Asthma exacerbations are acute worsening of asthma symptoms that can be life-threatening and impose a significant burden on patients and the healthcare system. Pathophysiological reasons cause asthma exacerbations, the most prevalent of which are viral respiratory infections, specifically caused by the human rhinovirus.

Exacerbations are not the same as difficult-to-control asthma. Diurnal variability measures airflow a doctor may use to determine whether a patient has asthma. Diurnal variability is a crucial indicator of inadequate asthma management since it quantifies the variation between an individual's peak expiratory flow rate test scores and lowest scores.

Causes of Asthma Exacerbations

The causes of asthma exacerbations are diverse and can be categorised into several groups:

Viral Infections

Human Rhinovirus (HRV): The most common trigger of asthma exacerbations, particularly in children.
Respiratory Syncytial Virus (RSV): Another significant viral trigger.
Influenza Virus: Also known to cause asthma exacerbations.

Bacterial Infections

Mycoplasma Pneumoniae: A common bacterial trigger.
Chlamydia Pneumoniae: Another bacterial trigger.

Allergens

Tree, Weed, and Grass Pollen: Seasonal allergens that can trigger exacerbations.
Indoor Allergens: Such as dust mites, cockroaches, and pet dander.

Occupational Exposures

Animal Exposures: These can cause asthma exacerbations in individuals with occupational exposure.
Chemical Exposures: Highly reactive chemicals and cleaning agents can trigger exacerbations.

Irritants

Airway Pollutants: Such as tobacco smoke and particulate matter.

Other Factors

Eosinophilic Inflammation: A type of inflammation that can contribute to asthma exacerbations.
Uncontrolled Allergies: Allergies that are not well-managed can lead to exacerbations.
Sinusitis: Chronic sinus infections can contribute to asthma exacerbations.
Obesity: Obesity is a risk factor for asthma exacerbations.
GERD: Gastroesophageal reflux disease can trigger asthma exacerbations.
Poor Access to Care: Limited access to healthcare can exacerbate asthma symptoms.

Other Triggers

Exercise: Physical activity can trigger asthma exacerbations in some individuals.
Cold Air: Exposure to cold air can trigger asthma exacerbations.
Smoking: Smoking is a significant risk factor for asthma exacerbations.

Signs and Symptoms of Asthma Exacerbations

The signs and symptoms of asthma exacerbations include:

Respiratory Symptoms

Coughing: A persistent, often dry cough that can be severe.
Wheezing: A high-pitched whistling sound when breathing out.
Chest Tightness: A feeling of constriction or heaviness in the chest.
Shortness of Breath: Difficult breathing or feeling like there is insufficient air.
Rapid Breathing: Increased respiratory rate.
Gasping for Air during Sleep: Waking up at night due to asthma symptoms.

Other Symptoms

Difficulty Speaking or Breathing: Struggling to speak or breathe due to airway constriction.
Increased Respiratory Rate: Faster breathing rate.
Decreased Oxygen Saturation: Lower levels of oxygen in the blood.

Treatment of Asthma Exacerbations

Treatment of asthma exacerbations involves a combination of medications, oxygen therapy, and other interventions to relieve symptoms, improve lung function, and prevent complications. The specific treatment approach depends on the severity of the exacerbation and the patient's overall health.

Medications

Inhaled Bronchodilators: Beta-2 agonists and anticholinergics are used to relieve immediate symptoms.
Systemic Corticosteroids: Given orally or intravenously to reduce inflammation and prevent relapse.
Antibiotics: Only prescribed when there is a clear indication of bacterial infection.
Heliox: A mixture of helium and oxygen that can help improve ventilation and reduce the work of breathing.

Oxygen Therapy

Supplemental Oxygen: Provided through a nasal cannula or face mask to maintain oxygen saturation above 90%.

Other Interventions

Mechanical Ventilation: Used in severe cases to assist breathing.
Volume-cycled Ventilation: A type of mechanical ventilation that helps maintain alveolar ventilation.
Extrinsic Positive End-Expiratory Pressure (PEEP): Used to prevent auto-PEEP and improve lung function.

Hospitalisation

Indications: Patients who do not respond to outpatient treatment have severe symptoms or a persistent peak expiratory flow (PEF) below 80% of baseline.
Goals: To relieve symptoms, improve lung function, and prevent complications.

Follow-up Care

Discharge Plan: Patients are given a written plan for managing symptoms, using medications, and seeking care if asthma worsens.
Follow-up Appointment: Scheduled to evaluate the need for additional corticosteroid treatment and to monitor lung function.

Prevention

Asthma Action Plan: Patients are taught to monitor symptoms and take appropriate action to prevent exacerbations.
Regular Medication Use: Patients are encouraged to use their medications regularly to control their asthma.

Key Points

Early Treatment: Early treatment is the most effective strategy for managing asthma exacerbations.
Severity-Based Treatment: Treatment approaches vary based on the severity of the exacerbation.
Oxygen Therapy: Supplemental oxygen is essential for maintaining oxygen saturation above 90%.
Mechanical Ventilation: Used in severe cases to assist breathing.
Follow-up Care: Patients are given a written plan for managing symptoms and a follow-up appointment to evaluate the need for additional corticosteroid treatment.

Conclusions

Asthma exacerbations are serious events most often triggered by viral respiratory infections. Identifying high-risk patients and optimising long-term asthma control with appropriate pharmacologic and biologic therapies are key to preventing these exacerbations and reducing the burden of asthma.

Reference links:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5950727/
https://www.medicalnewstoday.com/articles/asthma-exacerbation#signs-and-symptoms