Acute Asthma Exacerbation

Key considerations: Status asthmaticus, Anaphylaxis mimicking asthma, Foreign body aspiration

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history: Current medications and compliance (controller + rescue inhalers); Previous intubations or ICU admissions (marker of severe disease); Trigger: infection, allergen, exercise, medication (aspirin, beta-blockers); Duration and progression of symptoms; Last dose of bronchodilator; Oral steroid courses in past year; exam: Respiratory rate, SpO2, work of breathing; Wheezing: expiratory (mild-moderate), inspiratory + expiratory (severe); Silent chest: ominous — severe obstruction; Accessory muscle use, retractions, tripod position; Ability to speak: full sentences vs words only; Heart rate (tachycardia expected; bradycardia is pre-arrest); labs: VBG/ABG: pH, PCO2 — normal or elevated CO2 in asthma is a danger sign; Peak flow: <50% predicted = severe, <25% = life-threatening; CBC if infection suspected; BMP: electrolytes (albuterol causes hypokalemia); Lactate if sepsis suspected; imaging: CXR: only if suspecting pneumonia, pneumothorax, or foreign body; Not routinely needed for typical exacerbation; bedside: Peak expiratory flow rate (PEFR) — objective severity marker; Continuous pulse oximetry; Lung ultrasound: rule out pneumothorax, pleural effusion

immediate: Albuterol 2.5mg nebulizer q20min x3 OR MDI 8-10 puffs via spacer q20min; Ipratropium 0.5mg nebulized with first 3 albuterol treatments; Systemic corticosteroids: methylprednisolone 125mg IV or prednisone 60mg PO; Supplemental O2 to target SpO2 92–96%; general: Reassess after initial 3 treatments — determine response; Good response (PEF >70%): space treatments, observe; Poor response (PEF <50%): continuous nebulized albuterol; Steroids take 4-6 hours to have effect — give early; specific: diagnosis: Mild-Moderate (PEF >50%); steps: Albuterol q1-4h as needed; Prednisone 40-60mg PO x5 days; Step up controller therapy; Discharge with action plan; diagnosis: Severe (PEF <50%); steps: Continuous albuterol nebulization 10-15mg/hr; IV magnesium sulfate 2g over 20 min (smooth muscle relaxant); Consider epinephrine 0.3mg IM if not responding; Prepare for intubation if deteriorating; diagnosis: Status Asthmaticus / Impending Arrest; steps: Intubation: ketamine is preferred induction agent (bronchodilator); Low rate, long expiratory time — avoid auto-PEEP; IV epinephrine drip if hemodynamically compromised; Post-intubation: permissive hypercapnia (pH >7.2 acceptable)

admit: PEF <50% after treatment; Requiring continuous nebulization; Previous intubation for asthma; SpO2 <92% on room air after treatment; Severe exacerbation with slow response; Inability to obtain follow-up; discharge: PEF >70% predicted after treatment; Symptom improvement sustained for 1 hour; Able to use inhalers independently; Prednisone burst prescribed (40-60mg x5 days); Follow-up within 1 week with PCP or pulmonology; consults: Pulmonology: refractory asthma, recurrent exacerbations, possible biologic therapy; ICU: intubation, status asthmaticus, hemodynamic instability

A normal or rising PaCO2 in asthma is a danger sign — asthma patients should be hyperventilating and hypocapnic
IV magnesium sulfate 2g has strong evidence for severe exacerbations — give it early
Ketamine is the preferred RSI agent for asthma intubation — it is a bronchodilator
Post-intubation in asthma: use low respiratory rates (8-10/min) with long expiratory times to prevent auto-PEEP and barotrauma
Discharge patients need a written asthma action plan and follow-up within 1 week

GINA Asthma Guidelines 2024, NAEPP Expert Panel Report 3. Last reviewed: 2024-11-01