All posts by TheTraumaPro

Best of AAST #5: Pneumothorax – How Big Is Too Big?

Deciding when to place a chest tube can be challenging. Sometimes, it’s obvious: there is a large hemo- or pneumothorax staring you in the face on the chest x-ray. But sometimes, it’s there but “not that big.” The real question is, how big is too big.

That’s a question that’s been very difficult to quantify. The authors of this abstract, from the Medical College of Wisconsin, conducted a six-year retrospective review of every patient with an isolated pneumothorax at their Level I trauma center. Based on their previous research, a 35mm threshold was used to stratify patients into two groups. This measurement was obtained from axial images of a CT scan. Statistical analysis was performed to identify the predictive value in determining whether the patient could be managed without a chest tube.

Here are the factoids:

  • A total of 1767 patients had a pneumothorax during the 6-year period, and about half met inclusion criteria for the study
  • Of the 385 with pneumothorax alone, 92% were managed without a chest tube
  • Of those 353, 95% had a maximum chest wall to lung distance (335)
  • The 35mm measurement was statistically shown to be an independent predictor of successful management without a tube for both blunt and penetrating trauma

Bottom line: Not so fast! Although this looks like a slam dunk abstract, it’s really not. First, many (or most?) pneumothoraces are initially diagnosed using a plain old chest x-ray. A 35mm measurement is meaningless here because there can be significant changes in position of the pneumothorax on the image. Sometimes, the air is located anteriorly with little or no lateral component.  Does this mean we should CT every patient with a known or suspected pneumothorax? I think not.

And the second issue is the subjectivity surrounding the definition of a failure. What criteria were used when the tube was actually placed in this series. If every patient had to become symptomatic first, then I might agree. But I suspect the tubes were placed when followup imaging showed that the air was just “too big.” You can’t statistic away this kind of potential bias from subjectivity.

So what’s the answer? Unfortunately, there still isn’t one. The need for a chest tube must still be based on subjective size on a chest x-ray, physiologic status, and the patient’s ability to tolerate a given amount of lost lung function. It continues to boil down to the  assessments of each trauma professional as to “how big is too big.”

Reference: Observing pneumothoraces: the 35mm rule is safe for both blunt and penetrating chest trauma. Session XVA Paper 28, AAST 2018.

Best of AAST #4: Better Triage For Scene Helicopter Transport

There has been tremendous debate around the value and use of prehospital helicopter emergency medical services (HEMS). It’s fast, but also expensive, and there is always a small amount of added risk to patients during transport. Over the years, there has been a significant increase in the number of helicopter services, and in some cases it seems like several services are dashing to accident scenes in the hope that they can pick up the patient.

Overuse of HEMS has also been recognized, with some patients transported who could have just as easily and safely been moved by ground ambulance. This is a particularly vexing problem with pediatric patients.

The holy grail of trauma HEMS has been to find some easy to identify scene variables that reliably predict which patients should be transported by air. A group in North Carolina tapped the state trauma registry to attempt to develop such a system. They analyzed data in the registry over a three year period, mathematically analyzing for easily identified predictors of ED death or need for operating room, interventional radiology, or ICU admission.

Here are the factoids:

  • The percentage of flights from the scene increased from 7% to 9% compared to data from fifteen years prior to this study
  • Vital signs (SBP, pulse, GCS motor) had the best correlation with mortality, and these were used to develop a regression model for triage
  • Patients with normal SBP, pulse, and GCS motor of 6 were found to safely transported by ground EMS, with similarly low mortality for ground or air
  • During the study period, triaging patients that met these criteria would have saved the state system about $19 million

Bottom line: Every state should take a look at their guidelines for helicopter vs ground transport for scene runs. This is an expensive tool, and should be treated with respect. Just because a helicopter is available does not mean it should be used. The commander on the scene must make the proper decision based on variables like these, but also apply their knowledge of traffic patterns, time and distance from the most appropriate receiving trauma center.

Reference: Trauma system resource preservation: a simple scene triage tool can reduce helicopter emergency medical services (HEMS) over-utilization in a state trauma system. Session IV Paper 13, AAST 2018.

Best of AAST #3: Level I vs Level II Trauma Centers

There is an ongoing debate over the differences between Level I vs Level II trauma centers in the US. On paper, the major differences include resident rotations in trauma, research, and the available of certain specialty surgeons and services. There have been several papers that look at survival differences between the two levels.

One podium paper at AAST 2018 re-examines this debate. It is a medium-sized pooled series that looks at a particular type of injury, pelvic ring fractures. These injuries can be complex, and many times require specialized orthopedic expertise. ACS Level I centers are required to have at least one Orthopedic Trauma Association fellowship-trained surgeon among their orthopedists. This is not required for Level II centers, but many do have them.

The group at the University of Michigan examined patients with partially stable or unstable pelvic ring injuries in a trauma collaborative database including 29 Level I and Level II centers over a 7-year period. They used propensity matching to compare 610 patients admitted to Level I and 610 patients admitted to Level II centers with these injuries:

Here are the factoids:

  • Mortality was significantly increased at Level II centers ( 12%) vs Level I centers (8%)
  • Angiography was used significantly less at Level II centers (6% vs 11%)
  • Complex repairs were used significantly less frequently at Level II centers (32% vs 42%)
  • Patients were significantly less likely to be admitted to an ICU at Level II centers, and were more often admitted to stepdown units (45% vs 52%)
  • Failure to rescue rate was lower (better) in ICU patients

Bottom line: Obviously, there are some limitations to using this pooled data, but it does provide larger numbers than many similar papers have. It cannot distinguish Level II centers that have OTA-trained orthopedic surgeons from those that do not. But the results are rather striking. It’s not clear exactly which of the institutional differences might be responsible for the improved mortality, and they all probably contribute to some degree. But the abstract appears to show that Level II centers are not just non-academic Level Is. This work suggests that certain injury patterns really should be transferred to a center with the specialized resources to treat it well.

Best of AAST #2: Cervical Spine Clearance And Distracting Injuries

Debate has forever swirled around how to clear the cervical spine. Clear clinically? CT scan plus exam? CT only? Flexion/extension views? Distracting injury?

This last one has been problematic for a long time. What is a distracting injury? Is there a difference between lower extremity wounds vs upper chest/shoulder wounds from a distraction standpoint? Is it possible to clinically clear the cervical spine if one of these injuries exist?

Finally, a multi-institutional trial was performed that strives to answer this question. Seven Level I US trauma centers participated in this 3.5 year long study. All patients with GCS > 14 underwent a standard clinical exam regardless of whether a possible distracting injury was present. Then all underwent CT evaluation of the entire cervical spine.

Here are the factoids:

  • Distracting injuries were classified into three regions: head, torso, and extremities, but no further analysis was presented in the abstract
  • Nearly 3,000 patients were enrolled and 70% had a potential distracting injury
  • A total of 233 patients (8%) had a cervical spine injury identified by CT
  • 136 patients had a cervical injury AND distracting injury, and 14 were missed by clinical exam (10%)
  • 87 patients had a cervical injury BUT NO distracting injury, and 10 were missed by clinical exam (13%)
  • Only one injury missed by clinical exam required operation

Bottom line: This study shows the usual prevalence of cervical spine injury after blunt trauma, but adds some interesting information regarding distracting injury. Basically, clinical examination will miss about 1% of patients with a negative exam, regardless of distracting injury status. Therefore, the study suggests that clinical clearance should be attempted on all patients first, regardless of “distracting injury.”

Reference: Clearing the cervical spine for patients with distracting injuries: an AAST multi-institutional trial. Session I Paper 3, AAST 2018.

Best of AAST #1: The Price of Being a Trauma Center

The annual meeting of the American Association for the Surgery of Trauma (AAST) begins in two weeks. Today, I will kick off a series of commentaries on many of the abstracts being presented at the meeting. All readers should be aware that I have only the abstracts to work with. As I always caution, final judgement cannot be passed until the full paper has been reviewed. And many of these will not make the jump to light speed and ever get published. So take them with a grain of salt. They may point to some promising developments, but then, maybe not.

First up is a nice analysis on the price of being a trauma center. One of my mentors, Bill Schwab, always used to say that trauma centers are always in a state of “high-tech waiting.” It costs money to keep surgeons in house, other medical and surgical specialists at the ready, and an array of services and equipment available at all hours. Any hospital administrator can tell you that trauma is expensive. But how expensive, exactly?

The trauma group at the Medical Center of Central Georgia in Macon did a detailed analysis of the cost of readiness for trauma centers in the year 2016. The Georgia State Trauma Commission, trauma medical directors, trauma program managers, and financial officers from the Level I and II centers in Georgia determined the various categories and reported their actual costs for each. An independent auditor reviewed the data to ensure reporting consistency. Significant variances were analyzed to ensure accurate information.

Here are the factoids:

  • Costs were lumped into four major categories:  administrative, clinical medical staff, in-house OR, and education/outreach
  • Clinical medical staff was the most expensive component, representing 55% of costs at Level I centers and 65% at Level II
  • Only about $110,000 was spent annually on outreach and education at both Level I and II centers, representing a relative lack of resources for this component.
  • Total cost of being a Level I center is about $10 million per year, and $5 million per year for Level II

Here is a copy of the table with the detailed breakdown of each component:

Bottom line: Yes, it’s expensive to be a trauma center. It’s a good idea for any trauma center wannabe to perform a detailed  analysis to make sure that it makes sense financially. This is most important in areas where there are plenty of trauma centers already.  Tools have been developed to determine how many trauma centers will fit within a given geographic area (see below). Unfortunately, very few if any states use this tool to determine how many centers are reasonable. In come cities, it’s almost like the wild west, with centers popping up at random all over the place. This abstract suggests that an additional analysis is mandatory before taking the plunge into this expensive business.

Related post:

Reference: How much green does it take to be orange? Determining cost associated with trauma center readiness. Podium abstract #18, session VIII, AAST 2018.