Internal Medicine
What is acute severe asthma?
- The features of acute severe asthma are
- Respiratory rate ≥ 25/min
- Heart rate ≥ 110/min
- Inability to complete sentence in 1 breath
- PEF 33-50% predicted (< 200L/min)
Life Threatening Features of Acute Severe Asthma
- Silent chest
- Cyanosis
- Feeble respiratory effort
- Bradycardia or arrhythmias
- Hypotension
- PEF < 33% predicted (<100 L/min)
- SpO2 < 92% or PaO2 < 8 kPa (60mmHg)
- Exhaustion
- Coma
Treatment
- Oxygen - high concentration of oxygen to maintain oxygen saturation above 92%
- Inhaled Broncho dilator - ẞ2 agonist e.g. ventolin via Nebulizer
- Apratropium bromide (Atrovent) - anticholinergic drug, should be added to ventolin (revise correction)CC
- Systemic corticosteroid - intravenous
- IV fluids
- PEF should be recorded 15-30mins initially and then every 4-6 hours
- Pulse oxymetery - SaO2 should remain > 92%
- Arterial blood gases to be monitored
Indications for assisted ventilation in Acute Severe Asthma for resp acidosis
- Respiratory arrest
- Coma
- Deterioration of Arterial blood gas tensions despite therapy
- PaO2 < 8 kPa (60mmHg) and falling
- PaCO2 > 6 kPa (50 mmHg) and rising
- pH low and falling (H+ high and rising)
- Exhaustion, confusion, drowsiness
Prognosis
- Outcome of acute severe asthma is good. Death is rare
- Death can occur when failure to recognize the severity of attack by physician or the patient
When to discharge the patient who is admitted with severe acute asthma
- Nebulized therapy has been stopped for at least 24 hours
- Peak expiratory flow (PEF) has reached 75% of predicted value
- Give follow up appointment with GP within two days and specialist hospital in a month
Therapeutics
Definition
acute severe asthma (status asthmatics) is a condition in which bronchodilators are ineffective in relieving the attack after 24 hours.
Management:
- Hospitalization.
- Perform chest X-ray, ECG and blood samples for electrolytes.
- Epinephrine SC, if there is no contraindications
- Aminophylline: 500mg slowly IV (monitoring of serum levels).
- Hydrocortisone: 200mg IV / 6hs.
- Salbutamol nebulizer (to allow continuous administration of salbutamol and to allow simultaneous oxygen therapy).
- Humidified O2 or O2 helium mixture and bronchial lavage.
- Sedative as diazepam (5-10mg orally).
- Correction of acidosis and dehydration (Na HCO3 & 5% glucose respectively).
- Antimicrobials.
- Mucolytics and expectorants e.g. bromohexine & guaifenesin respectively;
- magnesium sulfate injection - bronchodilator effect - used in last resort - offlabel use