Mechanical ventilation
Policy
it is mandatory that nursing staff complete ventilation/weaning competencies
· all ventilator orders and changes to ventilation parameters must be recorded on the treatment order chart
· ventilation changes are to be initiated only by registered nurses with a post graduate qualification in cardiac/critical care who have completed all relevant competencies
· all ventilation changes must be within the ventilation/weaning protocol
· the CTSU registrar or relevant anaesthetist must review all patients prior to extubation
· all ventilator alarms must be addressed immediately
Changing of ventilation parameters by non-accredited staff is inappropriate and unsafe. Adherence to the following guidelines is mandatory!
Indications for mechanical ventilation
· post operative support of cardio-thoracic patients
· following cardiac arrest in step down ward
· respiratory failure
· anaesthetic not reversed
· frequently hypothermic
· rigid blood pressure control first 12-24 hours
Principles of institution of mechanical ventilation
· Default ventilation mode
MMV (SIMV on Star ventilator)10 BPM x TV (10 mls per kg) x FIO 2 .5 x Peep 5cms x PPS 10 cms (20 cms on Star ventilator)
· optimise oxygenation ( use lowest FIO2 to achieve PaO 2 > 80 mmHg)
· ventilate to maintain Ph 7.35 – 7.45 (if T° C <>
· optimise PaCO 2 ( adjust relative to premorbid state)
· reduce work of breathing (perform circuit compliance and prevent gas trapping by manipulation of autopeep)
· reduce haemodynamic effects of mechanical ventilation
· optimise sedation and analgesia
· prevent barotrauma ( maximum upper pressure limit 40 cm H2O, use pressure limited ventilation in susceptible patients)
· earliest possible extubation
Modes of mechanical ventilation
Synchronised intermittent mandatory ventilation (SIMV) + Peep (Pressure limited to 40 cm H 2O)
Indications:
· default ventilator setting
· baseline weaning mode
· patients with normal lung compliance
· mean airway pressure <>2 O
Complications:
· patient/ventilator dyssynchrony, gas trapping
· barotrauma
Pressure control ventilation (PCV) + Peep
Indications:
· requirements for full ventilation (not a weaning mode)
· patients with poor lung compliance
· mean airway pressure > 35 cm H 2 O
· high risk of barotrauma (ARDS, bullae, severe asthma)
Complications:
· high sedation requirement +/- muscle relaxants
· patient/ventilator dyssynchrony, gas trapping
Pressure support ventilation (PSV) + Peep
Indication:
Weaning mode
Complications of mechanical ventilation
Haemodynamic:
· reduced preload
· increased RV afterload
Respiratory:
· V/Q mismatch
· pneumonia
· ventilator dependency
· increased oxygen consumption
Metabolic:
· metabolic alkalosis
Local:
· vocal cord trauma from prolonged intubation
· lip, gum, teeth or skin damage from tapes securing ETT
