In The Next Trauma MedEd Newsletter: Some Potpourri!

Finally! It’s been a while, and now it’s time to put pen to paper once again. Fingers to keyboard? Whatever!

The April issue of Trauma MedEd will be sent out to subscribers on Friday, and will provide some random interesting topics.

This issue is being released to subscribers at 9am Central time on Friday. If you sign up any time before then, you will receive it, too. Otherwise, you’ll have to wait until it goes out to the general public at the end of next week. Click this link right away to sign up now and/or download back issues.

In this issue, learn about:

  • Who’s Better At Invasive Procedures? Advanced care providers or residents?
  • How Many Salt Tabs In A Liter Of Saline?
  • Mainstem Intubation In Pediatric Patients
  •    And How To Avoid It!
  • Giving TXA Via An Intraosseous Line?

As always, this month’s issue will go to all of my subscribers first. If you are not yet one of them, click this link right away to sign up now and/or download back issues.

Detecting Rib Fractures In The Elderly

It’s well known that our elders do less well than younger folks after injury. The number of complications is higher, there tends to be more loss of independence during recovery, and mortality is increased. This is not only true of high energy trauma like car crashes, but also much lower energy events such as a fall from standing.

Rib fractures are common after falls in the elderly and contribute to significant morbidity if not treated adequately. Traditionally, they are identified through a combination of physical exam and chest x-ray. Unfortunately, only half of rib fractures are visible on x-ray. It falls to the physical exam to detect the rest.

A group at Beth Israel Hospital in Boston explored the utility of using chest CT in an attempt to determine if this would result in more appropriate and cost-efficient care in the elderly. They performed a retrospective study of 3 years of their own data on patients aged 65 or more presenting after a mechanical fall and receiving a rib fracture diagnosis. Imaging was ordered at the discretion of the physician. A total of 330 patients were elderly, fell, and had both chest x-ray and chest CT obtained. This was a very elderly group, with a mean age of 84 years!

Here are the factoids:

  • Rib fractures were seen on chest x-ray in 40 patients (12%) and on CT in an additional 56 ; 234 patients had no fractures on either
  • When fractures were seen on both studies, CT identified a median of 2 more fractures than chest x-ray
  • Patients with fractures not seen on chest x-ray were admitted significantly more often than those without fractures (91% vs 78%)
  • Mortality, admission to ICU, ICU length of stay, and hospital length of stay were not different if fractures were seen only on CT
  • CT scan identified new issues or clarified diagnoses suggested by chest x-ray in 14 cases, including one malignancy
  • Rib detail images were obtained in 13 patients and proved to be better than chest x-ray, but not quite as good as CT scan

Conclusion: use of CT for rib fracture diagnosis resulted in a few more admissions, but no change in hospital resource utilization, complications, or mortality.

Bottom line: Hmm…, read the paper closely. The authors conclude that more patients with CT-only identified rib fractures are admitted. But compared to what? Unfortunately, patients without rib fractures on CT. What about comparing to patients who had fractures seen on chest x-ray too? If that number is the same, then of what additional use is CT? Identifying a few incidentalomas?

Given that there is no change in the usual outcome measures listed here, it doesn’t seem like there is any additional benefit to adding CT. And I can see a lot of downsides: cost, radiation, and possible exposure to IV contrast. In my mind, there is still nothing that beats a good physical exam and a chest x-ray. Skip the CT scan. And don’t even think about ordering rib detail images! That’s so 1990s. And even if no rib fractures are seen on imaging, physical exam is the prime determinant for admitting your patient for aggressive pain management and pulmonary toilet.

Reference: Chest CT imaging utility for radiographically occult rib fractures in elderly fall-injured patients. J Trauma 86(5):838-843, 2019.

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.

Antihypertensive Treatment In Acute TBI

Yes, we know high blood pressure can be bad. Over the long term, it can accelerate atherosclerotic heart disease and pound away at the kidneys and brain. And when it is acutely elevated to critical levels, it can lead to stroke.

But is it always bad in trauma? Trauma hurts like hell, so it’s no wonder than many of our patients (not suffering blood loss of course) are hypertensive.  But how often have you seen this scenario occur:

An elderly patient fell from standing, striking her head. She is brought to your ED by ground EMS. She has a GCS of 8 (E1 V3 M4) with a BP of 200/130 and pulse of 56.  This meets your trauma activation criteria and the team assembles to meet the patient.

As you move her onto the bed, one of your colleagues calls out for some nicardipine to control the pressure. Is this a wise move? Remember the First Law of Trauma:

Any anomaly in your trauma patient is due to trauma, no matter how unlikely it may seem.

What else can cause hypertension and bradycardia in your trauma patient? In this case, certainly a subdural or epidural hematoma.

And why is that happening? Because the intracranial pressure is elevated from the space-occupying lesion. Remember the formula for cerebral perfusion pressure (CPP):

CPP = MAP – ICP

Where MAP = mean arterial pressure and ICP = intracranial pressure.  Normally the MAP is around 90 torr and ICP is about 10 torr. Thus, the normal CPP is approximately 80. The range is 60  to well over 100 torr, and flow autoregulation keeps brain perfusion constant over this range.

But let’s say that we are psychic and know the ICP of our patient to be 60 because of a large subdural hematoma. Her current CPP is 150 – 60 or about 90 torr. What happens if we start her on a nicardipine drip or some other antihypertensive medication? We can certainly normalize the blood pressure to 120/80. But now her CPP drops to 90  – 60 = 30 torr!

Congratulations, you have just shut down circulation to her brain!

Bottom line: Think first before calling for antihypertensive medications in patients who may have increased intracranial pressure. You may be sabotaging the only mechanism protecting their brain while you are calling your neurosurgeon for help. Your top priority is to get them to the CT scanner while permitting that pressure. If it turns out that there is no evidence for pathology that would lead to increased ICP, then turn to the antihypertensive agents to help protect against stroke. 

Using Chest CT To Detect Occult Injuries

There are major belief systems when it comes to the use of trauma CT: selective scan vs pan scan. The selective scanners believe that too much radiation can be bad, and that the risk of excess exposure outweighs the value of scanning everything. The pan scanners believe that valuable information might be missed unless they routinely image everything.

Who is right? There’s probably value in each side of the argument. But do we have data? Good data? Two emergency medicine groups from UC-Irvine and UC-San Diego tried to answer this question via a prospective study involving 10 Level I trauma center EDs in California.  They tagged onto data collection underway for the NEXUS chest and chest CT studies from 2009-2012.

Patients with fresh (< 24 hours) blunt trauma who underwent chest imaging in the ED were included. Patients needed to have both CT scan and chest x-ray within 24 hours, at the discretion of the emergency physician. Weirdly, they skewed their sample by enrolling patients from 7am to 11pm daily due to availability of research personnel.

The researchers were looking for minor and major interventions necessitated by data discovered on the CT scan. Occult injuries were defined as clinically important if an intervention occurred because of it. Major interventions included surgery, mechanical ventilation for pulmonary contusion, or chest tube for hemo- and pneumothoraces.

Here are the factoids:

  • Nearly six thousand patients were enrolled, and 2,048 had at least one injury identified on either study
  • A total of 1,454 of these injuries (71% of injuries, but only 25% of patients) were occult, only being seen on the CT scan
  • Chest x-ray found all injuries in only 29% of patients (not surprising)
  • When pulmonary contusion was seen by CT only, 6% were placed on ventilators; when hemo- or pneumothorax were seen, 41% and 29% respectively had chest tubes inserted (wow!)
  • The authors tallied 241 major interventions for occult injury in 202 patients, 154 chest tubes for hemo/pneumothorax and/or mechanical ventilation, 9 operations for diaphragm or aortic injury, and the remainder appear to be for other chest wall fractures

The authors concluded that occult injuries were found in 71% of their patients, with the majority of those “requiring” chest tubes. They recognized some of the shortcomings in their study and stopped short of recommending a pan-scan type approach to major chest trauma.

Bottom line: This argument always boils down to diagnostic yield vs money vs radiation. Radiologists like to find as many things as they can, so CT is great. For me, it always comes back to that old saying: “if a tree falls in the woods when no one is around, does it make a sound?” 

The corollary is “if a diagnosis is found on CT that is not clinically relevant, do we care?” But wait, you say, they did have to intervene. Or did they?

Have you ever scanned a chest and seen something that makes you intubate the patient immediately and put them on a ventilator? Probably not. It’s a clinical judgement. The scan may make you a bit more wary, but you will still wait for some clinical signs that the patient needs that extra help. 

And what about chest tube insertion? I’m sure most of you have seen a modest pneumothorax on chest x-ray (1 cm away from the chest wall, extending to the 6th intercostal space, say). Ho hum. And then you get a CT scan and your eyes widen. It always looks much larger on the scan. It always does. Yet the patient is still lying there comfortably, with normal oxygen saturations. Do you really need to put a tube in? For decades, we used only the x-ray, and patients did fine.

So I don’t buy that the CT result made them do the interventions. It was the clinician’s choice based on how they interpreted the scan, not the patient’s clinical condition. Without specific guidelines that determine when interventions are indicated, it just boils down to “I do an intervention when I think the patient needs it.” And every clinician will have their own criteria and thresholds. It’s tough to learn from things done this way.

So I stick by my guns. We know that chest x-ray is flawed. But it does provide good clinical data even without a bunch of diagnostic minutiae. A good practice guideline that helps select the patients most likely to benefit from a CT scan is paramount.

As you can probably tell, I’m a selective scan kind of guy and still have not run across a study that is clean and compelling enough to make me change. And I think I’ll be waiting for a while for one of those to pop up!

Reference: Prevalence and clinical import of thoracic injury identified by chest computed tomography but not chest radiography in blunt trauma: multicenter prospective cohort study. Ann Emerg Med 66(6):589-600, 2015.