The Must-Read Acute Care Medicine Articles From 2021

When 2021 began, there appeared to be light at the end of the long and dark COVID-19 pandemic. A vaccine was introduced, the "curve" had been flattened, and by spring, businesses were slowly starting to open. Whereas the medical literature of 2020 seemed to be almost entirely focused on COVID-19, medical writers, researchers, and educators seemed to slowly start turning more attention back to non–COVID-related topics in 2021.

Unfortunately, as I write this, the Omicron variant of the coronavirus is in full swing, and much of our attention has once again turned back to COVID-19. However, we are able to look back on 2021 and acknowledge a wealth of fantastic original research articles and guidelines which have improved patient care in many ways. In this annual recap of my favorite articles of the past year, I will focus on what I believe every acute care physician should read and know, as they will improve patient care.

Specifically, I have chosen articles that did not appear to gain widespread notoriety in emergency medicine but are, nevertheless, worthy of your time and attention. Note that this write-up serves as a summary only, and I encourage interested readers to peruse the full manuscripts for further details. I am limiting my recap to two articles, but we will address other key topics from the recent literature in the coming months.

Recommendations on Difficult Airway Management

Emergency physicians are well-trained in airway management, and a major part of that training includes the pre-intubation anatomic assessment of the airway. However, there are few recommendations on the physiologic considerations for airway management.

A set of recommendations from the Society for Airway Management was written primarily with anesthesiologists in mind, but many of the recommendations listed below are very relevant to emergency physicians as well. The authors make recommendations for patients who are hypoxic or hypotensive prior to induction; for patients with right ventricular dysfunction; for patients with severe metabolic acidosis; and for neurologically injured patients. Some of the key pearls follow.

Patients with hypoxemia

The importance of pre-oxygenation before intubation is once again emphasized, and this can be performed using high-flow oxygen for at least 3 minutes, or (in a cooperative patient) with eight vital capacity breaths.
Maintenance of oxygenation during the apneic period should be continued. Apneic oxygenation can be provided with a nasal cannula at 15 liters per minute (LPM) or with a high-flow nasal oxygen system at 40-70 LPM.
For patients with significant shunt physiology or reduced functional residual capacity (eg, late pregnancy, obesity, acute respiratory distress syndrome), pre-oxygenation should be performed with positive end expiratory pressure (PEEP) using noninvasive positive pressure ventilation (NIPPV) or bag-valve mask ventilation with a PEEP valve.
- When higher levels of PEEP are required, an extraglottic device should be considered during pre-oxygenation.
For patients with refractory hypoxemia, awake intubation to maintain spontaneous respirations should be considered.
Patients should be pre-oxygenated in the upright position when possible.
Ramped-up position (head elevated so as to bring the external auditory canal in the same horizontal line as the sternal notch) should be performed when possible in order to improve the grade of view, improve oxygenation, and reduce aspiration.

Patients with hypotension

Patients should be screened for high risk for hemodynamic collapse prior to administration of induction medications and intubation by assessing the shock index (SI). An SI > 0.7 predicts a high risk. These patients should receive hemodynamic optimization (eg, intravenous fluids, administration of vasopressors) whenever possible, prior to administration of induction medications and intubation.
Vasopressor infusions are preferable to bolus-dosed vasopressors. However, if vasopressor infusions are not possible, bolus-dosed vasopressors should be available and used to maintain systemic pressure during and after the intubation until an infusion can be started.
- When bolus-dosed vasopressors are used, diluted epinephrine should be considered as the vasopressor of choice in patients with depressed myocardial function.

Patients with right ventricular (RV) dysfunction

Patients should be screened for significant RV dysfunction prior to intubation because of their high risk for hemodynamic decompensation with positive pressure ventilation.
RV dysfunction may sometimes worsen with fluid administration. Fluid-intolerant patients may instead need RV afterload reduction with inhaled or intravenous pulmonary vasodilators.
Patients with RV failure–induced shock should be considered for pre-intubation extracorporeal membrane oxygenation (ECMO) if available.
Patients with RV volume overload should receive diuresis prior to intubation.
Ventilator settings should aim to (1) avoid hypercapnia, (2) maintain low airway pressures, and (3) use a higher PEEP to avoid atelectasis.

Patients with severe metabolic acidosis

Patients with severe metabolic acidosis are at high risk for decompensation after intubation because of volume depletion and inadequate alveolar ventilation, resulting in profound acidosis.
Patients with high minute ventilation prior to intubation should be considered for awake intubation to maintain spontaneous respirations. Otherwise, consider a spontaneous breathing mode after intubation with a high minute ventilation (ie, use a higher-than-normal respiratory rate on the ventilator in order to reproduce the pre-intubation minute ventilation).
- Apnea time should be minimized in order to minimize worsening acidosis.
Pre-intubation bicarbonate boluses to prevent worsening acidosis are controversial and lack data showing any benefit.

Neurologically injured patients

Eucapnia and normoxia should be maintained before, during, and after intubation to maintain stable cerebral blood flow.
Hemodynamically neutral induction agents should be used.
Patients should be positioned with the head of bed elevated to 30° upright when possible.
Limit PEEP post-intubation in order to promote venous drainage.

Evidence Update for the Treatment of Anaphylaxis

The treatment of anaphylaxis is considered bread-and-butter in emergency and acute care medicine, but a great deal of what we have learned over the years is not well supported by the literature. In an article published in Resuscitation, the Anaphylaxis Working Group of the Resuscitation Council of the United Kingdom performed an evidence review regarding the emergency treatment of anaphylaxis.

A summary of key points includes:

Anaphylaxis is defined as a systemic hypersensitivity reaction, usually rapid in onset, with potentially life-threatening compromise in airway, breathing, and/or circulation.
The most important treatment is epinephrine (EPI), with an initial recommended dose in adults of 0.5 mg administered via the intramuscular (IM) route. Up to 10% of patients have a suboptimal response to one dose, but 98% will respond by the third dose; therefore, these authors recommend repeating the IM EPI every 5 minutes, if needed, up to three doses.
- There is no evidence to support any alternative or additional vasopressors, and so they should only be used if EPI is ineffective.
- Intravenous (IV) EPI is not recommended initially except in the perioperative setting where close monitoring can be performed. If IV EPI is used, the authors recommend an IV infusion rather than bolus dosing.
IV fluid bolus dosing is recommended in the majority of cases of anaphylaxis, regardless of presence or absence of hemodynamic compromise, because of the profound reduction in venous tone and third-spacing that typically occurs.
Antihistamines are not recommended in early treatment. They are only effective for reversing skin manifestations of anaphylaxis (which EPI treats as well), and the sedation they produce can confound the proper ongoing evaluation of the patient. Furthermore, the use of antihistamines early in the treatment of anaphylaxis has been found to produce delays in proper use of EPI.
Steroids are not recommended in early treatment. They help only with the late phase of inflammatory response, but despite that, there is no good evidence that they decrease the biphasic response of anaphylaxis.
- There is some emerging evidence that the use of steroids may actually be associated with increased morbidity even after correcting for anaphylaxis severity.
- The authors recommend the use of steroids in anaphylaxis only for patients with poorly controlled asthma and possibly for patients with refractory anaphylaxis.
Inhaled beta-agonists are recommended in anaphylaxis only for patients with lower respiratory tract symptoms caused by anaphylaxis, but the authors warn that the inhaled beta-agonists should not delay proper use of EPI.
The optimal observation period before discharge for stable patients is unknown. The authors do note the recommendations of the Joint Task Force on Practice Parameters of the American Academy of Allergy, Asthma, & Immunology and the American College of Allergy, Asthma, and Immunology:
- Biphasic reactions were more common in patients with severe initial symptoms — for example, those requiring more than one dose of EPI; therefore, these patients are recommended to have "extended observation".
- Lower-risk patients with resolved symptoms of anaphylaxis can be observed for 1 hour, which would capture 95% of biphasic reactions in this group of patients.

Summary and Other Honorable Mentions

There you have it. My two favorite practice-changing (non–COVID-19) articles of 2021. Not surprisingly, both articles deal largely with airway and hemodynamic concerns — the A-B-'C's of emergency medicine. Although these bulleted pearls provide key points from these two articles, the full discussions of those key points in the articles would provide a great deal more education than I can provide in this brief write-up, and so I strongly encourage everyone to read the full articles.

I also encourage readers to peruse the following "honorable mention" articles:

Stiell and colleagues published a "Best Practices Checklist" on behalf of the Canadian Association of Emergency Physicians pertaining to the management of acute atrial fibrillation and atrial flutter; and on behalf of the American Heart Association (in collaboration with several other major organizations), Gulati and colleagues published the 2021 Guideline for the Evaluation and Diagnosis of Chest Pain. Both publications show us how we should strive to manage atrial fibrillation and chest pain, respectively, in the emergency department for years to come. We are likely to address these topics in Medscape Emergency Medicine Viewpoints in the coming year.

Please be sure to note in the comments section whether you have a favorite article of 2021. Best wishes to all for a safe and happy 2022!

Amal Mattu, MD, is a professor, vice chair of education, and co-director of the emergency cardiology fellowship in the Department of Emergency Medicine at the University of Maryland School of Medicine in Baltimore.

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