1. Weaning From The Ventilator
Dr Laura Kettley
PICU Teaching Day, UTH
20th December 2016

2. Objectives Learn why we want to wean
Consider factors associated with successful weaning
Consider reasons for difficulty weaning
Understand different methods for predicting successful extubation

3. Weaning: what is it & why do it?
Process of:
Reducing ventilatory support
Patient breathing spontaneously
Extubation
Invasive ventilation is associated with complications
Increased time on the ventilator = increased risk of complications

4. LETS BRAINSTORM…..
What factors do you think need to be considered to successfully wean a patient off the ventilator?
(i)  has the underlying condition improved?
(ii)  is the patient’s general condition optimal?
(iii)  have potential airway problems been
identified and remedied?
(iv)  is breathing adequate?

6. Causes of difficult weaning
CENTRAL
NEUROMUSCULAR
INCREASED RESPIRATORY LOAD

7. CENTRAL DRIVE Direct insult to respiratory centre Sedatives
Loss of hypoxic drive
Hyperventilation/ low PaCO2

8. Critical Illness polyneuropathy
NEUROMUSCULAR
Primary NMD
Critical Illness polyneuropathy
Electrolyte abnormalities
Critical Care Myopathy/Malnutrition

9. Increased Respiratory Load
Increased resistance
Reduced compliance
Increased ventilation

10. A number of guidelines favour the use of the ratio of respiratory rate/tidal volume undertaken 1 min into a spontaneous breathing trial (SBT).3 In addition, a reasonable level of oxygenation should bedemonstrated,oftenassessedbythePaO2/FIO2 ratioatapositive end-expiratory pressure (PEEP) <5 cm H2O

11. Assessing adequacy of breathing
Traditional approach: Spontaneous breathing trials
Assess suitability for extubation or as tool for weaning
Variants:
T-piece
CPAP
Low level variable pressure support
No superiority
Successfully completing an SBT > extubation

12. Signs of failing SBT
Fail SBTs > slower form of weaning involving SBTs of a gradually increasing duration/consider tracheostomy

13. How to wean a patient who has failed a SBT
T-piece trials
supported ventilation being gradually broken up by SBTs of increasing duration (most trials increase these durations twice per day
Synchronized intermittent mandatory ventilation
gradually reducing the mandatory rate (most trials have done this by 2–4 bpm on a twice-daily basis, or more regularly if tolerated). The end-point for these SIMV patients is a rate of 4–5 min 1
Pressure support ventilation
gradually reducing the pressure to assist spontaneous breaths (most trials have done this by reducing the pres- sure support by 2–4 cm H2O twice a day and more often if tolerated). The end point is PSV at around 5–8 cm H2O for a duration that varies from 2 to 24 h.

15. Extubation Failure x5 increase risk of death Risk factors
<24 months
Syndromic condition
Chronic respiratory & neurological condition
Need to replace ETT at any point
COMMONEST REASON IS UPPER AIRWAYS OBSTRUCTION
Is there a role for steroids?

16. Conclusions
All patients on ventilatory support should be assessed on a daily basis for weaning suitability
If several preconditions are met trial an SBT
If unsuccessful, weaning should be attempted using either PSV or daily spontaneous breathing periods of increasing duration.
Consider tracheostomy in patients who are difficult to wean
Over 95% of patients should be weanable in this way