Emergency Medicine Literature of Note

Lack of IV Access, Harbinger of Death

Interesting observational study of 56,332 patients picked up in an EMS system in King County, looking at IV access and outcomes.

For reasons they don’t look into in this study, they find that IV access is an independent predictor of decreased in-hospital mortality. Not for the less-acute patients, but for patients of high-acuity, lack of IV access shows a pretty significant trend towards poor outcomes. They don’t look at fluid therapy, medication therapy, etc. as confounding variables – so we don’t know what it is specifically about IV access that confers a survival advantage.

They do a brief breakdown of the systolic blood pressure and the percentage of patients receiving IV access, and, as expected, more IVs are attempted at the extremes. This leads me to believe there are patients who were high acuity, required IV access, but had failed IV access attempts – but there’s no data on that either.

This is a study that could end up telling us something, or nothing. Interesting, nonetheless.

“Intravenous Access During Out-of-Hospital Emergency Care of Noninjured Patients: A Population-Based Outcome Study”
http://www.ncbi.nlm.nih.gov/pubmed/21872970

C-Collars Cannot Stabilize Unstable Injuries

This is another cautionary anatomic study that demonstrates cervical collars are not adequate immobilization devices – except in patients who already do not need them.

This is a cadaveric spinal immobilization study in which C5/C6 instability was induced, and the Ambu extrication collar, the Aspen collar, and no collar were evaluated for range of bending and rotation during a bed transfer simulation.

The results are pretty straightforward. Before the instability was induced, patients had minimal neck movement, whether immobilized or not. After instability was induced, the patients all had significant bending and rotation – nearly the same for the patients in the collars as in no collar at all.

This is consistent with the small amount of prior work done in actual unstable spines; most of the cervical collar data is in healthy volunteers. The limitations of a cervical collar should be recognized, and patients should have their cervical spine evaluated and cleared or intervened on immediately.

“Cervical collars are insufficient for immobilizing an unstable cervical spine injury.”
www.ncbi.nlm.nih.gov/pubmed/21397431

Linezolid Is Superior To Vancomycin For Pneumonia

This is consistent with prior studies and not particularly earthshaking, but if you needed more literature to support switching antibiotics in the case of treatment failure, this would be another one.

This is in pigs, and it’s an animal model of MRSA ventilator-associated pneumonia. Four groups – controls, twice-daily vancomycin, continuous vancomycin infusion, and linezolid. Treatment was initiated after 12 hours of bacterial inoculation in ventilated pigs. At the end of their 96 hour treatment period, 75% of controls, 11% of each vancomycin group, and 0% of linezolid pigs were BAL positive for MRSA by culture. Likewise, pathologic sections also showed decrease inflammation and damage in the linezolid group.

Short story, linezolid is better – but not quite better enough that we can’t still start with vancomycin and keep it in reserve.

N-acetylcysteine Overdose With Anaphylactoid Reaction and Myocardial Infarction

This is another toxicology case that illustrates a point I make (probably too often) to my residents – that every action we take has a risk of harm, whether known or unanticipated. I’m probably the only attending who cancels their IM ketorolac orders and changes them to PO ibuprofen. Why? Because of cases like this.

This is an entirely appropriate therapy – N-acetylcysteine given for hydrocodone-acetaminophen overdose – gone wrong because of a mixing error resulting in 10-fold overdose (126,000mg loading dose!). Anaphylactoid reactions are known side effects in N-acetylcysteine, and, unfortunately, this patient’s reaction was more severe than most, suffering an inferior MI with a peak troponin of 658ng/mL. He expired 17 hour after the N-acetylcysteine overdose.

I’ve seen epinephrine given IV instead of SQ more than once (one time resulting in an MI), many medications are tissue toxic if they extravasate, you can get sterile abscess formation from intramuscular injections, etc. The fewer interventions and the less invasive the interventions, the less risk at which we place our patients.

“Fatal myocardial infarction associated with intravenous N-acetylcysteine error”

www.ncbi.nlm.nih.gov/pubmed/21878099

Ethanol Hand Sanitizer Abuse

I imagine every department has a frequent-flier patient like this – they keep getting referred to rehab, but they don’t stop bouncing back. And the hand cleanser keeps mysteriously running out.

This is case report and literature review of the National Poison Data System that documents the accidental and intentional exposures to ethanol-containing hand sanitizer. And, really, their numbers probably underestimate the issue – considering the cases reported to poison control are primarily in children under age 6. There are plenty of teenagers and other adults abusing these substances as well, but they are far less likely to be reported to a poison control center.

The case report is rather amusing – a teenager with a g-tube “looking for a buzz” who put 500mL of 61% ethanol hand sanitizer into the tube and subsequently required intubation and then dialysis when his first ethanol level was 720mg/dL.

“The rising incidence of intentional ingestion of ethanol-containing hand sanitizers”
www.ncbi.nlm.nih.gov/pubmed/21926580

Featured on ERCast

Was fortunate enough to be invited to appear on one of the premier Emergency Medicine podcasts – ERCast, by Dr. Rob Orman (@emergencypdx).

We had a lovely chat about two posts from August, clearance of C-spine by CT vs. MRI (link) and CT within 6 hours for the diagnosis of SAH (link). The esteemed Dr. Scott Weingart of EMCrit also weighs in on the CT article.

He’s been podcasting far longer than I’ve been writing, and he has a lot of fantastic content and has been featured on EM:RAP as well. If you haven’t discovered it yet, you’re missing out.

Back Pain, Harbinger of Death

In Perth, Western Australia, clearly back pain is a different sort of entity than back pain here in the United States. This is a retrospective review of 22,000 back pain representing 1.9% of all visits over a five year period simply as an epidemiologic overview with descriptive statistics.

And, fascinating statistics they are. Highlights:
– 43.8% of patients were diagnosed with simple muscular back pain.
– 17.1% of muscular back pain patients required admission to the hospital with a mean length-of-stay of 6.4 days, and one that was hospitalized for 163 days!
– Patients at the extremes of age (< 15 years, > 75 years) were simple muscular back pain less than 40% of the time.
– Of the medical diseases found in the non-muscular group, the top were renal colic, sciatica, UTI/pyelonephritis.
– 24 myocardial infarctions, 53 pulmonary emboli, 17 aortic dissections, and 18 ruptured AAA were diagnosed in patients with a primary complaint of back pain.

How do 17.1% of simple muscular back pain patients get admitted to the hospital? For six days? It boggles the mind.

Finally – back pain at the harbinger of death – there was a 1.2% 30-day mortality rate in all patients presenting for any complaint of back pain, and 0.8% with non-specific or muscular back pain. That’s almost as lethal as our low-risk chest pain cohort here in the U.S.

Fascinating.

“Analysis of 22,655 presentations with back pain to Perth emergency departments over five years”
www.ncbi.nlm.nih.gov/pubmed/21923920

No Reversing The Harm of Etomidate

A small, but growing body of evidence is starting to correlate the physiologic adrenal suppression of etomidate with worsening clinical outcomes. This study is a French prospective cohort that really likes etomidate for RSI, so, they decided to ask the question whether a continuous hydrocortisone infusion has any substantial effect on cardiovascular parameters in the setting of etomidate use.

Short answer, no.

Their randomized groups are awfully small – 45 patients in each group – so their power to detect a difference is not great. But, at the minimum, there’s no profoundly obvious difference or any seemingly clinically significant trend between the two groups.

I trained using etomidate for everyone, but I’ve almost completely moved to alternative agents, ketamine being the most prominent of those agents. Most significantly, ketamine differs from the other agents in terms of having analgesic properties as well, and I think it is reasonable to provide some treatment for the pain associated with laryngoscopy. There is evidence that ketamine is a myocardial depressant and may be deleterious in patients with limited cardiac reserve, but so far in limited literature it holds up clinically well against etomidate and midazolam.

“Corticosteroid after etomidate in critically ill patients: A randomized controlled trial”
http://www.ncbi.nlm.nih.gov/pubmed/21926601

“Intubating ICU patients with ketamine: adverse effects that can occur.”
http://www.ncbi.nlm.nih.gov/pubmed/18079246

Blocking Frizzled Proteins Reduces Infarct Size

This is another window-to-the-future article that caught my eye because, really, I just wanted to see what a Frizzled signal was.

And, it turns out, it’s mildly interesting.

My area of expertise is not cell signaling and infarct-related myocardial fibroblast migration/inhibition, so the first few pages of cell plating and luciferase expression measurement are not my cup of tea. However, eventually, the authors get around to injecting UM206 into a mouse MI model and find significant reductions in infarct size, increased myofibroblasts, and, more importantly, increased ejection fraction/decreased mortality from heart failure.

Give it another five years, and maybe we’ll be giving our ACS patients aspirin, clopidogrel, and a Frizzled-antagonist.

“Blocking of Frizzled Signaling With a Homologous Peptide Fragment of Wnt3a/Wnt5a Reduces Infarct Expansion and Prevents the Development of Heart Failure After Myocardial Infarction.”
circ.ahajournals.org/content/…/CIRCULATIONAHA.110.976969.abstract

MRI After Negative CT in Obtunded Trauma

In contrast to the recently reviewed study showing 5 surgical injuries in 174 patients complaining of neck pain after a negative CT c-spine, this study of MRI in obtunded trauma patients with a negative CT c-spine showed no surgical injuries.

Specifically, this is a retrospective review from U.C. Davis in which they looked at 512 patients who underwent both CT c-spine and MRI c-spine. They found 150 patients who were confused/obtunded, had otherwise normal neurologic examination, and had a negative initial CT c-spine. Half of these patients had an injury identified on their MRI, but none of them were unstable ligamentous injuries or structural abnormalities requiring surgical intervention.

This is more relevant to our trauma colleagues who need to mobilize people in the ICU to prevent other complications, and external validity is limited in a single-center study, but it’s a mark on the side of keeping the standard of care at CT and not proceeding to MRI in an irrational manner.

“The Value of Cervical Magnetic Resonance Imaging in the Evaluation of the Obtunded or Comatose Patient With Cervical Trauma, No Other Abnormal Neurologic Findings, and a Normal Cervical Computed Tomography.”
www.ncbi.nlm.nih.gov/pubmed/21857257