Category Archives: General

Best Of: IV Contrast

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.

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Yes, Smoking is Bad!

Everybody knows that smoking is bad. But how often have you stopped by to see one of your trauma patients and have been told “they’re out smoking?” Well, it turns out it’s bad for their injuries as well.

A German group looked at the effects of smoking on healing of a “simple” tibial fracture. They looked at 103 patients who underwent treatment for an isolated tibial shaft fracture at a trauma center. Patients with more complicated problems like extension into a joint, open fracture (Gustilo III), or significant soft tissue injury were excluded. 

Patients were divided into non-smokers and smokers (including previous smokers). A total of 85 patients were studied, and there were roughly half in each group. The nonsmoking group experienced no delayed or non-unions of their fractures. The smoking group reported 9 delayed unions and 9 non-unions in 46 patients! As expected, time off work and eventual functional outcome was worse as well.

Bottom line: The exact mechanism for impairment of fracture healing by smoking is unclear. It may be due to physiologic effects of inhaled tobacco components on blood flow, blood vessels, transforming growth factor levels or collagen formation. It could also be a secondary effect of socioeconomic variables, patient compliance, or a host of other factors. Regardless, it’s bad. Smoking should be forbidden while in hospital, and should be strongly discouraged after discharge.

Reference: Cigarette smoking influences the clinical and occupational outcome of patients with tibial shaft fractures. Injury 42:1435-1442, 2011.

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Practice Guideline – Blunt Cardiac Injury (BCI)

The Eastern Association for the Surgery of Trauma recently released an update of their practice guideline for screening for blunt cardiac injury. Although the bulk of the guideline remains the same, a few areas have been updated to reflect advances since its original 1998 release.

Here is a quick summary of the new guidelines. Level 1 (best data):

  • If blunt cardiac injury is suspected, an EKG should be obtained (no change)

Level 2 (okay data):

  • If a new arrhythmia is seen on EKG, admit for monitoring. If not new, compare with an old EKG to determine need for admission. (updated)
  • If the EKG is normal and troponin I is normal, BCI is ruled out. If the EKG is normal and troponin I is abnormal, admit for monitoring. (new)
  • If the patient is unstable or the arrhythmia persists, obtain a cardiac echo. (updated)
  • Sternal fracture is not predictive of BCI (moved from level 3)
  • CPK should not be obtained (modified and moved from level 3)
  • Nuclear medicine studies should not be obtained (no change)

Level 3 (data not so good):

  • Elderly patients with known cardiac disease, unstable patients, and those with abnormal EKG can safely undergo surgery with appropriate monitoring (no change)
  • Troponin I should be measured routinely in suspected BCI, and if elevated should prompt monitoring and serial testing (new)
  • Cardiac CT or MRI may help differentiate acute MI from BCI to determine need for catheterization and/or anti-coagulation (new)

The EAST guidelines are just that, guidelines. They are not a complete management algorithm. I have combined this new information with an existing algorithm based on the old EAST guidelines. Feel free to download this algorithm using the link below. As always, I welcome any comments.

Click here to download the blunt cardiac injury algorithm

Reference: Screening for by cardiac injury: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma 73:(5) Supplement 4, S301-S306, 2012.

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Cardiac Enzymes And Blunt Cardiac Injury

Blunt cardiac injury (BCI), better known as cardiac contusion, has been poorly understood for decades. There has always been confusion about the best way to detect, monitor, and treat this condition. The Eastern Association for the Surgery of Trauma developed a set of practice guidelines in 1998 that provided solid, evidence-based principles to act upon. At that time, CPK was the only cardiac enzyme available. It was useless because it had no correlation with presence or absence of contusion, or even severity of injury.

With the arrival of troponin assays, a new tool for looking at cardiac injury became available. However, initial evaluations indicated that it was also not very reliable when used in the diagnosis of cardiac contusion. For years, I’ve been teaching that these enzymes are useless. However, additional work has been done that does show some limited usefulness.

A prospective study by Collins looked at the usefulness of troponin I (TnI) in patients with cardiac injury. As in previous retrospective studies, this test had a very low positive predictive value. In addition, they determined that a negative EKG alone ruled out blunt cardiac injury. So what good is it?

The new piece of information here is that if the EKG is abnormal and the troponin I is normal, then a cardiac contusion can be ruled out. This changes the overall algorithm by allowing us to eliminate some patients who have abnormal EKGs.

On Monday, I’ll provide my take on a comprehensive algorithm for evaluating and managing cardiac injury. Stay tuned.

Related posts:

Reference: The usefulness of serum troponin levels in evaluating cardiac injury. Am Surg 67:821-826, 2001.

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Contrast Blush in Children

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.

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