Setting the Vent & Problems

2 Aspects Oxygenation Ventilation

Initial Settings Set mandatory breaths – Pressure or Volume Set Assist & Trigger Set PEEP and FiO2 Set Rate Set Inspiratory Time Set Alarms

Mandatory Breaths –Pressure – Normal Lungs start about 20cmH2O then titrate to desired tidal volume. –Volume – Based on IBW – Start at 8ml/kg Assist - If Mandatory breaths are Pressure controlled set as (Inspiratory Pressure – PEEP) Trigger - 2 (L/min) PEEP – Start at 5 if normal lungs, 10 if not Rate – 12 unless metabolic acidosis then Inspiratory Time – Go for I:E 1:2

What’s the problem…..?

Causes of High AWP Patient –Bronchospasm –Sputum Plug –Coughing Tube –Blocked –Bronchial Intubation –Biting

Hypoxaemia (Generally a PO2 of >8kPa is fine) Is this to do with the vent settings?

Things that are nothing to do with vent settings should be excluded first. Tension Pneumothorax Collapse / Consolidation Cardiogenic / Non-Cardiogenic Pulmonary Oedema

Vent Settings Oxygenation is proportional to mean airway pressure so can be increased by: –Increasing the inspiratory pressure (keeping tidal volume <10ml/kg or <7ml/kg if ARDS and plateau pressure <30cm H2O) –Increasing PEEP –Increasing the inspiratory time (which ends up as inverse ratio) Only if this doesn’t work should FiO2 be increased.

Respiratory Acidosis This should be treated to a pH of >7.25 by lowering the pCO2 towards normal. If there is also a metabolic acidosis a decision needs to be made on an individual patient basis. Hypercapnia is corrected by increasing rate or tidal volume.

Lung Protective Ventilation Ventilator induced damage to lungs causes the release of cytokines causing multi-organ failure. Possibly only an issue in ARDS ARDSnet trial (2000) – Ventilation at 12ml/kg (Pplat <50) vs 6ml/kg (Pplat <30) dropped mortality from approx 40 to 30% with lower Vt. ‘Permissive hypercapnia’ unles concerns such as a raised ICP.

Fighting the Ventilator What does that mean?

Possible Causes Not enough sedation Not enough analgesia Airway obstruction Inappropriate vent settings

How would you assess and treat?

Check vent settings – are you asking the patient to do something unreasonable? Check analgesia Check for tube blockage Assess respiratory system (is there a pneumothorax etc?) Would the patient be better spontaneously breathing (with assist)? Bolus of sedation Muscle relaxation is a last resort.

Ventilator Care Bundle Oral hygeine Supraglottic suction Cuff Pressure monitoring Stopping PPIs if no longer required Head elevation VTE prophylaxis Sedation holds (with a view to extubate)