Non-invasive vent.

Neil MacIntyre, Talal Dahhan.

Please Take a look a this presentation by Dr. Macintyre.   It described approach to respiratory failure, oxygenation and ventilation using mechanical invasive and non invasive techniques (February 2016). It describes basic concepts.

Definition:

Applying positive pressure ventilation, using face masks for nose, nose and mouth.

What parameters to set up?

• Identify target Minute Ventilation (V_E).
• Titrate Inspiratory Positive Airway Pressure (IPAP) to an inspiratory pressure (Pi) of 5 – 20 cm H₂O, targetting a Tidal Volume (V_T) of 4-8 ml/Kg.
• Watch for lung protection (not to exceed 8 ml/Kg V_T).
• Titrate Expiratory Positive Airway Pressure (EPAP), as it may help oxygenation.
• Usually patients set their own RR. However, some machines can have a set rate.
• Choose FiO₂. Try to avoid an FiO2 of 60% (0.6) or above. Thereby also avoiding oxygen toxicity.

The following FiO2/EPAP table helps to choose FiO2 and EPAP for oxygenation. IPAPs as above.

When to consider Non-invasive Ventilation?

• Cardiogenic pulmonary edema: widely used with variable outcomes.
  • Beneficial: ↓mortality and intubation rates. (Peter et al, Lancet 2006)
  • Non-beneficial: no statistical significant mortality benefit. (Gray et al, NEJM 2008).
• Chronic Obstructive Pulmonary Disease (COPD) exacerbation.
  early use leads to more rapid improvement of physiological variables, a reduction in the need for invasive mechanical ventilation, and a reduction in in-hospital mortality (Plant et al, Lancet 2000).
• Patients at High Risk of Post-extubation failure (Ferrer et al, AJRCCM 2006):
  • Age > 65.
  • history of heart failure.
  • Relatively high severity of illness (APACHE II >12).
• Postoperative cases of abdominal surgery patients who develop hypoxemia. CPAP seems to delay re-intubation. (Squadrone wt al, JAMA 2005).
• End-of-Life Care: It is used for palliation. Read the review article for more details.
• Lung infiltrates in immune suppressed patients: In select patients, early initiation of noninvasive ventilation is associated with significant reductions in the rates of endotracheal intubation and serious complications and an improved likelihood of survival to hospital discharge (Hilbert et al, NEJM 2001).

When is Non-Invasive Ventilation Contraindicated?

• Airway protection for CNS disease.
• Significant hemodynamic instability.
• Lots of airway secretions.
• Worsening of gas exchange despite effective technique.