Telling Tall Tales: Dogma in Emergency Medicine
/In our training and education as Emergency Medicine providers, we often come to accept certain practice patterns as fact. When these established “facts” come along with fantastical clinical claims (don’t give your corneal abrasion patients tetracaine, it’ll melt their corneas; don’t use lido with epi for digital blocks, their finger will fall off; don’t use beta-blockers in patients on cocaine, their BP will skyrocket due to unopposed alpha-effects), we should probably look to question their supporting evidence.
Ilicki J. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. The Journal of Emergency Medicine 2015;49(5):799–809
Safety of epinephrine in digitial nerve blocks: a literature review is a review by Jonathan Ilicki looking at the safety of epinephrine primarily in digital nerve blocks for analgesia in fingers and toes. This is a review of studies previously published in several databases such PubMed. They ultimately reviewed 39 articles including prospective and retrospective studies, an in vitro analysis of cadaver vessel response to epinephrine, and several case series.
As the theme of this journal club was addressing dogma in EM, I wanted to point out that this article did a good job of highlighting where this dogma came from. The idea that epinephrine is dangerous in digial nerve blocks came from fifty case reports between 1889 and 1948 that described finger necrosis following digital nerve block. Note that more then half of this time frame falls into the pre-antibiotic era questioning the relevance of this information. Furthermore, half of the cases were digital nerve blocks without epinephrine suggesting that it cannot be the main culprit.
Anyway, the results of the review were that the only cases of digital compromise were due to confounders such as tourniquet use. They did not find any instances of digital necrosis in digital nerve blocks performed with epinephrine.
These results are limited by the fact that many of the studies were not designed to determine epinephrine safety, however, they reported safe blocks as a secondary outcome. Furthermore, many of these were performed by hand or plastic surgeons and not in the ED. However, they were performed for wound care just as they are in the ED. Perhaps the most significant limitation is the fact that patients with concern for impaired digital circulation, specifically diabetes, hypertension, and peripheral vascular disease were excluded in most of the trials. There were some trials that included these patients, however, the data is more limited.
Ultimately, I will use this data to back up my decision to perform digital nerve blocks with epinephrine. I will, however, take peripheral vascular disease into consideration and may not use epinephrine in these patients.
Pham D, Addison D, Kayani W, et al. Outcomes of beta blocker use in cocaine-associated chest pain: a meta-analysis. Emerg Med J 2018;35(9):559–63.
Background
Traditional teaching recommends against the administration of beta-blockers in cocaine intoxication due to unopposed alpha-adrenergic stimulation. Most of these recommendations were based on case reports and animal studies. Pham et al chose to perform a systematic review and meta analysis to evaluate the safety of beta blocker use in cocaine associate chest pain.
Design
A literature search was performed searching “cocaine”, “beta blocker”, as well as specific beta-blockers including “metoprolol”, “propranolol”, “esmolol” etc. Eligible studies included 1) retrospective or prospective study design 2) patients 18 years or older 3) symptoms consistent with chest pain suspicious for ACS, 4) cocaine use defined by positive drug screen or self reported use, 5) reported outcomes of non-fatal myocardial infarction or all cause mortality. Case reports, non-human studies, observational studies and review articles were excluded. Results originally produced 580 possible studies only 5 studies met all inclusion and exclusion criteria leaving a total of 1,756 patients. All studies were either single center or double center
Results
All 5 studies reports rates of non-fatal myocardial infarction, which showed no statistically significant difference of non-fatal myocardial infarction compared to the non beta-blocker group with rate of 15.4% to 14.1% (p = 0.39). Of the 5 studies, 3 studies looked at the other outcome of interest, all cause mortality. The mortality rate was
Limitations
Multiple limitations were brought up in the study and during discussion. First off, all of the studies were retrospective making it difficult to determine actual symptoms of patients and why they received beta-blockers given lack of access to primary patient data. There was also a lack of information on which beta-blockers were used and at what dose. Additionally, since urine drug testing for cocaine remains positive for 48-72 hours meaning that it would be difficult to determine whether someone was actually acutely intoxicated when they received their beta blockers.
Takeaways
Very interesting discussion was held at journal club in terms of how to apply these results. Most providers brought up the fact that beta-blockers are not the first line treatment for ACS whether related to cocaine intoxication or other etiologies. Therefore, it was unclear how applicable these results were. Most people agreed they would like start with benzos or vasodilators over beta-blockers specifically for the symptom of chest pain associated with cocaine intoxication. Since that was the main symptom that the authors focused on, this information cannot be extrapolated for other symptoms of cocaine intoxication such as dysrhythmia or severe hypertension. In conclusion, there are likely very few circumstances that we would consider beta-blockers as our first line of treatment for this patient population
Waldman N, Densie IK, Herbison P. Topical Tetracaine Used for 24 Hours Is Safe and Rated Highly Effective by Patients for the Treatment of Pain Caused by Corneal Abrasions: A Double-blind, Randomized Clinical Trial. Academic Emergency Medicine 2014;21(4):374–82.
Background
Traditional dogma regarding home tetracaine use in the setting of uncomplicated corneal abrasions includes the potential for delayed wound healing or the development of corneal ulceration. This study by Waldman et al attempted to assess the safety of tetracaine use for the first 24 hours of treatment of pain in patients with uncomplicated corneal abrasion.
Design
This was a single center, randomized, double blinded trial comparing 0.9% normal saline solution to preservative-free 1% topical tetracaine solution. Adult patients were eligible for enrollment if they presented within 36 hours after sustaining a corneal abrasion related to mechanical trauma, corneal foreign body, or ultraviolet keratitis. There were a number of exclusion criteria, the most important of which are bilateral eye injuries, contact lens wearers, and those patients with significant ocular trauma, including open globe, corneal ulceration, or corneal abrasion significantly affecting vision. Patients were enrolled using a convenience sample and were randomized to one of the two treatment arms using block randomization. They were given an envelope to take home which included the study drug, 1g paracetamol tablets, and pain questionnaires. All patients used chloramphenicol antibiotic ointment as well. Patients were re-evaluated at 48 hours in the emergency department to assess fluorescein uptake as a proxy for delayed wound healing as well as any additional ocular complications. They were also asked to document their pain scores at predefined intervals by the study team. The primary outcome was the number of complications related to the study drug. The secondary outcomes included patient reported pain scores and perceived efficacy of their intervention.
Results
A total of 116 patients were enrolled (59 in the tetracaine arm and 57 in the control arm), which was slightly less than what the authors had anticipated based on their power calculation.
Zero patients had complications related to topical tetracaine administration.
Using binomial probability confidence interval, the upper limit of the 95% confidence interval was 6.1%.
There was no difference in patients with persistent fluorescein uptake at 48 hours (24% vs. 21% in the tetracaine and control groups, respectively).
There was no difference in pain scores between groups.
Pain scores in both groups approached 10mm on VAS by 12 hours and approached 0 at 24 hours.
Tetracaine was perceived as more effective than the control (p < 0.0005).
Limitations
Patients were not asked to record how much of the study medication they used. This could be problematic if patients used tetracaine sparingly, which could confound the fact that no complications were identified related to tetracaine use in this study.
Patients were unlikely to be blinded to their treatment given the burning sensation associated with tetracaine instillation.
This was a single-center study in New Zealand, where the standard of care is somewhat different than that in the United States.
Takeaways
Most of the providers in our journal club discussion group do not currently prescribe or give tetracaine to patients with simple corneal abrasions to use at home for pain control. Based on our discussion, the general consensus was that we will be less hesitant to give patients the small bottle of tetracaine left over from their emergency department assessment, as this study is relatively convincing in that 24 hours of home tetracaine use is likely safe and will not negatively impact wound healing. This is especially true in patients who seem reliable and who are in severe, excruciating pain related to their corneal abrasion which we suspect will not improve significantly with enteral over-the-counter pain medications. Obviously, we have to be somewhat careful in how we generalize these findings, as patients with visual impairment, prolonged time before ED evaluation, and those who wear contact lenses were excluded from this study.
References
Ilicki J. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. The Journal of Emergency Medicine 2015;49(5):799–809.
Pham D, Addison D, Kayani W, et al. Outcomes of beta blocker use in cocaine-associated chest pain: a meta-analysis. Emerg Med J 2018;35(9):559–63.
Waldman N, Densie IK, Herbison P. Topical Tetracaine Used for 24 Hours Is Safe and Rated Highly Effective by Patients for the Treatment of Pain Caused by Corneal Abrasions: A Double-blind, Randomized Clinical Trial. Academic Emergency Medicine 2014;21(4):374–82.
Authorship
Digital Nerve Blocks - Amanda Humphries, MD
Beta Blockers in Cocaine-Associated Chest Pain - Kathyrn Banning, MD
Tetracaine - Andrew Golden, MD
Peer Review, Editing, and Posting - Jeffery Hill, MD MEd
