Skip to main content

Asthma

Stacy E Potts, MEd, MD Reviewed 05/2023
Email

Success

×

Oops, something went wrong. Please correct any errors and try again.

×

Send Email

Recipient(s) will receive an email with a link to 'Asthma' and will have access to the topic for 7 days.

Subject: Asthma

(Optional message may have a maximum of 1000 characters.)

reCAPTCHA verification required. Please check the box below and click "Submit."
×
 


BASICS

DESCRIPTION

  • A heterogeneous disease characterized as chronic inflammation of the airway  (1)

  • Common triggers: exercise, allergen-irritant exposure, change in weather, laughter, or viral respiratory infections

  • Patient may experience symptoms-free periods alternating with sporadic flare-up (exacerbations).

  • Most common asthma phenotypes:

    • Allergic asthma: usually present since childhood and has strong family history of allergic diseases

    • Nonallergic asthma

    • Late-onset asthma: more common in females

    • Asthma with fixed airflow limitation: due to airway remodeling

    • Asthma with obesity

  • Asthma severity is assessed retrospectively from treatment required to control symptoms.

    • Mild asthma: well controlled with Step 1 or 2 treatment (i.e., with as-needed ICS-formoterol alone or with low-intensity maintenance controller treatment)

    • Moderate asthma: well controlled with Step 3 or 4 treatment (i.e., low or medium dose ICS-LABA)

    • Severe asthma: remains "uncontrolled" with optimized treatment with high dose ICS-LABA or that requires high dose ICS-LABA to prevent it from becoming "uncontrolled"

EPIDEMIOLOGY

Incidence

Traffic-related air pollution may be attributable to 13% of global asthma incidence. 

Prevalence

Asthma affects 262 million individuals worldwide. 
  • 455,000 deaths worldwide reported in 2019 (2)

  • African Americans are three times more likely to die from asthma

  • Asthma affects about 10% of children ages 5 to 18 years in the United States.

  • Asthma prevalence is greater in boys than girls; however, in adults, women are more affected.

  • Obesity is associated with increased prevalence and incidence of asthma.

  • Rate of asthma deaths largest among those aged 65 and older

ETIOLOGY AND PATHOPHYSIOLOGY

Airway hyperreaction begins with inflammatory cell infiltration and degranulation, subbasement fibrosis, mucus hypersecretion, epithelial injury, significant smooth muscle hypertrophy and hyperreactivity, angiogenesis that then leads to intermittent airflow obstruction due to reversible bronchospasm. 

Genetics

Genetic association with increased interleukin (IL) or IgE production and airway hyperresponsiveness leading to asthma 

RISK FACTORS

  • Host factors: genetic predisposition, sex, obesity, preterm or small for gestational age (SGA)

  • Environmental: viral infections, animal and airborne allergens, tobacco smoke exposure, e-cigarette use, pollution, stress

  • Aspirin or NSAIDs hypersensitivity 

  • Persons with food allergies and asthma are at increased risk for fatal anaphylaxis from those foods.

COMMONLY ASSOCIATED CONDITIONS

  • Atopy: eczema, allergic conjunctivitis, allergic rhinitis

  • Obesity (associated with higher asthma rates)

  • Gastroesophageal reflux disease (GERD)

  • Obstructive sleep apnea (OSA)

DIAGNOSIS

HISTORY

History of variable respiratory symptoms: 
  • More than one symptom such as wheeze, SOB, cough, chest tightness

  • Symptoms worse at night, vary in time and intensity, worse with common triggers

PHYSICAL EXAM

  • May be normal

  • Focus on

    • Use of accessory muscles

    • Rhinitis, nasal polyps, swollen nasal turbinates

    • Expiratory wheezing, prolonged expiratory phase. Note: Wheezing may be absent in severe exacerbation due to severely reduced airflow.

    • Skin: eczema

DIFFERENTIAL DIAGNOSIS

  • In children

    • Upper airway diseases (allergic rhinitis or sinusitis)

    • Large airway obstruction (foreign body aspiration, vocal cord dysfunction, vascular ring or laryngeal web, laryngotracheomalacia, enlarged lymph nodes, or tumor)

    • Small airway obstruction (viral bronchiolitis, cystic fibrosis, bronchopulmonary dysplasia, heart disease, primary ciliary dyskinesia, bronchiectasis)

    • Other causes (recurrent cough, chronic upper airway cough syndrome, aspiration/GERD)

  • In adults

    • Chronic obstructive pulmonary disease, bronchiectasis, heart failure, pulmonary embolism, tumor, pulmonary infiltration with eosinophilia, Churg-Strauss syndrome, medication-induced cough (ACE inhibitors), vocal cord dysfunction

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

  • Blood tests are not required but may find eosinophilia or elevated serum IgE levels (allergic asthma).

  • Documented variable expiratory airflow limitation:

    • Spirometry with methacholine challenge: Normal test does not rule out asthma; measures the FVC and the FEV1; a reduced predicted ratio of FEV1/FVC with reversibility (increase of 200 mL and 12% of FEV1/FVC from baseline) after using a short-acting bronchodilator (SABA)

    • Excessive variability in twice daily peak expiratory flow (PEF) in 2 weeks (daily PEF variability >10%)

    • Bronchial challenge test: used mainly in adults, positive when there is a fall in FEV1 >20% with methacholine or histamine; or >15% with hypertonic saline or mannitol challenge

    • Exercise challenge test: fall in FEV1 >10% and 200 mL from baseline

    • Significant increase in lung function after 4 weeks of anti-inflammatory treatment

  • Chest x-ray is used to exclude alternative diagnoses.

Follow-Up Tests & Special Considerations

  • Asthma action plan: Patients monitor their own symptoms and/or peak flow measurements. Reassess action plan every 3 to 6 months.

  • Assess asthma symptoms control with simple screening tools, such as consensus-based Global Initiative for Asthma (GINA) symptom control tool or Primary Care Asthma Control Screening Tool (PACS). Use the review, assess, adjust method of ongoing management.

Diagnostic Procedures/Other

  • Allergy skin testing is not useful for diagnosis of asthma but may be to evaluate atopic triggers.

  • Measurement of fractional concentration of exhaled nitric oxide (FENO) suggests eosinophilic airway inflammation.

TREATMENT

GENERAL MEASURES

  • Focus on symptom control and prevention of exacerbations.

  • Use of holding chambers (“spacers”) with inhaled agents improves clinical outcomes.

  • Written asthma self-management action plan

  • Encourage physical activity, weight loss, smoking cessation, avoidance of irritants, emotional stress.

  • Avoidance of occupational exposure

  • Annual influenza vaccine; Pneumococcal vaccine recommended for high-risk patients

  • Patients at risk for anaphylaxis carry EpiPen.

  • Controller medications: used for regular maintenance, reduce airway inflammation, control symptoms, and reduce risk of exacerbations:

  • Inhaled corticosteroids (ICS)

  • Long-acting β-agonist (LABA) (formoterol, salmeterol)

  • The ICS can be delivered by regular daily treatment or, in mild well-controlled asthma, by as-needed low dose ICS-formoterol.

    ALERT

  • Treatment of asthma with SABAs alone is no longer recommended by the GINA Guidelines for adults and adolescents.

    • ICS therapy is essential to reduce risk of death and severe exacerbations.

  • Reliever (rescue medication) provided to all patients for as-needed relief of breakthrough symptoms

    • SABA–albuterol /levalbuterol

  • Add-on therapies for patients with severe asthma, when patients persist with symptoms despite optimized treatment with high-dose controller medications (ICS + LABA)

Pediatric Considerations
 
  • Tiotropium is not indicated in children <12 years.

  • Reliever for all management steps in children 6–11 years is as-needed SABA.

  • School-based programs including asthma self-management reduce emergency department visits, hospitalizations, and days of reduced activity.

Pregnancy Considerations
  • Do not use bronchial provocation test nor step down controller treatment until after delivery.

 
  • Asthma symptoms tend to worsen in 1/3 of patients, 1/3 improves, and 1/3 remains unchanged.

  • Exacerbations are common in 2nd trimester.

  • Poorly controlled asthma results in low birth weight, increased prematurity, and perinatal mortality.

  • All short-acting agents (SABA) are pregnancy Category C as well as ICS.

  • Cessation of ICS during pregnancy is a significant risk factor for exacerbation.

  • Montelukast and zafirlukast are Category B but are not studied extensively in pregnancy.

 
Geriatric Considerations

Underdiagnosed due to comorbidities

 

MEDICATION

First Line

  • Stepwise approach for asthma treatment for adolescents (>12 years) and adults:

    • Step 1: symptom driven treatment:

      • First: symptom driven as-needed low dose ICS-formoterol​​​​; controller alternatives: low-dose ICS whenever SABA taken; preferred reliever: ICS-formoterol

    • Step 2: low-dose controller + as needed reliever:

      • First: low-dose ICS + SABA; controller alternatives: LTRA or low-dose ICS whenever SABA taken (separate or combined)

    • Step 3: one or two controllers + as needed reliever:

      • First (adults/adolescents): low-dose ICS-LABA; controller alternatives: medium-dose ICS or low-dose ICS with LRTA. Preferred reliever: as-needed low-dose ICS/formoterol as both controller + reliever for those on maintenance therapy; first (ages 6 to 11 years) and second alternative (adults/adolescents): medium-dose ICS + SABA; third: low-dose ICS + LTRA

    • Step 4: two or more controllers + as-needed reliever:

      • First (adults/adolescents): medium-dose ICS-LABA as controller; controller alternatives: high-dose ICS, add-on tiotropium or LTRA. Consider house dust mite SLIT for sensitized patient with normal spirometry and allergic rhinitis; preferred reliever low-dose ICS-formoterol for those prescribed bud-form/BDP-form maintenance and reliever therapy, otherwise SABA reliever when on other ICS-LABA

    • Step 5: High-dose ICS-LABA, referral for phenotype assessment and consider add-on therapy (i.e., LAMA, anti-IgE, anti-IL5/5R, anti-IL4, tiotropium) or add low-dose OCS while considering risks versus benefits

  • Combination therapy with a LABA + ICS resulted in fewer asthma exacerbations than treatment with ICS alone.​

  • COVID-19 special considerations

    • Patients with asthma should continue taking their prescribed asthma medications, particularly ICS-containing medication and oral corticosteroids if prescribed.

    • Covid-19 vaccination is recommended for people with asthma.

ISSUES FOR REFERRAL

  • Specialized testing (e.g., bronchoprovocation)

  • Specialized treatments (e.g., immunotherapy)

  • Poorly controlled asthma, frequent exacerbation, or multiple emergency department visits

  • Occupational asthma due to legal implications​​​​​​.

ADDITIONAL THERAPIES

  • Exercise-induced bronchoconstriction (EIB): pharmacotherapy show to reduce symptoms, SABA prior exercise, or LTRA/chromones.

  • Allergen immunotherapy when clear relationship between symptoms and exposure

  • Management of acute exacerbation of asthma

    • Outpatient:

      • Mild: speak in full sentence, HR <120 bpm, oxygen saturation 90–95%, and peak flow >50% of predicted can be managed as outpatient in clinic; should start SABA with ICS or formoterol/ICS and prednisolone; if symptoms resolve within 1 hour, could be discharge home with close follow-up

      • Severe symptoms: not able to speak in full sentence, HR >120 bpm, oxygen saturation <90%, peak flow <50% predicted, drowsy, confused, or silent chest; transfer to inpatient facility.

    • Treatment for severe:

      • Oxygen: to maintain saturation 93–95%

      • SABA: within 1 hour of arrival, initially around the clock followed by on demand

      • Systemic steroids: Oral is as effective as IV. 50 mg prednisolone (morning dose) or 200 mg hydrocortisone divided in doses. Duration should be 5 to 7 days.

      • Epinephrine: only when asthma is associated with angioedema or anaphylaxis

      • Avoid sedative.

      • Vital signs, pulse oximetry, response and duration of response to SABA, a lung function such as PEF or FEV1

      • Asthma education

    • Discharge criteria

      • Minimal or absent asthma symptoms, Hypoxia has resolved, FEV1 or PEF ≥70% predicted or personal best, Bronchodilator response sustained ≥60 minutes

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

Admitted patients should continue, or commence, ICS-containing therapy 

ONGOING CARE

Smoking cessation if indicated 

FOLLOW-UP RECOMMENDATIONS

  • Identify triggers and control exposures.

  • Consider stepping down treatment once symptoms are controlled for 3 months.

PATIENT EDUCATION

PROGNOSIS

Prognosis is good for male patients, nonsmokers, and children with mild disease. 

COMPLICATIONS

  • Atelectasis, pneumonia, medication-specific side effects/adverse effects/interactions

  • Respiratory failure; death: ~50% of asthma deaths occur in the elderly (age >65 years)

REFERENCES

1
Global Initiative for Asthma. Global strategy for asthma management and prevention, 2021. https://ginasthma.org/wp-content/uploads/2021/05/GINA-Main-Report-2021-V2-WMS.pdf. Accessed October 20, 2021.
2
GBD 2019 Diseases and Injuries Collaborators. Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020;396(10258):1204–22.

ADDITIONAL READING

Expert Panel Working Group of the National Heart, Lung, and Blood Institute (NHLBI); National Asthma Education and Prevention Program Coordinating Committee (NAEPPCC), Cloutier MM, Baptist AP, et al. 2020 focused updates to the Asthma Management Guidelines. J Allergy Clin Immunol. 2020;146(6):1217–1270.  

CODES

ICD10

  • J45.20 Mild intermittent asthma, uncomplicated

  • J45.52 Severe persistent asthma with status asthmaticus

  • J45.51 Severe persistent asthma with (acute) exacerbation

  • J45.902 Unspecified asthma with status asthmaticus

  • J45.901 Unspecified asthma with (acute) exacerbation

  • J45.90 Unspecified asthma

  • J45.50 Severe persistent asthma, uncomplicated

  • J45.909 Unspecified asthma, uncomplicated

  • J45.21 Mild intermittent asthma with (acute) exacerbation

  • J45.9 Other and unspecified asthma

  • J45.30 Mild persistent asthma, uncomplicated

  • J44.0 Chronic obstructive pulmonary disease with (acute) lower respiratory infection

  • J45.5 Severe persistent asthma

  • J45.2 Mild intermittent asthma

  • J45.31 Mild persistent asthma with (acute) exacerbation

  • J45.42 Moderate persistent asthma with status asthmaticus

  • J45.3 Mild persistent asthma

  • J45.32 Mild persistent asthma with status asthmaticus

  • J45 Asthma

SNOMED

  • 427295004 Moderate persistent asthma

  • 426656000 Severe persistent asthma

  • 195949008 Chronic asthmatic bronchitis

  • 427679007 Mild intermittent asthma

  • 195967001 Asthma

  • 409663006 Cough variant asthma

  • 31387002 Exercise-induced asthma

  • 389145006 Allergic asthma

  • 426979002 Mild persistent asthma

  • 266361008 Intrinsic asthma

CLINICAL PEARLS

  • SABA plus ICS or formoterol/ICS is the most effective rescue therapy for acute asthma symptoms.

  • Holding chambers should be used by all.

  • ICSs are the preferred long-term control therapy for patients of all ages.

 
×