Asthma

by Ayse Ece Akceylan

Case Presentation

A 50-year-old male with a history of asthma presents to the emergency department (ED) with shortness of breath, tachypnea, and audible wheezing. The patient has taken his prescribed medications at home, but his symptoms did not relieve. His vitals were as follows: BP 130/90 mmHg, HR 120 bpm, RR 40 bpm, SpO2 92% on room air. Physical exam revealed accessory respiratory muscle use, expiratory wheezing and decreased breath sounds with expiratory rhonchi. Nebulized short-acting beta2-agonists (SABA) and systemic corticosteroid were ordered. Peak expiratory flow (PEF) measurements before and after treatment were 125 and 360, respectively. Auscultation after initial treatment revealed much-improved airflow. The patient was discharged following clinical improvement, with a prescription of oral corticosteroids in addition to his current medications.

Introduction

Asthma is a chronic inflammatory disorder of the airways characterized by recurrent episodes of variable expiratory airflow limitation. Asthmatic patients have hyperresponsive airways that constrict when exposed to various stimuli. Symptoms and airflow limitation are often reversible, either spontaneously or with treatment. However, reversibility may be incomplete in some patients. Although patients appear to recover completely clinically, some asthmatic patients may have chronic airflow limitation. The diagnosis of asthma should be based on the history of characteristic symptom patterns and evidence of variable airflow limitation documented by bronchodilator reversibility testing or other tests.

Pathophysiology

The mediators released in response to allergens and nonallergic stimuli cause inflammation, edema, mucus production, and airway smooth muscle hypertrophy. All of these lead to bronchoconstriction and hyperreactivity, aggravating airway obstruction and airflow limitation. The repetitive airway inflammation leads to persistent structural changes in airways, called airway remodeling. This results in increased airway resistance and a decrease in forced expiratory volumes and flow rates. As a result, the lungs become hyperinflated. Ventilation-perfusion mismatch develops despite increased work of breathing. The interaction of these features determines the clinical manifestations, the severity of asthma and the response to therapy.

Presenting Signs and Symptoms

The classic symptoms include the triad of dyspnea, wheezing and coughing. Physical findings during an asthma exacerbation can be variable. A patient with a mild exacerbation may merely be coughing and complaining of chest tightness, whereas a patient with a severe exacerbation will be in respiratory distress, with tachypnea and loud wheezing. At the other end of the spectrum are patients with a “silent chest,” which reflects very severe airflow obstruction and air movement insufficient to promote a wheeze.

The exacerbation begins with coughing and a sensation of chest constriction. As the attack advances, expiration is prolonged, wheezing becomes prominent, and accessory respiratory muscles are used. To decrease the effort of breathing, the patient may sit upright or lean forward. The appearance of paradoxical respirations reflects impending ventilatory failure. Alteration in mental status heralds respiratory arrest.

Critical Bedside Actions

  1. Ensure adequate oxygenation
  2. Give SABA to reverse airflow obstruction
  3. Give systemic corticosteroids to relieve inflammation
  4. Carry out serial assessments to monitor the response to therapy

General Approach

  • Obtain patient history, assess exacerbation severity and initiate treatment simultaneously. Respiratory rate, dyspnea, pulse rate, oxygen saturation and lung function reflect exacerbation severity.
  • Keep alternative causes of breathlessness in mind.
  • Start treatment with repeated doses of inhaled SABA by a puffer, spacer, or nebulizer. Give early oral corticosteroids and controlled flow oxygen in life-threatening exacerbations or if Forced Expiratory Volume in 1 Second (FEV1) is less than 30% of the predicted. Target oxygen saturation is 93-95% in adults and adolescents, and 94-98% in children between 6-11 years.
  • Monitor symptoms and oxygen saturation frequently or continuously. Measure lung function after one hour.3
  • Add ipratropium bromide to treatment in severe exacerbations. Consider intravenous magnesium sulfate if the patient is unresponsive to intensive initial treatment.
  • Do not routinely perform chest x-ray or blood gases, or prescribe antibiotics.
  • Prescribe ongoing controller treatment before discharge to reduce the risk of future exacerbations. Provide follow up for all patients, preferably within a week.

Differential Diagnosis

Wheezing, coughing, and dyspnea may be caused by many other conditions, including pneumonia, bronchitis, croup, bronchiolitis, chronic obstructive pulmonary disease, congestive heart failure, valvular heart diseases, pulmonary embolism, allergic reactions, gastroesophageal reflux disease, exposure to odors, dust, and gas, and upper airway obstruction from vocal cord dysfunction, edema, neoplasm or a foreign body. Any of these alternative diagnoses may also be found together with asthma.

History/Physical Examination Hints

History

  • Possible causes of the current exacerbation
  • The severity of symptoms compared with previous exacerbations
  • Other comorbidities
  • Current asthma medications and adherence to therapy
  • Any use of potential asthma triggering medication
    • Aspirin
    • Beta-blockers
    • Angiotensin-converting enzyme inhibitors
  • Any risk factors for asthma-related death
    • poor adherence to asthma medications
    • psychosocial problems
    • history of near-fatal asthma requiring intubation and mechanical ventilation
    • hospital visit for asthma in the past year
    • currently using or having recently stopped using oral corticosteroids
    • not currently using inhaled corticosteroids
    • over-use of SABAs
    • food allergies

Physical Examination

  • Check vital signs
  • Look for signs of exacerbation severity
    • use of accessory muscles
    • mentation
    • sitting position
    • level of consciousness
  • Look for complicating factors
    • Anaphylaxis
    • Pneumonia
    • Pneumothorax
  • Look for signs of alternative conditions that could explain acute dyspnea
    • cardiac failure
    • pulmonary embolism
  • PEF in patients older than 5 years

The most common finding on physical examination is expiratory wheezing. With severe airway obstruction, it decreases or vanishes because air movement velocity is insufficient to produce sound. Crackles and inspiratory wheezing are not features of asthma. They are more likely to be seen in pneumonia. Inspiratory and expiratoy crackles, however, are seen in pulmonary edema.

Patients with the mild or moderate attack can talk in full sentences or phrases. Patients may prefer sitting to lying, but accessory muscles are not used. Respiratory rate is increased, and the pulse rate is around 100-120 bpm. Oxygen saturation on room air is 90-95%, and PEF > 50% predicted or best.

Patients with a severe attack can only talk in words, sit hunched forwards, use accessory muscles and show agitation. Respiratory rate is >30/min. Pulse rate exceeds 120 bpm. Tachypnea and tachycardia are associated with severe obstruction, but a lower rate does not rule out severe asthma. Oxygen saturation on air is <90% and PEF≤50% predicted or best.

Patients with the life-threatening attack are drowsy or confused and have silent chest.

Emergency Diagnostic Tests And Interpretation

  • Pulmonary Function Tests: Bedside spirometry is used both for initial assessment and for evaluating the response to therapy. If possible, and without delaying treatment, record PEF or FEV1 before treatment. Patient cooperation is essential for these tests to be reliable. Monitor lung function at intervals until a clear response to treatment has occurred, or a plateau is reached. When possible, management decisions should be guided by the patient’s personal best PEF or FEV1 value or, if unknown, predicted values.
  • Pulse oximetry: is a noninvasive, convenient and continuous method for monitoring oxygen saturation before and during treatment.
  • Arterial Blood Gas (ABG) analysis: is helpful if there is a concern for hypoventilation with carbon dioxide retention and respiratory acidosis. It is not indicated in the majority of patients with mild to moderate asthma exacerbation. Consider ABG analysis for patients with a PEF or FEV1 <50% of the predicted, or for those who do not respond to initial treatment or continue deteriorating despite treatment. A PaO2 <60 mmHg and normal or increased paCO2 (especially >45 mmHg) indicate respiratory failure. Fatigue and somnolence suggest that pCO2 may be increasing and airway intervention may be needed. Do not wait for arterial blood gas confirmation treat ventilatory or respiratory failure.
  • Other Blood Testing: Laboratory studies are rarely helpful in an acute asthma attack.
  • Radiology Studies: Radiography is only indicated if there is the possibility of pneumothorax, pneumomediastinum, pneumonia, or other medical conditions.
  • Electrocardiogram and Cardiac Monitoring: A routine electrocardiogram is unnecessary. Older patients and patients with coexistent heart disease or with severe exacerbation should undergo continuous cardiac monitoring to detect dysrhythmias.

Treatment Options

  • Oxygen: Administer by nasal cannula or mask. Target arterial oxygen saturation of 93-95% (94-98% for children 6-11 years).
  • Inhaled short-acting beta2-agonists (SABAs): Use 4-10 puffs pMDI with a spacer in mild or moderate attacks. For severe attacks, administer 1 nebule every 20 minutes for 1 hour.
  • Epinephrine (for anaphylaxis): Indicated only if acute asthma is associated with anaphylaxis and angioedema.
  • Systemic corticosteroids: enhance the resolution of exacerbations and prevent recurrence. They should be utilized within 1 hour of presentation. Oral and intravenous administrations are equally effective. However, the oral route is preferred because it is less invasive and less expensive. Intravenous corticosteroids can be administered when patients are too dyspneic to swallow if the patient is vomiting, or when patients require non-invasive ventilation or intubation. Corticosteroid dose is 1 mg/kg (max. 50 mg) prednisolone for adults and 1-2 mg/kg (max. 40 mg) for children.
  • Inhaled corticosteroids: are well tolerated. However, the cost is a limiting factor. The effectiveness, dose, and duration of treatment in the ED remain unclear.
  • Ipratropium bromide: Use for moderate-severe exacerbations, along with SABA.
  • Magnesium: Intravenous magnesium sulfate is not recommended for routine use in asthma exacerbations. It reduces hospital admissions in patients who fail to respond to initial treatment and have persistent hypoxemia.
  • Helium-oxygen therapy: May be considered for patients who do not respond to standard therapy.
  • Non-Invasive Mechanical Ventilation (NIMV) and Intubation: If the patient begins to exhibit signs of acute respiratory failure including progressive hypercapnia and acidosis, intubation and mechanical ventilation is indicated. NIMV is still controversial in asthma. It improves work of breathing, gas exchange. However, increase the risk of barotrauma.

The below video demonstrates treatment of asthma. However, in the ER, the actions should be a lot faster.

Special Populations

Pregnancy

The advantages of actively treating asthma in pregnancy markedly outweigh any potential risks of the usual controller and reliever medications. To avoid fetal hypoxia, acute asthma exacerbations during pregnancy should be aggressively treated with SABA, oxygen, and administration of systemic corticosteroids.

Elderly

The elderly may not describe asthma symptoms or may associate breathlessness with their age or comorbidities (cardiovascular disease, obesity, etc.). The impact of comorbidities, concurrent treatments, medication side effects (cardiotoxicity with beta2-agonists; skin bruising, osteoporosis, cataracts with corticosteroids) and lack of self-management skills should be taken into account while managing asthma in the elderly.

Children

Management of asthma exacerbation for adults and children >5 years are mostly similar. This section points to the management of asthma exacerbations in children 5 years and younger.

  • The presence of any one of these features means a severe exacerbation:
    • altered consciousness
    • oxygen saturation from pulse oximetry of <92% on presentation
    • central cyanosis
    • silent chest
    • impaired mentation (the normal developmental capability of the child must be taken into account)
    • pulse rate (>200 beats/min for children 0-3 years, >180 beats/min for children 4-5 years).3
  • Oxygen: target oxygen saturation is 94-98%.
  • Bronchodilator therapy: Give 2-6 puffs of salbutamol by a spacer, or 2.5mg salbutamol by nebulizer, every 20 min for the first hour, then reassess severity. If symptoms persist or recur, give an additional 2-3 puffs per hour. For children with moderate-severe exacerbations and a poor response to initial SABA, ipratropium bromide may be added, as 2 puffs of 80 mcg (or 250mcg by nebulizer) every 20 minutes for 1 hour only.
  • Systemic corticosteroids: Systemic corticosteroids: Give initial dose of oral prednisolone (1-2 mg/kg up to a maximum 20 mg for children <2 years old; 30 mg for children 2-5 years, OR, intravenous methylprednisolone 1 mg/kg 6-hourly.
  • Magnesium sulfate: If the child is not responding to standard therapy, consider nebulized isotonic magnesium sulfate (150mg) 3 doses in the first hour of treatment OR intravenous magnesium sulfate (in a single dose of 40-50- mg/kg (max 2g) by slow infusion (20-60 min) for children aged ≥2 years with severe exacerbation.

Disposition Decisions

  • If pre-treatment FEV1 or PEF is <25% of the predicted or personal best, or post-treatment FEV1 or PEF is <40% of the predicted or personal best, hospitalization is recommended.
  • If post-treatment lung function is >60% of the predicted or personal best, discharge is recommended after considering risk factors and availability of follow-up care.
  • Patients with post-treatment lung function 40-60% of the predicted are the gray zone. Hospitalization or discharge decision should be made according to the patient’s risk factors and the availability of follow-up care.
  • Risk factors associated with the need for admission:3
    • Female sex, older age, and non-white race
    • Use of more than 8 beta2-agonist puffs in the previous 24 hours
    • Severity of the exacerbation (e.g.need for resuscitation or rapid medical intervention on arrival, respiratory rate >22 breaths/minute, oxygen saturation <95%, final PEF <50% predicted).
    • History of severe exacerbations requiring admission to hospital
    • Previous healthcare facility visits requiring the use of oral corticosteroids.
  • An asthma exacerbation does not resolve completely on discharge; airway inflammation and peripheral obstruction may take hours to days to dissipate.
    • Prescribe at least a 5-7 day course of oral corticosteroids (prednisolone or equivalent 1 mg/kg/day to a maximum of 50 mg/day), along with inhaled corticosteroids and reliever medication.
    • Implement strategies to reduce modifiable risk factors (irritant or allergen exposure, incorrect inhaler skills, inadequate long-term treatment, problems with adherence, or lack of a written asthma action plan).
    • Arrange follow-up appointment within one week

References and Further Reading

  • National Asthma Education and Prevention Program Expert Panel: Report 3: Guidelines for the Diagnosis and Management of Asthma. NIH Publication No. 08-5846. Washington, DC: U.S. Department of Health and Human Services, National Institutes of Health, National Heart, Lung and Blood Institute; 2007.
  • Cydulka RK, Bates CG. Asthma. In: Adams JG, Barton ED, Collings JL, DeBlieux PMC, Gisondi MA, Nadel ES, editors. Emergency Medicine: Clinical Essentials, 2nd Edition. Philadelphia, PA. Elsevier. 2013:397-404.
  • Global Initiative for Asthma. GINA At-A-Glance Asthma Management Reference. Global Strategy for Asthma Management and Prevention 2014. Available from: http://www.ginasthma.org (Access date: 20/05/2015)
  • Nowak RM, Tokarski GF. Asthma. In: Marx J, Hockberger R, Walls R, editors. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 8th Edition. Philadelphia, PA: Elsevier. 2013:941-955.
  • Global Initiative for Asthma. Pocket Guide for Asthma Management and Prevention (for Adults and Children Older than 5 years) 2014. Global Strategy for Asthma Management and Prevention 2014. Available from: http://www.ginasthma.org (Access date: 20/05/2015)
  • Asthma Emergency Room Treatment –  https://www.youtube.com/watch?v=poIKEY-A0Yo

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