EM Notes – Non-Invasive Positive Pressure Ventilation

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Options

  1. Adults / Children:
    1. Continuous Positive Airways Pressure (CPAP) – positive pressure throughout resp cycle.
    2. Bilevel Positive Airways Pressure (BIPAP) – 2 levels of pressure insp & exp (IPAP > EPAP)
  2. Neonates:
    1. Nasal CPAP (NCPAP)
  3. Infants:
    1. High Flow Nasal Cannulae (HFNC) – humidified high flow rates generate some NCPAP.

Benefits

  1. ↓Intubation, ↓Cx of intubation (airway trauma, sedation, nosocomial infection), ↓LOS
  2. ↑lung vol, ↑FRC, ↑TV/minute volume
  3. ↓WOB, splints airways open, ↓V/Q mismatch, and ↑CO by ↓pre-/afterload

Indications

  1. Best if reducing the work of breathing will likely address an acute & reversible cause.
  2. Acute on chronic ventilatory failure (PaCO2>50mmHg) or hypoxaemia (PaO2/FiO2<200).
  3. Requires a patent airway and intact respiratory drive.

Contraindications

  1. Cardiac/respiratory arrest
  2. Hypotensive shock, acute MI
  3. ↓LOC or unprotected airway
  4. Facial trauma/burns or upper airway obstruction
  5. Vomiting/upper GI bleed or recent upper GI Sx

Recommended Indications

  1. Primary:
    1. COPD
      1. BIPAP & CPAP useful
      2. Failure more likely if GCS<11, pH<7.5 or RR>30
    2. APO/CCF
      1. CPAP or BiPAP (but no evidence BiPAP is better)
      2. Improves symptoms and ↓mortality
      3. PEEP may worsen CO in cardiogenic shock
  2. Other (less evidence):
    1. Immunosuppressed
    2. Palliative/elderly
    3. Post-op/post-extubation
    4. Asthma
    5. Neuromuscular disease
    6. Partial upper airways obs
    7. Thoracic trauma
    8. Obesity hypoventilation

Settings

  1. CPAP:
    1. Start at 5cmH2O and ↑ in 2cmH2O increments
  2. BIPAP:
    1. Start 8-10/3-4
    2. In hypoxaemia: ↑EPAP in 2cmH2O increments and ↑IPAP to maintain 1:2.5 ratio
    3. In hypercarbia: ↑IPAP in 1-3cmH2O increments
  3. NB: Humidify if used ≥6h. Beware pressures >15cmH2O as ↑Cx.

Complications

  1. Poor tolerance/agitation in some patients
  2. ↓venous return/pre-/afterload, may → ↓BP
  3. Abdominal compartment syndrome
  4. Air trapping
  5. Respiratory alkalosis
  6. Mask: keeping seal, pressure areas