Reassess at 1 hour after starting bronchodilator, monitor and continue discharge
Continue to severe management if not improving
Remember
If not responding to any treatment during the 1 hour after bronchodilator, immediate transfer to high level care → move to life-threatening management.
Discharge
Discharge summary
Discharge medication (+spacer)
Educate
Asthma action plan
Follow up with GP
Acute Severe Asthma
Severe asthma defined as:
PEFR 33-55% predicated or best
RR >25
HR >110
SaO2 90- 95% room air
Can only speak a few words in one breath
Mild-moderate use of accessory muscle
Skin colour: Pallor
Chest auscultation: Wheeze
Management
Oxygen
Short-acting Beta2 receptor agonist (ie. Salbutamol with spacer)
Oral prednisolone (the earlier given in an attack, the better the outcome) – or IV hydrocortisone if unable to tolerate oral
Reassess at 1 hour after starting bronchodilator
Monitor
Discharge
+/- IV salbutamol
+/- IV magnesium sulphate immediately if very severe
+/- IV aminophylline some patients may respond, give if poor response to initial therapy
IV fluids – patients are often dehydrated
Antibiotics – if evidence of infection
Indications for invasive ventilation in asthma
Coma
Respiratory arrest
Exhaustion
Deteriorating ABG
Image from Australian asthma handbook
Life-threatening Asthma
Life-threatening asthma any one of:
PEFR <33%
SaO2 <90%
Silent chest (soft/absent breath sounds)
Cyanosis
Bradycardia/arrythmia/hypotension
Exhaustion
Confusion
Coma
Remember
Mneumonic CHEST for life-threatening asthma: Cynosis, Hypotension and Hypoxia (pO2 <90%), Exhaustion, Silent chest, Tachycardia and Threatening PEF < 33% best or predicted (in those >5yrs old).
Management
β-agonist (Salbutamol via continous nebulisation)
Anticholinergic – Ippatropium Bromide
Steroids (the earlier given in an attack, the better the outcome)
IV salbutamol
IV magnesium sulphate immediated if very severe
IV aminophylline some patients may respons, give if poor response to intitial therapy
+/- Intubation and ventilation
IV fluids patients are often dehydrated
Antibiotics only if an infection caused exacerbation
Indications for assisted ventilation in asthma
Coma
Respiratory arrest
Exhaustion
Deteriorating ABG
Remember
Mneumonic O-SHIT-MI for the management of Severe/Life-threatening asthma: Oxygen, Salbutamol, Hydrocortisone (Prednisolone), Ippatropium bromide, Theophylline, Magnesium sulphate, Intubation and ventilation.
Image from Australian asthma handbook
Pathogenesis Asthma Exacerbations
Airway obstruction occurs due to a combination of:
Inflammatory cell infiltration
Mucus hypersecretion with mucus plug formation
Smooth muscle contraction
Long-term uncontrolled asthma can lead to air trapping and asthma exacerbations through what is called dynamic hyperinflation.
Airflow obstruction → Slow expiratory airflow and incomplete gas exhalation dynamic hyperinflation → Patient takes next breath → Gas becomes trapped in alveoli
Gas becomes trapped in alveoli until the alveoli can not hold any more gas and exhaled volume = inhaled volume → Equilibrium
Mild asthma
Only most severely obstructed airways collapse
Collapsed airways with air trapping results in:
Decreased expiratory reserve volume
Increased residual volume
As asthma gets more severe
Expiratory reserve diminishes and this results in profound dyspnoea
Discussion