Acute Asthma Exacerbation

Rafael J. Fernandez III, Stacy McIntyre

Presentation 

  • Sub-acute to acute progressive worsening of dyspnea, chest tightness, wheezing, and cough
  • Important historical cues: Prior hx of asthma, adherence to controller medications, triggers (exercise, allergens, cold)
  • Risk stratifying: Hx of intubations/ exacerbations, recent steroid course for exacerbation
  • Physical exam: wheezing, poor air movement, tachypnea, ↑ work of breathing, hypoxemia
  • Peak flows can help and are often cited in literature but do not change management acutely, can be useful as baseline for assessing response to therapy.
  • PEF <200 L/min or PEF <50% predicted indicates severe obstruction, PEF <70% predicted indicates moderate exacerbation)

Evaluation 

  • Generally aimed at ruling out causes for exacerbation and other diagnoses; these are not required but should be considered in pts being admitted for inpt management:
    • EKG, trop, BNP, D-dimer to assess for cardiac cause (ACS, CHF, PE)
    • CXR to rule out underlying process (PNA, PTX, atelectasis)
    • ABG/VBG not routinely needed unless ill-appearing, tachypneic, or lethargic/altered
    • Dangerous signs and possible ICU if:
    • Tachypnea >30 and/or significantly increased work-of-breathing
    • Hypercapnia or even normocapnia (these pts are usually hyperventilating; a normal CO2 in a severe asthma exacerbation could indicate impending respiratory failure)
    • Altered mental status
    • Requiring continuous nebulizers

Management 

  • Good asthma care requires frequent re-evaluation. Generally, reassess q1h after treatment initiation. If deteriorating, step up the ladder of management
  • ABC: if not protecting airway, intubate and admit to ICU
  • Peak expiratory flow (Order in EPIC “Peak Flow Measurement”). If pt cannot do it, consider A/VBG if ill-appearing, tachypneic, lethargic/AMS, or thinking about engaging ICU
  • SpO2 goal 93-95%. Avoid hyperoxia
  • Further work-up: Not required, but aimed at ruling out causes of exacerbation and other dx
  • CBC w/ diff (looking at eosinophils)
  • CXR to rule out underlying process (PNA, PTX, atelectasis)

Mild/Moderate

Severe

ICU
Assessment Physical Exam
  • Wheezing
  • Phrase Dyspnea ∅ Accessory Muscle Use
  • Tachypnea
  • Tachycardia 100-120
Objective Data
  • O2 Saturation 90-95% on RA
  • PEF > 50% Predicted
 Physical Exam
  • Wheezing
  • Single Word Dyspnea + Accessory Muscle Use
  • Tripoding
  • Tachypnea >30
  • Tachycardia >120
Objective Data
  • O2 Saturation <90% on RA
  • PEF < 50% Predicted
 Physical Exam
  • Drowsy, AMS. silent chest
  • Increased work of breathing
Objective Data
  • CO2 on Blood Gas
  • Low at first (Hyperventilation)
  • Normal or High → Impending Respiratory Failure
  • Requiring Continuous Nebulizers to maintain O2 saturations
Management
  • SABA Nebulizer ± Ipratropium
  • Supplemental O2 to 93- 95%
  • Begin Oral Prednisone 60mg
  • SABA/Ipratropium Nebulizer
  • Supplemental O2 to 93- 95%
  • Begin Oral Prednisone 60mg
  • Consider IV Magnesium 4g 20 minutes
  • Consider High Dose ICS
  • Continuous DuoNebs IV Methylprednisolone 125 q6hr (as likely can’t protect airway)
  • IV Magnesium 4g 20 minutes Consider High Dose Inhaled Corticosteroid
  • NPO IV Fluids to make up insensible losses (consider comorbidities though)

Further Management 

  • Corticosteroids: dosing based on severity of illness
    • Oral equivalent to IV (Lancet 1986;1:181-184)
    • Transition to PO and lower dose after improving air movement, work of breathing and gas exchange
    • Will need minimum of 5-7 days of oral corticosteroids.
    • Good data for no need to taper in general population, sometimes considered in someone with multiple severe exacerbations.
  • Step down SABA-Nebulizer treatments based on wheezing
  • Inspiratory/Expiratory wheezing q2 -> q3; Mostly Expiratory wheezing q3 -> q4; Minimal Wheezing q4 -> q6 or PRN. (Pediatrics 2000; 106 (5): 1006–12)
  • No need for empiric antibiotics unless there is concern for bacterial infection, then treat as Pneumonia (see Pneumonia chapters)

Prior to discharge

  • Ensure that pt is on appropriate controller medications.
  • See outpt management section but consider starting an ICS/LABA as part of SMART (JAMA 2018; 319(14):1485–1496)
  • Evaluate for causes of acute exacerbation to prevent future events (noncompliance, resp viruses, allergies, exposures, etc.). Evaluate for asthma inflammatory phenotype after recovery (IgE, peripheral eos, ABPA)
  • Can consider writing a simple asthma action plan (https://ginasthma.org/wpcontent/ uploads/2021/05/GINA-Pt-Guide-2021-copy.pdf)
  • Consider follow up with PCP vs. pulmonologist for evaluation of outpt regimen
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