- An asthma exacerbation or acute asthma attack is an episode of worsening asthma symptoms and lung function (1).
- Acute asthma can manifest in response to a trigger such as a viral infection, allergen or lack of adherence to controller medication (1,2,3).
- Early recognition and intervention is vital – patients experiencing an acute asthma attack should be seen as a high priority (2)
- Acute asthma is a worsening of asthma symptoms and lung function.
- Early intervention is vital to prevent further deterioration.
- Asthma should be treated based on clinical severity.
- Seek senior help if severe or not improved by the initial treatment.
All patients with acute asthma should be seen within 30 minutes.
If a patient is deteriorating or at risk of imminent deterioration should be considered an emergency requiring immediate attention.
Clinical features #
- Features of Asthma
- Acute onset
- Chest tightness
- Trigger exposure
- Allergens e.g. pollen
- Respiratory tract infection
- Environmental/occupational: smoke, cold air
- Drugs: beta blockers, NSAIDs
- Past history:
- Age of diagnosis
- Asthma control
- Previous hospitalisations or ICU admissions
- Associated features:
- Coryzal symptoms (respiratory tract infection)
Note: wheeze is not a good indicator of severity (5)
Table 2: Clinical features of asthma that inform severity (4, 5, 6)
|Mild||Function: Can walkCan speak in complete sentences |
Mental state: Alert
Respiratory symptoms: Subtle or no increased WOB
|Moderate||Function: Some limitation to ability to talk |
Mental state: Alert
Respiratory symptoms: some increased WOB
|Function: Unable to complete sentences in one breath |
Mental state: Distressed
Respiratory symptoms: increased work of breathing with the use of accessory muscles (eg tracheal tug, intercostal or subcostal recession, marked abdominal breathing, chest wall recession in children)
SpO2: less than 94%
|Function: Exhaustion Collapse |
Mental State: reduced consciousness
Respiratory symptoms: soft or absent breath soundsTachypnoea OR Bradyopnea/poor respiratory effortcyanosis
SpO2 less than 90%
Diagnosis of acute asthma is largely clinical:
- History of intermittent symptoms typical of asthma
- Examination findings of characteristic musical wheezing (present in association with symptoms and absent when symptoms resolve) (3-6).
- Diagnosis can be confirmed after an acute episode has resolved with the demonstration of variable expiratory airflow limitation, preferably by spirometry and exclusion of alternative diagnoses (3).
- Foreign body aspiration
- Pulmonary infection: bronchitis, bronchiolitis
- Exacerbation of chronic disease: COPD, CFF
- Vocal cord dysfunction/transmitted upper airway sounds
- Pulmonary oedema (can be in absence of known cardiac disease)
- If chest pain/tightness – think cardiac aetiology – acute coronary syndrome
- If dyspnoea- broad DDx including PE
Investigations are not usually required (5,6).
In severe asthma:
|ABG||Rising or normal CO2 heralds imminent respiratory collapse |
Below results indicate SEVERE ASTHMA: PaO2 lower than 60 mmHg on room air
PaCO2 higher than 45 mmHg or PaCO2 within the normal range
pH less than 7.35
|FBE||Elevated WCC (infection), eosinophilia|
|Respiratory virus PCR||Infective trigger|
Further investigations (5,6)
|Chest X-ray||If sudden deterioration or suspect: pneumonia, atelectasis, pneumothorax, or pneumomediastinum.|
Management depends on clinical severity.
Involve senior help early – especially if not improved by initial therapy.
Continue regular inhalers.
Can monitor response with peak flow.
- Oxygen therapy
- Bronchodilator therapy
- Corticosteroid therapy
Oxygen (5): #
- If sats <92%
- Titrate to SpO2 of 92 to 96%
Bronchodilator Therapy #
Management – mild to moderate #
Mild to moderate asthma bronchodilator therapy (5).
|salbutamol 100 micrograms per puff, 1 puff at a time via pMDI with spacer.|
adult or child 6 years or older: 4 to 12 puffs; repeat as required.
Management – severe #
Bronchodilator therapy in an adult or child 6 years or older with severe acute asthma (5):
|salbutamol 100 micrograms per puff, 12 puffs (1 at a time) via pMDI with spacer (and mask, if required); repeat every 20 minutes for the first hour (or sooner if needed)|
ipratropium 21 micrograms per puff, 8 puffs (1 at a time) via pMDI with spacer (and mask, if required); repeat every 20 minutes for the first hour (or sooner if needed).
Consider nebuliser therapy in those unable to breathe through a spacer
Nebuliser therapy in an adult or child 6 years or older with severe acute asthma (5):
|salbutamol 5 mg via intermittent nebulisation every 20 minutes for the first hour (or sooner if needed)|
ipratropium 500 micrograms via intermittent nebulisation every 20 minutes for the first hour (or sooner if needed).
Management – critical/life-threatening #
Arrange immediate transfer to critical care or high-dependency facility.
Early involvement of senior staff is desirable for very sick patients.
For an adult or child 6 years or older with life-threatening acute asthma (5):
|salbutamol 10 mg at a time via continuous nebulisation|
ipratropium 500 micrograms added to nebulised solution every 20 minutes for the first hour.
If not responsive to initial therapy (5):
|magnesium sulfate 10 mmol (child 2 years or older: 0.1 to 0.2 mmol/kg up to 10 mmol) |
diluted to 100 mL in a compatible fluid, by slow intravenous injection over 20 minutes.
If the patient is unresponsive, has poor respiratory effort, and cannot inhale bronchodilators, or is considered to be peri-arrest, consider adrenaline (epinephrine). Give (5):
|Adrenaline 1 mg/mL (1:1000, 0.1%) solution, 0.01 mg/kg up to 0.5 mg (0.5 mL) intramuscularly; repeat after 3 to 5 minutes if required.|
- Recommended in all cases of acute asthma in those >6 years (except in the mildest of cases)
|prednisone 37.5 to 50 mg PO, within 1 hour of presentation; continue once daily for a total of 5 to 10 days|
dexamethasone 16 mg PO, within 1 hour of presentation; repeat dose once the next day.
ORIf oral therapy is not tolerated in adults, use:hydrocortisone 100 mg IV, 6-hourly for up to 24 hours; switch to an oral corticosteroid once tolerated. If IV therapy is still required after 24hrs, reduce frequency to 12-hourly.
Useful Resources #
- Fanta C.H. Acute exacerbations of asthma in adults: Home and office management. In: Bochner B.S. Hollingsworth H. editors. UpToDate [Internet]. Waltham (MA): UpToDate Inc; 2021 [Updated 2021 Feb; cited 2021 Oct 2] Available from: https://www.uptodate.com/contents/acute-exacerbations-of-asthma-in-adults-home-and-office-management#H23099132
- Fanta C.H. Acute exacerbations of asthma in adults: Emergency department and inpatient management. In: Bochner B.S. Hockberger R.S. Hollingsworth H. editors. UpToDate [Internet]. Waltham (MA): UpToDate Inc; 2021 [Updated 2021 Sep; cited 2021 Oct 2] Available from: https://www.uptodate.com/contents/acute-exacerbations-of-asthma-in-adults-emergency-department-and-inpatient-management?search=acute%20asthma%20&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2#H906728101
- Fanta C.H. Asthma in adolescents and adults: Evaluation and diagnosis. In: Bochner B.S. Barnes P.J. Hollingsworth H. editors. UpToDate [Internet]. Waltham (MA): UpToDate Inc; 2021 [Updated 2020 Jan; cited 2021 Oct 2] Available from:
- Australian Asthma Handbook [Internet]. National Asthma Council Australia Ltd 2019. Acute Asthma [updated 2019 Mar; cited 2021 Oct 2]. Available from: https://www.asthmahandbook.org.au/static/files/Australian-Asthma-Handbook-v2.0-Acute-asthma.pdf
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2021. Acute Asthma [updated 2020 Dec; cited 2021 Oct 2]. Available from: https://tgldcdp.tg.org.au/viewTopic?topicfile=asthma-acute-management§ionId=rsg6-c05-s5
- Clinical Practice Guidelines [Internet]. Melbourne (Vic) Royal Children’s Hospital Melbourne Ltd 2021. Acute Asthma [updated 2020 Dec; cited 2021 Oct 2]. Available from: https://www.rch.org.au/clinicalguide/guideline_index/Asthma_Acute/
Reviewing Consultant/Senior Registrar
Dr Luke Foley
Dr Asha Bonney