Asthma – ED

Asthma

  • subtype:
    • Aspirin sensitive asthma
      • prior sensitization to NSAID + chronic rhinosinusitis + nasal polyps + asthma
  • Atopic syndrome: allergic asthma, dermatitis, rhinitis (hay fever)
    • Samter’s triad: asthma, ASA/NSAIDs sensitivity, nasal polyps
  • Type 1: inflammation – female + URI – slow progressive and response to tx
  • Type 2: brochospasm – male + allergy/exercise – rapid onset & response to Tx

Pathophysiology (triad):

  • airway inflammation & hypersensitivity
  • bronchospasm / bronchial hyperresponsiveness
  • intermittent airway obstruction due to thick mucous secretion

COPD

  • Triad: Reactive airway disease, Emphysema – airway collapse (not reversible), Bronchitis – airway inflammation
    • 1) chronic bronchitis (blue bloater) – obese, mild dyspnea, hypoxima, inc lung markings, live longer
    • 2) emphysema (pink puffer) – thin, major dyspnea, normal PaO2, hyperinflated lungs
  • Pathophysiology: smoking, a1-antitrypsin deficiency

1. When a patient presents with a first episode of wheezing, consider a wide differential diagnosis (e.g., foreign body, croup/bronchiolitis, airway obstruction, CHF, PE, pneumonia, anaphylaxis) before concluding it is asthma.

DDx of wheezing:

  • infection: pneumonia, bronchiolitis, croup
  • Allergy: Asthma, anaphylaxis
  • Cardiac: pulmonary edema / CHF
  • Other: FB aspiration, BPD, vocal cord dysfunction, bronchiectasis, CF, COPD, PE

CHF vs COPD

  • COPD – BNP <80, ECG – no LVH, inc E/I ratio, quiet heart sounds
  • CHF – BNP >400, ECG – LVH
  • both can have: leg edema, PND, wheezing, similar CXR findings

PE in COPD

  • always consider PE in COPD-E; if no apparent COPD trigger, 20-25% has PE
  • use D-dimer / CTA
  • low FiO2 corrects hypoxia in COPD; if not, consider PE,PNA,ARDS, pulm Edema

2. In a patient with an exacerbation of asthma/COPD, look for a high-risk history (e.g., previous ICU stays/intubations, recent steroid use, multiple ER visits) to help determine optimal management.

High risk history:

    • Hx of ICU admission or intubation
    • multiple admissions (>1 hospitalizations or >2ED visits/yr)
    • Recent steroids use
    • Concurrent disease
    • Hx of sudden severe exacerbations
    • Difficulty perceiving severity of attack (pysch)
    • low socioeconomic status / urban residence / long way from hospital
    • IVDU
    • Poor f/u or lack of PCP

Asthma

  • Triggers: URI, cold/weather changes, exercise, cigarette, allergens
    • less common: NSAIDs hypersensitivity, B-blocker use, emotional stressors
  • Symptoms: wheezing, persistent cough at night, dyspnea, chest tightness

Dx of COPD-E

  • worsening dyspnea, cough, sputum; other symptoms: wheeze, coryza, sore throat, F, weak, AMS
  • Triggers: URTI, Smoking, inappropriate / noncompliance Tx, environmental exposure / allergies

3. In a patient with an exacerbation of asthma/COPD, use objective measures to establish the severity of episode (e.g., FEV1/peak flows, rising pCO2, fatigue, mental status).

Exam:

  • prolonged expiratory phase
  • wheeze – the presence of inspiratory wheeze / stridor prompt evaluation of upper airway obstruction
  • Severe obstruction:
    • Poor air movement as absence of wheezing
    • tachypnea >40 bpm, tachycardia >120bpm, hypoxemia
    • pulsus paradoxus (>10 sBP drop with inspiration)
    • accessory muscle use
    • altered mental status

Objective measures / Bedside tests:

  • PEF <100 L/ml before Tx or <300 L/ min after Tx; <25% predicted = impending airway
  • CXR (4Fs)
    • First episode of wheezing, Fever, Focal findings, Failure to respond to Tx
    • usually normal – to r/o pneumonia, CHF, pneumothorax, FB
  • Pulse oximetry (oxygenation) and capnography (ventilation)
  • ABG
    • mild:           pH inc             PCO2 dec          PO2 normal
    • moderate:  pH normal     PCO2 normal   PO2 dec
    • Severe:       pH dec             PCO2 inc           PO2 dec

4. Given a patient with asthma and comorbid conditions, identify and treat the comorbid conditions in a timely fashion (e.g., CHF, CAD, pneumonia, pneumothorax).


5. When a patient presents with acute asthma, initiate treatment to stabilize prior to definitive diagnosis (e.g., early beta agonists, steroids, oxygen, anticholinergics).

Initial Treatment:

  • Oxygen to keep saturation normal
  • IVF if dehydration
  • Short acting beta agonist: albuterol 15-20mg/hr continuous neb x 4hr
  • Ipratropium 0.5mg neb (0.25mg for child)
    • works better in children and COPD; dry secretions
  • Prednisone 50mg po daily or solumedrol 125mg IV
  • inhaled corticosteroids: Pulmicort Neb

Other adjuncts

  • Antibiotics – usually in COPD if dyspnea, inc sputum production / purulence
  • Epi 1:1000 0.3mg IM lateral thigh
  • MgSO4 1-2g IV over 30min
  • Terbutaline / Theophylline / Heliox
  • BiPaP – dec ICU/Tx complication/intubation/hospital stay/mortality(COPD)
    • c/i: arrest, severe encephalopathy, GIB, unstable pt, facial trauma/deformity, inability to protect airway, high risk of aspiration, inability to clear secretions
  • Ketamine – intubation
    • avoid whenever possible
    • Plateau pressure <35 (>35 associated with barotrauma); Peak pressure is better tolerated
    • use higher flow rate with shorter inspiratory times & long expiratory time (no PEEP) + permissive hypercapnia

6. Given a patient with an asthma or COPD exacerbation, use steroids (systemic and/or inhaled) when indicated.

Indication: steroid dependent, allergic component to COPD, not responding to other therapy

  • prednisone 30-40mg po for mild exacerbation
  • solumedrol 125mg IV for severe exacerbation
  • 5 days most for COPD exacerbation, no taper req

7. In a patient with impending respiratory failure that may not be obvious, look for and recognize the important clinical indicators of worsening respiratory deterioration (e.g., signs of fatigue on physical exam, confusion, hypoxia, hypercarbia), and initiate early, aggressive, non-invasive airway support as needed (e.g., BiPAP, CPAP, Heliox).

Tx:

  • O2 to achieve SpO2 sat >94% in peds and >90% in adult
  • MIld (FEV1 or PEFR <70% predicted)
    • albuterol & ipratropium MDI / Neb
    • oral corticosteroids
  • Moderate (FEV1 or PEFP 40-69%)
    • albuterol (5mg) and ipratropium (0.5mg) Q1hr neb or continuous neb or MDI
      • Peds: ventolin 0.03ml/kg Q20min
      • peds: ipratropium 125-250mcg Q60min
    • oral / IV steroids
      • 1mg/kg in peds (po 7 days)
    • IV magnesium
  • Severe exacerbation (FEV1 or PEFR <40%)
    • albuterol and ipratropium continue neb
    • IV corticosteroids
    • Iv magnesium
    • Epinephrine (1:1000) 0.2-0.5mg IM
    • BiPAP,
    • intubation
      • Low tidal volume (6-8ml/kg ideal body weight)
      • low respiratory rate (10-12bpm)
      • High inspiratory flow rates to allow max time for expiration)
      • moderate hypercapnia (PaCO2 <100) should be allowed while maintaining a pH 7.15-7.2
      • IV ketamine (bronchodilator, no histamine release, and maintain airway reflex) – induction agent of choice
    • Less used: heliox, IV terbutaline

Complications

  • pneumothorax
  • pneumomediastinum
  • hypokalemia from prolonged albuterol

Post-Intubation cardiac arrest in asthmatics

  • Causes: DOPE
    • Displaced ETT
    • Obstruction in tubes
    • Pneumothorax
    • Equipment failure
  • 5 Must dos
    • Disconnect the ventilator & check connections
    • Check the tube – position / obstruction
    • Hug the patient – push air out of chest
    • Bilateral chest tube insertions
    • Fluid bolus IV

8. Prior to discharging a patient after management of an acute exacerbation of asthma/COPD: a) Ensure that the episode is truly resolved (e.g., patient passes a “road test” on exertion and objective measurements such as FEV1 are good) b) Review disease management with the patient to reduce the likelihood of early recurrence and return (e.g., ensure proper MDI technique, adequate prescriptions, timely follow-up)

  • Home O2 for COPD if appropriate
  • Stop smoking to slow rate of FEV1 decline
  • Spiriva – c/i: glaucoma, bladder neck obstruction

Source: Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8th edition

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