Table of Contents
Overview #
Definition
- 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).
Prioritisation
- Early recognition and intervention is vital – patients experiencing an acute asthma attack should be seen as a high priority (2)
Key points
- 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.
Triage #
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 #
History (2-6):
- Features of Asthma
- Acute onset
- Wheeze
- Cough
- Chest tightness
- Dyspnoea
- Trigger exposure
- Allergens e.g. pollen
- Respiratory tract infection
- Environmental/occupational: smoke, cold air
- Drugs: beta blockers, NSAIDs
- Exercise
- Past history:
- Age of diagnosis
- Asthma control
- Previous hospitalisations or ICU admissions
- Associated features:
- Coryzal symptoms (respiratory tract infection)
- Atopy
:
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 SpO2: >94% |
| Moderate | Function: Some limitation to ability to talk Mental state: Alert Respiratory symptoms: some increased WOB SpO2: >94% Tachycardia |
| Severe ANY OF: | 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% |
| Critical ANY OF: | Function: Exhaustion Collapse Mental State: reduced consciousness Respiratory symptoms: soft or absent breath soundsTachypnoea OR Bradyopnea/poor respiratory effortcyanosis SpO2 less than 90% |
Diagnosis #
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).
Differential diagnosis:
- Anaphylaxis
- 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
- Anxiety
Investigations #
Investigations are not usually required (5,6).
In severe asthma:
Investigations (5,6)
| Investigation | Significance |
| 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 |
| CRP | Inflammatory/infective cause/trigger |
| Respiratory virus PCR | Infective trigger |
Further investigations (5,6)
| Investigation | Indication |
| Chest X-ray | If sudden deterioration or suspect: pneumonia, atelectasis, pneumothorax, or pneumomediastinum. |
Management #
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.
Overview:
- 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) PLUS 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). |
OR
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) PLUS 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 PLUS 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. |
Corticosteroids #
- Recommended in all cases of acute asthma in those >6 years (except in the mildest of cases)
Adults (5):
| prednisone 37.5 to 50 mg PO, within 1 hour of presentation; continue once daily for a total of 5 to 10 days OR 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 #
References #
- 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/
Contributors
Reviewing Consultant/Senior Registrar
Dr Luke Foley
Dr Asha Bonney
