Mechanical ventilation

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