This past summer, it became quite apparent that larger and more intense forest fires were contributing to poor health in the United States.¹ One of the consequences of the increase in forest fires was more air pollution. The incidence of asthma is higher if the air in your neighborhood is more polluted.² The more nitrogen dioxide and carbon monoxide in the air, the more asthma. In fact, a recent study out of Calgary in Canada suggested that there were 13 percent more asthma exacerbations presenting to emergency departments (EDs) when there was visible wildfire smoke in the city.³ Asthma presentations to EDs have increased recently.⁴ Ten people die from asthma daily in the United States, deaths that are nearly all preventable.^5,6 This article outlines how appropriate risk stratification and management of asthma in the ED can reduce preventable deaths and minimize bounce backs.

While you may be aware of the aphorism, “All that wheezes is not asthma,” it can also be stated that “asthma does not always wheeze.” The diagnosis of asthma is usually obvious, with the patient having recurrent exacerbations and visits to the ED. However, the diagnosis is not so obvious, and sometimes what appears to be a recurrent exacerbation is a more sinister diagnosis, like a pulmonary embolism. It is therefore important to entertain wide age-appropriate differential diagnoses, including heart failure and pneumonia in adults and foreign body and bronchiolitis in pediatric patients. Anaphylaxis may overlap with asthma, and when both are present, aggressive treatment is necessary to prevent death. Stridor may be mistaken for wheeze. While stridor is predominantly an inspiratory sound and wheeze an expiratory one, stridor may cause an expiratory sound that can be mistaken for wheeze. The absence of wheeze and a silent chest to auscultation may indicate life-threatening asthma.

Once the diagnosis of asthma exacerbation has been established in the ED, risk stratification is necessary, as this helps guide management and disposition. Risk stratification in the ED can be gleaned simply from the history and physical exam. The most predictive factor for admission is previous hospitalizations for asthma. The next two most predictive variables for admission are room-air O2 saturation less than 95 percent and peak expiratory flow (PEF) severity category (severe/very severe versus mild/moderate).⁷ Risk factors for asthma-related death that should be gathered from the history include a history of requiring intubation and mechanical ventilation, having a hospitalization or ED visit for asthma in the previous year, not currently using or poorly adherent with therapy, overusing beta agonists, a history of psychiatric disease or psychosocial problems, concomitant food allergy, and currently using or having recently stopped oral corticosteroids.⁸

It is unclear whether ED PEF monitoring improves outcomes. While some guidelines include improving PEF measurements and greater than 60-80 percent of personal best (or predicted) in their algorithm for safe discharge from the ED, ACEP reviewed the literature on the topic and concluded that ED PEF monitoring for adults with asthma exacerbation does not improve outcomes, predict need for hospitalization, or decrease mortality.^9,10 One study suggested that PEF done at discharge was not predictive of relapse in patients discharged from the ED with asthma exacerbations.¹¹ On the other hand, PEF measurements can be a useful screening tool for hypercapnia, making routine assessment of blood gases unnecessary in most patients. The decision to perform PEF monitoring should be individualized and considered a single data point within the clinical context to aid in disposition decision making. Blood gases are not routinely required. They should be considered in patients with a PEF less than 50 percent predicted or for those patients who do not respond to initial treatments and who are deteriorating.¹²

After history-based risk stratification comes an assessment of severity of illness to further help guide management. Mild or moderate asthma exacerbation is characterized by the patient being able to talk in phrases, preferring sitting to lying, not appearing agitated, and having an elevated respiratory rate, no accessory muscle use, heart rate of 100-120 bpm, oxygen saturation of 90-95 percent, and PEF of greater than 50 percent predicted or best. Severe asthma exacerbation is characterized by the patient being able to talk in words only (not phrases), appearing agitated, and having a respiratory rate greater than 30/min, accessory muscle use, heart rate greater than 120 bpm, oxygen saturation less than 90 percent and PEF less than or equal to 50 percent predicted or best. Life-threatening asthma is characterized by drowsiness, confusion, or silent chest to auscultation.¹³

For mild to moderate asthma exacerbations, current treatment recommendations include short-acting beta agonists (SABA) at 4-10 puffs via MDI with spacer repeated every 20 minutes for one hour, prednisolone 40-50 mg orally, and oxygen supplementation to a target saturation of 93-95 percent. Reassessment should be considered in one hour or less with continued SABA treatment as needed. Corticosteroids should be given within one hour of presentation to patients with moderate to severe exacerbations.

For severe exacerbations treatment, recommendations include adding ipratropium bromide 4-8 puffs via MDI with spacer, repeated every 20 minutes for one hour, continued SABA treatments, and magnesium sulphate 2 g IV if there is little or no improvement with initial therapies.^14,15 Non-invasive positive pressure ventilation, continuous SABA, repeated magnesium sulfate, epinephrine, helium–oxygen mixtures, and endotracheal intubation with ketamine should be considered in patients who deteriorate despite these treatments or who present with life-threatening asthma.¹⁶

Perhaps the most important aspect of ED management of non-life-threatening asthma exacerbations is providing evidence-based discharge instructions and appropriate prescription medications. A common pitfall in the management of asthma exacerbations is neglecting to prescribe an inhaled corticosteroid in addition to a beta agonist on discharge from the ED. Inhaled corticosteroids are seldom prescribed on discharge from the ED, in one study at a rate as low as 6 percent.¹⁷ Inhaled steroids used as a controller therapy improve lung function and symptom control, while also reducing airway inflammation, the risk of exacerbation, the need for repeat ED visits, and the total exposure to systemic steroids.¹⁸ Even patients who are provided a prescription for a short course of oral corticosteroids additionally require one for inhaled corticosteroids, which should be used for at least three to six weeks after ED discharge. In a randomized controlled trial, the addition of high-dose inhaled corticosteroids to a course of oral corticosteroids at discharge was associated with a lower risk of relapse of the asthma exacerbation at 21 days than the use of oral corticosteroids alone.¹⁹ Inhaler technique should ideally be taught before discharge home. Poor inhaler technique is associated with poor asthma control and increased ED visits, so teaching patients proper MDI plus spacer technique before discharge from the ED may prevent bounce backs.²⁰ Asthma care plans have been shown to decrease bounce backs, as well. Patient education should include the role of each medication and the avoidance of allergens, irritants, and workplace exposures.²¹ Robust evidence supports the role of written asthma action plans that detail how to prevent and manage future exacerbations, and every ED should provide online and/or paper access to such plans.^22,23 Written action plans should include when to increase therapy, how to increase it, how long to increase it, and when to seek medical care.

The simple principles outlined here of risk stratification, treatment, and discharge instructions will keep our patients with asthma healthy and prevent frequent ED visits, morbidity, and mortality.

A special thanks to Dr. Leeor Sommer and Dr. Sameer Mal for their expert contributions to the EM Cases podcast that inspired this article.

Dr. Helman is an emergency physician at North York General Hospital in Toronto. He is an assistant professor at the University of Toronto, Division of Emergency Medicine, and the education innovation lead at the Schwartz/Reisman Emergency Medicine Institute. He is the founder and host of Emergency Medicine Cases podcast and website (www.emergencymedicinecases.com).

References

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