Asthma is a condition characterized
by paroxysmal narrowing of the
bronchial airways due to
inflammation of the bronchi and
contraction of the bronchial smooth
muscle. The inflammatory
component is central to the
pathogenesis of symptoms:
dyspnea, cough, and wheezing.
Common causes of acute
asthma include viral upper
respiratory infections;
exposure to allergens (eg,
dustmites, animal
dander); smoke
inhalation; and cold, dry
weather
Incidence of acute asthma, defined as the number
of persons who develop asthma within a specific
time period, is approximately 0.2-0.4% annually.
Childhood asthma persists into adulthood in
approximately 50% of cases. Those with symptoms
persisting into the second decade of life usually
have asthma throughout adulthood. Asthma
prevalence is 6-10% (ie, 20-25 million persons); one
half of these cases are children (ie, 8-20% of all
children). Overall, acute asthma represents about
2% of all ED visits
Mild intermittent asthma
Symptoms of cough, wheeze, chest tightness, or
difficulty breathing less than twice a week
Flare-ups brief, but intensity may vary
Nighttime symptoms less than twice a month
No symptoms between flare-ups
Lung function test FEV1 equal to or above 80% of
normal values
Peak flow less than 20% variability am-to-am or
am-to-pm, day-to-day.
Mild persistent asthma
Symptoms of cough, wheeze, chest tightness,
or difficulty breathing 3-6 times a week
Flare-ups may affect activity level
Nighttime symptoms 3-4 times a month
Lung function test FEV1 equal to or above
80% of normal values
Peak flow less than 20-30% variability
Moderate persistent asthma
Symptoms of cough, wheeze, chest tightness, or
difficulty breathing daily
Flare-ups may affect activity level
Nighttime symptoms 5 or more times a month
Lung function test FEV1 above 60% but below 80%
of normal values
Peak flow more than 30% variability
Differential Diagnoses
Chronic Obstructive Pulmonary Disease and Emphysema
Anaphylaxis (adult, pediatric)
Bronchiolitis (pediatric)
Foreign body ingestion (pediatric, adult incompetent,
neurologically impaired)
Polyarteritis nodosa
Adrenal insufficiency if steroids stopped too abruptly
Congestive heart failure and myocarditis
Pulmonary embolism (especially multiple)
Upper airway disease
Panic disorder and hyperventilation syndrome
Pneumonia, bronchitis
Paradoxic vocal cord dysfunction
F I G U R E 5 – 1 . CLASSIFYING SEVERITY O F ASTHMA
EXACERBATIONS I N THE URGENT OR EMERGENCY CARE
SETTING
Note: Patients are instructed to use quick-relief medications if
symptoms occur or if PEF drops below 80 percent
predicted or personal best. If PEF is 50–79 percent, the patient
should monitor response to quick-relief medication
carefully and consider contacting a clinician. If PEF is below 50
percent, immediate medical care is usually required.
In the urgent or emergency care setting, the following
parameters describe the severity and likely clinical course of
Symptoms and Signs Initial PEF (or FEV1) Clinical
Course
Mild Dyspnea only with activity (assess
tachypnea in young children)
PEF ≥70 percent predicted or personal best
􀀎 Usually cared for at home
􀀎 Prompt relief with inhaled SABA
􀀎 Possible short course of oral
systemic corticosteroids
Key: ED, emergency department; FEV1, forced expiratory
volume in 1 second; ICU, intensive care unit; PEF, peak
expiratory flow; SABA, short-acting beta2-agonist
Moderate Dyspnea interferes with
or limits usual activity
PEF 40−69 percent
predicted or personal
best
􀀎 Usually requires office or ED visit
􀀎 Relief from frequent inhaled SABA
􀀎 Oral systemic corticosteroids;
some symptoms last for 1–2 days
after treatment is begun
Key: SABA, short-acting beta2-agonist
Severe Dyspnea at rest;
interferes with
conversation
PEF <40 percent
predicted or personal
best
􀀎 Usually requires ED visit and likely
hospitalization
􀀎 Partial relief from frequent inhaled
SABA
􀀎 Oral systemic corticosteroids;
some symptoms last for >3 days
after treatment is begun
􀀎 Adjunctive therapies are helpful
Subset: Life
threatening
Too dyspneic to speak; perspiring
PEF <25 percent
predicted or personal best
􀀎 Requires ED/hospitalization;
possible ICU
􀀎 Minimal or no relief from frequent
inhaled SABA
􀀎 Intravenous corticosteroids
􀀎 Adjunctive therapies are helpful
Key: ED, emergency department; ICU, intensive care unit;
PEF, peak expiratory flow; SABA, short-acting beta2-agonist
Inhaled Short-Acting Beta2-Agonists (SABA)
Albuterol
Nebulizer solution
(0.63 mg/3 mL,1.25 mg/3 mL,2.5 mg/3 mL,5.0 mg/mL)
0.15 mg/kg (minimum dose 2.5 mg) every four hours as needed
Status Asthmaticus;
in ED, may give every 20 minutes for
3 doses then 0.15–0.3 mg/kg
up to 10 mg every 1–4 hours
as needed, or 0.5 mg/kg/hour
by continuous nebulization.
May mix with ipratropium nebulizer solution.
Ipratropium bromide
Nebulizer solution
(0.25 mg/mL) 0.25–0.5 mg every 20 minutes to four hours
May mix in same nebulizer with albuterol.
Should not be used as first-line therapy; should be
added to SABA therapy for severe exacerbations.
Ipratropium has not
been shown to provide further benefit once admitted to hospital
MDI (metered dose inhaler)
(90 mcg/puff) 2 puffs every 4 hours as needed
Status Asthmaticus;
In ED, 4–8 puffs every 20 minutes
for 3 doses, then every 1–4
hours inhalation maneuver as
needed. Add mask
in children <4 years.
4–8 puffs every 20 minutes
up to 4 hours, then every
1–4 hours as needed.
Asthma Exacerbation
• Add steroid if not improving with inhaled
albuterol/salbutamol
• Prednisone 1-2mg/kg/day daily or divided BID
• If severe or cannot take po; use IV;
• Methylprednisolone 2-4mg/kg/day divided
BID or QID
Asthma Exacerbation
• Other medicines used less often include;
• subcutaneous epinephrine
IV magnesium
theophylline