II. Precautions

  1. Severe Asthma Exacerbations are shock states
    1. Airway obstruction results in air trapping and Barotrauma (risk of Pneumothorax)
    2. Venous return is obstructed with Hypotension (also due to the often associated Hypovolemia)
  2. Severe Asthma patients progress from loud (Wheezing, Tachypnea) to quiet (Respiratory Failure)
    1. Do not be reassured by cessation of Wheezing (check for hypoventilation, shallow inspiration)
    2. Do not be reassured by a normalizing pH or CO2
      1. May be compensated only be non-sustainable Hyperventilation, verging on Respiratory Failure
  3. References
    1. Swadron (2019) Pulmonary 1, CCME Emergency Medicine Board Review, accessed 5/28/2019

III. Signs: Red Flags suggestive of impending Respiratory Failure

  1. See Asthma Exacerbation Severity Evaluation
  2. See Status Asthmaticus
  3. Inability to speak more than 1-2 words at a time
  4. Increased Somnolence
  5. Cyanosis
  6. Wheezing paradoxically decreases (silent chest)
    1. Secondary to increased airway obstruction and less air movement
  7. Pulsus Paradoxus >25 mmHg
  8. PaCO2 normalization or hypercapnia (ominous)
  9. Bradycardia
  10. Severe Hypoxia

IV. Management: Follow Initial Management per other protocols

V. Management: Additional Measures for extremis

  1. Nebulized Albuterol with Ipratropium continuously to hourly
  2. Systemic Corticosteroid
  3. Adrenergic agonists
    1. Epinephrine (preferred)
      1. High dose: 0.01 mg/kg up to 0.3 mg SC and may be repeated every 5 minutes
      2. Low dose: 0.001 mg/kg (1-2 mcg/kg) IV in small push doses, titrated to effect
        1. Orman and Sloas in Herbert (2015) EM:Rap 15(6):16
    2. Terbutaline (alternative)
      1. Adult: 0.25 mg SC now and repeated up to once within 15-30 min
        1. Maximum: 0.5 mg per 4 hours
      2. Child: 0.01 mg/kg (up to 0.25 mg) SC every 20 min for up to 3 doses
        1. May be repeated up to every 2-6 hours
  4. Oxygen 100% (warm, humidified)
    1. Delivery by nonrebreather mask or
    2. High Flow Nasal Cannula
      1. Child: 20 L/min maximum
      2. Teen: 40 L/min maximum
  5. Two Intravenous Lines
  6. Hypotension
    1. Hypotension is common in Severe Asthma (increased thoracic pressure prevents venous return)
    2. Consider fluid bolus of Normal Saline 10-20 ml/kg IV (to 500 to 1000 ml IV)
    3. Chest XRay to evaluate for Tension Pneumothorax
  7. Consider Magnesium 40-75 mg/kg up to 2 grams IV for 1 dose delivered over 15-20 min
    1. Drug infusion rate is much faster than the typical 2 hour Magnesium infusion
    2. Rapidly effective in pediatric Asthma Exacerbations
    3. Also shown effective in severe adult acute Asthma
    4. Some studies question benefit
    5. References
      1. Silverman (2002) Chest 122:489-97 [PubMed]
      2. Hughes (2003) Lancet 361:2114-7 [PubMed]
  8. Consider Ketamine
    1. May improve Status Asthmaticus (not limited to intubation)
    2. May allow patients to tolerate BiPap, as well as progress via Delayed Sequence Intubation
    3. May increase airway secretions
    4. Bolus: 1-2 mg/kg (consider 1 mg/kg to start)
    5. Maintenance: 2-3 mg/kg/hour (consider 0.25 mg/kg/hour to start)
  9. Consider Noninvasive Positive Pressure Ventilation (CPAP, BIPAP, HHFNC)
    1. Allows for diaphragmatic rest
    2. See High Humidity High Flow Nasal Oxygen (HHFNC)
    3. See Non-Invasive Positive Pressure Ventilation (BIPAP)
    4. See Delayed Sequence Intubation (e.g. Ketamine with initial BiPap)
    5. Contraindications (exception: Delayed Sequence Intubation)
      1. Patient not alert or able to control their own airway (aspiration risk)
      2. Hemodynamically unstable (positive pressure reduces negative chest pressure and Preload)
      3. Cardiopulmonary arrest or significant Cardiac Arrhythmia
      4. Upper airway Trauma or obstruction (requires secure airway)
    6. Starting settings (Bipap)
      1. Inspiratory pressure: 12
      2. Expiratory pressure: 6
    7. Consider in combination with Ketamine for sedation (often poorly tolerated otherwise)
      1. Use the lower doses listed above (1 mg/kg bolus then 0.25 mg/kg/hour)
      2. May be used as bridge to intubation (See Delayed Sequence Intubation)

VI. Management: Measures to Avoid

  1. Avoid Heliox (helium to oxygen 80:20 70:30 or 60:40)
    1. Originally showed promise, but does not appear to improve Status Asthmaticus or COPD
      1. Appeared to reduce work of breathing and to improve Peak Flow in original studies
    2. Effective in the obstruction of the larger upper airway (e.g. Airway Foreign Body)
      1. However, not effective in the obstruction of the many small to medium airways affected by Asthma
    3. Risk of Hypoxemia if FIO2 of oxygen in mixture is too low
  2. Avoid Aminophylline or Theophylline
    1. Risk of adverse effects outweigh any marginal benefit
    2. Rare indication may be a patient in such distress that will not tolerate the nebulizer
  3. May continue home maintenance Asthma medications, but do not add these medications to control acute Asthma
    1. Do not initiate Mast Cell stabilizers, long acting beta agonists or leukotriene modifiers to control acute Asthma

VII. Management: Intubation and Mechanical Ventilation

  1. Precautions: Intubation is best done semi-electively before crisis
    1. Intubation criteria are based on clinical judgment (not on ABG or other lab criteria)
    2. Best if intubation can be avoided due to high risk of complications in Asthma (esp. Barotrauma)
      1. Even with Pneumothorax, Barotrauma to small alveoli may have longterm remodeling effects
    3. Hypercarbia in Status Asthmaticus is a failure of ventilation (not oxygenation)
      1. Hypercapnea is corrected with Respiratory Rate and Tidal Volume
      2. Respiratory Rate increases Breath Stacking and Tidal Volume increases Barotrauma
  2. Indications (indicated in 0.5% of Asthma Exacerbations)
    1. Impending or actual respiratory arrest
    2. Extreme muscle Fatigue
    3. Altered Mental Status
    4. Significant respiratory distress
    5. Severe Respiratory Acidosis and Metabolic Acidosis
    6. Hemodynamic instability (e.g. Hypotension)
    7. Persistent Hypoxemia and hypercapnia
      1. Arterial Blood Gas is not required as a criteria for intubation (clinical status is preferred)
      2. Arterial Blood Gas is indicated after intubation to adjust Ventilator settings
  3. Oral intubation is preferred
    1. Lower resistance and easier suctioning
    2. Lower Incidence of Sinusitis
  4. Endotracheal Tube selection
    1. Choose largest Endotracheal Tube possible (uncuffed if necessary)
  5. Rapid Sequence Intubation
    1. Sedation
      1. Ketamine (preferred in Asthma Exacerbation)
        1. Use with paralytic due to laryngospasm risk
      2. Etomidate
        1. Use as an alternative
    2. Paralytic
      1. Succinylcholine (preferred due to shorter duration)
      2. Rocuronium (if Hyperkalemia risk)
    3. Consider Lidocaine for pretreatment
    4. Consider Normal Saline bolus (10-20 cc/kg) to prevent post-intubation Hypotension
    5. Maximize preoxygenation (see Rapid Sequence Intubation for protocol)
  6. Post-intubation Management
    1. Avoid repeated Paralytic Agents after intubation if possible
    2. Continue aggressive Asthma Management after intubation
      1. Duonebs
      2. Magnesium
      3. Corticosteroids
    3. Ketamine may be preferred for post-intubation (Bronchodilator and mucolytic)
      1. See doses above
    4. Permissive hypercapnea (allowing CO2 to rise)
      1. Preferred over aggressive Hyperventilation with risk of Barotrauma (Pneumothorax risk)
      2. Settings to prevent baratrauma
        1. Ventilator rate: Low (start at 10-12 breaths/min, or start as low as 6 breaths/min)
          1. Allow for adequate exhalation time (prevents Breath Stacking, Auto-PEEP)
        2. Tidal Volume: Low
          1. Start at 6 ml/kg
          2. May titrate to 8-10 ml/kg (but keep plateau pressure <30 cm H2O)
          3. Risk of braotrauma at higher Tidal Volumes
        3. Inspiratory Flow rate: High (start at 80-100 ml/hour)
        4. Expiratory Time: High (long)
        5. FIO2: Lowest level to keep Oxygen Saturation >90%
        6. Plateau pressure: <30 cm H2O
        7. Consider PEEP 3-5
          1. Requires close observation for Auto-PEEP by patient
        8. SIMV Mode may be preferred over AC in Status Asthmaticus
          1. Allows for patient to trigger breath and prevent Breath Stacking
    5. Difficult to ventilate patients
      1. Optimize pulmonary toilet
      2. Consider bronchoscopy
      3. May benefit from inhalation gasses in operating room or ECMO
    6. Observe for intubation complications
      1. Barotrauma (e.g. Pneumothorax)
      2. Hemodynamic compromise (Hypotension)
      3. Pulmonary hyperinflation (Breath Stacking)

VIII. Management: Cardiac Arrest

  1. Disconnect the Ventilator
    1. Manually ventilate slowly
    2. Prevents Breath Stacking
  2. Decompress the chest manually
    1. Bear hug to remove trapped air
  3. Place bilateral Chest Tubes
    1. High risk of Tension Pneumothorax
    2. May temporize with bilateral needle thoracostamy
  4. Empirically give Intravenous Fluids (1 Liter)
    1. See Hypotension above
  5. Consider other measures
    1. Anesthetic gases (as bridge to ECMO)
    2. ECMO

IX. References

  1. Serrano (2014) Crit Dec Emerg Med 28(6):2-10
  2. Sherman (2014) Crit Dec Emerg Med 8(2): 12-18
  3. Majoewsky (2012) EM:RAP-C3 2(2): 1
  4. (1997) Management of Asthma, NIH 97-4053
  5. (1995) Global Strategy for Asthma, NIH 95-3659
  6. Pollart (2011) Am Fam Physician 84(1): 40-7 [PubMed]
  7. Ciarallo (2000) Arch Pediatr Adolesc Med 154:979-83 [PubMed]
  8. Sarfone (2000) Ann Emerg Med 36:572-8 [PubMed]

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Related Studies

Ontology: Status Asthmaticus (C0038218)

Definition (MSHCZE) Těžký a prolongovaný záchvat bronchiálního astmatu se závažnou poruchou dýchání, změnami v parciálním tlaku krevních plynů a ve vnitřním prostředí. (Velký lékařský slovník online, 2012 http://lekarske.slovniky.cz/ )
Definition (MSH) A sudden intense and continuous aggravation of a state of asthma, marked by dyspnea to the point of exhaustion and collapse and not responding to the usual therapeutic efforts.
Concepts Disease or Syndrome (T047)
MSH D013224
ICD9 493.91
ICD10 J46
SnomedCT 36979006, 195980003, 266363006, 155577001, 57546000
English Asthmatic Crises, Asthmatic Crisis, Asthmatic Shock, Asthmatic Shocks, Asthmaticus, Status, Crises, Asthmatic, Crisis, Asthmatic, Shock, Asthmatic, Shocks, Asthmatic, Asthma, unspecified type, with status asthmaticus, STATUS ASTHMATICUS, Status asthmaticus NOS, Status Asthmaticus, status asthmaticus, status asthmaticus (diagnosis), Asthma w status asthmat, Status Asthmaticus [Disease/Finding], acute severe asthma, asthma asthmaticus status, asthmatic crisis, severe acute asthma, asthmaticus status, (Severe asthma attack) or (status asthmaticus NOS), Status asthmaticus NOS (disorder), Status asthmaticus (disorder), Severe asthma attack, (Severe asthma attack) or (status asthmaticus NOS) (disorder), Status asthmaticus, Asthma with status asthmaticus, Acute severe asthma, Asthma with status asthmaticus (disorder), asthmaticus; status, status; asthmaticus, Status asthmaticus -RETIRED-, Asthmatic crisis
German STATUS ASTHMATICUS, Asthmakrise, Asthma, unspezifische Typ, mit Status asthmaticus, Asthmaanfall, Asthmatischer Schock, Status asthmaticus
Spanish CRISIS ASMATICA, Crisis asmática, Estatus asmático, Asma, tipo no especificado, con estatus asmático, asma agudo severo, Choque Asmático, estado de mal asmático, SAI, estado asmático - RETIRADO -, estado asmático - RETIRADO - (concepto no activo), estado de mal asmático, SAI (trastorno), Shock Asmático, asma con estado asmático (trastorno), asma con estado asmático, asma con estado de mal asmático (trastorno), asma con estado de mal asmático, mal asmático, SAI (trastorno), mal asmático, SAI, Crisis Asmática, Estado Asmático
Dutch astmacrisis, astma, niet-gespecificeerd type, met status asthmaticus, asthmaticus; status, status; asthmaticus, status asthmaticus, Astmatische crisis, Astmatische shock, Status asthmaticus
Portuguese Crise asmática, Asma de tipo NE com estado asmático, ESTADO DE MAL ASMATICO, Estado de mal asmático, Choque Asmático, Crise Asmática, Estado Asmático
French Asthme, de type non précisé, avec état de mal asthmatique, ETAT DE MAL ASTHMATIQUE, Etat de mal asthmatique, État de mal asthmatique, Crise d'asthme
Italian Asma, tipo non specificato, con stato asmatico, Shock asmatico, Crisi asmatica, Stato asmatico
Japanese 喘息発作重積, 喘息クリーゼ, 重積状態の喘息、型不明, ジュウセキジョウタイノゼンソクカタフメイ, ゼンソククリーゼ, ゼンソクホッサジュウセキ, 喘息持続状態, 喘息性ショック, 喘息様発症, 喘息発作重積状態
Swedish Status asthmaticus
Czech status asthmaticus, Nespecifikované astma se status asthmaticus, Status asthmaticus, Astmatická krize, astmatický záchvat, astmatický stav
Finnish Status asthmaticus
Korean 천식지속 상태
Polish Stan astmatyczny, Przełom astmatyczny, Przełom dychawiczy, Stan dychawiczy
Hungarian Asthmás crisis, Status asthmatikus, Nem meghatározott típusú asthma, status asthmaticussal
Norwegian Astmatisk krise, Astmatisk sjokk, Status asthmaticus