List the indications for and contraindications to the use of non-invasive ventilation in acute respiratory failure.

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College Answer

Non-invasive ventilation usually encompasses face mask (full or nasal) CPAP with or without additional ventilatory support
Indications can be based on physiology or on specific aetiological cause:

1.  Desire to provide increased respiratory support without the need for endotracheal intUbation.
The respiratory support make take the form of:            ·
•  increased FI(closed circuit)
•  increased End Expiratory Pressure, or
• increased inspiratory pressure (as continuous positive airway pressure or additional inspiratory support in the form of pressure or volume assisted breaths)

2.   Desire  to. delay  or  prevent  the  complications  and  morbidity  associated  with  mechanical ventilatory support via an endotracheal tube.
The specific types of respiratory failure that may benefit from Non-Invasive Ventilation should be listed (ideally with some indication of the level of evidence in the published  literature to support the approach).

Conditions that may benefit include:
•  Hypercapnic respiratory failure:
- . acute  exacerbation   of  COPD,  post-extubation  acute  respiratory  failure,  respiratory failure in patients  with cystic fibrosis,  patients awaiting  lung-transplantation,  patients who are not candidates for intubation (eg. DNR?, terminal illness).

•  Hypoxaemic respiratory failure
- cardiogenic   pulmonary   oedema,   postoperative   respiratory   failure,   post-traumatic respiratory  failure,  respiratory  failure  in AIDS, patients  who  are  not  candidates  for intubation.

A list of contraindications should include those situations that make the potential disadvantages or complications  of  non invasive  ventilation  worse.  Differentiation  into  absolute  and  relative  is arbitrary.
•  lack of experience in technique (technical & mechanical problems), intubation required for other reasons including airway protection and sputum clearance, uncooperative patients (confused, comatose, reluctant), full stomach (risks of aspiration), local trauma (nose/face),
fractured base of skull, oesophageal surgery (risks of gastric/oesophageal insufflation)

Discussion

A model answer might benefit from point form:

Strong indications

  • Pulmonary oedema
  • Asthma
  • COPD
  • Lung infection in the neutropenic patient

Weak indications

  • weaning from invasive ventilation
  • prevention/avoidance of intubation

Contraindications

  • decreased level of consciousness
  • vomiting, high aspiration risk
  • facial trauma
  • hemodynamic instability, particularly poor preload states