Tag Archives: ct scan

Imaging, Resuscitation

ACS Trauma Abstract #6: Scanning Unstable Trauma Patients???

Leave a comment

If you’ve read my stuff for very long, you know I frown on sending unstable patients anywhere but to the OR. Instability tends to get worse, and that always happens at inopportune locations like hallways, elevators, and CT scanners. Imagine my surprise when I noticed an abstract being presented at the Clinical Congress of the American College of Surgeons this week suggesting that it was okay to scan hemodynamically unstable patients before “definitive therapy.”

Here’s the title:

“Computed tomography in hemodynamically abnormal thoracoabdominal trauma safely enhances surgical triage”

The devil is in the details and the language. This group from USC included all patients who were hemodynamically abnormal on arrival to the trauma bay but who normalized to SBP > 90 during the resuscitation were included.  A total of 253 of these patients were reviewed over a 9 year period, and the usual variables were analyzed (mortality, complications, hospital, ICU, and vent days, etc).

Here are the factoids:

  • Of the 253 patients studied, 45 went to straight to OR and 208 were taken to CT
  • Injury severity was identical for the two groups
  • Lengths of stay and mortality were not different, but only p values were given
  • Patients taken to CT cleared their lactic acidosis faster (12 vs 5 hours), and used a bit less plasma and significantly less blood transfusions
  • The OR group underwent more procedures (31% vs 13%), although what these were and when they were performed is not listed

Bottom line: The title of this abstract is misleading, and may fool those who don’t read the rest of the abstract. It should read:

“Computed tomography in previously hemodynamically abnormal thoracoabdominal trauma safely enhances surgical triage”

Someone who just skims through this issue of the journal may get the idea that it’s okay to scan an unstable patient. The authors are not saying this at all. If you read the conclusion carefully, you can see that the patients had to be resuscitated to a SBP > 90 before they considered taking to scan. And they did that for the majority of these patients.

The real question is, why do the scanned patients clear their lactic acidosis faster, need less blood, and undergo fewer procedures? It appears that there is some bias or selection process in play. Otherwise, why not use the magic CT scanner to make them all better?

Reference: Computed tomography in hemodynamically abnormal thoracoabdominal trauma safely enhances surgical triage. JACS 225(4S2):e175-176, 2017.

Imaging

ACS Trauma Abstracts #5: Pan-scan vs Selective CT For Pediatric Patients

Leave a comment

In major adult blunt trauma, there are still two factions: those who pan-scan for diagnosis, and those who use CT selectively. The pan-scan proponents argue that they find everything, including things that would have been missed with selective scanning. The selective scanners argue that those things are typically not clinically significant, and radiation exposure is reduced.

Who is right? We’re still not sure. But when it comes to children, most believe that less radiation is always better. The group at USC decided to look at their experience with pan-scan vs selective imaging in blunt pediatric trauma patients, defined as those < 16 years of age. They reviewed their experience over a three year period, excluding those who had low blood pressure (<90). A total of 648 children met these criteria, and an array of variables were analyzed to try to determine “superiority.”

Here are the factoids:

  • 88% of these patients had low injury severity (ISS < 15), 567 patients
  • The low severity group who were selectively scanned had a half-day decrease in length of stay*, a quarter-day decrease in ventilator days, lower morbidity (15% vs 24%)*, and radiation exposure (8 vs 18 mSv)*, with the asterisked variables being “statistically significant”
  • The high severity also showed positive differences in decreased ICU length of stay, ventilator days, morbidity*, and radiation exposure*
  • For both pan- and selective-scanning, additional imaging led to no additional interventions in 95% of cases

Bottom line: Ugh! This is not a good abstract. It shows association, but not causation with anything but the radiation exposure calculations. Yes, if you scan less in the selective arm, there better be less exposure. But the other variables are either not clinically significant, or not defined well (i.e. morbidity).

The authors conclude that selective scanning is the way to go based on this (extremely weak) data. This is why I always recommend that you read the whole paper, not just the abstract, or in this case the whole abstract and not just the conclusion. The data, as presented in this abstract, do not support this at all.

The authors don’t say how many of these patients were very young, and how many of them actually received pan-scans. But any pediatric trauma surgeon would cringe if they read this  article. Although you may be a big believer in pan-scanning, reserve it for adults only until we have some better data. Don’t irradiate kids unnecessarily!

Reference: Selective CT imaging is superior to liberal CT imaging in the hemodynamically normal pediatric blunt trauma patient. JACS 225(4S1):562, 2017.

Imaging

When Can You Take A Hypotensive Patient To CT?

Leave a comment

The last two posts, I went on a rant about taking hypotensive patients to CT. The bottom line is that this is a generally bad idea, even if bad papers say it’s okay. However, we all know that there are no absolutes, especially in trauma.

So yes, there are two cases where one could justify taking a hypotensive patient to CT scan. Here they are:

  1. You believe that your patient has a catastrophic brain injury which is responsible for the hypotension. You would like CT confirmation so you can begin to withdraw support and terminate any other interventions.
  2. Your patient has sustained a cervical spinal cord injury and has neurogenic shock. You have started fluid resuscitation and are considering a pressor to normalize blood pressure, but would like to continue your diagnostic routine.

But before you can even consider leaving your resuscitation room, you must ensure that there is no other source of hypotension. This means getting chest and pelvic xrays to look for hemothorax or fractures. It means getting a good FAST exam to make sure there is no significant hemoperitoneum. It also means making sure that any fractures are properly splinted and there is no uncontrolled external bleeding.

You can only go to CT scan once all of these other potential bleeding sources have been ruled out. If in doubt, you must proceed to OR to either stop the bleeding or prove that it does not exist.

Are there any other reasons to take one of these patients to CT that you can think of? If so, leave comments or tweet!

Related post:

Imaging

Can I Take A Hypotensive Patient to CT? Part 2

2 Comments

In my last post, I commented on a paper that tried to claim that there is no reason not to take a patient to CT if they are hypotensive. It had issues, as you saw. Today, I want to share another paper from a few years ago that tried to do the same. Again, read the abstract!

I’ve said it before: hypotension and CT scanners don’t play together well. For years I’ve cautioned against this, having seen a number of patients crash and burn in this area early in my career. But it’s a common error, and may jeopardize your patient’s safety. A paper that is now in press looked at this practice in a trauma hospital in Taiwan.

Patients who had blunt abdominal trauma were retrospectively reviewed. Those who remained hypotensive (SBP<90) after 2L of crystalloid were scruitnized. The CT scanner was described as being located in the same area as the ED resuscitation rooms. Furthermore, several physicians and nurses were present during scans, and a full selection of resuscitation equipment was available in the scan area.

Here are the factoids:

  • 909 patients were entered into the study
  • Only 91 patients remained hypotensive after initial resuscitation, and only 58 of these were scanned before definitive management
  • As expected, patients who were hypotensive after initial resuscitation had more serious injuries (ISS 22 vs 12), required more blood transfusions (938 vs 202 cc), and had a higher mortality (10% vs 1%).
  • There were no significant differences in comparing hypotensive patients who went to CT scan vs those who did not if they underwent some sort of hemostatic procedure (laparotomy, angioembolization)
  • In the hypotensive patients, time to OR in the CT scan group was 58 minutes vs 62 minutes for those who skipped the scan.
  • In the same patients, time to angio in the CT scan group was 147 minutes vs 140 minutes without a scan first.

The authors conclude that “hypotension does not always make performing a CT scan unfeasible.” (weak!)

Read this paper closely and don’t get fooled! It is very retrospective and very small. And if you look at the times carefully, you will see some funny business. How can time to OR or angio be virtually identical regardless of whether CT is used? Is it the world’s closest, fastest scanner? Probably not.

The authors showed that hypotensive patients have a ten-fold increase in mortality. They also recognized that definitive control of hemorrhage is the key to saving the patients. Unfortunately, there are factors in this retrospective study, such as various biases and some undocumented factors that make their two patient groups look artificially alike. This gives the appearance that the CT scan makes no difference.

In reality, the fact that there is no difference in times ensures that there is no clinical difference in outcome. To really answer this question, this kind of study must be done prospectively, and must have an adequate population size.

Bottom line: Don’t even consider going to CT with hypotensive patients. Even if you have the fastest, closest scanner in the world. Shock time still kills, and most CT scan rooms are very poor resuscitation rooms. If your patient is unstable in the ED, do your ABCs, get a quick exam, then transport to the area where you can get control of the bleeding. This will nearly always be your OR.

Reference: Hypotension does not always make computed tomography scans unfeasible in the management of blunt trauma patients. Injury, 46(1):29-34, 2015.

Philosophy, Resuscitation

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

Leave a comment

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.