COMMENTARY

Three Must-Read Emergency Medicine Articles From 2018

Amal Mattu, MD

Disclosures

January 16, 2019

The 2018 calendar year was once again rife with outstanding additions to the emergency medicine literature from numerous journals in many specialties. In selecting this year's three "must-read" articles, I focused on what I believe is practice-changing and once again chose to avoid articles that I've covered in prior Viewpoints.

These are excellent reads with take-home points that go beyond my simple summaries. I hope all acute care physicians will take some time to read them. Until then, enjoy these synopses.

Clinical Policy: Critical Issues in the Evaluation and Management of ED Patients With Suspected Non-ST-elevation Acute Coronary Syndrome

The evaluation of patients with potential acute coronary syndrome (ACS) has been the bane of emergency medicine for decades. For many years, we have been overadmitting patients for potential ACS, leading to costly negative workups. A major reason for the excessively conservative approach to these patients has been fear of litigation in the event that we miss ACS. Litigation would often be based on failure to follow guidelines, which have, for many years, stated that all of these patients need to receive a provocative test after being ruled out for myocardial infarction (MI).[1] The result is that an inordinate number of low-risk patients would be sent for provocative testing, which typically would also be negative.

A fact that we tended to ignore, however, was that a significant number of these patients would have false-positive results, leading to unnecessary cardiac catheterization and even bypass surgery.[2] What, then, is the appropriate threshold for risk in potential ACS below which mandating further workup potentially can induce more harm than benefit?

The American College of Emergency Physicians Clinical Policies Subcommittee stepped up to address this challenge and has indicated in its Clinical Policy that after a patient has been ruled out for MI, if the patient's risk for ACS is less than 2%, there is likely to be greater harm than benefit by mandating further provocative stress testing or coronary CT angiography.[3]

Is there a way to decide when a patient's risk of ACS is less than 2%? The answer is a resounding yes! Recently developed accelerated diagnostic protocols, the most popular of which is the HEART score,[4] have allowed us to risk-stratify patients to sufficiently low risk so as to bypass further testing. Specifically, if a patient's HEART score is ≤ 3, the estimated rate of major adverse cardiac events (MACE) is less than 2% at 1 month. This MACE is based on clinical factors, ECG interpretation, and a conventional troponin at the time of the patient's arrival. Physicians can opt to obtain a second troponin 3 hours after arrival, and if this is normal, the patient's risk for 1-month MACE is less than 1%. In either case, the Clinical Policy recommends that physicians should "not routinely use further diagnostic testing (coronary CT angiography, stress testing, myocardial perfusion imaging) prior to discharge" but instead simply "arrange outpatient follow-up in 1-2 weeks for low-risk patients in whom MI has been ruled out."[3]

This Clinical Policy goes into greater detail regarding accelerated diagnostic protocols, conventional and highly sensitive troponins, and use of antiplatelet medications, and the reader is encouraged to review the policy for some additional great practice recommendations.[3] But the key point here for all of us is that we finally have a formal endorsement from a major national organization stating that we no longer have to "stress" about getting provocative tests on our patients who are at low risk for ACS.

Cardiac Arrest and Mortality Related to Intubation Procedure in Critically Ill Adult Patients: A Multicenter Cohort Study

Cardiac arrest occurs in an estimated 2%-3% of patients in the first few minutes following emergent intubation.[5,6] Given that the vast majority of patients being intubated emergently are fairly sick to start, these numbers may not be surprising. Nevertheless, providers are often unprepared for such dramatic and rapid decompensation. DeJong and colleagues,[7] as well as previous authors,[5,6] have evaluated these intubation scenarios and found some consistent predictors for which patients are at highest risk for post-intubation arrest.

In this intensive care unit study, the authors retrospectively evaluated 1847 intubations and identified 49 cases (2.7%) of post-intubation cardiac arrest, including 14 (28.6%) who could not be resuscitated. They found that the main predictors of intubation-related cardiac arrest were hypoxemia prior to intubation (odds ratio, 3.99), absence of pre-oxygenation (odds ratio, 3.58), hypotension (systolic blood pressure < 90 mm Hg) prior to intubation (odds ratio, 3.41), age > 75 years old (odds ratio, 2.26), and overweight/obesity (body mass index > 25 kg/m2; odds ratio, 2.005). Not surprisingly, the 28-day mortality of intubated patients was markedly higher in patients who had post-intubation cardiac arrest (73.5% vs 30.1%).

It was notable that of the five independent risk factors that were identified for cardiac arrest, the top three are potentially modifiable. Acute care providers should take this study to heart and do everything possible, when time allows, to optimize oxygenation and blood pressure before intubation. Resuscitate before you intubate!

In-Flight Medical Emergencies: A Review

I'm sure the majority of us have at some point in our careers heard those words over the intercom: "Is there a doctor onboard? Please ring your call bell!" These are certainly not words that we like to hear. Although we feel an ethical duty to respond, we also feel unprepared to handle such emergencies outside the comfort of our clinical sites.

I myself am accustomed to seeing a triage note and some vital signs before I see a patient. Even when my patients are rushed in, moribund, without any clinical information, I feel comfortable in my cocoon of the emergency department with my stethoscope, a nearby ultrasound, and staff colleagues to help get the patient undressed, place the patient on a monitor, get good intravenous access, and show me an ECG. But on an airplane, it's just me, a patient, and a hundred passengers and crew staring at me and expecting me to know what to do. Fortunately, Martin-Gill and colleagues[8] have provided an excellent resource that should make us all a bit more comfortable.

In-flight emergencies are rare, occurring in approximately 1 per 604 flights.[8] Passenger cabins are pressurized to the equivalent of being at an altitude of 5000-8000 feet, producing mild hypoxia that contributes to some of the conditions that occur while flying. The authors discuss a few other physiologic reasons for the emergencies, a detailed review of which is beyond the scope of our brief review. Syncope and near-syncope are the most common in-flight emergencies, accounting for 30% of cases. Gastrointestinal illness (15%), respiratory distress (10%), and cardiovascular symptoms (7%) are the next most common presentations. Cardiac arrest, fortunately, accounts for only 0.2% of cases.

On-board providers should be reassured that the vast majority of patients do well and that diversion of the airplane is rarely necessary. Furthermore, decisions regarding the need for diversion are almost always made in conjunction with ground-based medical support. In the United States, the Aviation Medical Act affords "Good Samaritan" protection from liability except in cases of gross negligence or willful misconduct, although providers who seek compensation may lose such protection. Providers should also be aware that outside of the United States they are subject to different international laws, which may not afford the same level of Good Samaritan protection, and those laws may also require medical professionals to respond rather than allowing them the option of volunteering. The authors provide a potpourri of other pearls pertaining to epidemiology, medical equipment, ethical issues, and specific management. I strongly recommend that all medical providers read this fantastic review before their next trip.

That concludes this year's top three must-read articles. Please share your thoughts and especially your own picks for top articles. Thanks for reading, and Happy New Year to everyone!

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