Asthma Exacerbation

Immediate Assessment and Management in ED

	Mild-moderate	Severe	Life threatening
Assessment	All of: Can walk, speak whole sentences in one breath $S_{\text{p}}\mathrm{O}{}_2$ (room air) > 94%	Any of: Unable to complete sentences in one breath Use of accessory muscles of neck or intercostal msucles/tracheal tug/subcostal recession during inspiration Obvious respiratory distress $S_{\text{p}}\mathrm{O}{}_2$ (room air) ≤94%	Any of: Reduced consciousness/collapse exhaustion/confused/agitated Cyanosis Poor respiratory effort $S_{\text{p}}\mathrm{O}{}_2$ (room air) <92% Poor respiratory effort, soft/absent breath sounds
Immediate treatment	Give salbutamol 4-12 puffs via pMDI and spacer	Start bronchodilators: Salbutamol 12 puffs via pMDI and spacer If can’t use spacer give 5mg nebule via nebuliser Ipratropium 8 puffs via pMDI and spacer every 20 minutes for first hour Start $\mathrm{O}{}_2$ supplementation if $S_{\text{p}}\mathrm{O}{}_2$ <92% on room air and titrate to 92-96%	Arrange immediate transfer to higher-level care Start bronchodilators Salbutamol 2x5mg nebules via continuous nebulisation driven by oxygen Ipratropium 500mcg added to nebulised solution every 20 minutes for the first hour Maintain $S_{\text{p}}\mathrm{O}{}_2$ 92-96%
Continued treatment	Repeat salbutamol 4-12 puffs every 20 miutes for the first hour (or sooner if needed) Then reduce to every 4-6 hours if needed	Repeat salbutamol 12 puffs every 20 minutes for the first hour (or sooner if needed) Repeat bronchodilators every 4-6 hours for 24 hours If salbutamol delivered via nebuliser, add 500mcg ipratropium to nebulised solution every 20 minutes for first hour Repeat 4-6 hourly	Repeat bronchodilators 4-6 hourly When dyspnoea improves consider changing to salbutamol via pMDI plus spacer or intermittent nebuliser

Severe asthma attack

Indicated by any of the following:

• RR ≥25 breaths/min
• Tacycardia ≥110 beats/min
• PEFR or FEV1 = 33-50% of predicted or known, despite nebuliser therapy Management includes steroid

Life-threatening attack with risk of Acute Respiratory Failure

Indicated by any of the following:

• Silent chest, cyanosis or feeble respiratory effort
• Bradycardia, arrhythmia or hypotension
• Altered mental status with exhaustion or confusion
• $S\mathrm{a}\mathrm{O}{}_2$ <92%; $P\mathrm{a}\mathrm{O}{}_2$ <60mmHg or normal or raised $Pa\mathrm{CO}{}_2$ >34-45 mmHg on ABG If precipitate onset also consider Anaphylaxis; look for other features (e.g. urticaria, erythema, pruritis or angio-oedema)

• First line management
  • Commence high-dose oxygen via a mask maintaining $S\mathrm{a}O2$ >95% and attach pulse oximetry monitoring
  • Give salbutamol 5mg via an oxygen-driven nebuliser, diluted with 3mL normal saline
    • Add ipratropium 500mcg to a second dose of salbutamol 5mg via the nebuliser if there is no response or there is a severe attack
    • Give prednisolone 50mg PO or hydrocortisone 200mg IV if unable to swallow
  • Avoid all sedatives, anxiolytics, NSAIDs and histamine-releasers (morphine)
• If patient’s condition does not improve
  • Give repeated salbutamol 5mg nebulisers (up to 3 doses in first hour)
  • Continue regular ipratropium 500mcg every 6 hours
• If patient’s condition is deteriorating or life-threatening features
  • Obtain IV access, ensure steroids have been given, perform a CXR and call for senior help
  • Give continuous salbutamol nebulisers
  • Obtain ABG to check $P\mathrm{a}\mathrm{CO}{}_2$, pH and potassium which may be 2° low to beta-agonist therapy
    • Treat if <3.0 mmol/L
  • Start bronchodilator infusion IV with ECG monitoring and arrange ICU bed
  • Give magnesium sulfate 2.5g IV (10 mmol) over 20-30 minutes
  • Give salbutamol 250-500 mcg IV over 10 minutes
    • Follow with infusion of salbutamol 5mg in 5% dextrose running at 60mL/h (10mcg/min) initially and titrate up to 120-240mL/h (20-40mcg/min)

Secondary Assessment

• Secondary assessment to be completed when feasible after starting salbutamol and oxygen
  • Physical examination including vital signs
  • Chest auscultation assessing for signs of complications (e.g. Pneumothorax, Pneumonia)
  • Obtain an ABG if life-threatening acute asthma
  • Obtain a chest radiograph to detect the presence of pneumothorax, consolidation or evidence of heart failure
  • Obtain spirometry when patient able
• Brief history including:
  • Reliever taken for this episode before presentation (dose, number of doses, time of last dose)
  • Whether oral corticosteroid has been started (e.g. from asthma action plan)
  • Current asthma medications
  • Whether the patient has been prescribed a preventer (inhaled corticosteroid or combination of inhaled corticosteroid and long acting beta-2 agonist taken as maintenance or budesonide-formoterol as needed)
    • Ask about adherence
  • What triggered this episode if known (e.g. allergies, medicines, respiratory infections)
    • Rarely triggered by food allergies but food allergy is a risk factor for life-threatening asthma
  • Presence of co-existing heart or lung disease, including COPD
  • Smoking/vaping status and exposure to environmental smoke/vaping
  • Peak flow measurements at home
  • Previous admission(s) to hospital (esp. in last 4 weeks)
• Socioeconomic challenges
  • Homeless, unemployed, living alone
  • Drug or alcohol use
  • Psychiatric illness

Additional Therapy

• Start systemic corticosteroids within 1 hour of presentation if indicated; systemic corticosteroids are indicated for all severe and life-threatening acute asthma exacerbations and should be considered in other exacerbations on a case-by-case basis
  • Adults: Oral prednisone/prednisolone 37.5–50 mg, then repeat each morning on second and subsequent days (total 5–10 days)
  • Adolescents: Oral prednisone/prednisolone 1 mg/kg (maximum 50 mg) once daily for 3–5 days
• Assess clinical response after each dose of bronchodilator
  • If dyspnoea/increased work of breathing is partially relieved within the first 5 minutes, reassess the need for repeated bronchodilator at 15 minutes.
  • If dyspnoea/increased work of breathing is not relieved, or condition deteriorates, repeat bronchodilator dose and consider adding inhaled ipratropium bromide (if not part of initial treatment) or IV magnesium sulfate.
    • Inhaled ipratropium bromide: Adults and adolescents: 8 actuations (21 microg/actuation) via pressurised metered-dose inhaler and spacer every 20 minutes for first hour. Repeat 4–6 hourly for 24 hours
    • Intravenous magnesium sulfate: Adults and adolescents: 0.2 mmol/kg (maximum 10 mmol) diluted in a compatible solution as a single IV infusion over 20 minutes
• ABG is expected to be initially respiratory alkalosis but with tiring $P_{\text{a}}\mathrm{CO}{}_2$ rises (respiratory acidosis) and metabolic lactic acidosis occurs
• Remember to monitor $\mathrm{K}{}^{+}$ with ongoing salbutamol use
• Consider XR chest
• Other non-established treatments:
  • Adrenaline – nebulised 5mg, SC 0.5mg, IV – load with 1mg → 1-20mcg/min
  • Heliox – reduces turbulent air flow, 70:30 (He:O2)
  • Ketamine – 0.5-2mg/kg/hr
  • Inhalational agents – sevoflurane, anaesthetic machine or custom fitted ventilator required
  • Leukotriene anatagonists – some benefit in chronic asthma
  • BAL – can clear mucous plugging but transiently worsens bronchospasm
• Rapid sequence induction
  • Induction agent: ketamine preferred because of bronchodilation, haemodynamic stability and preservation of respiratory drive
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Differentials to Consider

• LVF
• Anaphylaxis
• Aspiration
• Upper airway obstruction (vocal cord dysfunction, tracheal stenosis)
• Inhaled foreign body
• PE
• Hyperventilation syndrome
• Pneumothorax
• Parodoxical motion of the vocal cords

Discharge criteria

• After respiratory distress or increased work of breathing has resolved and symptoms stabilised observe the patient for at least 4 hours
• Repeat spirometry and peak expiratory flow before discharge
• Ensure the patient has adequate maintenance doses of ICS and sufficient oral corticosteroid to complete the short course:
  • ICS-formoterol (budesonide-formoterol or beclometasone-formoterol) to be taken as maintenance treatment and also as needed for relief of symptoms
  • A combination of ICS and long-acting beta-2 agonist taken as maintenance treatment, with a short-acting beta-2 agonist (e.g. salbutamol) taken as needed for relief of symptoms
• Patient to see GP within 3 days with comprehensive assessment in 2-4 weeks to reassess risk factors and review treatment regimen

Useful Links

• Australian Asthma Handbook | Managing acute asthma in adults and adolescents
• Australian Asthma Handbook | Managing acute asthma in children 6–11 years
• Australian Asthma Handbook | Managing acute asthma in children 1–5 years

Sources

• On call handbook
• Asthma handbook (links above)
• Acute Severe Asthma SID • LITFL • CCC Respiratory
• Critical asthma exacerbation - EMCrit Project