Category: Trauma

23.4% – The Next Great Hypertonic Saline

Mannitol and hypertonic saline are the most commonly used medications to ward off the catastrophic complications of malignant increased intracranial pressure.  Hypertonic saline, in my experience, has typically been 3%, but there are multiple different concentrations in use.

These authors perform a systematic review and meta-analysis of 23.4% saline.  After all, the theory goes, a more osmotically powerful concentrated solution will exert greater physiologic effects.  They identified 11 articles, six of which they included in a meta-analysis to identify an effect size for intracranial pressure reduction.  Using the pooled data, the measured effect was a 55.6% (CI 44%-67%) decrease in ICP within 60 minutes.  Their systematic review uncovered few adverse effects of 23.4% – transient hypotension and rare hemolytic anemia – and even reported acute reversal of herniation syndromes with good neurologic outcomes.

There is a ton of heterogeneity between studies – both in dosing of 23.4% saline, co-administration of mannitol, and underlying pathophysiology of ICP.  Most studies are also tiny, ranging between 8 and 68, and either retrospective reviews or prospective non-random selection.  Many studies did not report patient-oriented outcomes, so it’s hard to truly compare this practice to the current standard of care.

That being said, it seems interesting for potential use as “rescue” therapy when the alternative is permanent cerebral asphyxiation – and further study is needed to describe the appropriate (if any) population for use.

For reference: the salinity of seawater is about 3.5%, the Great Salt Lake varies between 5-27%, and the Dead Sea is approximately 33.7%.  Definitely not appropriate for a peripheral intravenous line!

“High-Osmolarity Saline in Neurocritical Care: Systematic Review and Meta-Analysis”

Happy Independence Day!

I ought to have posted this piece regarding firework injuries on Wednesday to get folks in the mood – but, better late than never!

This is an entertaining little experiment published in JAMA investigating the mechanism of ocular trauma from fireworks.  These authors created a setup in which a cadaveric eye was suspended in a network of sensors – and then concussive charges and fireworks were exploded at various distances.

Based on their experiments, these authors conclude most of the ocular injury potential is superficial and results from flying debris, rather from any explosive pressure wave.  Fascinating little study!

“Mechanisms of Eye Injuries From Fireworks”
www.ncbi.nlm.nih.gov/pubmed/22760285

Which Traumatic ICH Needs Transfer?

Answer:  Not isolated subarachnoid hemorrhage.

Caveats abound, of course.  In this retrospective review of 404 patients transferred to a facility with neurosurgical capabilities for traumatic intracranial hemorrhage, only 48 suffered subsequent neurologic deterioration.  Of this cohort, 75 were isolated traumatic SAH, and only 1 deteriorated – and that was due to an aspiration event in a 98 year-old male.  Therefore, these authors, citing prior literature, feel this population appropriate for a prospectively-evaluated more-restrictive transfer protocol.

Their study is, of course, retrospective.  Their sample size is rather small.  There’s no granular data on characteristics of individual head injuries; not all traumatic SAH or SDH is created equal.  Few of their odds ratios for deterioration were helpful in making predictions; isolated SAH had an OR for deterioration of 0.078, while SDH and epidural injuries were twice as likely to deteriorate as baseline (particularly since they tended to co-occur with other intracranial injuries).

But, in our era of cost-conscious medicine, these authors clearly describe the presence of a spectrum of intracranial disease that does not benefit from transfer or hospitalization.

“Patients with traumatic subarachnoid hemorrhage are at low risk for deterioration or neurosurgical intervention”
www.ncbi.nlm.nih.gov/pubmed/23694879‎

FFP:PRBC Ratio Survival Bias?

Modern trauma care has essentially, based on several articles published in the Journal of Trauma, migrated to 1:1 ratios of FFP to PRBC in massive transfusion.  This was motivated in part by the outcomes observed in battlefield trauma associated with the use of whole blood.  However, multiple individuals feel the true answer might lay somewhere in between – and that the observed association between equivalent transfusion ratios and survival is related to “survival bias”.  In essence, trauma patients arriving the ED receive blood first – and the FFP only arrives if they survive long enough to receive it.  Therefore, on retrospective analysis, the data is automatically skewed in favor of the folks who receive FFP, simply because they survived long enough to do so.

This is another retrospective review, but one that attempts to control for time-dependent exposure in the transfusion ratio.  These authors generate hour-by-hour transfusion ratios throughout the first 48 hours of a patient’s hospital stay – and use these sort of time-dependent ratios to make their associations with outcomes.  Using the “conventional” model – as other studies have done – there is a 2.50-fold (1.54 – 4.05) risk of death among patients with a low FFP:RBC ratio.  With their “time-dependent” model, the adjusted hazard rate is only 1.25-fold (0.78 – 2.00).

There are, of course, a few problems with methods.  Emergency transfusions where RBCs were in the Emergency Department had time imputed from retrospective analysis, rather than from blood bank issue time.  In the 10 randomly selected patients the authors performed chart review to validate their analysis, they saw a median difference of 0.14 hours between issue time and transfusion time – but with an interquartile range of 0.0 – 2.5 hours.  This means some of their analysis is based off extraordinarily imprecise data.  Then, the reviewing anesthesiologist performing the outcome review was not consistently blinded to the transfusion ratio of the patient – which potentially biases the results in whatever manner suits the authors.

In the end, it’s another inconclusive data point in the massive transfusion literature.  Luckily, there is a prospective trial already in progress.

“Effect of Plasma-to-RBC Ratios in Trauma Patients: A Cohort Study With Time-Dependent Data”
http://www.ncbi.nlm.nih.gov/pubmed/23782963

Negative CTs and Pediatric Abdominal Trauma

I am biased – I helped set the Pediatric Emergency Care Applied Research Network up back as a research assistant peon before medical school – so it always pleases me to report on PECARN’s newest outputs.

This is a preplanned sub-analysis of their massive observational pediatric blunt trauma study.  Their pediatric blunt trauma decision instrument, unfortunately, turned out to not be terribly useful.  This data on the outcomes of patients with negative abdominal CT scans, at least, ought to help us.

Of the 3,819 patients enrolled with normal abdominal CTs following blunt trauma, 6 went on to have clinically significant abdominal injuries requiring intervention.  They provide a lot of detail about the patient population, but their conclusion is pretty simple: don’t routinely admit these trauma patients for observation to try and catch that 0.02%.  If there’s no other indication for admission, they may be discharged with appropriate symptom return precautions.

“A Multicenter Study of the Risk of Intra-Abdominal Injury in Children After Normal Abdominal Computed Tomography Scan Results in the Emergency Department”
www.ncbi.nlm.nih.gov/pubmed/23622949

Neurosurgery’s Takedown of Steroids in SCI

A brave new day dawns – clinicians who otherwise lived in fear of medicolegal reprisal from failing to administer steroids in acute spinal cord trauma may now safely withhold them.

The steroids in spinal cord debate, a one-man crusade lead by Michael Bracken, distorted by performing Cochrane Reviews of his own articles, has hopefully been definitively settled.  These authors, as part of a comprehensive update on the diagnosis and management of acute spinal cord injury, definitively summarize the flawed literature supporting methylprednisolone administration.  Their recommendation:

Administration of methylprednisolone (MP) for the treatment of acute spinal cord injury (SCI) is not recommended. Clinicians considering MP therapy should bear in mind that the drug is not Food and Drug Administration (FDA) approved for this application. There is no Class I or Class II medical evidence supporting the clinical benefit of MP in the treatment of acute SCI. Scattered reports of Class III evidence claim inconsistent effects likely related to random chance or selection bias. However, Class I, II, and III evidence exists that high-dose steroids are associated with harmful side effects including death. 

We’ve come a long way since the NIH faxed a letter to every Emergency Department in the country instructing physicians to give steroids.  Another amazing saga demonstrating the danger of inadequately reviewed medical evidence.

“Pharmacological Therapy for Acute Spinal Cord Injury”
http://www.ncbi.nlm.nih.gov/pubmed/23417182

Tongue Blade For Mandible Fractures

The “tongue blade test” is one of the fun, functional tests in Emergency Medicine.  If you’ve got facial trauma and you’re concerned about a mandible fracture, simply align a wooden tongue blade over the molars in a patient’s mouth and have them bite down firmly.  Then, twist the blade medially.  If the patient is not limited by pain, they’ll be able to hold the blade until it breaks.  If they’re limited by pain, such as in the presence of a mandible fracture, the patient won’t be able to hold the blade until it breaks.

This is an observational study enrolling 190 eligible patients for the tongue blade test in the presence of suspected mandible fracture.  66 patients had negative (normal) tongue blade tests, while 124 had positive (abnormal) tests.  All patients received a CT for definitive diagnosis.  There were 5 false negatives and 29 false positives.  Therefore, the sensitivity of the test is 95% and specificity 68%.  These results are consistent with some prior reviews of this test’s characteristics.

Not a “zero miss” test, but, depending on the pre-test likelihood based on other clinical factors, a very useful screening test.

“Re-evaluating the diagnostic accuracy of the tongue blade test: still useful as a screening tool for mandibular fractures?”
www.ncbi.nlm.nih.gov/pubmed/23490109

Does Size Matter? (Chest Tube Size)

That is, apparently, the question being asked by the trauma folks at Los Angeles County Hospital.  Traditionally, traumatic pneumothorax with accompanying hemothorax is routinely treated by the largest chest tube possible.  Theoretically, smaller chest tubes will clog with debris or blood clot, requiring additional thoracostomy tubes or interventions.

However, these authors note several simulations of chest tube drainage indicating tubes as small as 14 French may be adequate.  They also hypothesize these larger chest tubes are as painful as tragically possible, and the tradition of large chest tubes results in undue suffering.

The answer…remains unsettled.  There was no difference observed in their analysis of chest tubes of maximum size versus smaller-than-maxiumum size.  But, a 28-32 Fr chest tube is still a pretty darn large tube.  I’m not surprised that pain and drainage characteristics were not different.  If they really wanted to push the envelope, they ought to look at the truly small tubes – at least, if their goal is clinically relevant pain reduction.

“Does size matter? A prospective analysis of 28–32 versus 36–40 French chest tube size in trauma”
www.ncbi.nlm.nih.gov/pubmed/22327984

Pediatric Blunt Trauma Remains Confounding

The latest output from the Pediatric Emergency Care Applied Research Network is a clinical decision instrument intended to assist clinicians in managing pediatric blunt abdominal trauma.

Like previous PECARN studies, this is a multi-center, prospective, observational study conducted in tertiary pediatric emergency departments.  This study enrolled 12,044 children with blunt trauma and prospectively collected structured data regarding their mechanism, external injuries, and physiologic variables.  Using the magic of statistical partitioning, the authors derived a decision instrument for use in risk-stratifying a patient as “very low risk for intra-abdominal injury requiring acute intervention.”  If the patient meets all criteria, the prediction rule is 97.0% sensitive, missing 6 out of 203 abdominal injuries.

This is critically valuable data – but, as a decision-instrument in a zero-miss environment, I’m not sure if it helps.  The authors note that use of their CT decision-instrument actually increased resource utilization if retrospectively applied to the derivation cohort, if the requirement is held that a patient be negative for every variable.  If the threshold is raised to 1 or 2 variables present, then sensitivity drops to 82% and 77%, respectively.  Only about half received a CT scan, and a small percentage were lost to follow-up – though, given the outcome of “injuries requiring intervention”, the methodology is reasonable.  However, because intervention-requiring injuries only represented 26% of all radiographically-identified intra-abdominal injuries, this study is still going to be ignored out-of-hand by folks who want to identify all injuries, not just intervention-requiring injuries.  After all, the grade 1 splenic laceration may be intervention-free, but remains important regarding activity restrictions to prevent future morbidity.

The authors also note these findings require external validation – wherever they’re going to find another pedatric emergency care network to enroll 12,000 patients!

“Identifying Children at Very Low Risk of Clinically Important Blunt Abdominal Injuries”
http://www.ncbi.nlm.nih.gov/pubmed/23375510

Don’t Waste the Saline

This is a study that follows-up and confirms the prior “mythbusting” literature regarding the management of minor soft-tissue lacerations in the ED.  Specifically, this article evaluates the need for wound irrigation with sterile saline ($) as compared with tap water (free).

Unsurprisingly – and consistent with prior literature – this relatively contemporary study of 663 patients at Stanford University hospitals shows no difference in subsequent rates of wound infection, regardless of irrigation solution.  The sterile saline group suffered 6.4% (9.1 to 3.7%) subjective wound infections in follow-up, compared to 3.5% (5.5 to 1.5%) infections in the warm tap water irrigation.  A few patients were lost to follow-up, and the study has some generalizability limitations due to predefined exclusion criteria – frequently seen ED comorbidities such as diabetes, alcoholism, and immunocompromise were excluded.

But, it’s another piece of the puzzle that tells us suturing of uncomplicated wounds needs not be made more complicated.  There’s no evidence to suggest that anything more than tap water, absorbable sutures, and non-sterile techniques are needed for optimal patient outcomes.

“Water is a safe and effective alternative to sterile normal saline for wound irrigation prior to suturing: a prospective, double-blind, randomised, controlled clinical trial”
http://bmjopen.bmj.com/content/3/1/e001504.full