Tag Archives: ct scan

The Role Of Postop CT Scan In Penetrating Trauma

CT scans are commonly used to aid the workup of patients with blunt trauma. They are occasionally useful in penetrating trauma, specifically when penetration into a body cavity is uncertain and the patient has no hard signs that would send him or her immediately to the operating room.

Is there any role in operative penetrating trauma, after the patient has already been to the OR? The dogma has always been that the eyeballs of the surgeon in the OR are better than any other imaging modality. Really? The surgical group at San Francisco General addressed this question by retrospectively reviewing 6 years of their operative penetrating injury registry data. They were interested in finding how many occult injuries (seen with CT but not by the surgeon) were found on a postop CT. A total of 225 patients who underwent operative management of penetrating abdomen or chest injury were included. Here are the factoids:

  • Only 110 patients had a postop CT scan; 73 had scans within the first 24 hours, the other 37 were scanned later
  • Rationale for early scan was to investigate retroperitoneal injury in half of patients, but frequently no indication was given (41%)
  • Rationale for late scan was for workup of ileus in one third, or for evaluation of new or unexpected clinical problems
  • Occult injuries were found in about half of early CT patients (52%), and 22% of late CT patients
  • The most common occult injuries were fractures, GU issues, regraded solid organ injury, and unrecognized vascular injuries
  • Ten patients had management changes, including:
    • Interventional radiology for four injuries with extravasation
    • Operation for orthopedic or GU injury in seven patients
    • One patient underwent surgery for an unstable spine fracture

Bottom line: There appears to be a significant benefit to sending some penetrating injury patients to CT in the early postop period. Specifically, those with injury to the retroperitoneum, deep into the liver, near the spine, or with multiple and complicated injuries would benefit. Simple stabs and gunshots that stay away from these areas/structures probably do not need followup imaging. 

Reference: Routine computed tomography after recent operative exploration for penetrating trauma: What injuries do we miss? J Trauma 83(4):575-578, 2017.

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 were usually about 850highest-level activations per year at the time, and traditionally the CT scanner had 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.

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

Arms Up or Arms Down In Torso CT Scans?

CT scan is a valuable tool for initial screening and diagnosis of trauma patients. However, more attention is being paid to radiation exposure and dosing. Besides selecting patients carefully and striving for ALARA radiation dosing (as low as reasonably achievable) by adjusting technique, what else can be done? Obviously, shielding parts of the body that do not need imaging is simple and effective. But what about simply changing body position?

One simple item to consider is arm positioning in torso scanning. There are no consistent recommendations for use in trauma scanning. Patients with arm and shoulder injuries generally keep the affected upper extremity at their side. Radiologists prefer to have the arms up if possible to reduce scatter and provide clearer imaging.

Radiation physics research has examined arm positioning and its effect on radiation dose. A retrospective review of 690 patients used dose information computed by the CT software and displayed on the console. Radiation exposure was estimated using this data and was stratified by arm positioning. Even though there are some issues with study design, the results were impressive.

The dose results were as follows:

  • Both arms up: 19.2 mSv (p<0.0000001)
  • Left arm up: 22.5 mSv
  • Right arm up: 23.5 mSv
  • Arms down: 24.7 mSv

Bottom line: Do everything you can to reduce radiation exposure:

  1. Be selective with your imaging. Do you really need it?
  2. Work with your radiologists and physicists to use techniques that reduce dose yet retain image quality
  3. Shield everything that’s not being imaged.
  4. Think hard about getting CT scans in children
  5. Raise both arms up during torso scanning unless injuries preclude it.

Reference: Influence of arm positioning on radiation dose for whole body computed tomography in trauma patients. J Trauma 70(4):900-905, 2011.

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.