Trauma – Page 8 – Emergency Medicine Literature of Note

It’s Ultrasound Fightin’ Time

Trauma showdown: pneumothorax. Chest x-ray or ultrasound?

The answer on the surface is pretty clear – unless you delve a little deeper into the precise question asked.

This meta-analysis of head-to-head ultrasound vs. CXR studies for the diagnosis of pneumothorax shows what we all essentially expect: the sensitivity of ultrasound is greatly superior, while specificity is statistically similar. Sensitivities for ultrasound were better for trauma, using the linear (high frequency) probe, and when performed by Emergency Physicians, and ranged from 73% to 85%. CXR sensitivities ranged from 32.6% to 49%, with heterogeneity based on study enrollment methods. Specificities for each were ~99%.

What the study does not address – are these pneumothoracies clinically meaningful? Ultrasound certainly finds more disease, but the newly identified disease will all be closer to the benign end of the spectrum. I guarantee there are patients out there with normal CXR in the setting trauma, who then receive an ultrasound positive for pneumothorax, and are then referred to CT scan and surgical evaluation – would have ultimately been fine. Before we move along to detecting more “disease”, we ought to examine the downstream consequences of missing or detecting these small pneumothoracies.

“Pleural ultrasonography versus chest radiography for the diagnosis of pneumothorax: review of the literature and meta-analysis”
ccforum.com/content/17/5/R208‎

Unicycles, Not All Fun And Games?

Finally a study on Unicycles! According to Dr. Marvin Wang, the author of the recently published article “Unicycle Injuries In the United States”, his chart review of the National Electronic Injury Surveillance System (NEISS) is the entirety of the world’s literature on unicycle injuries. To my utter disappointment there were zero cases of falls from a tight rope or burns from a mishandled flaming juggling pin. Even the author himself observes that unicycles, once exclusively ridden by professional “circus folk” and acrobats, have now become primarily an amateur endeavor.

Ironically the same inherent mechanics and “sense of danger” that made the unicycle a popular circus act, makes it far safer than its two-wheeled cousin when used by the general public. Because of its single wheel, riders are far less capable of attaining high speeds and it is therefore infrequently used as a functional means of transportation. Given this lack of functional utility, riders of unicycles seem to have escaped the more serious types of cycle accidents such as high-speed crashes and collisions with motor vehicles. Upon review of the 85 cases of documented unicycle injuries found in the NEISS database from 1991 to 2010, the author extrapolates that 168 people a year visit the emergency department for unicycle related injuries in the United States. The most common injuries acquired were extremity fractures, sprains and strains. Very few head and neck injuries occurred, and the majority of these were scraps and abrasions.

The biggest weakness of this study is that we are unable to determine a denominator. Since we do not know what percentage of the US population at any time are riding unicycles, we are unable to quantify the risk of riding such a contraption. It may be that only a small percentage of riders will sustain an injury that requires an ED visit. Conversely it is possible that the risk is much higher. If you do decide to mount one of these single wheeled cycles you may be taking your life, or at least your limb into your own hands…

“Unicycle Injuries In the United States”
www.ncbi.nlm.nih.gov/pubmed/23871477

For more nihilism, emergency medicine and the art of doing nothing see emnerd.com and @CaptainBasilEM

Unicycles, Not All Fun And Games?

“Unicycle Injuries In the United States”
www.ncbi.nlm.nih.gov/pubmed/23871477

For more nihilism, emergency medicine and the art of doing nothing see emnerd.com and @CaptainBasilEM

The Trauma Log Roll is Dead

Among unproven interventions, back-boarding, cervical collars, and log-rolling have been part of the dogma of trauma since Alfred Nobel invented the electric slide. We’ve finally started to put an end to uncomfortable and unwarranted back-boarding, we’ve re-designed cervical collars, and this article takes on log-rolling. The assertion of these authors is clinical examination of an otherwise alert major trauma patient is unreliable, does not obviate imaging, and may thereby be omitted from the initial secondary survey.

Unfortunately, this is a very specific, limited, retrospective registry review. Only patients from the trauma registry at the Alfred Hospital were included: major trauma (ISS >15) and admitted for 24 hours, or isolated thoracolumbar injuries requiring 72 hours of hospitalization. This identified 1,161 patients with thoracolumbar fractures, and these authors further pared it down to 538 who were GCS >15 as their proxy for potentially reliable examination. How many of these alert, appropriate trauma patients with thoracolumbar fractures complained of pain on log-roll and spinal palpation?

60.3%.

So, yes, if the clinical examination is only 60.3% sensitive for significant thoracolumbar fractures, then we ought to stop bothering to log-roll our patients. But, generalizing the evidence from this retrospective review in a highly selected population is grossly irresponsible. It is reasonable, as the accompanying letter states, if the decision has already been made in a major trauma to progress to full-body computed tomography – a test more sensitive and specific for spinal fractures than clinical examination – log-roll and complete physical examination may be deferred. The theoretical risks to log-roll – lack of true thoracolumbar stability, possibility of disturbing internal hemostasis – if there is no benefit, are appropriate considerations if physical examination does not change clinical evaluation. It is, however, excessive to universally posit, as the letter authors do, “Log-rolling a blunt major trauma patient is inappropriate in the primary survey.”

“Can initial clinical assessment exclude thoracolumbar vertebral injury?”
www.ncbi.nlm.nih.gov/pubmed/22915226‎

“Log-rolling a blunt major trauma patient is inappropriate in the primary survey”
www.ncbi.nlm.nih.gov/pubmed/24136122‎

Watch & Wait For Stab Wounds

Thankfully, very few of us actually deal with these sorts of injuries on a regular basis – and even fewer of us are actually responsible for managing these injuries.

However, this is an important article out of USC pushing back against the trend towards utilizing CT for every traumatic injury possible. There certainly seems, universally in medicine, to be a regression in reliance on the clinical examination along with a corresponding increased use of technology. There are many reasons this occurs – convenience, patient satisfaction, and “zero-miss” mentality – and we’re just now fully accounting for the tremendous costs associated with this flawed evolution in practice.

In this study, all diagnostically equivocal abdominal stab wounds underwent a structured protocol including CT and observation. Over a two-year period, 177 stable patients qualified for this protocol. Overall, 87% were managed non-operatively – but, most importantly, clinical deterioration directed all necessary operative interventions, rather than CT findings. Of the 23 patients who underwent operative intervention, 4 patients underwent operative intervention based solely on CT findings – and all four detected no injury during exploration. The final test characteristics for CT were sensitivity of 31.3% and specificity of 84.2%.

I think these authors are entirely appropriate in describing the use of CT in abdominal stab wounds as inferior to clinical observation. They don’t specifically emphasize the false positives from CT in their discussion, but these findings lead to real patient harms – even just in their small cohort. One of the four CT-directed interventions underwent negative pericardial window for suspected hemopericardium – and suffered a peri-operative cardiac arrest due to complications from anesthesia.

Let’s try to avoid that.

“Prospective Evaluation of the Role of Computed Tomography in the Assessment of Abdominal Stab Wounds”
http://www.ncbi.nlm.nih.gov/pubmed/23824102

“Distracting”, But Not Distracting

Cervical spine clearance is always a fun topic. Once upon a time, it was plain radiography, clinical re-assessment, and functional testing with dynamic radiography. Now, a zero miss culture has turned us mostly to CT – and, beyond that, even some advocate for MRI.

But, as far as clinical clearance of the cervical spine goes, we usually use the NEXUS criteria or the Canadian C-Spine criteria. One of the elements of the NEXUS criteria that is, essentially, subjectively defined is the presence of “distracting injury”. Many have questioned the inclusion of this element.

These authors looked at cervical spine clearance in the presence of “distracting injury”, which, for the purpose of research protocols, was essentially a fracture somewhere, an intracranial injury, or an intra-abdominal organ injury. They found, when assessing a GCS 14 or 15 trauma patient, even in the presence of these other injuries, clinical examination picked up 85 of 86 cervical spine injuries. One patient did not report midline cervical spine tenderness – with humerus and mandible fractures, as well as frontal ICH – and had a 2nd vertebrae lateral mass fracture.

So, clinical examination is mostly reliable in the presence of a “distracting injury”. I think the best interpretation of this study is “distracting injury” has to be determined on a case-by-case basis – one patient might be a reliable reporter in the presence of long-bone fracture, while another might need such a high level of pain control for initial management they are no longer aware of their cervical spine injury. It’s fairly clear it is reasonable to remove the cervical collar and forgo imaging for most patients who can be adequately clinically assessed.

“Clinical clearance of the cervical spine in patients with distracting injuries: It is time to dispel the myth”
http://www.ncbi.nlm.nih.gov/pubmed/23019677

Suture Everything Closed

Management of dog bites still exhibits significant variability. Antibiotics, traditionally generally prescribed, are only selectively necessary. Another element of mythology, primary closure of wounds for optimal cosmesis, is the subject of this trial.

These Greek authors randomized 182 patients to either primary suturing or non-suturing of traumatic bite lacerations. Obviously, the lacerations receiving primary closure had much improved cosmetic outcome. The infection rate of suturing was 9.7% vs. 6.9% without, and this study was underpowered to confirm whether this small difference occurred by chance alone. The main predictor of subsequent infection was treatment >8 hours after injury. All patients, unfortunately, received local scrubbing with povidone-iodine and were prescribed amoxicillin/clavulanic acid, neither of which were likely helpful.

I think it’s absolutely reasonable to approximate wound edges for dog bite lacerations after gentle and thorough cleansing. This study doesn’t provide any truly conclusive guidance for wounds >8 hours old – as they had similarly poor outcomes, regardless – other than to offer information to patients on their sub-optimal prognosis.

“Primary closure versus non-closure of dog bite wounds. A randomised controlled trial”
http://www.ncbi.nlm.nih.gov/pubmed/23916901

“NEXUS Chest” Decision Instrument

Low-yield radiography in the setting of trauma is pervasive and costly, but, unfortunately guidance regarding appropriateness is poor. The NEXUS group previously derived a chest imaging decision instrument, and this newly published article describes the validation study.

The good: 98.8% (CI 98.1-99.3%) sensitivity for any thoracic injury on imaging, and 99.7% (CI 98.2-100%) sensitivity for injuries of major clinical significance.

The really, really bad: 13.3% (CI 12.6-14.1%) specificity for thoracic injury or 12.0% (11.3-12.6%) specificity for major significance.

And, these numbers are probably subject to some limitations, considering about half the patients only received chest x-ray, rather than chest CT. That said, the injuries missed by x-ray are not likely of major clinical significance – and the patients selected for x-ray alone in the run of standard practice were likely selected for a low pretest probability of serious injury, regardless.

The authors suggest their instrument, despite it’s terrible specificity, still represents a valuable rule-out option, theorizing that even the small reduction in imaging this rule represents is beneficial. However, as we’ve covered before, one-way decision instruments are subject to cognitive bias and use as two-way rules, which may paradoxically increase imaging – although, in trauma, it’s hard to imagine a way to order more. Careful adoption of this instrument will be required – perhaps only after clinical evaluation as a screening decision-support question in the CPOE, asking one last time if the patient possibly meets this very-low-risk criteria prior to ordering.

The exclusion from very-low-risk criteria, by the by:

Older than 60 years
Rapid deceleration mechanism (fall >20 ft, MVC >40mph)
Chest pain
Intoxication
Abnormal mental status
Distracting painful injury
Tenderness to chest wall palpation

“NEXUS Chest – Validation of a Decision Instrument for Selective Chest Imaging in Blunt Trauma”
http://www.ncbi.nlm.nih.gov/pubmed/23925583

Observation of Minor TBI Prevents Harms

This study regarding the observation of children following minor traumatic brain injury is a little bit oddly spun by its authors and the medical news.

As we all know, most children presenting to the Emergency Department for minor head trauma do not have a clinically significant injury. Regardless, a significant portion of these children receive non-therapeutic cranial radiation to further assure parents and clinicians alike. The PECARN group, a few years back, published a rough decision instrument to help classify ~50% of these patients as “very low risk” (<0.05% risk of TBI) to give clinicians a tool to obviate CT scanning.

This group at Boston Children’s prospectively evaluated clinicians’ use of immediate CT scanning versus delayed CT scanning (observation). They find, of course, that observing children in the ED for a short period, rather than making an immediate decision regarding CT use, resulted in decreased use of CT. Thusly, the press releases state “Waiting and Watching Can Reduce Use of Brain Scans for Kids in the Emergency Department“.

But, watching and waiting doesn’t benefit the children in this cohort – other than preventing avoidable harms. The eight children who had CT scans showing clinically important injuries were easily identified by clinicians as requiring immediate CT. The period of observation doesn’t change the short-term clinical outcome of any of the patients – it only “treats” the risk-aversion of clinicians and parents. “Watching and waiting” may reduce scans – but discharging the entire observation cohort immediately would have reduced scans even further, without missed cTBI (although the study is underpowered to truly detect all events down to an appropriate “zero-miss” threshold).

While I agree this is an important clinical problem to address, I simply find an odd discordance between the patient-oriented features and the resource utilization-oriented outcome measured.

“Effect of the Duration of Emergency Department Observation on Computed Tomography Use in Children With Minor Blunt Head Trauma”
www.ncbi.nlm.nih.gov/pubmed/23910481

A Break in Massive Transfusion Evidence

The standard of care in trauma centers for massive transfusion in the setting of trauma has rapidly evolved to a fixed-ratio protocol, attempting to provide a physiologically balanced 1:1:1 mixture of PRBCs, FFP, and platelets. The evidence upon which this is based stems from observational battlefield data, as well as retrospective trauma service registries. However, as I’ve noted before (parroted, really, from folks smarter than me), these retrospective reviews are prone to survivorship bias – folks too sick to thaw FFP in time will die, and appear to reflect increased mortality association with not receiving FFP.

There is a large, multi-center prospective trial underway attempting to determine the optimal ratio of blood products – testing PRBC:FFP:platelets in 1:1:1 vs. 2:1:1 – because there are concerns especially with complications & costs associated with increasing FFP and platelet transfusions. This article describes a single-center, prospective study of the feasibility of even implementing a 1:1:1 ratio, given the difficulty of having plasma products on hand – but has the interesting side effect of providing some rather interesting and unexpected comparative outcomes data.

These authors enrolled, over a two year period, 78 patients from a pool of 203 screened for eligibility, and randomized them in unblinded fashion to 1:1:1 fixed ratio transfusion or their “usual care” control. “Usual care” for this institution consists of transfusion product balance guided by laboratory results (Hgb, INR, PTT, and fibrinogen). They found, as the primary outcome of their study, that the 1:1:1 ratio was feasible – but resulted in over twice as many wasted units of FFP (22% vs. 10% of thawed units).

The secondary outcomes reported include coagulation monitoring targets and mortality data. There was, for the most part, no statistically significant difference in any reported outcome. The coagulation monitoring targets all had p-values ranging from 0.4 to 0.8 and, truly, are not different. The mortality data, on the other hand, showed 29.7% mortality in the 1:1:1 group and 9.4% mortality in the usual care group – 20.3% difference (95% CI 2.5 to 38.2).

This is not practice-changing evidence. It’s a small sample size data coming from secondary outcomes in a feasibility study. But, regardless, it is very interesting to see.

“Effect of a fixed-ratio (1:1:1) transfusion protocol versus laboratory-results–guided transfusion in patients with severe trauma: a randomized feasibility trial”
www.ncbi.nlm.nih.gov/pubmed/23857856