Stages of weaning

There are 7 stages of weaning

1. Pre-weaning: treatment of the underlying condition. Titration of ventilation
2. Suspicion: Diagnostic triggering
3. Measuring weaning predictors
4. Decreasing ventilatory support
5. Extubation
6. Non-invasive ventilation after extubation
7. Re-intubation (if unsuccessful)

Criteria for weaning

Think ABCDE

Airway

Patent upper airway: airway can be visualised with laryngoscope, or, more commonly a ‘leak test’ can be performed by deflating the cuff

Breathing

Oxygenation: f_iO₂ <0.4, PEEP <8

Ventilation: Pressure support <10cmH₂0

Ventilator drive: On spontaneous mode!

Ability to clear secretions and comply with physiotherapy

Circulation

Haemodynamic stability

Disability

Sufficient level of consciousness to protect airway

Everything else

Original pathology resolving

No general anaesthesia planned in immediate future

Weaning predictors

 

Indices	Cut-off value
Rapid shallow breathing index (resp rate / VT)	<105 breaths/minute/litre
P0.1 (airway occlusion pressure	< -5cmH20
Minimum inspiratory pressure (MIP)	< -30cmH20
P0.1/MIP	<0.09-0.14cmH20
Peak cough flow	>60L/min

Risk factors for extubation failure

Age >65

COPD

Heart failure

OSA / obesity

Neuromuscular disorders

P_aCO₂ > 6.5kPa

Positive fluid balance

Ventilation >6 days