Medicine articles

The essential articles on acute care medicine of 2021

As 2021 began, there seemed to be light at the end of the long, dark COVID-19 pandemic. A vaccine was introduced, the “curve” had been flattened, and by spring businesses were slowly starting to open. While the medical literature of 2020 seemed to be almost entirely focused on COVID-19, medical writers, researchers, and educators seemed to be slowly starting to focus more on non-COVID 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 to COVID-19. However, we are able to look back to 2021 and recognize a host of fantastic original research papers and guidelines that have improved patient care in so many ways. In this annual recap of my favorite articles from the past year, I’ll focus on what I think every acute care physician should read and know because they will improve patient care.

Specifically, I’ve picked out articles that didn’t seem to have garnered much notoriety in emergency medicine, but are nonetheless worthy of your time and attention. Note that this article serves as a summary only, and I encourage interested readers to peruse the full manuscripts for more details. I limit my recap to two articles, but we will cover other key topics of recent literature in the coming months.

Recommendations on Difficult Airway Management

Emergency physicians are well trained in airway management, and much of that training includes pre-intubation anatomical airway assessment. However, there are few recommendations on the physiological airway management considerations.

A Society for Airways Management set of recommendations was written primarily with anesthesiologists in mind, but many of the recommendations listed below are also highly relevant to emergency physicians. The authors make recommendations for hypoxic or hypotensive patients before induction; for patients with right ventricular dysfunction; for patients with severe metabolic acidosis; and for patients with neurological damage. Some of the key pearls follow.

Patients with hypoxemia

  • The importance of pre-oxygenation before intubation is again emphasized, and this can be achieved using high-flow oxygen for at least 3 minutes, or (in a cooperative patient) with eight breaths of vital capacity.

  • Maintenance of oxygenation during the apnea period should be continued. Apneic oxygenation can be delivered 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, obesityacute respiratory distress syndrome), pre-oxygenation should be performed with positive end-expiratory pressure (PEEP) using non-invasive positive pressure ventilation (NIPV) or bag-valve mask ventilation with a PEEP valve.

  • For patients with refractory hypoxemia, awake intubation to maintain spontaneous breathing should be considered.

  • Patients should be pre-oxygenated in an upright position when possible.

  • Elevated position (head elevated so as to bring the external auditory canal into the same horizontal line as the sternal notch) should be performed when possible in order to improve quality of sight, improve oxygenation, and reduce suction.

Patients with hypotension

  • Patients should be screened for high risk of hemodynamic collapse prior to administration of induction drugs and intubation by assessing the stroke index (SI). An SI > 0.7 predicts high risk. These patients should receive hemodynamic optimization (eg, intravenous fluids, administration of vasopressors) whenever possible, before administration of induction drugs and intubation.

  • Vasopressor infusions are preferable to boluses vasopressors. However, if vasopressor infusions are not possible, bolus vasopressors should be available and used to maintain systemic pressure during and after intubation until an infusion can be started.

    • When bolus vasopressors are used, diluted epinephrine should be considered 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 due to their high risk of hemodynamic decompensation with positive pressure ventilation.

  • RV dysfunction can sometimes worsen with fluid administration. Fluid-intolerant patients may instead require RV afterload reduction with inhaled or intravenous pulmonary vasodilators.

  • Patients with shock-induced right ventricular failure should be considered for extracorporeal membrane oxygenation (ECMO) prior to intubation, 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 higher PEEP to avoid atelectasis.

Patients with severe metabolic acidosis

  • Patients with severe metabolic acidosis are at high risk of post-intubation decompensation due to 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 breathing. Alternatively, consider a spontaneous breathing pattern after intubation with high minute ventilation (i.e. use a higher than normal respiratory rate on the ventilator to replicate pre-intubation minute ventilation).

  • Pre-intubation boluses of bicarbonate to prevent worsening acidosis are controversial and lack data showing any benefit.

Neurological injured patients

  • Eucapnia and normoxia must 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 headboard elevated to 30° vertical when possible.

  • Limit post-intubation PEEP to promote venous drainage.

Updated evidence for the treatment of anaphylaxis

The treatment of anaphylaxis is considered the bread and butter of emergency and acute care medicine, but much of what we have learned over the years is not well supported by the literature. In an article published in ResuscitationThe UK Resuscitation Council’s Anaphylaxis Task Force carried out a review of the evidence regarding the emergency treatment of anaphylaxis.

A summary of key points includes:

  • Anaphylaxis is defined as a systemic hypersensitivity reaction, usually of rapid onset, with life-threatening airway, breathing, and/or circulation impairment.

  • The most important treatment is epinephrine (EPI), with a recommended adult starting dose of 0.5 mg given intramuscularly (IM). Up to 10% of patients have a suboptimal response at one dose, but 98% will respond at the third dose; therefore, these authors recommend repeating IM EPI every 5 minutes, if necessary, for up to three doses.

    • There is no evidence to support 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 done. If IV PEI is used, the authors recommend an IV infusion rather than a bolus.

  • Administration of an IV fluid bolus is recommended in the majority of cases of anaphylaxis, regardless of the presence or absence of hemodynamic compromise, due to the profound reduction in venous tone and third-party spacing which usually occurs.

  • Antihistamines are not recommended at the start of treatment. They are only effective in reversing the cutaneous manifestations of anaphylaxis (which EPI also treats), and the sedation they produce may confound appropriate ongoing patient assessment. Additionally, the use of antihistamines early in treatment for anaphylaxis has been shown to delay appropriate use of EPI.

  • Steroids are not recommended at the start of treatment. They only help in the late phase of the inflammatory response, but despite this there is no good evidence that they decrease the biphasic response of anaphylaxis.

  • Inhaled beta-agonists are recommended in anaphylaxis only for patients with lower airway symptoms caused by anaphylaxis, but the authors caution that inhaled beta-agonists should not delay appropriate use of EPI .

  • The optimal observation period before discharge for stable patients is unknown. The authors note the recommendations of the American Academy of Allergy, Asthma, & Immunology and American College of Allergy, Asthma, and Immunology Joint Practice Parameters Task Force:

Summary and other honorable mentions

Here. My two favorite articles of 2021 on practice change (non-COVID-19). Not surprisingly, both papers deal largely with respiratory and hemodynamic issues – the AB-‘C of emergency medicine. While these bullet points provide key points from both of these articles, full discussions of these key points in the articles would provide far more education than I can provide in this brief article, and so I strongly encourage everyone to read the full articles.

I also encourage readers to check out the following “honorable mention” articles:

Stiell and colleagues have published a “Best Practices Checklist” on behalf of the Canadian Association of Emergency Physicians regarding the management of acute atrial fibrillation and atrial flutter; and on behalf of the American Heart Association (in conjunction with several other major organizations), Gulati and colleagues published the 2021 guideline for the assessment and diagnosis of chest pain. These two publications show us how we must strive to manage atrial fibrillation and chest pain, respectively, in the emergency department for years to come. We will likely cover these topics in Medscape Emergency Medicine Viewpoints over the coming year.

Don’t forget to rate in the comments section if you have a favorite article from 2021. Best wishes to all for a safe and happy 2022!

Amal Mattu, MD, is a professor, vice president 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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