Date: February 19th, 2021
This is an SGEM Xtra episode. I had the honour of presenting at the Lehigh Valley Health Network Grand Rounds on February 4th, 2021. The title of the talk “Dogmalysis: Five Medical Myths in Emergency Medicine”. The presentation is available to listen to on iTunes and GooglePlay and all the slides can be downloaded using this LINK.
Five Medical Myths in Emergency Medicine
- Myth #1: The use of non-selective NSAIDs will cause a nonunion in long bone fractures
- Myth #2: Topical anesthetics will cause blindness if used in simple corneal abrasions for less than 48 hours
- Myth #3: Mild paediatric gastroenteritis is best treated with expensive oral electrolyte solutions
- Myth #4: Tranexamic acid (TXA) has been proven to saves lives and results in good neurologic function in patients with isolated traumatic brain injuries (TBI)
- Myth #5: Epinephrine in adult out-of-hospital cardiac arrests (OHCA) results in better patient-oriented outcomes (POOs)
Each of the five myths is presented with some background information and the PICO (population, intervention/exposure, comparison and outcome). Key results are provided with a number of the study limitations (dog leash) identified. There is an SGEM bottom line and a link to the original SGEM episode to provide more results and critical appraisal. There is also a link to the original article for people to read the primary literature for themselves.
Myth #1: The use of non-selective NSAIDs will cause a nonunion in long bone fractures
When bones break, they usually heal with either surgical or non-surgical management. Sometimes the healing process can take longer than usual (delayed union), does not heal (non-union) or in poor alignment (malunion). Non-union is defined as “a failure of the fracture-healing process” and occurs in up to 1 in 10 fractures.
Several risk factors have been associated with increased risk of delayed or non-union: issues about the fracture (open/closed, displacement, location, etc) tobacco use, older age, severe anemia, alcohol intake, diabetes, low vitamin D levels, hypothyroidism, poor nutrition, infection, open fracture and certain medications (ex. steroids).
One class of medication that has been implicated in negatively impacting bone healing is NSAIDs. Non-selective NSAIDs and COX-2 inhibitors. There have been multiple studies investigating this issue with mixed results.
The final cohort consisted of 339,864 patients identified in over 15 years. Less than 1% were diagnosed with a nonunion (2,996/339,864).
The mean age was in the 50’s and around 60% were female. The most common fractures were radius, neck of the femur and humerus.
Key Result: Patients who filled prescriptions for selective COX-2 inhibitors and opioids but not non-selective NSAIDs were associated with an increased risk of nonunion.
SGEM Bottom Line: There is no high-quality evidence to support the claim that non-selective NSAIDS cause an increased risk of nonunion.
SGEM#317: Dese bones gonna heal again, with or without a non-selective NSAID
Reference: George et al. Risk of Nonunion with Nonselective NSAIDs, COX-2 Inhibitors, and Opioids. J Bone Joint Surg Am. 2020
Myth #2: Topical anesthetics will cause blindness if used in simple corneal abrasions for less than 48 hours
Even small corneal abrasions can cause significant pain because the cornea is highly innervated. The first documented use of topical ophthalmologic anesthetics was in 1818. A cocaine derivative was employed to effectively block nerve conduction in the superficial cornea and conjunctiva (Rosenwasser).
A number of proposed dangers have limited the use of topical anesthetic agents for the treatment of corneal abrasion associated pain. These dangers include delayed healing secondary to mitosis inhibition and decreased corneal sensation. The latter issue is of concern because of the potential for the abrasion to progress to an ulcer without the patient noticing. Additionally, these agents may have direct toxicity to corneal epithelium with prolonged use, leading to increased corneal thickness, opacification, stromal infiltration, and epithelial defects.
The fear of these complications has led to the pervasive teaching that topical anesthetics should never be used for outpatient management of corneal abrasions. This is reflected in the condemnation of their use in major Emergency Medicine textbooks, including Rosen’s and Tintinalli’s.
Some of the evidence used to support the claim of local anesthetics causing corneal harm comes from case reports, animal models or local anesthetic injected directly into the anterior chamber of the eye for cataract surgery. More information on the where the no topical anesthetic use on corneal abrasions come from can be found on a REBEL EM blog post.
They enrolled 118 patients into the trial. The median age was in the mid 30’s and 60% were male. Baseline NRS for pain was 7 out of 10. Just over 10% had a metallic foreign body and more than ¼ had another foreign body.
Key Result: Topical tetracaine was highly effective in reducing pain from simple corneal abrasions.
SGEM Bottom Line: Topical tetracaine use for 24-48 hours provides effective pain control and seems to be safe when prescribed early after corneal abrasions and you are confident it is only a simple corneal abrasion.
SGEM#315: Comfortably Numb with Topical Tetracaine for Corneal Abrasions
Reference: Shipman et al. Short-Term Topical Tetracaine Is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A Double-Blind, Randomized Clinical Trial. Annals of EM 2020
Myth #3: Mild paediatric gastroenteritis is best treated with expensive oral electrolyte solutions
Gastroenteritis is a common illness in children and these children are at risk of dehydration from inadequate intake, excessive losses or both together. If children are unable to tolerate oral hydration we often have to use intravenous fluids and sometimes require admission to hospital for ongoing fluids.
Goldman et al Pediatrics in 2008 published a helpful table describing the degree of dehydration in children ranging from mild, moderate to severe.
Most cases of gastroenteritis are mild, self-limiting and can be treated effectively with oral rehydration. For more information on visit this site on Oral Rehydration Therapy. The Canadian Pediatric Society also has an algorithm for oral rehydration.
Children with vomiting from gastroenteritis, and mild-moderate dehydration, should have a trial of oral rehydration therapy. Failing this, ondansetron should be administered. Failing that, intravenous fluid should be considered.
3,668 children presenting to the emergency department were assessed for eligibility. There were 647 children randomized into the study (n=323 for half-strength apple juice/preferred fluids and n=324 for electrolyte solution). The majority of exclusions were because no research personnel were present to enroll the child (1,297). It was about evenly split between boys and girls and the mean age was 28 months. There were not differences between groups at baseline.
Key Result: Treatment failure was seen in 16.7% half-strength apple juice and preferred fluid group vs. 25.0% electrolyte solution group.
SGEM Bottom Line: When advising parents with children with mild gastroenteritis and minimal dehydration, offering half-strength apple juice and preferred fluids compared to electrolyte solutions is a better choice.
SGEM#158: Tempted by the Fruit of Another – Dilute Apple Juice for Pediatric Dehydration
Reference: Freedman et al. Effect of dilute apple juice and preferred fluids vs. electrolyte maintenance solution on treatment failure among children with mild gastroenteritis: A randomized clinical trial. JAMA. May 2016
Myth #4: Tranexamic acid (TXA) has been proven to saves lives and results in good neurologic function in patients with isolated traumatic brain injuries (TBI)
TXA is a synthetic derivative of lysine that inhibits fibrinolysis and thus stabilizing clots that are formed. We have covered TXA as a treatment for bleeding a number of times on the SGEM. The evidence for TXA providing a patient-oriented outcome (POO) has been mixed.
TXA seems to work for epistaxis, fails to cause a decrease in all-cause mortality in post-partum hemorrhage, does not demonstrate an improved neurologic outcome in hemorrhagic strokes but does have 1.5% absolute mortality reduction in adult trauma patients.
- Epistaxis – SGEM#53 and SGEM#210
- Post-Partum Hemorrhage – SGEM#214
- Stroke due to Intracranial Hemorrhage – SGEM#236
- CRASH-2 Trial – SGEM#80
REBEL EM has also looked at TXA for those conditions plus a few others. It is unclear if it provides a benefit for gastrointestinal bleeds (GIB). Nebulized TXA shows promise for both post-tonsillectomy bleeding and hemoptysis. However, better studies are needed to confirm these observations.
Zehtabchi et al published a SRMA of TXA for traumatic brain injuries (TBI). They found only two high-quality randomized control trials with 510 patients having TBI that met inclusion criteria. The results were no statistical difference in in-hospital mortality or unfavorable neurologic functional status. However, there was a statistical reduction in intracranial hematoma expansion size with TXA compared to placebo.
The CRASH-3 investigators randomly allocated 12,737 patients with TBI to receive either TXA or placebo. There were 9,202 (72%) who were enrolled within 3 hours of injury. The mean age was 42 years, 80% were male, 80% had both pupils reactive and about 2/3 had a GCS less than 12.
Key Result: No statistical difference in head-injury related mortality with TXA compared to placebo.
SGEM Bottom Line: We cannot recommend the routine use of TXA for patients with isolated traumatic brain injuries at this time.
SGEM#270: CRASH-3 TXA for Traumatic Head Bleeds?
SGEM#305: Somebody Get Me A Doctor – But Do I Need TXA by EMS for a TBI?
Reference: CRASH-3 Trial Collaborators. Effects of tranexamic acid on death, disability, vascular occlusive events and other morbidities in patients with acute traumatic brain injury (CRASH-3): a randomised, placebo-controlled trial. The Lancet October 2019
Reference: Rowell et al. Effect of Out-of-Hospital Tranexamic Acid vs Placebo on 6-Month Functional Neurologic Outcomes in Patients With Moderate or Severe Traumatic Brain Injury. JAMA 2020.
Myth #5: Epinephrine in adult out-of-hospital cardiac arrests (OHCA) results in better patient-oriented outcomes (POO)
The use of epinephrine in OCHAs is part of the advanced cardiac life support (ACLS) algorithm. There is the classic OPALS trial by Dr. Ian Stiell (SGEM#64) that questioned the efficacy of ACLS drugs. This was a before and after study to see if ACLS techniques, including IV epinephrine, would improve survival to discharge.
While there was an improvement in return of spontaneous circulation (ROSC) and survival to hospital admission there was not an increased survival to hospital discharge. There was also no increase in survivors with good neurological outcomes with ACLS.
There have been a number of papers published since OPALS that support the findings of not using ACLS drugs like epinephrine for OHCA (Olavseengen et al. JAMA 2009, Hagihara et al. JAMA 2012 and Cournoyer et al. AEM 2017).
A limitation of these studies is their observational nature. There is one randomized control trial on epinephrine for OHCA by Jacobs et al. published in Resuscitation 2011. This Australian trial showed better ROSC with epinephrine but not better survival to hospital discharge in 534 patients.
Unfortunately, the trial failed to achieve their sample size for a variety of reasons which left it underpowered. This means there is a lack of high-quality data to rely upon in deciding whether or not to use epinephrine in OHCA situations.
There was a total of 8,007 patients include in the analysis. The mean age was 70 years with almost 2/3 being male and 2/3 witnessed arrests. CPR was performed in 70% of the cases and less than one in five had a shockable initial cardiac rhythm.
Key Result: 30-day survival was statistically higher in the epinephrine group compared to placebo but not statistically higher survival with good neurologic outcome.
SGEM Bottom Line: The use of epinephrine in adults with OHCA to improve survival with favorable neurologic outcome is not supported by the literature and protocols should be changed to reflect the data.
SGEM#238: The Epi Don’t Work for OHCA
Reference: Perkins et al. A Randomized Trial of Epinephrine in Out-of-Hospital Cardiac Arrest. NEJM 2018.
Five Medical Myths in Emergency Medicine: Busted
- Non-selective NSAIDs are not associated with increased risk of nonunion in long bone fractures
- Topical anesthetics use for less than 48 hours for simple corneal abrasions do not have an increase in adverse events
- Mild paediatric gastroenteritis treated with 1/2 strength apple juice and preferred fluids is superior to an electrolytes solution
- TXA for isolated TBI does not have a disease specific or all-cause mortality benefit
- Epinephrine in adult OHCA does not result in better survival with a patient-oriented outcome (POO) of good neurologic outcome
The SGEM will be back next episode doing a structured critical appraisal of a recent publication and will continue trying and to cut the knowledge translation window down from over ten years to less than one year using the power of social media. Ultimately we want patients to get the best care, based on the best evidence.
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