Overview
Definition:
Asthma is a chronic inflammatory disorder of the airways characterized by reversible airflow obstruction, bronchial hyperresponsiveness, and recurrent symptoms
The inpatient pathway focuses on acute exacerbations requiring hospitalization, particularly addressing the optimal use of inhaled corticosteroids and the spacing of bronchodilator administration.
Epidemiology:
Asthma is a leading cause of pediatric hospital admissions
Prevalence varies globally, with significant impact on healthcare systems
Recurrent wheezing illnesses in early childhood are a strong predictor of persistent asthma
Exacerbations are often triggered by viral infections.
Clinical Significance:
Effective management of acute asthma exacerbations in inpatients is critical to reduce morbidity and mortality
Understanding evidence-based protocols for medication timing and administration ensures optimal bronchodilation and anti-inflammatory effects, preventing severe respiratory failure and improving patient outcomes
This knowledge is vital for residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Severe shortness of breath
Persistent cough, often worse at night
Wheezing on auscultation
Chest tightness
Difficulty speaking in full sentences
Accessory muscle use
Tachypnea
Tachycardia
Cyanosis in severe cases.
Signs:
Audible wheezing, often expiratory
Prolonged expiratory phase
Diminished breath sounds (severe obstruction)
Retractions (supraclavicular, intercostal, subcostal)
Nasal flaring
Accessory muscle use
Pulsus paradoxus (severe exacerbations)
Altered mental status (hypoxia/hypercapnia).
Diagnostic Criteria:
Diagnosis is primarily clinical, based on recurrent symptoms, airflow obstruction, and variability
In hospitalized children, assessment involves severity scoring (e.g., Pediatric Asthma Severity Score), vital signs, and response to initial therapy
Spirometry may be difficult in acute settings but can confirm persistent airflow limitation upon recovery.
Diagnostic Approach
History Taking:
History of previous asthma exacerbations and hospitalizations
Triggers (viral infections, allergens, irritants)
Medications used at home (response to bronchodilators, adherence to inhaled corticosteroids)
History of atopy
Family history of asthma
Duration and severity of current symptoms
Red flags: poor response to home therapy, inability to feed, altered mental status.
Physical Examination:
Assess general appearance (distress, alertness)
Auscultate lung fields for wheezing, crackles, and breath sounds intensity
Evaluate for accessory muscle use, retractions, and nasal flaring
Monitor vital signs: respiratory rate, heart rate, oxygen saturation
Assess for pulsus paradoxus
Palpate for accessory muscle hypertrophy.
Investigations:
Arterial blood gas (ABG) or venous blood gas (VBG) to assess oxygenation and ventilation, especially in moderate to severe exacerbations
Serum electrolytes and glucose
Chest X-ray to rule out other causes of respiratory distress (pneumonia, pneumothorax)
Peak expiratory flow rate (PEFR) or forced expiratory volume in 1 second (FEV1) upon recovery to assess lung function
White blood cell count and inflammatory markers may be used judiciously
Pulse oximetry is essential for continuous monitoring.
Differential Diagnosis:
Bronchiolitis
Pneumonia
Foreign body aspiration
Cystic fibrosis exacerbation
Vocal cord dysfunction
Tracheomalacia/bronchomalacia
Congenital heart disease with pulmonary edema
Anaphylaxis
Upper airway obstruction.
Management
Initial Management:
Immediate assessment of airway, breathing, and circulation
Administer supplemental oxygen to maintain saturation >90-92%
Assess severity using a validated score
Continuous pulse oximetry monitoring
Establish IV access for hydration and potential medication administration
Avoid triggers.
Medical Management:
Short-acting beta-agonists (SABA) like Albuterol (Salbutamol) via nebulizer or metered-dose inhaler (MDI) with a spacer
Initial dose: 2.5 mg (nebulizer) or 4-8 puffs (MDI) every 20 minutes for 3 doses, followed by 0.5-1 mg/kg/hr (max 20 mg/hr) continuous infusion or intermittent doses every 1-4 hours as needed
Systemic corticosteroids (e.g., Prednisolone 1-2 mg/kg/dose PO/IV, max 60 mg/day) are crucial to reduce airway inflammation
onset of action is typically 4-6 hours
Ipratropium bromide (0.5 mg nebulized with SABA) may be added in severe exacerbations or if there is inadequate response to SABA alone
Magnesium sulfate (25-75 mg/kg IV, max 2g) can be considered for severe, life-threatening exacerbations unresponsive to initial therapy
Consider IV aminophylline or even mechanical ventilation in refractory cases.
Bronchodilator And Steroid Spacing:
Bronchodilators (SABAs) are administered frequently during acute exacerbations to provide rapid relief of bronchoconstriction
Initial aggressive dosing is key
Once the patient stabilizes, the frequency of SABAs is gradually reduced based on symptom improvement and objective measures (e.g., reduced work of breathing, improved SpO2, normal lung sounds)
Systemic corticosteroids, while essential for controlling inflammation, have a delayed onset of action and are not used for immediate bronchodilation
They are given concurrently with bronchodilators and continued as the patient improves to maintain anti-inflammatory effects and prevent relapse
The key is continuous assessment of the patient's response
bronchodilators are used as needed to manage bronchospasm, while steroids address the underlying inflammation
Spacing is dictated by symptom severity and response, not a fixed time interval between bronchodilators and steroids, though both are administered throughout the initial treatment phase.
Supportive Care:
Maintain adequate hydration
Encourage oral intake if tolerated, otherwise consider IV fluids
Monitor respiratory status closely, including work of breathing, breath sounds, and oxygen saturation
Implement comfort measures
Monitor for side effects of medications
Mobilize patient as tolerated once stable.
Complications
Early Complications:
Respiratory failure requiring mechanical ventilation
Pneumothorax (especially with barotrauma)
Status asthmaticus (prolonged, severe exacerbation unresponsive to initial treatment)
Hypoxemia and hypercapnia
Dehydration
Electrolyte imbalances
Adverse effects of medications (e.g., tachycardia, tremors from SABAs
hyperglycemia from steroids).
Late Complications:
Airway remodeling leading to fixed airflow obstruction
Frequent exacerbations leading to school absenteeism and reduced quality of life
Development of chronic asthma
Psychological distress.
Prevention Strategies:
Adherence to inhaled corticosteroid therapy for all asthmatic patients
Prompt recognition and treatment of early signs of exacerbation
Education on trigger avoidance
Development of a written asthma action plan
Regular follow-up with a healthcare provider
Vaccination against influenza and pneumococcus.
Prognosis
Factors Affecting Prognosis:
Severity and frequency of exacerbations
Age at diagnosis
Adherence to maintenance therapy
Presence of comorbidities
Socioeconomic factors
Access to healthcare
Early and aggressive treatment of exacerbations improves prognosis.
Outcomes:
With optimal management, most children with asthma can achieve good symptom control, normal lung function, and lead active lives
However, severe exacerbations can lead to long-term lung damage or be fatal
Recurrent hospitalizations are associated with poorer long-term outcomes.
Follow Up:
Regular follow-up appointments (every 3-6 months) are essential to monitor symptom control, lung function, adherence to medication, and review the asthma action plan
Education on inhaler technique and trigger avoidance should be reinforced
Adjust maintenance therapy as needed based on the patient's status.
Key Points
Exam Focus:
The cornerstone of acute asthma management is prompt administration of inhaled SABAs and systemic corticosteroids
Understand the typical dosing and frequency of SABAs in exacerbations
Recognize indications for adding ipratropium bromide and magnesium sulfate
The delay in steroid action means bronchodilators are the primary immediate relief
Differentiate between SABA use for relief and ICS for maintenance.
Clinical Pearls:
Always assess respiratory distress and work of breathing objectively
Continuous pulse oximetry is crucial
Use spacer devices with MDIs for better drug delivery in children
Consider viral-induced exacerbations and their management
Re-evaluate the patient frequently to assess response to treatment and adjust therapy
Educate parents and patients on home management and early signs of worsening
Be aware of potential side effects of high-dose SABAs and systemic steroids.
Common Mistakes:
Delayed initiation of systemic corticosteroids
Inadequate frequency or dose of SABAs
Relying solely on bronchodilators without addressing underlying inflammation
Over-reliance on chest X-rays to diagnose asthma exacerbations
Discharging patients without adequate follow-up plans or education on maintenance therapy.