Acute Asthma

• Asthma

  A chronic inflammatory disease of the airways in which many cells and cellular elements play a role, particularly mast cells, neutrophils, eosinophils, T lymphocytes, macrophages, and epithelial cells. In susceptible individuals, this inflammation causes recurrent episodes of coughing, wheezing, breathlessness, and chest tightness. The episodes are usually associated with widespread but variable airflow obstruction that is reversible either spontaneously or as a result of treatment.
• Status asthmaticus


  A refractory state that does not respond to standard therapy such as inhaled beta agonists or subcutaneous epinephrine. It may persist for several hours.
• It is estimated that 300 million people have asthma. An increase in prevalence to 400 million is anticipated by 2025.
• Asthma accounts for around 440,000 hospitalizations and 1.8 million emergency department visits yearly in the U.S.
• Asthma is now more common in adults (7.5% of children vs. 7.7% of adults).
• Overall, mortality secondary to asthma has declined in the U.S. to 10.5 per 1 million but has not changed for children ages 1 to 14 yr.
• 50% to 80% of children with asthma develop symptoms before 5 yr of age.
• Early Childhood Risk Factors for Persistent Asthma

  • Parental asthma
  • Allergic rhinitis
  • Food allergy
  • Inhalant allergen sensitization
  • Pneumonia
  • Bronchiolitis requiring hospitalization
  • Wheezing apart from colds
  • Male gender
  • Low birth weight
  • Environmental tobacco smoke exposure
  • Possible use of acetaminophen (Paracetamol)
• Risk Factors for Severe and Fatal Asthma in Adults

  • History of prior nonfatal asthma attack
  • Prior intubation
  • Female gender
  • Age >65 yr
  • African American ethnicity
  • Obesity
  • Tobacco use
  • Inhalational drug abuse
  • Poorly controlled disease
  • Poor recognition of dyspnea and other symptoms
  • Steroid dependence
  • Misuse or lack of proper use of maintenance medications
  • Lack of access to medical care
  • Lack of ability to limit triggers (i.e., persistent exposure to pollutants, dust)
  • Comorbid heart disease, obesity, and/or diabetes
• Physical examination findings in asthma

  • May reveal a normal lung examination
  • Some degree of wheezing and prolonged expiratory phases of respiration are usually present with persistent or acute disease
  • Tachycardia and tachypnea
  • Use of accessory respiratory muscles
  • Pulsus paradoxus (inspiratory decline in systolic blood pressure >10 mm Hg)
  • Absence of wheezing (silent chest) or decreased wheezing can indicate worsening obstruction
  • Mental status changes: Generally secondary to hypoxia and Hypercapnia and constitute an indication for urgent intubation
  • Paradoxical abdominal and diaphragmatic movement on inspiration (detected by palpation over the upper part of the abdomen in a semi recumbent position) indicates diaphragmatic fatigue, another sign of impending respiratory crisis
• Allergic (atopic, extrinsic) asthma

  Triggered by various aeroallergens or nonallergic (nonatopic) nonspecific (e.g., dust, cigarette smoke, fumes, cold air, exercise) exposures in patients who are prone to develop IgE antibodies in response to various exposures.
• Factors that contribute to worsening asthma control and coexisting conditions

  • Tobacco use
  • Gerd
  • Obesity
  • Obstructive sleep apnea
  • Occupational exposure to certain organic or nonorganic agents
  • Dampness and mold
• Exercise-induced asthma

  Seen most frequently in adolescents and manifests with bronchospasm after beginning of exercise and improves with discontinuation of exercise.
• Drug-induced asthma


  Associated with use of NSAIDs, β blockers, sulfites, and certain foods and beverages.
• There is a strong association of the ADAM 33 gene with asthma and bronchial hyper responsiveness.
• Differential diagnosis of asthma

  • Post infectious bronchitis
  • Rhinitis with postnasal drip
  • Paradoxical vocal fold motion (vocal cord dysfunction)
  • Chronic obstructive pulmonary disease (COPD)
  • Gastroesophageal reflux disease (GERD)
  • Pneumonia and other respiratory tract infections
  • Foreign body aspiration (most frequent in younger patients)
  • Anxiety disorder
  • Interstitial lung disease
  • Hypersensitivity pneumonitis
  • Heart failure
  • Pulmonary embolism
• Forced expiratory volume in 1 second (FEV1)

  The maximum amount of air that a person can forcefully exhale in one second, measured as a percentage of the person's predicted value. A lower FEV1 suggests a reduced lung function and is associated with obstruction in the airways, such as in asthma.
• Airflow reversibility

  Increase in forced expiratory volume in 1 sec (FEV 1 by at least 12% and 200 ml) after inhaling a short-acting bronchodilator. The degree of reversibility measured by spirometry correlates with airway inflammation, and patients with a high degree of reversibility have a greater risk of irreversible airflow obstruction in subsequent years.
• Negative spirometry results do not rule out asthma. Patients with high clinical suspicion should undergo bronchial challenge testing with methacholine or other specific agents.
• In the absence of spirometry, variability of peak flow measurements can be used to diagnose asthma.
• Asthma severity classification

  Patients are divided into four groups based on the severity of their asthma symptoms and number of exacerbations.
• Asthma control

  The level of asthma control should be used to guide decisions either to maintain or adjust therapy.
• Factors important to the current asthma exacerbation

  • Exposure to common precipitants (environmental allergens, occupational exposure, viral upper respiratory tract infections, cold, exercise, aspirin or nonsteroidal anti-inflammatory drug use)
  • Duration and severity of symptoms
  • Past history and frequency of exacerbations
  • Prior hospitalizations and intubations
  • Number of recent emergency department (ED) visits
  • Current medications
  • Comorbidities
• Asthma severity features


  • Mild: Exertional symptoms, able to speak normally, good response to usual treatment, FEV1 = > 60%
  • Moderate: SOB at rest, able to speak short sentences, chest tightness, wheeze, partial or short term relief with therapy, nocturnal symptoms, FEV1 = 40% - 60%
  • Severe: Labored respiration, sweating, restless, tachycardia, HR = > 120, tachypnea, RR = > 25/min, speaking in words (3 words max at a time), FEV1 = < 40%, SpO2 = < 90% on atmospheric air
  • Life threatening: Exhaustion, confusion or coma, cyanosis, silent chest, inability to speak, poor respiratory effort, arrhythmia or bradycardia, hypotension, FEV1 = inappropriate, SpO2 = < 90% even with supplemental O2
• Arterial blood gases (ABGs)


  Can be used during acute bronchospasm in staging the severity of an asthmatic attack:

  Mild: Decreased PaO2 and PaCO2, increased pH

  Moderate: Decreased PaO2, normal PaCO2, normal pH

  Severe: Marked decreased PaO2, increased PaCO2, and decreased pH
• Complete blood count


  Leukocytosis with left shift may indicate the existence of bacterial infection. Elevated eosinophils point toward allergic component of asthma.
• Serum IgE and eosinophil levels help guide treatment for patients with severe persistent asthma and monitor response to treatment in this group.
• Spirometry is recommended at the initial assessment and at least every 1 to 2 yr after treatment is initiated and when the symptoms and peak expiratory flow have stabilized. Spirometry may be performed more frequently, if indicated, based on severity of symptoms or lack of response to treatment.
• Peak expiratory flow rate (PEFR)


  Can be used to assess severity of an acute exacerbation episode. Values should be compared with individual's personal best number.
• Chest x-ray findings in asthma


  • Usually normal, may show evidence of thoracic hyperinflation (e.g., flattening of the diaphragm, increased volume over the retrosternal air space)
• ECG findings in asthma


  • Tachycardia, nonspecific ST-T wave changes are common during an asthma attack; may also show cor pulmonale, right bundle branch block, right axial deviation, counterclockwise rotation
• Nonpharmacologic therapy for asthma

  • Avoidance of triggering factors, environmental, or occupational triggers
  • Encouragement of regular exercise
  • Patient education regarding warning signs of an attack and proper use of medications (e.g., inhalers)
• Treatment of status asthmaticus

  1. Oxygen generally started at 2 to 4 L/min by nasal cannula or Venti-Mask at 40% FiO2; further adjustments are made according to oxygen saturations

  2. Bronchodilators: Initiate treatment with salbutamol nebulizer solution: 2.5 to 5 mg every 20 min over the first hr, then 2.5 to 10 mg every 1 to 4 hr as needed or 10 to 15 mg/hr continuously. Other useful medication is ipratropium nebulizer solution (0.25/ml [0.025%])

  3. Corticosteroids: Early administration is advised, particularly in patients using steroids at home. Patients may be started on systemic corticosteroids; prednisone, or prednisolone may be used. Dose range is from 40 to 80 mg/day in one or two divided doses, generally given until peak expiratory flow reaches 70% of predicted value. Generally for corticosteroid courses <1 wk; there is no need to taper the dose

  4. IV hydration: Judicious use is necessary to avoid heart failure in elderly patients. Aggressive IV hydration is not recommended

  5. IV antibiotics are indicated when there is suspicion of bacterial infection (e.g., infiltrate on chest radiograph, fever, or leukocytosis)

  6. Intubation and mechanical ventilation are indicated when previous measures fail to produce significant improvement
• Objectives when treating an asthma exacerbation

  Correct hypoxemia, rapidly reverse airflow obstruction, and reduce the likelihood of recurrence of severe airflow obstruction
• How the objectives are achieved when treating an asthma exacerbation

  First-line treatment includes inhaled β2-agonists, systemic corticosteroids in moderate exacerbations, and supplemental oxygen if needed. Hypoxemia is usually corrected by administration of supplemental oxygen with a goal oxygen saturation of >90%. Relief of bronchoconstriction is usually accomplished by administration of either intermittent or continuous doses of aerosolized β2-agonists. Early administration of systemic corticosteroids addresses the inflammatory component of acute asthma and has been demonstrated to reduce hospitalizations, although beneficial effects of corticosteroids are often not noted until several hours after administration. Ipratropium, an anticholinergic agent, should be added when treating severe exacerbations to decrease the need for hospitalization, and is most effective in children and smokers. Epinephrine may be administered subcutaneously to patients unable to manage aerosolized treatments in severe exacerbations only.
• Medications Used to Treat Asthma and COPD Exacerbations

  • Inhaled Short-Acting β2-Agonists: Albuterol nebulizer solution (5 mg/mL), Albuterol MDI (90 µg/puff): Must be used with spacer device
  • Systemic (Injected) β2-Agonists: Epinephrine 1:1000 (1 mg/mL)
  • Inhaled Anticholinergics: Ipratropium nebulizer solution (0.25 mg/mL)
  • Systemic Corticosteroids: Prednisone or prednisolone
• Bronchodilators


  Medications that help to relax and open up the airways in the lungs, making it easier to breathe. They work by relaxing the smooth muscle around the airways, which allows the airways to widen.
• Anti-inflammatories


  Medications that help to reduce inflammation in the airways, which can help to prevent and treat asthma symptoms. They work by reducing the production of substances that cause inflammation, such as histamine and leukotrienes.
• Salbutamol (also known as albuterol)


  A type of bronchodilator that is used to quickly open up the airways and make it easier to breathe. It works by relaxing the smooth muscle around the airways, which allows the airways to widen.
• Ipratropium


  A type of bronchodilator that is used to relax the smooth muscle around the airways and make it easier to breathe. It is often used in combination with other bronchodilators, such as salbutamol.