All posts by TheTraumaPro

IV Contrast In Trauma Imaging

We use CT scanning in trauma care so much that we tend to take it (and its safety) for granted. I’ve written quite a bit about thoughtful use of radiographic studies to achieve a reasonable patient exposure to xrays. But another thing to think about is the use of IV contrast.

IV contrast is a hyperosmolar solution that contains some substance (usually an iodine compound) that is radiopaque to some degree. It has been shown to have a significant impact on short-term kidney function and in some cases can cause renal failure.

Here are some facts you need to know:

  • Contrast nephrotoxicity is defined as a 25% increase in serum creatinine, usually within the first 3 days after administration
  • There is usually normal urine output and minimal to no proteinuria
  • In most cases, renal function returns to normal after 3-4 days
  • Nephrotoxicity almost never occurs in people with normal baseline kidney function
  • Large or repeated doses given within 72 hours greatly increase risk for toxicity
  • Old age and pre-existing diabetic renal impairment also greatly increase risk

If you must give contrast to a patient who is at risk, make sure they are volume expanded (tough in trauma patients), or consider giving acetylcysteine or using isosmolar contrast (controversial, may still cause toxicity).

Bottom line: If you are considering contrast CT, try to get a history to see if the patient is at risk for nephrotoxicity. Also consider all of the studies that will be needed and try to consolidate your contrast dosing. For example, you can get CT chest/abdomen/pelvis and CT angio of the neck with one contrast bolus. Consider low dose contrast injection if the patient needs formal angiographic studies in the IR suite. Always think about the global needs of your patient and plan accordingly (and safely).

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Reference: Contrast media and the kidney. British J Radiol 76:513-518, 2003.

Insert A Subclavian IV Near A Clavicle Fracture? The Answer

Yesterday’s question involved inserting a good old subclavian IV in a trauma patient with a clavicle fracture. Is there ever any reason to do it on the fractured side? As I mentioned, there’s no literature on this, just “feelings.”

Here’s my take:

  • Landmarks – The usual anatomic landmarks (clavicle, first rib) may be out of place or non-palpable, making the procedure technically more difficult.
  • Vessel location – The actual location of the vessels may have changed due to hematoma formation. This will decrease the likelihood of successful cannulation.
  • Aspiration of blood – The usual way the trauma professional identifie if they have entered the vein is free aspiration of dark blood. A fresh fracture hematoma looks and feels exactly the same, and may be aspirated into the needle just as easily. So you think you’re in the vein, but you’re not.
  • Contamination risk – There is the possibility that you may contaminate the fracture hematoma, leading to bone healing complications.

What if the fracture side is the lesser of two evils? Let’s say the contralateral side has even more severe injuries. I recommend abandoning the subsclavian approach on either side and choosing another site, like the internal jugular.

What if there’s a pneumothorax (occult or obvious) on the side of the clavicle fracture? Traditionally, we would choose that side for the line, because it may need a chest tube anyway and it removes any worry about causing a pneumothorax from the insertion procedure. In my opinion, that’s not a good enough reason to struggle with the four issues listed above.

Bottom line: Don’t even consider inserting a subclavian IV on the side of a clavicle fracture. The odds are stacked against you being successful, and there are essentially no benefits. Juice to squeeze ratio equals zero!

Hat tips to Corey Heitz and wasatch for their comments!

Related post: What do you think? Subclavian IV and clavicle fracture?

What Do You Think? Insert A Subclavian IV Near A Clavicle Fracture?

Someone asked me an interesting question: If I have a patient with a clavicle fracture, is it okay to insert a subclavian line on that side?

Don’t try to look it up. As far as I’ve been able to determine, there is no literature on this simple little question. For most people, the first reaction is “No way!” But think about it a bit, and see if you can come up with any reasons it might be preferred.

Please post your comments, or tweet them out. I’ll answer this pesky one tomorrow.