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Invasive ventilation

Intensive care exam revision on intubation and ventilation for medical student finals, PLAB exams and MRCP PACES

Invasive ventilation requires endotracheal intubation or a tracheostomy. It is a complex subject and will not be covered in detail here. However, invasive ventilation allows the intensivist to manipulate the patient’s respiratory physiology controlling the respiratory rate, tidal volume, inspiratory flow, inspiration-expiration ratio, the FiO2 and the airway pressure. Click on the plus symbol below to expand:

Indications for invasive ventilation

Invasive ventilation is generally used to treat severe respiratory failure either immediately or after a trial of NIV has failed. Other indications for invasive ventilation (in the appropriate clinical context) are:

  • Apnoea
    • E.g. secondary to cardiac arrest or severe respiratory muscle weakness
  • Airway protection if the GCS is less than 8
  • Airway obstruction secondary to trauma, laryngeal oedema, tumour or burns
  • Severe haemodynamic instability
  • Raised respiratory rate (>30)
  • PaO2 <11 on FiO2 of >0.4
  • High PaCO2 with a respiratory acidosis (PH< 7.2)
  • Exhaustion
  • Confusion
  • Severe shock
  • Severe left ventricular failure

Although ventilation can be imperative and lifesaving, it is important to carefully consider patients who are appropriate as it is also associated with haemodynamic instability, barotrauma, problems associated with sedation, damage to the trachea, volume trauma, impaired cough and secretion retention, ARDS and ventilator acquired pneumonias.

Patients who are ventilated may also take a long time to wean and during this time they will become physically deconditioned and rely on nasogastric feeding. Patients who are ventilated are managed very carefully and need stress ulcer prophylaxis, DVT prophylaxis, daily chest physiotherapy, oxygen humidification and intensive monitoring of gaseous exchange.