Viva - Weaning from Ventilation

Question 1

What is weaning

Answer 1

The process of liberating a patient from mechanical ventilation and acheiving extubation

Question 2

What common conditions or situations impacts on weaning

Answer 2

Resp
Cardiac
Neuromuscular
Nutritional

Question 3

Resp Factors

Answer 3

Increased work of breathing - due to inappropriate settings (inadequate insp flow or flow trigger)

Increased resistance, bronchospasm, secretion management

Reduced compliance - pneumonia, oedema, pneumothorax, splinting, effusions

Increased ventilatory requirements: metabolic acidosis, shock, PE

Question 4

Cardiac fators

Answer 4

IHD
Valvular heart disease
Systolic/diastolic dysfunction
Pulmonary hypertension

Question 5

Neuromuscular factors

Answer 5

Lack of central drive - sedatives, metabolic alkalosis, brainstem haemorrhage/ischaemia, loss of hypoxic drive

Neuromuscular patholgoy - GBS, myasthenia etc
CIPN, CIM
Malnutrition
Electrolytes - low K, low PO3, low Mg, Low Ca
Hypothyroid

Delerium anxiety depression,

Nutrition - anaemia, malnutirion, obesity (FRC reduced, compliance down)

Question 6

How to initiate weaning

Answer 6

Are they ready?
   Has the illness resolved or getting better
   Absence of excess secretions
   Adequate cough
   Co-operative

Objective measures
Haemodynamically stable - low vasopressors
PF >200, FiO2< 0.5, pH >7.25, PEEP< 10

Predictive measures
   RR<35
   VT >5ml/kg
   RSBI <65 - likly to succeed
   65-105 - may be successful
   >105 likely to failure

RSBI - RR/Vt

Airway occlusion pressure 0.1 sec >5cmH2O
MIP<20

Question 7

How to do the trial

Answer 7

Originally connect patient to T-piece

Use of CPAP, 0 PSupp or low level PSupp as tube compensation
(Note the European approach is a zero PEEP approach)

Duration 30 minutes is the same as 120 minutes

Patients who fail may require a slower period of weaning

Extubate if SBT ok, neuro status good, no excess secretions, no airway issues

Question 8

How to define SBT failure

Answer 8

RR>35
Sats< 90%
HR >140 orchange by 20%
Systolic > 180 or < 90

Subjective
Agitated
Sweating
Anxiety or increased WOB

Question 9

Trachestomy in weaning - why

Answer 9

Prolonged respiratory wean

Reduced sedation, and possible reduced delieruum
therefore reduced CINM

Reduce dead space and improve WOB
Trachel toilet, suction
Communication - talk through cuff down

Question 10

NIV?

Answer 10

Extubate to NIV is good for people with COPD, no evidence for the general population