II. Contraindications

  1. See Advanced Airway Indications
  2. Respiratory failure or apnea
    1. Cardiopulmonary Arrest
    2. Comatose patient
  3. Airway protection
    1. Status Epilepticus
    2. Upper airway tenuous with risk of complete obstruction
    3. Uncontrolled Gastrointestinal Bleeding
    4. Intractable Emesis

III. Indications

  1. See Endotracheal Intubation Preoxygenation
  2. Hypoxemic respiratory failure or Inadequate oxygenation (CPAP)
    1. Cardiogenic pulmonary edema
    2. Congestive Heart Failure exacerbations
  3. Hypercarbic respiratory failure or Inadequate ventilation (BIPAP)
    1. Chronic Obstructive Pulmonary Disease exacerbations
  4. Immunocompromised patients
    1. Early initiation of Noninvasive Ventilation reduces intubation risk
      1. Adda (2008) Crit Care Med 36(10): 2766-72 [PubMed]
    2. Non-intubated immunocompromised patients have lower mortality
      1. Related to risk of Ventilator-Associated Pneumonia
  5. Other indications with mixed efficacy or inadequate studies
    1. Asthma
    2. Pneumonia
    3. Acute Lung Injury (Acute Respiratory Distress Syndrome)
    4. Thoracic Trauma

IV. Precautions

  1. Start Noninvasive Ventilation early, before severe respiratory Fatigue occurs
    1. When starting Supplemental Oxygen, consider whether Noninvasive Ventilation would be a better choice
  2. Prepare the machine in advance of patient arrival (e.g. EMS radio report)
    1. Plug in the Bipap or Cpap machine
    2. Attach to wall oxygen
    3. Attach mask to machine
    4. Set initial FIO2 to 100%
    5. Set initial Inspiratory pressure (IPAP) to 10-15 H2O, and expiratory pressure (EPAP) to 5 H2O

V. Physiology

  1. Pressures required to allow inspiration must equal the airway pressures to overcome
    1. Ventilator pressures (CPAP, BIPAP) allow for lower respiratory muscle pressures (work of breathing)
  2. Pressures required to allow inspiration
    1. Respiratory Muscle Pressures or work of breathing (pMuscle)
    2. Ventilator pressures (pApplied)
  3. Airway pressures to overcome
    1. Airway elastance with a predilection for airway collapse (pElastance)
    2. Airway resistance such as that due to bronchospasm or inflammation (pResistance)
    3. Airway impedance to flow from other factors such as anatomy in Sleep Apnea (pThreshold)

VI. Adverse Effects

  1. Gastric insufflation
    1. Increases work of breathing (against a distended Stomach)
    2. Risk of Vomiting and aspiration
    3. Abdominal Compartment Syndrome is a rare associated complication
    4. Avoid BIPAP inspiratory pressures >20 cm H2O
  2. Mask malplacement effects
    1. Nasal or facial ulcerations
  3. Decreased Cardiac Output
    1. Results from decreased Preload related to increased intrathoracic pressure
    2. Manage with increased fluid Resuscitation
  4. Barotrauma
    1. Pneumothorax may occur at higher pressures

VII. Management: Approach to Non-Invasive Positive Pressure Ventilation Selection

  1. Hypoxemic respiratory failure (Inadequate oxygenation)
    1. Concepts
      1. Increase oxygen delivered to the lung or
      2. Increase mean airway pressure (or Positive End-Expiratory Pressure)
    2. Interventions
      1. Continuous Positive Airways Pressure (CPAP)
    3. Conditions
      1. Cardiogenic pulmonary edema
      2. Congestive Heart Failure exacerbations
  2. Hypercarbic respiratory failure (Inadequate ventilation)
    1. Concepts
      1. Increase Tidal Volume or
      2. Increase Respiratory Rate
    2. Interventions
      1. Bilevel Positive Airway Pressure (BiPap)
    3. Conditions
      1. Chronic Obstructive Pulmonary Disease exacerbations
      2. BIPAP may be used for any of the Hypoxemia cases as well instead of CPAP
        1. Includes CHF (without increased risk of Myocardial Infarction)
        2. Vital (2013) Cochrane Database Syst Rev 5:CD005351 +PMID:18646124 [PubMed]
  3. References
    1. Mallemat and Runde in Herbert (2015) EM:Rap 15(2): 7-8

VIII. Protocol: Indications for intubation (failed Noninvasive Ventilation)

  1. See Bilevel Positive Airway Pressure (BIPAP) for re-evaluation based on ABG criteria
  2. Based on re-evaluation by Arterial Blood Gas every 1-2 hours
  3. Major Criteria (based on COPD cohort)
    1. See Advanced Airway indications
    2. Respiratory arrest (despite noninvasive Ventilator back-up rate)
    3. Gasping for air
    4. Loss of consciousness with respiratory pauses
    5. Agitation requiring Sedation
    6. Heart Rate <50 bpm and loss of alertness
    7. Hemodynamic instability with systolic Blood Pressure <70 mmHg
  4. Minor Criteria (2 of the following, based on COPD cohort)
    1. Respiratory Rate >35 breaths/minute (at any time)
    2. Respiratory Rate >20-25/minute (after one hour of Noninvasive Ventilation)
    3. pH <7.30 and decreased from onset
    4. PaO2 <45 mmHg despite Supplemental Oxygen
    5. Decreased Level of Consciousness or worsening encephalopathy
  5. References
    1. Hoo (2012) Noninvasive Ventilation, Medscape EMedicine,
      1. http://emedicine.medscape.com/article/304235-overview#aw2aab6b5

IX. References

  1. Martin and Hall (2015) Crit Dec Emerg Med 29(2): 11-8

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