Exacerbations of asthma are episodes characterized by a progressive increase in symptoms of shortness of breath, cough, wheezing or chest tightness and progressive decrease in lung function, i.e. they represent a change from the patient’s usual status that is sufficient to require a change in treatment. These can range from mild to life threatening exacerbations. There is also a decline in lung function, which can be quantitated with measurements of PEF or FEV1 . The exacerbations are categorized as severe or non-severe.
Severe exacerbation of asthma are characterized by
- Increase in dyspnea, with patient unable to complete one sentence in onebreath (In children: interrupted feeding, agitation)
- Respiratory rate > 30/minute
- Heart rate > 120/minute
- Use of accessory muscles of respiration
- Pulsus paradoxus > 25 mm Hg
- PEF < 60% personal best or > 100L/minute (in adults)
Patient with severe exacerbations should be managed at the health care facility, and if the episode does not remit within two hours, should be referred to a tertiary health care centre.
Patient not meeting the criteria for severe exacerbations are categorized as non-severe exacerbations, and can be managed, in most instances, on an outpatient basis.
Exacerbations usually occur in response to
- Exposure to an external agent (e.g. viral upper respiratory tract infection, pollen or pollution)
- And/or poor adherence with controller medication;
- However, a subset of patients present more acutely and without exposure to known risk factors.
- Severe exacerbations can occur in patients with mild or well-controlled asthma
Factors that increase the risk of asthma-related death
- A history of near-fatal asthma requiring intubation and mechanical ventilation
- Hospitalization or emergency care visit for asthma in the past year
- Currently using or having recently stopped using oral corticosteroids (a marker of event severity)
- Not currently using inhaled corticosteroids
- Over-use of SABAs, especially use of more than one canister of salbutamol (or equivalent) monthly
- A history of psychiatric disease or psychosocial problems.
- Poor adherence with asthma medications and/or poor adherence with (or lack of) a written asthma action plan
- Food allergy in a patient with asthma
Management of non-severe exacerbations
Patients with non-severe exacerbations can be usually managed on an outpatient basis, with
- Repeated administration of rapid-acting inhaled b2-agonists (2 puffs every 20 minutes for the first hour), which is the best and most cost-effective method to achieve rapid reversal of airflow limitation. In this regard, pMDI with holding chambers(spacers) have outcomes that are almost equivalent to nebulizer delivery.
- Increased doses of ICS +LABA Patients who quadrupled their ICS dose (to average of 2000mcg/day BDP equivalent) after their PEF fell were significantly less likely to require OCS.
- In adult patients with an acute deterioration, high-dose ICS for 7–14 days (500–1600mcg BDP-HFA equivalent) had an equivalent effect to a short course of OCS.
- Oral glucocorticoids (1 mg/kg prednisolone daily for 7-10 days) should be used in all except the mildest exacerbations as they significantly reduce the number of relapses and decreases beta-agonist use without an apparent increase in side effects.
A rough guide is to use oral steroids if response to the rapid acting inhaled b2-agonist alone is not prompt or sustained (PEF > 80 % personal best) after 1 hour. However, no additional medication is necessary if the rapid acting inhaled b2-agonist produces a complete response (PEF returns to greater than 80 percent of personal best), and the response lasts for at least 3 to 4 hours.
Management of severe exacerbations
severe exacerbations of asthma can be life-threatening, and should be managed as an emergency. Certain points which are important in management of acute severe asthma, are summarized below:
- A hand-held chamber is as effective as a nebulizer for the delivery of drugs used in acute asthma.
- The combination of rapid-onset LABA (formoterol) and ICS (budesonide or budesonide) in a single inhaler as both the controller and the reliever medication is effective in improving asthma control and in at-risk patients, reduces exacerbations requiring OCS, and hospitalizations.
- The use of intravenous aminophylline does not result in any additional bronchodilation compared to inhaled beta-agonists. But, the frequency of adverse effects is higher with aminophylline. Thus it should be used only if patient is not able to cooperate for any form of inhaled therapy, or if inhaled therapy is ineffective.
- Controlled oxygen therapy (if available) Oxygen therapy should be titrated against pulse oximetry (if available) to maintain oxygen saturation at 93–95% (94–98% for children 6–11 years). Controlled or titrated oxygen therapy gives better clinical outcomes than high-flow 100% oxygen therapy.
- The use of continuous beta-agonists s and ICS (defined as truly continuous aerosol delivery of beta-agonist medication using a large-volume nebulizer or sufficiently frequent nebulisations that medication delivery was effectively continuous i.e. 1nebulisation every 15 minutes or 4 / hour) in patients with severe acute asthma improves their pulmonary functions and reduces hospitalization in patients who present to the emergency department.
- Glucocorticoids are the mainstay of therapy.
Indications for OCS is for patients who:
- Fail to respond to an increase in reliever and controller medication for 2–3 days
- Deteriorate rapidly or who have a PEF or FEV1 <60% of their personal best or predicted value
- Have a history of sudden severe exacerbations
- Initial SABA treatment fails to achieve lasting improvement in symptoms
- The exacerbation developed while the patient was taking OCS
- The patient has a history of previous exacerbations requiring OCS
The use of corticosteroids within 1 hour of presentation to an emergency department significantly reduces the need for hospital admission in patients with acute asthma.
Daily doses of OCS equivalent to 50 mg prednisolone as a single morning dose, or 200 mg hydrocortisone in divided doses, are adequate for most patients. There is also no advantage of a particular preparation of glucocorticoids in acute asthma, and a maxmum dose of 40-60 mg/day of prednisolone is effective in most cases.
Prednisolone (40-60 mg daily) is given and continued for atleast 7-10days or until recovery.
Patients who quadrupled their ICS dose (to average of 2000mcg/day BDP equivalent) after their PEF fell were significantly less likely to require OCS.
In adult patients with an acute deterioration, high-dose ICS for 7–14 days (500–1600mcg BDP-HFA equivalent) had an equivalent effect to a short course of OCS.
7. For adults and children with moderate-severe exacerbations, treatment in the emergency department with both SABA and ipratropium, a short-acting anticholinergic, was associated with fewer hospitalizations and greater improvement in PEF and FEV1 compared with SABA alone.
8. Slow intravenous aminophylline infusion is helpful, but toxicity is common, especially in patients who are already on maintenance oral theophylline therapy. It should therefore be used with caution.
9. There is no evidence to support the use of intravenous beta2-agonists in patients with acute severe asthma. Where and when possible, these drugs should be given by inhalation.
10. In patients with acute severe asthma who have not had a good initial response, administration of a single dose of intravenous magnesium sulfate (2 gm over 20 minutes) improves pulmonary function when used as an adjunct to standard therapy.
11. The treatment should however be used with great caution under proper monitoring.
There is no role of routine use of antibiotics except if patient has fever, leucocytosis, purulent sputum or radiographic infiltrates suggestive of an infection.
12. A proper written discharge should be given, specifically mentioning the drugs, their dosages, frequency and requirement for follow-up visits.
13. Patient must be clearly informed and explained the importance of continuation of therapy.
14. Intramuscular epinephrine (adrenaline) is indicated in addition to standard therapy for acute asthma associated with anaphylaxis and angioedema. It is not routinely indicated for other asthma exacerbations.
15. Helium oxygen therapy there is no role for this intervention in routine care, it may be considered for patients who do not respond to standard therapy; however, availability, cost and technical issues are the limitations.
16. Sedation should be strictly avoided during exacerbations of asthma because of the respiratory depressant effect of anxiolytic and hypnotic drugs. An association between the use of these drugs and avoidable asthma deaths has been reported
17.The evidence regarding the role of NIV in asthma is weak