolic events despite my frequent use of heparin to sway me back to lovenox yet.

 

[mikecwru]

Had a recent patient with a PE. Non-smoker, 3wks out from hip replacement, b/l ankle swelling, at nursing home was suddenly in the 80%'s SpO2 correcting with NRB, (non-tachy, though), no base crackles (negative physical exam), no CP, decreased exercise tolerance. Neg Doppler at rehab home prior to coming in. Despite the vitals, she appeared relatively stable. But she stopped breathing temporarily (did not require resusc) while on the CT machine. This was approximately 1-2 hours after I saw her and ordered the test. She had fairly extensive b/l PE's

Now my question is, does anyone consider starting heparin BEFORE you can confirm it in a medium or high-risk patient, and then canceling if it comes back negative? I realize starting heparin is not without risk, but I wonder what the risk:benefit ratio is when PE is already number 1 on your differential?

The question on timing and the reasoning of pre-test probability have already been answered. There is another issue to consider. Heparin is aimed at preventing the NEXT pulmonary embolism, not the one sitting in the pulmonary vasculature. If the patient is sick, hemodynamically unstable, or "stopping breathing" the current debate is when to give a lytic.

 

[txterp98]

I'm with Mike. Heparin/Lovenox is only to help prevent clot propagation. It's allowing the body's intrinsic thrombolytic mechanism deal with the PE.

Truly, it's a matter of thrombolytics or not. (i.e. cardiopulmonary instability, hemodynamic lability, etc)

Why rush on the administration of Heparin/Lovenox before the CT when, as mentioned by other posters, aortic pathology has not been ruled out yet?

 

[ERNerd]

I agree with the previous two posts. While I wouldn't say that administration of heparin before the CT scan is always wrong, I can see little advantage to doing so and a clinically significant disadvantage should the patient prove to have a dissection. Heparin allows the body's own fibrinolytic system to lyse the clot, and this takes quite a bit of time, so why not wait for the scan?

Now if the patient's renal function is poor and you want to wait for a V-Q scan, pre-treat for contrast, or if you plan to give the heparin regardless of the results of the imaging study, then yes, by all means, start the heparin empirically. The question of when to give lytics is a difficult one, and I've seen intensivists and C-T surgeons spend a lot of time arguing over it....

 

[RADRULES]

Please stop saying things like "Spiral" CT. All CT is "spiral". A better word would CT angiogram.

 

[southerndoc]

I'll do a single full dose without a creatinine if I they don't have any hx of renal insufficiency and nothing to make me think renal failure currently. Right or wrong? I'm not sure.

Whether they have renal failure or not, the initial dose is the same. If the creatinine clearance is <30 then you'll just redose at 1 mg/kg in 24 hours as opposed to 12 hours.

 

[DrMom]

Whether they have renal failure or not, the initial dose is the same. If the creatinine clearance is <30 then you'll just redose at 1 mg/kg in 24 hours as opposed to 12 hours.

I know, but every hospitalist I've ever dealt with completely freaks out if you give someone in renal failure even a single dose of lovenox. They all say you *have* to use heparin.

 

[southerndoc]

I know, but every hospitalist I've ever dealt with completely freaks out if you give someone in renal failure even a single dose of lovenox. They all say you *have* to use heparin.

That's like saying you can't give Zosyn in somebody with renal failure.

 

[DrMom]

I'm not saying it is logical, just that it is what they choose to freak out about. This is the case where I train and where I moonlight (which has no hospitalists that trained where I train, so it isn't just tied to a single institution).

 

[Hernandez]

I'm not saying it is logical, just that it is what they choose to freak out about. This is the case where I train and where I moonlight (which has no hospitalists that trained where I train, so it isn't just tied to a single institution).

It's not just in your area either. as I've said before, I will not use lovenox in a CKD pt with the 3 train wreck compolications I've seen on Lovenox.

The data is out there, but the prescribing info just hasn't been updated, complications due to lovenox in CKD and ESRD pts isn't that uncommon.

 

[DrMom]

Single doses or CKD pts receiving multiple doses?

 

[Hernandez]

Single doses or CKD pts receiving multiple doses?

I've actually seen all 3. 1 pt with single dose 1mg/kg who also was ESRD, 1 pt with 30mg bid for prophylaxis, and 1 pt after several full 1mg/kg doses.

This has been a fairly hot topic in many studies in the past decade, especially in ESRD the affect seems to not be fully measured even if you were to send a Xa assay. retroperitoneal hematoma's seem to be the most commonly reported major event.

The pharmacokinetics of enoxaparin do not correlate with its pharmacodynamic effect in patients receiving dialysis therapies.Brophy DF, Carr ME Jr, Martin EJ, Venitz J, Gehr TW.
Department of Pharmacy, Coagulation Special Studies Laboratory, Virginia Commonwealth University/Medical College of Virginia (VCU/MCV), Richmond, Virginia, USA.

The pharmacokinetics and pharmacodynamics of enoxaparin were studied in healthy volunteers and hemodialysis and peritoneal dialysis subjects. Antifactor Xa activity estimated the pharmacokinetics, whereas thrombin generation time (TGT) estimated the pharmacodynamics. Enoxaparin 1 mg/kg was given subcutaneously to all subjects. Antifactor Xa Amax and AUC(0-12) were similar between groups, but the TGTmax was significantly greater in the dialysis groups (P = .001). The thrombin generation time remained significantly more prolonged throughout the 12-hour study period, and there was a trend toward greater TGT AUEC(0-12) for both dialysis groups (P = .07). Patients receiving hemodialysis had greater sensitivity to enoxaparin compared to the other groups. These results suggest that in dialysis patients, there may be accumulation of active heparin metabolites that are undetected by the antifactor Xa assay. Therefore, these subjects exhibit greater thrombin generation time prolongation despite similar antifactor Xa exposure. Further large-scale studies are needed to corroborate the results of this exploratory pilot study.​

If you do a pubmed search, you'll find tons of case reports and case series. but since the patent will be up in Feb 2012 no one is going to do this study.