History and exam
Key diagnostic factors
common
presence of risk factors
Strong risk factors include viral infection, exposure to inhaled allergens, exercise, non-adherence to preventive medication, history of atopic disease in the patient or a first-degree relative, history of severe asthma exacerbations, low socio-economic status, and history of environmental irritants (e.g., tobacco smoke).
wheezing
Polyphonic, high-pitched, widespread wheeze on auscultation is a characteristic sign. Intensity of wheeze is a poor predictor of severity due to the lack of wheeze in severe airflow obstruction (silent chest). Wheeze may become biphasic with increasing airway obstruction.
Auscultation sounds: Expiratory wheeze
Auscultation sounds: Polyphonic wheeze
expiratory airflow limitation
Auscultation may reveal a prolonged expiratory phase, with an inspiratory-to-expiratory ratio of 1:2 or greater.
shortness of breath
Characteristic symptom.
tachypnoea
Characteristic sign.
chest tightness
May be present.
Other diagnostic factors
common
cough
While cough may be a component, it is rarely the sole manifestation. Viral infections are the most common cause of asthma exacerbations.
exercise limitation
Parents or the patient complain of an inability to exercise due to shortness of breath.
tachycardia
Commonly accompanies tachypnoea.
inability to speak or feed
Directly related to degree of breathlessness. Needs to be evaluated in relation to the developmental age of the child. In infants, ability to feed reflects the degree of respiratory distress.
intercostal, sub-costal, or sternal retraction
May accompany respiratory distress and reflects the large negative pressures that are being generated in an attempt to increase air flow. Other associated features are nasal flaring and tracheal tug.
accessory muscle use
Sternocleidomastoid, parasternal, and scalene muscles, among others, are recruited with more severe respiratory distress. In young infants, accessory muscle recruitment may manifest as head bobbing.
uncommon
pulsus paradoxus
Defined as a fall of >10 mmHg in systolic BP with inspiration. A poor indicator of exacerbation severity and should not be routinely used.
sleep disturbance
May be present. Used as an indicator of baseline asthma symptom control.
bradycardia
Pre-terminal sign in acute asthma.
cyanosis
Pre-terminal sign indicating severe hypoxaemia and respiratory failure.
exhaustion
Indicates impending respiratory arrest.
decreased consciousness level
Indicates impending respiratory arrest.
Risk factors
strong
viral infection
Viral infection is the most common trigger in children.[6][30] Rhinovirus is the most common cause.[9]
Viral upper respiratory tract infection triggers up to 80% of asthma exacerbations in children; rhinovirus, respiratory syncytial virus, pertussis, influenza, parainfluenza, and human metapneumovirus trigger most exacerbations.[6][8][9]
uncontrolled asthma symptoms
high use of short-acting beta-2 agonists (SABA)
High use of SABA to relieve asthma symptoms is associated with increased risk for exacerbation and all-cause respiratory and asthma-related mortality.[32] SABA overuse may be a marker of patient frailty, severe asthma, poor asthma control, or incorrect inhaler technique.
inadequate use of inhaled corticosteroids (ICS)
Inadequate use of ICS is a potentially modifiable risk factor for exacerbations. This could be due to ICS not being prescribed, poor adherence, or incorrect inhaler technique.[33]
incorrect inhaler technique
Incorrect inhaler technique is a potentially modifiable risk factor for exacerbations. Poor inhaler technique is associated with increased unscheduled use of healthcare resources and poor clinical control.[33]
low forced expiratory volume in 1 second (FEV₁)
high bronchodilator reversibility
inhaled allergens
Wide range of potential allergic triggers, including house dust mite, pets (cats and dogs), pollen (tree, weed, and grass), food allergens, fungi (Alternaria), and cockroaches. Sensitisation to environmental allergens affects disease control and exacerbations, and sensitisation to the fungus Alternaria is associated with more severe asthma exacerbations.[13][14][37]
exercise
Airway obstruction is stimulated by evaporative water loss from the airway surface during exercise.[22]
poor adherence with regular asthma medication
Risk of asthma exacerbation is reduced in children more adherent to their asthma controller compared with those who are less adherent.[38]
history of asthma
Most exacerbations occur in children already known to have asthma.
history of other atopic disease
Other atopic diseases such as eczema, allergic rhinitis, and food allergies are risk factors for the development of asthma and acute exacerbations.[26]
family history of atopic disease
Presence of any atopic disease in a first-degree relative increases the risk of asthma.
history of hospitalisation for asthma exacerbations
one or more severe or life-threatening exacerbations in the past 12 months
low socio-economic status
air pollution
A significant association has been shown between air pollutants and both emergency department visits and hospitalisations for asthma.[16][17] Indoor and outdoor air pollutants associated with risk include sulfur dioxide, nitrous dioxide, ozone, environmental tobacco smoke, evaporative volatile organic compounds, cooking- and heating-related particles, and particulate matter with aerodynamic diameter ≤10 micrometres or ≤2.5 micrometres (e.g., during wildfires).[17][18][19][20] Environmental irritants can also worsen exacerbations triggered by other factors.
vitamin D deficiency
obesity
younger age
One meta-analysis found that younger age in children with asthma is associated with a slightly increased risk of asthma attacks.[26]
smoking
vaping
Use of electronic nicotine delivery systems (vaping) has been associated with higher rates of self-reported asthma and asthma exacerbations, and even reports of status asthmaticus.[29]
weak
bacterial infection
emotion
Anger and anxiety or the act of laughter may trigger asthma exacerbations.
non-steroidal anti-inflammatory drug (NSAID) use
NSAID-sensitive asthma is much less common in children than in adults, with an incidence of 2% noted in one paediatric study.[47]
gastro-oesophageal reflux disease
Gastro-oesophageal reflux disease is associated with cough and night-time symptoms.
One systematic review and meta-analysis reported a modest association between gastro-oesophageal reflux disease and asthma exacerbation in paediatric patients.[28]
chronic rhinosinusitis
Chronic rhinosinusitis has been associated with exacerbation frequency in severe asthma.[27]
African-American ethnicity
Historical data indicate a moderately increased risk of asthma attacks in African-American children with asthma.[26]
Disparities in asthma exacerbation rates between ethnicities may be attributable to higher asthma prevalence among specific ethnic groups, which translates into a higher proportion of those groups at risk of adverse asthma outcomes.[48][49]
low parental education
One meta-analysis found a slightly increased risk of asthma attacks in children of families with low parental education level.[26]
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