Tag Archives: ct scan

When To Obtain A Dedicated Facial CT

Initial CT scan evaluation for blunt trauma patients is fairly standardized. The usual palate consists of scans of the head, cervical spine, chest, abdomen and pelvis. Some choose their “colors” individually, and others just slop everything on the canvas.

However, there are a few other scans that are occasionally helpful and/or necessary. Think soft tissue views, or CT angiogram of the neck, or CT angiogram of potential extremity vascular injuries.

Another study that is occasionally needed but many times unnecessarily ordered is the dedicated CT of the facial bones. This study spans the entire area from mandible to frontal sinus and is performed using finer cuts to display greater detail.

The unfortunate truth is that a large number of dedicated facial CTs either do not show fractures, or show fractures that don’t require operation. The scan does deliver a nice dose of radiation, though. Is there any way to be more selective about ordering it?

About 10 years ago, a plastic surgery group in Madison developed what came to be called the “Wisconsin criteria” for ordering facial imaging.  Here they are:

  • Bony step-off
  • Periorbital ecchymosis
  • GCS < 14
  • Malocclusion
  • Missing teeth

The authors claimed 97% sensitivity and 2.6% missed fracture rate, although external validation suggested those numbers were a bit generous. The Plastic Surgery group from the University of Minnesota and Regions Hospital recently re-studied these criteria with a large number of patients, looking at accuracy as well as cost-savings.

They performed a retrospective review of 1000 patients (based on a power analysis) who had a facial CT and adequate documentation of the Wisconsin criteria in the chart. Here are the factoids in table form:

(click table for larger copy)

  • Periorbital ecchymosis was the most common criterion, which had the highest sensitivity of 70% (terrible)
  • The other criteria fared even worse from a sensitivity standpoint
  • But if you roll them all up together, the presence of any one of the five yielded a 90% sensitivity (true positives) and 52% specificity (true negatives)
  • The negative predictive value was 93% if none of the criteria were present, which means it’s a good tool for ruling out the need for a CT scan
  • The overall missed fracture rate was 2.8%, and only 0.12% for ones that required operation
  • Cost savings by limiting CT to patients who met the criteria was over $300K in 2014

Bottom line: What to do? It’s clear that using the absence of any of the Wisconsin criteria to avoid a facial CT scan is helpful. This makes sense, because 4 of the 5 criteria are findings on facial exam. But it also means that a lot of scans will still get done for low sensitivity criteria. 

How about this? Since nearly all of these patients will have head and cervical CT scans, review the head scan first for facial fractures. Single, non-displaced fractures are nearly always nonoperative in nature. If patterns of fractures are present, or there are significant displacements, a dedicated facial scan will be very helpful in determining operative management.

But remember, the head CT does not include the mandible. A good physical exam and occlusion check is mandatory, and any suspicion of injury should prompt a full scan of the face.

Thanks to Chris Stewart, the lead author on this study for sending it to me for review.

Rreference: Validation of the “Wisconsin criteria” for obtaining dedicated facial imaging and its financial impact at a Level I trauma center. Craniomaxillofacial Trauma & Recon 13(1):4-8, 2020.

Best Practice: Use of CT Scan In Trauma Activations – Part 2

In my last post, I described how the unscheduled and random use of CT scan in trauma activations can interfere with normal radiology department workflow, creating access problems for other emergency and elective patients. Today, I’ll detail a project implemented at my hospital to analyze the magnitude of this problem and try to resolve it.

We started with a detailed analysis of how the scanner was being used for trauma activation patients. Regions Hospital has a single-tier trauma activation system, with no mechanism of injury criteria other than penetrating injury to the head, neck, and torso. There are usually about 850 activations per year, and traditionally the CT scanner has been “locked down” when the activation is announced. The CT techs would complete the current study on the table, then hold the scanner open until called or released by the trauma team.

Since we are a predominantly blunt trauma institution, we scan most stable patients. Our average time in the trauma bay is a bit less than 20 minutes. Add this time to the trauma activation prenotification time of up to 10 minutes, and the scanner has the potential to sit idle for up to half an hour. And in some cases when scan is not needed (minor injuries, rapid transport to OR) the techs were not notified and were not aware they could continue scanning their scheduled cases.

A multidisciplinary group was created and started with direct observation of the trauma activation process and a review of chart documentation and radiology logs. On average it was calculated that the scanner was held idle for an average of 17.9 minutes too long. This is more than enough time to complete one, or even two studies!

A new process was implemented that required the trauma team leader to call out to the ED clerk placing orders for the resuscitation 5 minutes before the patient would be ready for scan. I still remember the first time this happened to me. I was so used to just packing up and heading to scan, I got a little irritated when told that I hadn’t made the 5-minute call. But it’s a good feedback loop, and I never forgot again!

We studied our workflow and results over a 9-week period. And here are the factoids:

  • The average CT idle time for trauma activations before the project was 17.9 minutes
  • This decreased to an average idle time of 6.4 minutes during the pilot project
  • Total idle time for all activations was 8.3 hours, but would have been 36 hours under the old system
  • A total of 28.6 hours were freed up, which allowed an additional 114 patients to be scanned while waiting for the trauma activation patients

This was deemed a success, and the 5-minute rule is now part of the routine flow of our trauma activations. We rarely ever have to wait for CT, and if we do it’s usually due to the team leader not thinking ahead.

Bottom line: This illustrates the processes that should be used when a quality problem surfaces in your program:

  • Recognize that there is a problem
  • Convene a small group of experts to consider the nuances
  • Generate objective data that describes the problem in detail
  • Put on your thinking caps to come up with creative solutions
  • Test the solutions until you find one that shows the desired improvement
  • Be prepared to modify your new systems over time to ensure they continue to meet your needs

Best Practice: Use of CT Scan In Trauma Activations – Part 1

Computed tomography is an essential part of the diagnostic workup for many trauma patients. However, it’s a limited resource in most hospitals. Only so many scanners are affordable and available.  Typically, trauma centers have a scanner located in or very near the trauma bay, which makes physical access easy. Others may be located farther away, which can pose logistical and safety issues for critically injured patients.

Even if the CT is close to the ED, availability can be an issue. This availability applies not only to trauma scans, but to others as well. There is an expectation that CT be immediately available when needed for trauma activation patients. However, chances are that the same scanner is also used for high priority scans for services other than trauma, such as stroke evaluation.

Who gets the scanner first? Obviously, many trauma patients need rapid diagnosis for treatment of their serious injuries. But a fresh stroke patient also has a neurologic recovery countdown clock running if they might be eligible for lytic administration.

And don’t forget that trauma and stroke aren’t the only services vying for that scanner. The hospital undoubtedly has a stream of elective scans queued up for other in-house patients. Every urgent or emergent scan needed for trauma sets the elective schedule back another 30 minutes or more.

How does your trauma center manage CT scan usage for trauma? The vast majority essentially lock it down at some fixed point. This is typically either upon trauma activation, or at patient arrival. The former is very common, but also very wasteful because there can be a significant wait for the patient to actually arrive. Then add on the time it takes to complete the trauma bay evaluation. Up to an hour may pass, with no throughput in the CT scanner. This can be a major work flow headache for your radiology department.

Is there another way? My center was one of those that stopped the scanner after the current patient was finished at the time the trauma activation was called. We have two scanners just 30 feet from the trauma bays, so one could continue working while the other was held. However, this cut their throughput by 50% for roughly half an hour. We recognized that this was a creating a problem for the whole hospital, so we worked with the radiology department to come up with a better way.

Tomorrow I’ll detail the new system we implemented, and provide data showing the real impact of this new system on CT scan productivity.

IV Contrast and Trauma – Revisited

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. And finally, consider what changes will be made if the study is positive. For example, if a CT angio of the neck for blunt carotid/vertebral injury is being considered, the intervention for a positive result is usually just aspirin. Since this is a very benign medication, why not forgo the scan and just start aspirin if there is a significant risk of kidney injury from the contrast. Always think about the global needs of your patient and plan accordingly (and safely).

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

Radiation Exposure From Imaging At Adult vs Pediatric Trauma Centers

Anyone who reads this blog already knows I am a big believer in well-crafted and focused practice guidelines. And by focused I mean directed toward a clinical problem that typically sees a lot of variability between care providers. Use of imaging is one of these clinical problems. A surgeon may order a certain set of studies for a major blunt trauma patient, and their emergency medicine colleague might order a somewhat different set for someone with the exact same history, physical exam, and injury pattern. Who is right? Neither!

And the variability is even greater when we throw a pediatric patient into the mix. Trauma professionals tend to be even more “generous” when ordering studies on children because they are afraid they might miss something. Unfortunately, this has the potential for overuse of imaging and exposure to unnecessary radiation.

Avery Nathens and a consortium of pediatric trauma centers used the Trauma Quality Improvement Database (TQIP) to review CT imaging practices on children age < 18 over a four year period. Only blunt trauma patients were studied, and the Abbreviated Injury Scale had to be at least 2 for a minimum of one organ system. Transfer patients were excluded because there is no data on imaging for the referring hospital in the TQIP database for them. Comparisons were made between practices at adult trauma centers treating children (ATC), mixed adult/pediatric centers (MTC) and pediatric only trauma centers (PCT).

Here are the factoids:

  • Over 59,000 pediatric trauma patients were identified in the data, and about half (31,081) received at least one CT scan
  • The distribution among the three types of trauma centers was even, with roughly a third seen at each
  • Of the study group 46% had a head CT, 17% a chest CT, and 26% underwent abdominal CT
  • Injured children were more likely to undergo CT if they were older, had a higher ISS, lower motor GCS, were involved in a car crash, or had severe injuries to head or torso
  • Overall CT rates were about the same across the three types of centers (56% ATC, 57% MTC, 43% PTC)
  • Chest CT was performed 8x as much at ATC/MTC vs PTC (!)
  • Abdominal CT was performed 2x as much at ATC/MTC vs PTC
  • Lesser injured children received relatively more CT scans at ATC/MTC when compared to PTC
  • Using standard estimates of cancer risk from all CT scans received, children treated at adult or mixed trauma centers received enough radiation to cause 17 additional lifetime cancers per 100,000 patients
  • About 35 additional lifetime cancers per 100,000 would be caused by the chest and abdominal scans performed at the ATC/MTC centers when compared to pediatric-only centers

Bottom line: This is yet another reason to adopt a well-designed pediatric imaging guideline. Not only are adult centers using CT scanning much more that pediatric-only centers, but they are unnecessarily adding to the lifetime risk for cancer of our children!

As I always recommend, find a well-designed imaging guideline from an established pediatric center and “borrow” it. Sure, it may need a few minor tweaks to fit well with your hospital. That’s okay. Just get it done so your team can begin to order the initial imaging studies consistently and intelligently.

Reference: Computed tomography rates and estimated radiation-associated cancer risk among injured children treated at different trauma center types. Injury 2018, in press.  https://doi.org/10.1016/j.injury.2018.09.036