Rosen & Barkin's 5-Minute Emergency Medicine Consult (80 page)

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Authors: Jeffrey J. Schaider,Adam Z. Barkin,Roger M. Barkin,Philip Shayne,Richard E. Wolfe,Stephen R. Hayden,Peter Rosen

Tags: #Medical, #Emergency Medicine

BOOK: Rosen & Barkin's 5-Minute Emergency Medicine Consult
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ETIOLOGY
  • Inflammatory process of the airways evidenced by episodic and reversible airflow obstruction and hyper-responsiveness with many cells and cellular elements contributing to the disease:
    • Neutrophils
    • Mast cells
    • Eosinophils
    • Macrophages
    • T lymphocytes
    • Epithelial cells
    • Cytokines
  • Triggers:
    • Pollen
    • Dust mites
    • Molds
    • Animal dander
    • Other environmental allergens
    • Viral upper respiratory infections
    • Occupational chemicals
    • Tobacco smoke
    • Environmental change
    • Cold air
    • Exercise induced
    • Emotional factors
    • Menstrual associated
    • Drugs:
      • Aspirin
      • NSAIDs
      • β-blockers
DIAGNOSIS
SIGNS AND SYMPTOMS
  • Wheezing
  • Dyspnea
  • Chest tightness
  • Cough
  • Tachypnea
  • Tachycardia
  • Respiratory distress:
    • Posture sitting upright or leaning forward
    • Use of accessory muscles
    • Inability to speak in full sentences
    • Diaphoresis
    • Poor air movement
  • Impending failure:
    • Altered mental status
    • Worsening fatigue
  • Pulsus paradoxus >18 mm Hg
ESSENTIAL WORKUP
  • Primarily a clinical diagnosis
  • Measure and follow severity with peak expiratory flow rate (PEFR)
  • Assess for underlying disease
DIAGNOSIS TESTS & NTERPRETATION
Lab
  • Arterial blood gas:
    • Not helpful during the initial evaluation
    • The decision to intubate should be based on clinical criteria.
    • Mild–moderate asthma: Respiratory alkalosis
    • Severe airflow obstruction and fatigue: Respiratory acidosis and PaCO
      2
      >42
  • Pulse oximetry:
    • <90% is indicative of severe respiratory distress.
    • Patients with impending respiratory compromise may still maintain saturation above 90% until sudden collapse.
  • WBC:
    • Leukocytosis is nonspecific
    • Pneumonia
    • Chronic steroid use
    • Stress of an asthma exacerbation
    • Demargination occurs after administration of epinephrine and steroids.
Diagnostic Procedures/Surgery
  • PEFR:
    • Estimates the degree of airflow obstruction:
      • Normal peak flow (adult) is 400–600.
      • 100–300 indicates moderate airway obstruction.
      • <100 is indicative of severe airway obstruction.
      • Use serially as an objective measure of the response to therapy
  • Forced expiratory volume (FEV):
    • More reliable measure of lung function than PEFR
    • Difficult to use as a screening tool
    • Often unavailable in the ED
    • Severe airway obstruction: FEV
      1
      <30–50%
  • CXR:
    • Indications:
      • Fever
      • Suspicion of pneumonia
      • Suspicion of pneumothorax or pneumomediastinum
      • Foreign body aspiration
      • 1st episode of asthma
      • Comorbid illness: For example: Diabetes, renal failure, CHF, AIDS, cancer
      • Not responding to treatment
    • Typical findings:
      • Hyperinflation
      • Scattered atelectasis
  • ECG:
    • Indicated in patients at risk for cardiac disease:
      • Dysrhythmias
      • Myocardial ischemia
    • Transient changes in severe asthma:
      • Right axis deviation
      • Right bundle branch block
      • Abnormal P-waves
      • Nonspecific ST–T-wave changes
DIFFERENTIAL DIAGNOSIS
  • Allergic reaction
  • Angioedema
  • Bronchiolitis
  • Bronchitis
  • Carcinoid tumors
  • Chemical pneumonitis
  • Chronic cor pulmonale
  • Chronic obstructive pulmonary disease
  • CHF
  • Croup
  • Foreign body aspiration
  • Immersion injury
  • Myocardial ischemia
  • Pneumonia
  • Pulmonary embolus
  • Smoke inhalation
  • Upper airway obstruction
  • Venous air embolus
TREATMENT
PRE HOSPITAL
  • Recognize the “quiet chest” as respiratory distress.
  • Supplemental oxygen
  • Continuous nebulized β-agonist
  • Administration of IM/SC epinephrine
INITIAL STABILIZATION/THERAPY
  • Immediate initiation of inhaled β-agonist treatment
  • Intubate for fatigue and respiratory distress.
  • Steroids
ED TREATMENT/PROCEDURES
  • Oxygen:
    • Maintain an oxygen saturation >90%
  • β-adrenergic agonist:
    • Selective β
      2
      -agonists (albuterol)
      • Mild–moderate asthmatic: Administer every 20 min
      • Severe asthmatic: Continuous nebulized treatment
    • SC β-agonist (terbutaline and epinephrine):
      • Severe exacerbations
      • Limited inhalation of aerosolized medicine
      • More side effects because of systemic absorption
      • Terbutaline—longer acting β-2 agonist with bronchodilating effects equivalent to epinephrine in acute asthma.
      • Relative contraindication: Age >40 yr and coronary disease
  • Corticosteroids:
    • Reduce airway wall inflammation
    • Administered early
    • Onset of action may take 4–6 hr
    • Administer IV or PO
    • IV Solu-Medrol in the treatment of severe asthma exacerbation
    • Mild–moderate exacerbations may be treated with oral prednisone burst or Depo-Medrol IM
    • Inhaled corticosteroids are currently not recommended as initial therapy.
  • Anticholinergic agents:
    • If minimal response to initial β-agonist treatment
    • Severe airflow obstruction
    • Inhaled anticholinergic agents should be used in conjunction with β-agonists.
  • Magnesium sulfate:
    • No benefit in mild–moderate asthma
    • May have a benefit in severe asthma
  • Aminophylline:
    • Rare utility in acute management
  • Leukotriene inhibitors:
    • Not currently recommended for acute exacerbation
  • Heliox:
    • Mixture of helium and oxygen (80:20, 70:30, 60:40)
    • Less dense than air
    • Decrease airway resistance.
    • Decrease in respiratory exhaustion
    • Not currently recommended for routine use
    • Consider in severe asthma
  • Noninvasive positive pressure ventilation:
    • CPAP and BiPAP
    • May improve oxygenation and decrease respiratory fatigue
    • Can only be used in an alert patient
    • Should not replace intubation
    • Not currently recommended for routine use
    • Consider in severe asthma
  • Ketamine:
    • Bronchodilator and an anesthetic agent
    • Useful as an induction agent during intubation
    • Contraindications:
      • HTN
      • Coronary disease
      • Preeclampsia
      • Increased intracranial pressure
  • Halothane:
    • Inhalation anesthetics are potent bronchodilators.
    • Refractory asthma in intubated patients
  • Intubation of the asthmatic patient:
    • Rapid sequence intubation
    • Lidocaine to attenuate airway reflexes
    • Etomidate or ketamine as an induction agent
    • Succinylcholine should be administered to achieve paralysis.
    • A large endotracheal tube >7 mm should be used to facilitate ventilation.
    • May need to mechanically exhale for the patient
    • Permissive hypercapnia
MEDICATION
  • β-agonists
    • Albuterol: 2.5 mg in 2.5 mL NS q20min inhaled (peds: 0.1–0.15 mg/kg/dose q20min [min. dose 1.25 mg])
    • Epinephrine: Adult: 0.3 mg (1:1,000) SC q0.5h–q4h × 3 doses (peds: 0.01 mg/kg up to 0.3 mg SC)
    • Terbutaline: 0.25 mg SC q0.5h × 2 doses (peds: 0.01 mg/kg up to 0.3 mg SC)
  • Corticosteroids:
    • Methylprednisolone: 60–125 mg IV (peds: 1–2 mg/kg/dose IV or PO q6h × 24 h)
    • Prednisone: 40–60 mg PO (peds: 1–2 mg/kg/d in single or divided doses)
    • Depo-Medrol 160 mg IM
  • Anticholinergics
    • Ipratropium bromide: 0.5 mg in 3 mL NS q1h × 3 doses
  • Magnesium: 2 g IV over 20 min (peds: 25–75 mg/kg)
  • Aminophylline: 0.6 mg/kg/h IV infusion
  • Rapid sequence intubation:
    • Etomidate: 0.3 mg/kg IV,
      or
      ketamine: 1–1.5 mg/kg IV
    • Lidocaine: 1–1.5 mg/kg IV
    • Succinylcholine: 1.5 mg/kg IV
FOLLOW-UP

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