Management Of Acute Asthma In The Emergency Department

Table of Contents

 

1. Abstract
2. Case Presentation
3. Introduction
4. Critical Appraisal Of The Literature
5. Epidemiology
   1. Prevalence Of Asthma And Acute Exacerbations
   2. Epidemiology Of Asthma Hospitalizations And Deaths
6. Etiology And Pathophysiology
   1. Acute Exacerbations
7. Differential Diagnosis
   1. Chronic Obstructive Pulmonary Disease
   2. Acute Decompensated Heart Failure
   3. Other Disease Processes In The Differential Diagnosis
8. Prehospital Care
9. Emergency Department Evaluation
   1. Mild Exacerbations
   2. Moderate Exacerbations
   3. Severe Exacerbations
10. Diagnostic Studies
    1. Laboratory Studies
    2. Arterial Blood Gas
    3. End-Tidal Carbon Dioxide Monitoring
    4. Chest Radiography
    5. Peak-Flow Measurements
11. Treatment
    1. Beta Agonists
       1. Racemic Albuterol Versus Levalbuterol
    2. Holding Chambers
    3. Metered-Dose Inhalers Versus Nebulizers
    4. Intermittent Versus Continuous Nebulizer Treatments
    5. Inhaled Versus Intravenous Or Subcutaneous Beta Agonists
    6. Ipratropium Bromide
    7. Corticosteroids
       1. Magnesium Sulfate
    8. Epinephrine
    9. Ventilation
       1. Clinical Pearls For Ventilator Management
12. Controversies And Cutting Edge
    1. Theophylline
    2. Aminophylline
    3. Heliox
    4. Long-Acting Beta Agonists
    5. Ketamine
    6. Leukotriene Inhibitor Agonists
    7. Noninvasive Positive Pressure Ventilation
13. Special Circumstances
    1. Pediatric Patients
       1. Pregnancy
14. Disposition
    1. Admission Versus Discharge
    2. Asthma Scoring Systems
15. Summary
16. Risk Management Pitfalls For Asthma Management In The Emergency Department
17. Time- And Cost-Effective Strategies
18. Case Conclusions
19. Clinical Pathway For Management Of Asthma In The Emergency Department
20. Tables and Figures
    1. Table 1. Risk Factors For Death From Asthma
    2. Table 2. Differential Diagnosis Of Wheezing In Adults ANd Children
    3. Table 3. Common Pediatric Complaints Misdiagnosed As Asthma
    4. Table 4. Suggested Peak Flow Rate When Height And Baseline Measurements Are Not Available
    5. Table 5. Suggested Drug Dosing Guide For The Treatment Of Asthma
    6. Table 6. Recommended Initial Ventilator Settings
    7. Figure 1. Illustration Of Breath-Stacking On The Ventilator Tracing
    8. Figure 2. Normal Ventilator Flow Tracing
    9. Figure 3. Breath-Stacking On The Ventilator Tracing
21. References

Abstract

Asthma is primarily a clinical diagnosis that is made from a combination of historical features and clinical examination findings. The mainstay of asthma treatment includes short-acting beta agonist therapy (albuterol) and steroids. Handheld inhalers are sufficient for most inhaled therapy; all patients on inhalers should be provided with a spacer. The severity of asthma exacerbations is determined by 3 features: (1) clinical presentation, (2) peak expiratory flow rates, and (3) vital signs. Additional testing, such as chest x-ray and blood gas measurements, is reserved for select patients. Spirometry aids in the diagnosis of asthma and measurement of severity, but it is not always required, nor should it be solely relied upon to make disposition decisions. Inhaled ipratropium decreases hospitalization rates, and it should be routinely used. Levalbuterol provides little to no advantage over less-expensive racemic albuterol. Noninvasive positive pressure ventilation may be utilized in patients with moderate to severe exacerbations. Ketamine may be considered in severe exacerbations, but it should not be used routinely. Magnesium sulfate may be beneficial in severe asthma exacerbations, but routine use for mild to moderate exacerbations is not indicated.

Case Presentation

A 19-year-old college student presents with marked dyspnea and dysphagia. He reports a history of asthma, for which he takes albuterol as his only medication. Over the last 3 days, he has been coughing and wheezing with increasing severity. Even though he has been using his albuterol inhaler every 2 hours, there has been minimal to no response. EMS administered a 10-mg albuterol nebulizer treatment and magnesium sulfate intravenously en route to the ED. Upon arrival, the patient appears in extremis, and you wonder if there is something you can do to avoid intubation . . .

While establishing IV access and calling respiratory therapy for your first patient, a 24-year-old Hispanic female with a history of asthma who is 15 weeks pregnant presents with tachypnea and acute shortness of breath with audible wheezing. She has been taking albuterol and fluticasone at home with no relief of symptoms. She has a blood pressure of 110/78 mm Hg, heart rate of 110 beats/ min, respiratory rate of 40 breaths/min, and pulse oximetry of 93% on room air. Physical exam demonstrates accessory respiratory muscle usage, decreased breath sounds, and expiratory wheezing. You recognize that your patient is at risk for deteriorating, and you wonder which interventions are safest to use in pregnancy . . .

Just as you think you are getting control of your first 2 patients, a 6-year-old girl is brought in by her mother with the chief complaint of “mild bronchitis.” Her mother reports that the girl’s symptoms began 3 days ago, with initial upper respiratory infection symptoms that progressed to nocturnal cough and mild wheezing. She is otherwise well. According to her mother, the girl has 2 to 3 bouts per year of this “bronchitis” that require emergency care. She has had 2 ED visits within the last year, with no prior hospitalization for her bronchitis. Her vital signs are: blood pressure of 95/55 mm Hg, heart rate of 98 beats/min, respiratory rate of 28 breaths/min, temperature of 37.2°C, and a pulse oximetry of 94% on room air. Her physical exam is only significant for end-expiratory wheezing with no use of accessory muscles and no stridor. The case seems straightforward, but you wonder if there is something you are missing . . .

Introduction

Asthma is the most common chronic respiratory disease, affecting up to 10% of adults and 30% of children in the Western world. Asthma is a worldwide health problem, affecting over 300 million individuals of all ages and ethnicities. It is estimated that, worldwide, 250,000 people die prematurely each year as a result of asthma.¹ Asthma is a chronic inflammatory disorder of the lungs that is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing. The airflow obstruction caused by asthma is reversible either spontaneously or with medication.

Asthma is defined by its clinical, physiologic, and pathologic characteristics, with reversible wheezing as the most common finding. From a public health point of view, understanding the underlying causes of asthma and its exacerbants is key to preventive strategies. From an emergency medicine perspective, having clear strategies on how to best manage acute presentations is key to good outcomes. This issue of Emergency Medicine Practice provides an evidence-based review of asthma as it relates to emergency department (ED) care and establishes best-practice approaches to management.

Critical Appraisal Of The Literature

The Ovid MEDLINE®, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and PubMed databases were searched using the subject heading asthma. Major terms included: asthma, emergency department, epidemiology, score, treatment, steroid, inhaled, nebulizer, and guideline. The literature search was initially limited to relevant titles from the past 10 years; however, upon finding literature suitable for this review, additional references were added. Additionally, searches were conducted using the minor headings listed throughout this review. Searches identified observational studies, case series, and randomized trials that were available in English. The Cochrane Database of Systematic Reviews was also searched. Reference listings from major textbooks and significant primary literature were reviewed for relevant articles. National Asthma Education and Prevention Program (NAEPP) Expert Panel Report 3 (EPR-3) guidelines were included, and their references were reviewed.

Existing literature on asthma is very broad and spans several decades. Surprisingly, there is a limited amount of new research on acute asthma management that impacts clinical decision-making, and many of the treatments used today have been vetted over several decades. In performing this review, we prioritized data from randomized controlled trials to form recommendations and opinions, but such highquality evidence was not always available. Given the rarity of severe asthma, studies involving critically ill patients are extremely limited, compared to mild and moderate asthma. As such, the amount of highquality prospective data are limited, and we were often forced to draw conclusions from literature that is subject to bias.

Currently, the literature on treatments for mild and moderate asthma is robust, and most modalities have been well evaluated. Future studies should focus on severe asthma. Reliable methods for triaging asthma exacerbations do not currently exist, and this is yet another area in need of futurestudies. It is also worth noting that most ED-based literature on asthma uses a “working” definition of asthma rather than relying on strict criteria; thus, some of the studies likely enrolled patients with nonasthmatic wheezing.

Risk Management Pitfalls For Asthma Management In The Emergency Department

1. “The treatment seemed straightforward; I didn’t think their home situation was any of my business.” Psychosocial problems need to be identified and addressed as part of asthma management, because, even with best practice, these problems place patients at an increased risk of dying. Family psychosocial problems and financial problems are associated with increased risk of mortality for patients aged > 31 years but not for younger patients. Males were at increased risk of mortality from asthma exacerbation overall, but females with family problems are at greater risk than males with family problems. Alcohol use increased the risk of mortality for individuals who received only verbal instructions without a written action plan.
2. “I thought the longer-acting medication would help reduce the need for repeat treatments.” Clinical studies of long-acting beta agonists compared to placebo in asthma patients using variable doses of inhaled corticosteroids have raised the issue of mortality risk in patients with asthma who are taking regular longacting beta agonists. Long-acting beta agonists added to inhaled corticosteroids reduces asthma-related hospitalizations compared to inhaled corticosteroids alone, and there is no statistical increase in mortality. However, longacting beta agonist treatment without inhaled corticosteroids does increase mortality risk in asthma. Healthcare providers must understand the essential need for adequate dosing of inhaled corticosteroids to control airway inflammation. Risk Management Pitfalls For Asthma Management In The Emergency Department
3. “The patient didn’t have any questions, so I didn’t think she really wanted to hear all the intricate details. “ Prescription of steroids in the treatment of acute asthma can lead to the following complications: avascular necrosis, mood changes, visual complaints, and infection. A provider treating patients with steroids must be diligent in explaining the potential side effects of steroids. The informed consent process, documentation, and close monitoring of patients are critical to avoid potential litigation.
4. “I was concerned about the fetal side effects and figured that short-acting beta agonist therapy was sufficient.” Maternal asthma is associated with an increased risk of spontaneous abortion. Standard medical treatment of acute asthma does not increase the risk of congenital anomalies in the offspring when taken during the first trimester of pregnancy.
5. “I thought I would see how the patient responded to standard therapies before starting noninvasive positive-pressure ventilation.” Noninvasive ventilation (NIV) has been shown to be effective in a wide variety of clinical settings; however, reports of NIV in asthma patients are scarce. There are a few prospective clinical trials reporting promising results in favor of the use of NIV in a severe asthma attack. A trial of NIV prior to invasive mechanical ventilation seems acceptable and may benefit patients by decreasing the need for intubation and by supporting pharmaceutical treatments. Although selecting the appropriate patients for NIV use is a key factor in successful NIV application, how to distinguish such patients is still quite controversial. If this technology is going to be employed, reaching for it early will likely yield more benefit.
6. “I knew the patient was sick, but ETCO2 seemed sufficient.” In adult asthma patients with acute exacerbations, concordance between ETCO2 measured by capnography and PaCO2 measured by blood gas is high. However, capnography is not a replacement of blood gas as an accurate means of assessing alveolar ventilation in acute asthma.
7. “We had trouble getting IV access, so I thought the nebulized therapy would suffice.” The use of IV magnesium sulfate (in addition to beta agonists and systemic steroids) in the treatment of acute asthma improves pulmonary function and reduces the number of hospital admissions for children; it only improves pulmonary function for adults. Though the use of nebulized magnesium sulfate appears to produce benefits for adults, the routine use of this form of magnesium sulfate should not be considered standard of care at this point. Risk Management Pitfalls For Asthma Management In The Emergency Department
8. “Steroids from the discharge pharmacy seemed much easier.” Early administration of steroid therapy is essential. Current literature suggests that early administration decreases hospitalization rates and bounce-back rates. When treating for acute exacerbations, steroid therapy should be administered early.
9. “PEF rate values were improved, so discharge seemed appropriate.” Proper triage of acute exacerbations must be based on complete clinical and psychosocial factors as a package. There is no single clinical factor that can be relied upon for triaging. Additionally, lack of historical risk factors does not equal lack of morbidity and mortality risk.
10. “It seemed that if we could have held off a little bit longer, the patient’s course would turn around.” When intubation is clinically indicated, the emergency clinician should proceed without delay. Waiting to intubate when intubation is clinically indicated will lead to increased likelihood of procedural complications and respiratory arrest. We recommend that only the most experienced provider perform the procedure, given the increased need for firstpass success.

Tables and Figures

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study will be included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the authors, are noted by an asterisk (*) next to the number of the reference.

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