Definition

Asthma is a chronic inflammatory and airway obstruction disorder, which can be preceded by certain triggers and is at least partially reversible with treatment or by removing the triggers. The symptoms are wheezing, chest tightness, and cough, especially at night or during early morning hours. Asthma has 3 stages of airway hyperresponsiveness: early (1 hour) phase that results from the histamine and leukotriene constriction of bronchial smooth muscle; late phase (4-6 hrs) caused by inflammatory chemokines inducing airway obstruction and edema; and the chronic phase where airway remodeling and thickening occurs with increased mucosal tissue.

Key History

Key Physical Exam

Risk Factors

Classification Systems

• Daytime asthma symptoms < 2 times/week
• < 2 nocturnal awakenings/month
• PEF or FEV1 measurements when asymptomatic are within 80% of predicted normal range
• < 20% change in PEF during day
• Or asthma only with vigorous exercise or certain triggers, like viral infection or exposure to cats

• Daytime asthma symptoms > 2 times/week
• > 2 nocturnal awakenings/month
• PEF or FEV1 measurements when asymptomatic are within 80% of predicted normal range
• < 30% change in PEF during day

• Daily asthma symptoms
• > 1 nocturnal awakenings/week
• Asthmatic attacks that interfere with activity
• Daily need for bronchodilator medications (short or long-acting)
• PEF or FEV1 60–80% of predicted normal range

• Symptoms with minimal exercise
• > 2 nocturnal awakenings/week
• Asthma exacerbations occur frequently
• Require multiple asthma medications on a regular basis
• PEF or FEV1 < 60% of predicted normal range
• Widely varying PEF from day to day
• Lung function may consistently remain abnormal

A well-controlled asthmatic is one that has daytime symptoms no more than twice per week and no more than twice per month at night.

Differential Diagnosis

Diagnostic Testing

• Peak expiratory flow rate (PEFR)
• Spirometry
• Chest x-ray
• CBC
• Allergy testing
• Response to treatment

Clinical Risk

• Personal or family history of atopy
• Family history of asthma and allergies
• Asthmatic symptoms as a child

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Treatment

• No daily medications needed
• Quick-acting inhaled beta-2 selective adrenergic agonist
• If trigger is well known (i.e. exercise) – use inhaler 10 minutes prior to exposure.
• Mast cell stabilizing agent- cromolyn sodium and nedocromil for prevention only
• Patient education and frequent monitoring is essential.

• Add anti-inflammatory medications- inhaled corticosteroids and leukotriene modifying agents.
• Continue inhaled bronchodilator for relief of symptoms acutely and prevention of known triggers.
• Patient education and frequent monitoring is essential.

• Daily medications necessary
• Low-dose inhaled corticosteroids plus long-acting inhaled beta agonist
• Alternative: low-dose inhaled corticosteroids plus leukotriene modifier
• Patient education and frequent monitoring is essential.

• Daily medications necessary
• Medium to high doses of inhaled corticosteroids in addition to one or more other controller medications (long-acting inhaled beta-agonists, leukotriene modifying agents, omalizumab)
• Preferred choice = mod/high dose ICS plus long-acting inhaled beta agonist
• Patient education and frequent monitoring is essential.

A rescue course of systemic corticosteroids may be used at any step when needed.

• IV, O2, Monitor
• Aerosolized or parenteral beta-adrenergic agents are first line: Albuterol Sulfate 1.25 to 5mg and Metaproterenol 10 to 15 mg; give in rapid succession or continuously.
• Subcutaneous or IM Epinephrine (1:1000, 0.1-0.3 mL) or Terbutaline Sulfate (0.25-0.5 mL). Avoid Epinephrine in 1st trimester of pregnancy and with cardiovascular disease.
• Steroids: 40-60 mg prednisone or 60-125 IV methylprednisolone. May give every 4-6 hours.
• May give ipratropium (500 mg = 2.5 mL) nebulized with or without albuterol.
• Administer IV magnesium sulfate (1-2 gm over 30 minutes) for severe asthma exacerbation.
• Ketamine (1-2 mg/kg IV) for refractory asthma requiring intubation
• Intubation
• Discharge meds: 3-10 day course of prednisone 40-60 mg/day and rescue inhaler.

Complications

• Hypoxia
• Death

Pregnancy

Pregnant asthmatics with poorly controlled disease have a minimal increase in preterm birth, stillbirth, and low-birth-weight babies. Asthma improves in one-third of patients, stays the same in one-third, and worsens in one-third during pregnancy. The symptoms can be the same in pregnancy, but an increased concern for PE should also be considered. Inhaled glucocorticoids, B2-agonist nebulizer treatments, IV methylprednisolone and oral prednisone, subcutaneous epinephrine, and oxygen may all be used during pregnancy for treatment. Peak flow rates should not be altered with pregnancy and should be measured. The most severe symptoms are usually seen in the 24^th-36^th weeks of gestation.

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