All posts by TheTraumaPro

Don’t Just Read The Abstract: CT Scanning The Unstable Patient

I’ve said it many times before: “don’t just read the abstract.” They can be misleading, and doing so makes it impossible to see the shortcomings of the research model and the veracity of the conclusions. Yet good trauma professionals do it all the time.

So I’ve selected a recent poster child to demonstrate this tenet. Let’s go over the study details:

This paper is a retrospective, registry review from Japan. The authors point out that one of the long-held rules is to avoid scanning unstable trauma patients in the “tunnel of death.” The authors cite a prior study that did not show an increase in mortality from this practice. So they decided to repeat/confirm it using 11 years of national registry data.

They included all patients who arrived at the trauma center with blood pressure < 90. Interestingly, they excluded patients in frank or near arrest. And finally, patients with critical data points missing were excluded. They used a regression method to control for covariates such as age, ISS, and vitals upon arrival.

Here are the factoids:

  • Out of nearly 200,000 patients, about 7,000 were initially eligible. About 1,000 were excluded by the criteria above or because they were treated at a low volume facility. Only 5,809 were included in the study and another 500 were excluded because of missing covariates.
  • The authors found that there were significantly fewer deaths in the group of unstable patients taken to CT (20 fewer per 100 patients) (!!!?)
  • However, when corrected for confounders, this significant difference went away completely
  • But the authors conclusion in the abstract was: “We suggest physicians should consider CT as one of the diagnostic options even when patients are unstable.”

Bottom line: What? The study went from showing that taking an unstable patient to CT was amazing for decreasing mortality, to no different after applying more statistical methods. And since there was no difference, why not just go?

Here’s why. In-hospital and 24 hour mortality are not good indicators of anything because there are so many patient and hospital factors involved. And because it was a registry study, there was no way of knowing if the patient was hypotensive at the time they were taken to CT. They could have had a low blood pressure and responded well to resuscitation. Or they could have been normotensive on arrival and became hypotensive before CT scan. There is no way to cleanly identify the correct study group without a prospective study, or a very painstaking retrospective one.

One of the most important aspects of this study is some background info that is not stated in the paper. Surgeon involvement in initial resuscitation in Japan is not nearly as integrated as it is in the US. So if the resuscitating physicians can’t do anything about the bleeding in the ED, why not just scan them while awaiting arrival of the surgeon? If the patient crashes, was it due to the scan, or a delay in getting to the OR?

So don’t just read the abstract. If it seems to be too good to be true, it is. Or at least self-serving. Read the nitty gritty details and decide for yourself!

Next week: more on unstable patients and the CT scanner

Reference: Computed tomography during initial management and mortality among hemodynamically unstable blunt trauma patients: a nationwide retrospective cohort study. Scand J Trauma 25(1):74, 2017.

The Pan-Scan For Trauma

Diagnostic imaging is a mainstay in diagnosing injuries in major trauma patients. But the big questions are, how much is enough and how much is too much? X-radiation is invisible but not innocuous. Trauma professionals tend to pay little attention to radiation that they can’t see in order to diagnose things they can’t otherwise see. And which may not even be there.

There are two major camps working in emergency departments: scan selectively vs scan everything. It all boils down to a balance between irradiating enough to be satisfied that nothing has been missed, and irradiating too much and causing harm later.

A very enlightening study was published last year from the group at the University of New South Wales. They prospectively looked at their experience while moving from selective scanning to pan-scanning.They studied over 600 patients in each cohort, looking at radiation exposure, missed injuries, and patient injury and discharge disposition variables.

Here are the factoids:

  • Absolute risk of receiving a higher radiation dose increased with pan-scanning from 12% to 20%. This translates to 1 extra person of every 13 evaluated receiving a higher dose.
  • The incidence of receiving >20 mSv radiation dose nearly doubled after pan-scanning. This is the threshold at which we believe that cancer risk changes from low (<1:1000) to moderate (>1:1000).
  • The risk of receiving >20 mSv was lower in less severely injured patients (sigh of relief)
  • There were 6 missed injuries with selective scanning and 4 with pan-scanning (not significant). All were relatively minor.

Bottom line: Granted, the study groups are relatively small, and the science behind radiation risk is not very exact. But this study is very provocative because it shows that radiation dose increases significantly when pan-scan is used, but there was no benefit in terms of decreased missed injury. If we look at the likelihood of being helped vs harmed, patients are 26 times more likely to be harmed in the long term as they are to be helped in the short term. The defensive medicine naysayers will always argue about “that one catastrophic case” that will be missed, but I’m concerned that we’re creating some problems for our patients in the distant future that we are not worrying enough about right now.

Related posts:

Reference: Comparison of radiation exposure of trauma patients from diagnostic radiology procedures before and after the introduction of a panscan protocol. Emerg Med Australasia 24(1):43-51, 2012.

Is Decompressive Craniectomy Any Better Than Craniotomy?

Severe TBI consists of a primary injury to the brain, followed by swelling, vascular, and ischemic problems which may cause a secondary injury. Much of the critical care management of this injury involves avoiding or ameliorating secondary injury. This is typically accomplished via medical means first, and through surgical procedures when medical management is insufficient.

Two types of surgical decompression are currently practiced: craniotomy and evacuation of blood/clot, and decompressive craniectomy with removal of a bone flap. The latter can be performed prophylactically before severe swelling occurs, or therapeutically as a damage control procedure when ICP is refractory to all other measures.

There has been a decades-old debate as to whether craniectomy, which is a major undertaking with months of skull/bone flap management, is actually worthwhile. Most studies have examined the utility of damage control craniectomy for refractory ICP. The results have not really been convincing one way or the other.

But what about prophylactic decompressive craniectomy (DC) to avoid future ICP problems while the patient is in the ICU? The surgical group at the University of Arizona at Tucson performed a five year retrospective review of their experience. Using propensity score matching, they identified 99 severe TBI patients who underwent DC (33) or craniotomy only (CO, 66). A power analysis showed that this sample size should be sufficient to demonstrate a significant difference.

Here are the factoids:

  • Both groups were similar with respect to age, GCS, ISS, AIS-head, and type of bleed
  • 26% died and 63% were discharged to rehab or skilled nursing facility
  • When comparing DC to CO groups, there were no differences in mortality, discharge to skilled nursing facility, discharge GCS or Glasgow Outcome Scale
  • There were more complications in the DC group, including shunt insertion for hydrocephalus (9% vs 0%), and reoperation (12% vs 2%)
  • Rates of wound infection and ventriculitis were the same for both groups (0-3%)

Bottom line: Although the study is small, it supposedly had enough patients for identification of significant differences. And basically, it didn’t show a positive difference for prophylactic decompressive craniectomy. There is certainly some opportunity for selection bias by the neurosurgeons that cannot be controlled for by this retrospective design. But it is yet another piece of the decompressive craniectomy puzzle. 

Overall, the literature support for either prophylactic or damage control craniectomy is not very strong. If it were, we would have identified some real benefits by now. What we don’t know is if there are specific subgroups of severe TBI patients who might benefit from it. So if your center is not involved in a project to study this, you should probably ask your neurosurgeons to base their practice only on what we know about this procedure to date. 

When Is It Not An “Unplanned ICU Admission?”

All US trauma centers verified by the American College of Surgeons (ACS) must now subscribe to the ACS Trauma Quality Improvement Program (TQIP). This program allows each center to benchmark themselves against other trauma centers that are just like them (level, volume, acuity, etc).  Every quarter, TQIP members receive a report that details their performance in a number of key categories. The report slices and dices a large number of data points, and shows how they compare to those other trauma centers.

One of the more interesting portions of the TQIP report deals with risk-adjusted complications. The one I wrote about yesterday, the “ICU bounce back,” is officially called an “unplanned ICU admission.”

I’ve had several trauma centers ask me what constitutes an unplanned ICU admission. Is it any bounce back? What about patients who were never in the ICU?

This questions is particularly important to me because my own center’s TQIP report shows that we have a significant number of unplanned ICU admissions. But I know for a fact that they are not surprises. We have an inpatient trauma unit, with capabilities somewhere between the usual ward bed and an ICU bed. Patients can get telemetry, continuous oximetry, vital signs every 2 hours, and more. It functions as a kind of step-down unit, so we frequently admit patients who may require ICU admission at other hospitals.

Every once in a while, a patient who is receiving care in the trauma unit shows signs that they are going to need a true ICU level of care. In that case, we promptly move them to the ICU before they decompensate any further.

Is that situation an “unplanned ICU admission?” In my opinion, no. The patient received the highest level of care while outside the ICU, and ultimately a considered decision was made to move them. In my mind, this is a “planned ICU admission.”

Bottom line: There are two issues at play if your “unplanned ICU admissions” get flagged on your TQIP report. The first is determining if it was truly unplanned. If the Rapid Response Team (RRT) was called, then it was almost certainly unplanned. But if the patient was being monitored properly, showed signs that they would need an ICU level of care, and was preemptively transferred there, it was not. Similarly, if one of your surgical specialists wants the patient transferred (e.g. MAP goals), then that is also a planned admission.

The second factor is figuring out why the admissions are getting reported to TQIP as unplanned. This is usually a trauma registrar issue. They may be looking for any ward to ICU transfer, and classifying it as unplanned. Educate all your registrars on the nuances of what is planned and what isn’t.

If you are on the receiving end of a TQIP variance on unplanned ICU admissions, use the drill-down tool to identify the exact patient records involved. Review the involved medical records, paying close attention to vital signs, monitoring, and all decision making leading up to the time of the ICU transfer. If it isn’t truly unplanned, educate your registrars. But if it is, make sure that it was properly dealt with by your trauma performance improvement program.

The ICU Bounce Back

We’ve all experienced it. A seriously injured trauma patient is admitted to the ICU and begins the process of recovery. Everything looks well, and after a few days they’re transferred to a ward bed. But then they languish, never really doing what we expect. Finally (and usually in the middle of the night), they begin to look bad enough where we have to transfer them back to the ICU. Before or after the call to the Rapid Response Team. Yes, it’s the feared “unexpected readmission to ICU.”

What’s the problem here? A failure of the ICU team? Did they send the patient out too soon? Did we all miss something about the patient? And is there any way we can avoid this problem? The major issue is that these “bounce backs” tend to do poorly compared to patients who successfully stay in their ward bed. Estimates are that mortality for patients successfully and finally discharged from the ICU range from 4-8%, whereas the mortality in bounce back patients is 20-40%!

Researchers at the Medical University of South Carolina in Charleston looked at the characteristics that defined the bounce back patient. They reviewed nearly 2000 patients discharged from their trauma ICU and analyzed the variables that predicted an unplanned bounce back. They noted the following interesting factoids:

  • More than two thirds of bounce backs occurred within 3 days
  • Males, patients with an initial GCS < 9, transfer during the day shift  were the major risk factors
  • More comorbidities was associated with a higher chance of bounce back
  • Mortality in the bounce back group was 20%
  • The most common immediate factors causing bounce back were respiratory failure or bleeding

Bottom line: This is an intriguing single-institution study that supports my own personal observations. Fewer bounce backs occur at night because staffing tends to be lower and there is more resistance to transfers out of the ICU then. Both the ICU team and the ward team need to scrutinize every transfer carefully. Significant head injury or the presence of medical comorbidities should trigger a careful assessment to make sure that the transfer is appropriate. Otherwise, your patient may be placed in unnecessary jeopardy.

Next, I’ll discuss when an unexpected return to ICU is not an unexpected return!

Reference: Intensive care unit bounce back in trauma patients: An analysis of unplanned returns to the intensive care unit. J Trauma 74(6):1528-1533, 2013.