Tag Archives: contrast

Imaging

CT Contrast Administration Via Intraosseous Cathether

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The standard of care in vascular access in trauma patients is the intravenous route. Unfortunately, not all patients have veins that can be quickly accessed by prehospital providers. Introduction of the intraosseous device (IO) has made vascular access in the field much more achievable. And it appears that most fluids and medications can be administered via this route. But what about iodinated contrast agents via IO for CT scanning?

Physicians at Henry Ford Hospital in Detroit published a case report on the use of this route for contrast administration. They treated a pedestrian struck by a car with a lack of IV access sites by IO insertion in the proximal humerus, which took about 30 seconds. They then intubated using rapid sequence induction, with drugs injected through the IO device. They performed full CT scanning using contrast injected through the site using a power injector. Images were excellent, and ultimately the patient received an internal jugular catheter using ultrasound. The IO line was then discontinued.

This paper suggests that the IO line can be used as access for injection of CT contrast if no IV sites are available. Although it is a single human case, a fair amount of studies have been done on animals (goats?). The animal studies show that power injection works adequately with excellent flow rates.

The authors prefer using an IO placement site in the proximal humerus. This does seem to cause a bit more pain, and takes a little practice see the video above). A small xylocaine flush can be administered to reduce injection discomfort in awake patients. Additionally, the arm cannot be raised over the head for the torso portion of the scan.

Bottom line: CT contrast can be injected into an intraosseous line (IO) with excellent imaging results. Insert the IO in a site that you are comfortable with. I do not recommend power injection at this time. Although the marrow cavity can support it, the connecting tubing may not. Have your radiologist hand-inject and time the scan accordingly.

Note: long term effects of iodinated contrast in the bone marrow are not known. For this reason, and because of smaller marrow cavities, this technique is not suitable for pediatric patients.

Related post: Air embolism from an intraosseous line

Reference: Intraosseous injection of iodinated computed tomography contrast agent in an adult blunt trauma patient. Annals Emerg Med 57(4):382-386, 2011.

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General

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

AAST 2011: Acute Kidney Injury From IV Contrast

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Yesterday, I wrote about using acute kidney injury (AKI) as a predictor for multiple organ failure. But what about kidney failure that we may inadvertently create through the use of IV contrast during CT scan evaluation? Contrast is generally safe for use in the general trauma population, but is known to cause renal problems in high risk groups like the elderly and critically ill.

Investigators at UCSD retrospectively reviewed ICU patients who had no history of pre-existing renal disease. A total of 570 eligible patients were identified, and 170 (30%) developed AKI. Being old (age>=75) or severely injured (ISS>=25) was a predictor of AKI, but IV contrast was not. Even during subgroup analysis, the addition of contrast to the elderly or severely injured patient population did not predict AKI.

Bottom line: This limited study shows that IV contrast exposure may be considered safe, even in the elderly and severely injured. However, I still recommend that all risks and benefits be thoroughly weighed in every patient, and that scans that have little diagnostic and therapeutic benefit be avoided.

Reference: Is contrast exposure safe among the highest risk trauma patients? AAST 2011 Annual Meeting, Paper 69.

General

CT Contrast Administration Via Intraosseous Cathether

Leave a comment

The standard of care in vascular access in trauma patients is the intravenous route. Unfortunately, not all patients have veins that can be quickly accessed by prehospital providers. Introduction of the intraosseous device (IO) has made vascular access in the field much more achievable. And it appears that most fluids and medications can be administered via this route. But what about iodinated contrast agents via IO for CT scanning?

Physicians at Henry Ford Hospital in Detroit have just published a case report on the use of this route for contrast administration. They treated a pedestrian struck by a car with a lack of IV access sites by IO insertion in the proximal humerus, which took about 30 seconds. They then intubated using rapid sequence induction, with drugs injected through the IO device. They performed full CT scanning using contrast injected through the site using a power injector. Images were excellent, and ultimately the patient received an internal jugular catheter using ultrasound. The IO line was then discontinued.

This paper suggests that the IO line can be used as access for injection of CT contrast if no IV sites are available. Although it is a single human case, a fair amount of studies have been done on animals (goats?). The animal studies show that power injection works adequately with excellent flow rates. 

The authors prefer using an IO placement site in the proximal humerus. This does seem to cause a bit more pain, and takes a little practice. A small xylocaine flush can be administered to reduce injection discomfort in awake patients. Additionally, the arm cannot be raised over the head for the torso portion of the scan. 

Bottom line: CT contrast can be injected into an intraosseous line (IO) with excellent imaging results. Insert the IO in a site that you are comfortable with. I do not recommend power injection at this time. Although the marrow cavity can support it, the connecting tubing may not. Have your radiologist hand-inject and time the scan accordingly.

Note: long term effects of iodinated contrast in the bone marrow are not known. For this reason, and because of smaller marrow cavities, this technique is not suitable for pediatric patients.

Related post: Air embolism from an intraosseous line

Reference: Intraosseous injection of iodinated computed tomography contrast agent in an adult blunt trauma patient. Annals Emerg Med 57(4):382-386, 2011.

General

GI Contrast In CT Scanning for Blunt Trauma

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Torso CT scanning has become a mainstay in the evaluation of major blunt trauma. The question of using GI contrast in these CTs arises from time to time. There is an ongoing battle between the ED physician/trauma surgeon, who want quick clinical and relevant results, and the radiologist, who wants nice pictures and a comprehensive list of diagnoses.

IV contrast is so helpful and immediately available that it is virtually a no-brainer to use. The only exception is in patients who have a known allergy to it. GI contrast is more complicated. Ideally, it should be given in divided doses over about an hour, and there just isn’t time for it in trauma patients.

We designed a prospective, randomized study more than 10 years ago that looked at groups of patients who either did or did not receive oral contrast. We studied 394 patients and looked a the need for laparotomy based on study results, delayed diagnoses, and nausea/vomiting.

Thirteen percent of the patients in each group vomited. There were two aspirations, both in the non-contrast group. There were 50 abnormal scans in the contrast group and 55 in the no-contrast group. Nineteen contrast and 14 no-contrast patients were taken to OR.

Most interesting, there were 6 bowel injuries in the contrast group and one was not seen by CT. There were 3 bowel injuries in the no-contrast group and all were seen on CT. We found that there were always other signs of injury, such as mesenteric stranding or bubbles. 

Bottom line: Oral contrast is not necessary in acute blunt trauma patients undergoing CT of the abdomen.