Tag Archives: angiography

General

How Does That Work?: Angioembolization Coils

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Ever wonder how interventional radiologists stop bleeding? They are very skilled in getting access to complicated areas of the arterial tree. Once they have located a bleeding point, they’ve got to plug it up with something.

Over the years, a wide variety of things have been used. They include blood clot, tiny metal or plastic spheres, superglue, and a variety of other creative things. One of the more recent additions is the metal coil.

On xray, these look like little pieces of piano wire in various shapes after they are inserted. But how do they work? They’re metal, and fairly smooth. How does that promote fast clotting?

The answer is more obvious when you look at one of these before it’s been inserted. Note the “fuzz”. These are synthetic fibers that are wrapped into the coil itself, and they are what actually promote clotting when the coil is in place.

General

Angiography And Splenic Salvage

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Variations in the way we deal with trauma can have a significant impact on patient outcome. This has been documented most recently in the use of angioembolization when dealing with patients with spleen injuries. The first paper presented at EAST 2013 looked at outcomes at hospitals that use angio more heavily vs those who don’t.

They analyzed 1275 patients presenting to 4 Level I trauma centers. Two centers were high-use (11% and 19% usage) and the other 2 were low-use (1% and 4%). The outcomes studied were the splenic salvage rate and success in nonoperative management. And although patients at the low angio use centers had a higher ISS, the splenic injury grade was the same.

Interesting findings included:

  • Admission splenectomy rate was the same, meaning that both types of centers used the same criteria when the patient rolled through the door
  • High angio use centers had higher overall salvage rates (82% vs 77%)  and greater success with nonoperative managment (96% vs 92%)
  • In high grade injury (grade 3 and 4) the salvage rate was still better (67% vs 56%) and nonop success rates were much better (92% vs 80%)
  • In patients who were initially managed nonoperatively, use of angio was associated with salvage
  • Patients in high angio centers were more likely to leave the hospital with their spleen where it should be
  • There was no analysis of complications from angiography
  • There was no comment on how these patients were managed on a day to day basis

Bottom line: There is a considerable amount of variation in how trauma centers use angiography for spleen injury. Unfortunately, this variability is allowing people to lose their spleens at centers who don’t use it as much. The overall success rate in managing spleen injury (all comers) has historically been about 93%. More aggressive use of angiography is now shown to improve that to 97%. Given this new data, angio needs to be considered in patients with grade 3+ injury and in any with contrast extravasation. And the overall management should be standardized as well.

Reference: Variation in splenic artery embolization and spleen salvage: a multicenter analysis. Paper 1, EAST annual scientific assembly, Jan 15, 2013.

Complications

Post-Embolization Syndrome?

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I’ve seen a number of trauma patients who have developed pain and elevated WBC after embolization of solid organs for trauma. For kidneys and main splenic artery embolization, it’s fairly common in my experience. Turns out, this phenomenon was described in 2007-2008 in patients undergoing embolization of hepatic tumors and uterine fibroids. It was termed post-embolization syndrome, and consists of pain, fever, nausea and ileus.

An article was just published in the Journal of Trauma describing this syndrome in children after splenic embolization for blunt trauma. The authors looked at their own trauma registry over a 12 year period. Yes, it took that long to find 448 children with blunt splenic injury. Of those, only 11 underwent arterial embolization (sigh of relief).

The average age was about 13 and ISS was 16 in both groups. Kids who underwent embolization were more likely to spend some time in the ICU, had a longer hospital stay (8 vs 5 days(!)), and took longer to resume their diet (5 vs 2 days). These differences occurred despite the fact that most of the embolized children had isolated splenic injuries. Additionally, the embolized children were more likely to receive blood (3 units vs none) and plasma.

My first question about this paper is, why? Broken spleens in children do not act like broken spleens in adults. The vast majority of the cases of contrast extravasation in children stops on its own without intervention. So why did we even have to find out that post-embolization syndrome occurs in children? They shouldn’t be going through this procedure anyway! Fortunately, a deeper read of the paper provides the answer. The indication for angio was splenic pseudoaneurysm in 2, and ongoing hemorrhage in the other 9. In the case of these latter 9, it did keep the children from having their spleens operated on.

Bottom line: In general, don’t send kids for splenic angiography (99.3% of kids in this study did not have it). Ongoing hemorrhage (prior to hypotension, which is an absolute indication for OR) is probably the only indication I can think of. Pseudoaneurysm and extravasation of contrast are not indications like they are in adults. But if you do have to send them, just be aware that they may develop pain, fever and ileus that will keep them in the hospital and/or ICU for a few extra days.

Reference: Transarterial embolization in children with blunt splenic injury results in postembolization syndrome: A matched case-control study. J Trauma 73(6):1558-1563, 2012.

General

Best Of: IV Contrast

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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).

Related posts:

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

General

Contrast Blush in Children

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A contrast blush is occasionally seen on abdominal CT in patients with solid organ injury. This represents active arterial extravasation from the injured organ. In most institutions, this is grounds for call interventional radiology to evaluate and possibly embolize the problem. The image below shows a typical blush.

Splenic contrast blush

This thinking is fairly routine and supported by the literature in adults. However, it cannot be generalized to children!

Children have more elastic tissue in their spleen and tend to do better with nonoperative management than adults. The same holds true for contrast blushes. The vast majority of children will stop bleeding on their own, despite the appearance of a large blush. In fact, if children are taken to angiography, it is commonplace for no extravasation to be seen!

Angiography introduces the risk of local complications in the femoral artery as well as more proximal ones. That, coupled with the fact that embolization is rarely needed, should keep any prudent trauma surgeon from ordering the test. A recently released paper confirms these findings.

The only difficult questions is “when is a child no longer a child?” Is there an age cutoff at which the spleen starts acting like an adult and keeps on bleeding? Unfortunately, we don’t know. I recommend that you use the “eyeball test”, and reserve angiography for kids with contrast extravasation who look like adults (size and body habitus).

Reference: What is the significance of contrast “blush” in pediatric blunt splenic trauma? Davies et al. J Pediatric Surg 2010 May; 45(5):916-20.