Noninvasive ventilation

(Redirected from CPAP)


Mechanism of Action

  • Augments inspiratory/expiratory pressures throughout a spontaneous respiratory cycle.
    • Recruits compressed alveoli to reduce atelectasis.
    • Prevents small airway collapse during inspiration.
    • Counteracts intrinsic PEEP (Positive End Expiratory Pressure).
    • Decreased both preload and afterload in heart failure exacerbations.
    • Improves lung compliance and V/Q matching.
    • Decreases the work of breathing.
  • Reduces need for intubation and mortality in acute cardiogenic pulmonary edema[1] and acute COPD exacerbation[2]


Illustration of difference between CPAP and BPAP.
    • Use for isolated hypoxia
    • Increasing CPAP increases oxygenation
  • BPAP = PEEP + (IPAP = Inspiratory Pressure Support)
    • Use for hypoxia and hypoventilation (decreases work of breathing)
    • Increasing IPAP (specifically IPAP-CPAP) increases ventilation
      • Note: BiPAP is a brand name of one of the BPAP machines. Both names are often used interchangeably.



  • Obtunded patients
  • Uncooperative patients
  • Vomiting or inability to protect the airway (aspiration risk)
  • Facial trauma or burns
  • Facial, esophageal, or gastric surgery
  • Poor mask fit


Patient on BPAP.
CPAP mask on EMS manikin.
Home CPAP device.
  1. Prepare intubation equipment in case of BPAP/CPAP failure.
  2. Position the patient in a 30-90° upright position.
  3. Apply the mask.
    • Select the appropriately-sized mask.
    • Secure it in place by fastening the Velcro straps.
    • Note: Some experts recommend allowing the patient to get used to the mask first, PRIOR TO starting the positive airway pressures.
  4. Prepare the patient.
    • Patients will often require frequent coaching throughout this process.
    • In moderately anxious patients, consider low-dose fentanyl, a benzodiazepine or ketamine to assist with patient-ventilator synchrony.
  5. Adjust the settings.
    • For BPAP, begin with an IPAP of 8-10 cm H2O and an EPAP of 2-4 cm H2O.
    • Gradually titrate upward IPAP and EPAP 1-2 cm every 5-15 minutes with a goal IPAP 10-16 cm H2O and EPAP of 8-10 cm H2O depending upon patient response.
  6. Continue close monitoring.
    • A doctor, nurse, or respiratory therapist should be with the patient at all times during BPAP/CPAP use.


  • Skin irritation
  • Nasal bridge pain
  • Mucosal dryness
  • Eye irritation
  • Gastric distention
  • Decreased cardiac output
  • Barotrauma (rarely)

See Also

Mechanical Ventilation Pages

External Links


  1. Peter JV, Moran JL, Phillips-Hughes J, Graham P, Bersten AD. Effect of non-invasive positive pressure ventilation (NIPPV) on mortality in patients with acute cardiogenic pulmonary oedema: a meta-analysis. Lancet. 2006;367(9517):1155-1163. doi:10.1016/S0140-6736(06)68506-1
  2. Ambrosino N, Vagheggini G. Non-invasive ventilation in exacerbations of COPD. Int J Chron Obstruct Pulmon Dis. 2007;2(4):471-476.