trauma CT scan

[rohit76]

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Do you follow any cut-offs for s. creatinine while doing CT scans with IV contrast to r/o trauma related solid organ injury or aortic injury?

 

[SoCuteMD]

radiology's cut off for us is 1.5. We occasionally negotiate (severe mechanism, high suspicion for injury in which CT will affect disposition).

 

[diphenyl]

not for trauma, but the bicarb bolus treatments usually help us negotiate with CT. HAHA. unfortunately in the case of trauma I have had to argue w/ CT that there is no reason to wait for a chem 7 in a young healthy patient to obtain a CT in a patient that could be emergent.

 

[EMS5]

just out of pure nerdy curiosity (spare me the "you've got plenty of time before you worry about this" speech), can someone briefly explain the clinical importance of creatinine levels in a trauma ct?

 

[Apollyon]

just out of pure nerdy curiosity (spare me the "you've got plenty of time before you worry about this" speech), can someone briefly explain the clinical importance of creatinine levels in a trauma ct?

Contrast can be nephrotoxic (because of the same reason that it shows up opaque on radiographic studies - it's dense), and, if the renal function isn't optimal, the contrast bolus can cause renal failure. When I was a resident, the cards guys would encounter this - patient needed a cath, but renal function was poor, and they know that the cath would be the last hurrah for the patient's kidney (and dialysis thereafter), but they needed cath.

In your average trauma victim, the age is generally younger than your polymorbid medical patient. The possibility of poor kidney function is there, but MUCH less likely than in the other group of patients.

 

[kajunman]

at my shop (level one. @85K pts/year) for trauma activations the pt is in the scanner about 30 seconds after the blood is drawn, so no we don't have arguments with rads about giving contrast...if its trauma we just scan and get the renal labs when then come back.

YODA

 

[KYTNOH]

It depends on our clinical suspicion. If there is a low clinical suspicion we will wait on the creatinine to return, but if there is a high clinical suspicion for a significant chest or abd injury we scan immediately. Correct me if I'm wrong, but it is my understanding (I admittedly haven't done all that much reading on this subject) that the creatinine bump after a contrast bolus is temporary and it is rare for it to cause anything more than a short-term AKI. One thing I have learned is that if you feel like you're going to need an aorta get it at the same time you get the abd since it saves a bolus of contrast. I've made the mistake twice of not getting an aorta and having a persistently wide mediastinum on supine and upright CXRs which caused the patient to go back to the scanner for more radiation and contrast. Also, I'm moving more and more to the opinion that if you're going to get CTs of the spine and abd then you might as well get the aorta as well. There's no additional radiation or contrast exposure and I've picked up a few chest-tube worthy pneumothoraces on CT that weren't evident on supine CXR in addition to the multiple rib fractures and pulmonary contusions that suddenly become evident on CT.

 

[EMS5]

Contrast can be nephrotoxic (because of the same reason that it shows up opaque on radiographic studies - it's dense), and, if the renal function isn't optimal, the contrast bolus can cause renal failure. When I was a resident, the cards guys would encounter this - patient needed a cath, but renal function was poor, and they know that the cath would be the last hurrah for the patient's kidney (and dialysis thereafter), but they needed cath.

In your average trauma victim, the age is generally younger than your polymorbid medical patient. The possibility of poor kidney function is there, but MUCH less likely than in the other group of patients.

That clears it up. Never really thought about the possible toxicity from giving contrast of all things to someone with failing kidneys...again, just my lowly medic's interpretation, but won't a fudged up aorta or hemo/pneumo kill you way quicker than renal failure induced by contrast? I'd scan now and ask chem levels later looking at things from a layman's point of view.

 

[Janders]

Generally if I have a trauma I am worried about, i am not waiting for a Cr to return to scan them. Same for, say, a sick suspected dissection.

Now, if I happen to have a Cr that is up, and then figure out I am worried about trauma... well, like everything it becomes risk/reward.

 

[Apollyon]

Correct me if I'm wrong, but it is my understanding (I admittedly haven't done all that much reading on this subject) that the creatinine bump after a contrast bolus is temporary and it is rare for it to cause anything more than a short-term AKI.

The only way you can call it "short-term" is retrospectively. If the Cr is 3 and you give a big contrast bolus, chances are good that HD is on the map, and those kidneys will not recover.

That clears it up. Never really thought about the possible toxicity from giving contrast of all things to someone with failing kidneys...again, just my lowly medic's interpretation, but won't a fudged up aorta or hemo/pneumo kill you way quicker than renal failure induced by contrast? I'd scan now and ask chem levels later looking at things from a layman's point of view.

You're absolutely correct, and that is the question at the heart of this matter.

 

[WilcoWorld]

When it comes to a sick trauma patient and the contrast/Cr issue I feel it's better to beg for forgiveness than to ask for permission, so I scan them before the labs are back.

Now, on the patient who is not sick and who has a low pretest probability of traumatic injury and a high PTP for renal insufficiency I'll check a Cr and hydrate while waiting for results. I hydrate for 2 reasons: 1) Often times the Cr will come down to below the "cut-off" with a little IVF and 2) The most important factor in preventing contrast induced nephropathy is ensuring adequate hydration prior to contrast administration.

 

[EMS5]

When it comes to a sick trauma patient and the contrast/Cr issue I feel it's better to beg for forgiveness than to ask for permission, so I scan them before the labs are back.

Now, on the patient who is not sick and who has a low pretest probability of traumatic injury and a high PTP for renal insufficiency I'll check a Cr and hydrate while waiting for results. I hydrate for 2 reasons: 1) Often times the Cr will come down to below the "cut-off" with a little IVF and 2) The most important factor in preventing contrast induced nephropathy is ensuring adequate hydration prior to contrast administration.

All the more reason to start a large-bore IV and give a liter of fluid in the field 🙂

 

[SoCuteMD]

That clears it up. Never really thought about the possible toxicity from giving contrast of all things to someone with failing kidneys...again, just my lowly medic's interpretation, but won't a fudged up aorta or hemo/pneumo kill you way quicker than renal failure induced by contrast? I'd scan now and ask chem levels later looking at things from a layman's point of view.

Remember, only a small subset of trauma patients have immediately life-threatening illnesses (or is that only where I am?). Sure, if a patient has hemodynamic abnormalities, send them to the scanner and worry about the kidneys later. However, if the patient is hemodynamically normal or has only small abnormalities, isn't it better to watch and potentially save a patient from dialysis (which lands them on disability and raises their 10 year mortality significantly)? There may be a way to get the images you need without contrast.

 

[southerndoc]

unfortunately in the case of trauma I have had to argue w/ CT that there is no reason to wait for a chem 7 in a young healthy patient to obtain a CT in a patient that could be emergent.

I now have the luxury of having point-of-care (I-STAT) testing where I work. It takes only 5 minutes to get a chem-8 (10 for a troponin and BNP). It's hard to defend oneself against nephrotoxicity even in a young person if you have access to POC testing. It really doesn't hold up things very much to do a POC chem-8 prior to CT.

 

[deleted109597]

snip...which lands them on disability and raises their 10 year mortality significantly.../snip

Where I am, the trauma patients come in with their disability forms pre-filled, with only the MD signature required.
They also ask for narcotics by name.

 

[Arcan57]

I now have the luxury of having point-of-care (I-STAT) testing where I work. It takes only 5 minutes to get a chem-8 (10 for a troponin and BNP). It's hard to defend oneself against nephrotoxicity even in a young person if you have access to POC testing. It really doesn't hold up things very much to do a POC chem-8 prior to CT.

Yeah, but then you hold off on CTing someone who may need it because of fear of nephrotoxicity. I'm not talking about the person you're scanning because you think the medicolegal environment requires it. I'm talking about the person that you think has real disease and has a Cr of 1.8. I've seen this several times with people that had aortic dissections that died while the various services fought about the best way to image them. T