Characterized by increased symptoms, deterioration in lung function and increased airway inflammation. The most common cause is viral infections; mould and air pollutants have also been implicated. Some exacerbations may occur over hours to days, but others appear with little or no warning, also known as brittle Asthma.
Management of mild to moderate exacerbations;
Short courses of ‘rescue’ glucocorticoids are required to regain control; Prednisone 30 to 60 mg daily. Indications are;
- Onset or worsening of sleep disturbance by Asthma
- Persistence of morning symptoms till midday
- Fall of PEF below 60% of the patient’s personal best recording
- Progressive diminished response to inhaled bronchodilator
- Symptoms severe enough to warrant treatment with nebulized or injected bronchodilators
Management of acute severe Asthma
Features include;
- Heart rate>110/ minute
- Respiratory rate>25 per minute
- PEF 33 to 50% of predicted
- Inability to complete sentences in one breath
Life-threatening features;
- “Silent chest”
- PEF <33% predicted( <100L/ min)
- SpO2<92%
- Normal or raised PaCO2
- Cyanosis, bradycardia or arrhythmias, feeble respiratory effort, exhaustion, hypotension, delirium, comma
-Near-fatal Asthma; raised PaCO2 and/or needing mechanical ventilation with high inflation pressures.
Treatment
1. Oxygen therapy- high concentrations to maintain SpO2 above 92%. Mechanical ventilation if there is a failure to achieve adequate oxygenation
2. High doses of inhaled bronchodilators- SABAs are the agent of choice.
- It can be given via a nebulizer with oxygen or via a metered-dose inhaler
- Ipratropium should be added in severe or life-threatening attacks
3. Systemic glucocorticoids- can be administered orally as Prednisone or as IV hydrocortisone in those who are unable to swallow or are vomiting
Other measures;
- IV fluids for those who are dehydrated
- Potassium supplements may be required since salbutamol can lower serum potassium.
- IV magnesium in those with a very low PEF
- Recording of PEF should be every 15 to 30 minutes and then every 4 to 6 hours.
- Repeat blood gas analysis
Indications for assisted ventilation;
- Respiratory arrest
- Coma
- Deterioration of blood gases despite optimal therapy
- Exhaustion, delirium, drowsiness
Prognosis;
Many preventable deaths occur; early recognition is important
Discharge;
- The patient should have discontinued nebulized therapy for atleast 24 hours.
- PEF should have reached 75% of the predicted best
- The patient to avoid any triggers
- Asthma education and a written asthma plan
- The patient should see a GP within two days of discharge
- Follow up with a specialist clinic
