Clinical presentation and assessment of exacerbation severity
A classic BA attack includes paroxysmal cough, signs of lung hyperinflation, and expiratory dyspnea with wheezing audible from a distance. The severity of the condition is assessed by several parameters:
- Mild exacerbation: mild dyspnea, wheezing heard at the end of expiration. Forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF) > 80%, saturation > 95%. Activity and speech are preserved.
- Moderate exacerbation: distinct expiratory dyspnea with accessory muscle use. FEV1 and PEF range between 60–80%, saturation drops to 91–95%. The patient speaks in phrases, psychomotor agitation is present.
- Severe exacerbation: pronounced dyspnea, orthopnea, loud wheezing, and tachycardia. FEV1 and PEF < 60%, saturation < 90% (severe hypoxemia). Speech is severely impaired, "respiratory panic" is characteristic.
- Status asthmaticus (extremely severe): stage of decompensation. Tachypnea is replaced by bradypnea, and tachycardia by bradycardia, indicating exhaustion. "Silent chest" syndrome develops (wheezing is not transmitted due to critical spasm), with paradoxical thoracoabdominal breathing. Partial pressure of carbon dioxide (paCO2) exceeds 45 mm Hg, consciousness is depressed up to coma. Performing a forced expiration maneuver is impossible.
Features of the course and diagnosis in children under 5 years
In early childhood, BA is often disguised under "masks" (acute bronchiolitis, obstructive bronchitis) or presents as equivalents: nighttime cough leading to awakening, or prolonged obstructive syndrome.
Diagnosis in preschoolers is based on GINA criteria:
- Trigger specificity: cough, dyspnea, and wheezing are triggered by physical exertion, laughter, crying, or pollutants (tobacco smoke) independent of an obvious acute respiratory viral infection (ARVI).
- Reduced exercise tolerance: the child tires quickly when walking, asks to be carried, and is less active in games.
- burdened medical history: presence of concomitant atopy in the child or BA in close relatives.
- Diagnosis ex juvantibus: prescribing a trial treatment with low-dose inhaled corticosteroids (ICS) and short-acting beta-2-agonists (SABA). Improvement within 2–3 months and recurrence of symptoms after drug withdrawal confirm the diagnosis.
Instrumental and laboratory studies
To confirm the diagnosis in children over 6 years of age, objective methods for assessing pulmonary function testing (PFT) are used:
- Spirometry: reveals an obstructive pattern — a decrease in FEV1, the Tiffeneau index (FEV1/FVC), and PEF with normal or reduced forced vital capacity (FVC). To confirm obstruction reversibility, functional tests with a bronchodilator and physical exertion are performed.
- Peak flow monitoring: routine home monitoring of PEF (morning and evening) to control the disease.
Blood tests often reveal moderate eosinophilia. To monitor the activity of eosinophilic inflammation, the fraction of exhaled nitric oxide (FeNO) is measured, and sputum eosinophils are counted. Allergic workup includes skin prick tests and determination of total and specific IgE levels. Routine chest X-ray is not indicated; it may reveal signs of hyperinflation and peribronchial infiltration.
Predictors of BA and differential diagnosis
At an early age, bronchial obstruction is often transient, associated with anatomical and physiological features, and resolves spontaneously by 5 years of age. True BA is characterized by a chronic course, obstruction episodes more than 3 times a year, nocturnal cough, and onset after 3 years of age.
To assess the risk of early obstruction transforming into persistent BA, predictors are used:
- One major risk factor: family history of BA or presence of atopy in the child.
- Two minor risk factors: blood eosinophilia, allergic rhinitis, or episodes of wheezing outside of ARVI.
When making a diagnosis, other causes of obstructive syndrome must be excluded: foreign body aspiration, cystic fibrosis, bronchopulmonary dysplasia, primary ciliary dyskinesia, and vascular and bronchial anomalies.
To memorize the severity criteria of exacerbation based on FEV1 and PEF values, use the "20% step": greater than 80% — mild, from 60 to 80% — moderate, less than 60% — severe.
Class and exam questions
What is a "silent chest" and when does it occur?
This is a pathological condition where, due to critical narrowing of the bronchi, breath sounds and wheezing are no longer audible upon auscultation. It is a ominous sign of status asthmaticus.
From what age can a child undergo spirometry?
Spirometry to detect an obstructive pattern is routinely ordered and reliably evaluated in children starting from 6 years of age.
How does ex juvantibus diagnosis work in asthma?
The child (usually under 5 years old) is prescribed a trial course of controller therapy (ICS + SABA). Improvement in well-being within 2–3 months and subsequent deterioration after drug withdrawal confirm the diagnosis.
What else to study on this topic
- The concept of the atopic march and the link between BA and allergic rhinitis
- Mechanisms of transient obstructive syndrome development in infants
- Classification of persistent BA severity (symptom frequency)
- Functional tests with a bronchodilator and physical exertion
- Differential diagnosis of obstruction: from cystic fibrosis to vascular anomalies
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Other topics in "Chapter 5. Allergic Diseases"
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