Weaning and Discontinuation of Ventilation

Question 1

What might we expect from a simple wean?

Answer 1

A patient can be removed directly off the ventilator with minimal titration.

Question 2

What might we expect from a challenging wean?

Answer 2

Patients that will require some time and effort to wean and extubate.

Question 3

What might we expect from a prolonged wean for a patient?

Answer 3

The weaning process may take weeks to months.

Question 4

What does it mean to have a patient who is incapable of weaning?

Answer 4

They will never be able to live without the assistance of a mechanical ventilator.

Question 5

What are the two ways we can wean?

Answer 5

1. Slow, stepwise titration
2. Burst of exercise dropping from high support to minimal or no support with periods of rest in between

Question 6

Describe the process of gradual weaning and at what point we would end it.

Answer 6

PSV is used to slowly decrease the support level over time. The target value is usually between 5 and 10 depending on disease process, diameter of ETT, and humidification type.

Question 7

Why do we use PSV over SIMV when weaning?

Answer 7

SIMV increases weaning times, sedation use, patient anxiety, dys-synchrony, etc.

Question 8

What are some alternative modes that could be used to wean and why?

Answer 8

PAV and NAVA because they allow more accurate titration of support, decrease dys-synchrony, and give a more accurate indication of patient WOB

Question 9

What would our end point be when weaning on PAV or NAVA?

Answer 9

PAV of 35% or less, NAVA of <1.0

Question 10

What is a spontaneous breathing trial?

Answer 10

Patient is transitioned from control mode or high level of support to low or no support and assessed. If the patient is able to ventilate on their own we can directly extubate from here.

Question 11

How long should a SBT be?

Answer 11

Usually are 30, 60, or 120 minutes

Question 12

What is a T-piece SBT?

Answer 12

It is a spontaneous breathing trial on a T-piece using the ventilator’s high flow function.

Question 13

When should we start considering weaning a patient?

Answer 13

When the patient is in the recovery stage of their disease course, when other organ systems are relatively stable, cardiac function is adequate, neurological status allows for spontaneous breathing, adequate GCS and minimized sedation.

Question 14

What change in heart rate is concerning when weaning?

Answer 14

An increase of 20% or more, or a sudden drop.

Question 15

What general parameter goals are we trying to meet for extubation?

Answer 15

PSV 5-10
FiO2 <40%
PEEP 5-8

Question 16

What does it mean when a patient is classified as a “failure to wean?”

Answer 16

The patient will have a very prolonged weaning process or never be successfully weaned off the ventilator.

Question 17

What are some reasons that a patient may be a failure to wean?

Answer 17

Impaired respiratory mechanics
Respiratory muscle dysfunction
Cardiac dysfunction
Neuro-muscular disorders
Metabolic disorders

Question 18

What can cuff leak tell us when weaning?

Answer 18

If there is airway edema an narrowing which can be a cause of failure.

Question 19

Describe cuff leak protocol.

Answer 19

1. Switch to volume control and drop PEEP to 5
2. Set target Vt to 400 or 500 ml
3. Deflate cuff (have yankuer available)
4. Compare inhaled vs exhaled Vt over next several breaths
5. Re-inflate cuff and return to support mode
   We are looking for a drop in Vt of >25% between inspired and expired (100mls if using 400 ml Vt)

Question 20

What should we do if there is no leak when doing a cuff leak test?

Answer 20

Consider causes leading to lack of leak such as upper airway edema, size of tube, anatomical reasons. If swelling is likely cause give dexamethasone and re-evaluate the leak in 12-24 hours. If we choose to extubate without a leak, be prepared for re-intubation.

Question 21

What is NIF?

Answer 21

How much negative inspiratory force the patient can generate. It is a good indicator of extubation failure if the values are poor, but not a good indicator of success.

Question 22

What is the minimal NIF needed to extubate?

Answer 22

-20 cmH2O, but more negative is better.

Question 23

What is a vital capacity maneuver?

Answer 23

A measure of the patient’s vital capacity. Tells us the patient’s ability to coordinate their breathing and follow commands but is a poor indication of success or failure.

Question 24

Describe the process of a vital capacity maneuver.

Answer 24

1. Switch to CPAP
2. Coach patient to take a large breath in, then from maximal inspiration coach them to exhale until they reach FRC
3. Use the exhaled Vt as your VC, it will record the last breath exhaled out.

Question 25

What is a P0.1 and what ventilators can it be done on?

Answer 25

Measures the negative pressure generated in the first 0.1 seconds of a normal breath. Indication of ventilatory drive to breath and muscle strength which doesn’t require patient coordination. Found on Servo and PB vents

Question 26

What values of a P0.1 indicate readiness to wean?

Answer 26

Normal is -1 to -2, cut-off for weaning is -8 but less negative is better. We also do not want above -1 because this may indicate weak respiratory muscles.

Question 27

What is an RSBI and what is the formula for it?

Answer 27

Rapid Shallow Breathing Index which is a comparison of Vt to RR. The idea is that if the patient has a low Vt and high RR they are probably too weak to wean. RSBI = RR/Vt (in liters)

Question 28

Describe the process of a RSBI?

Answer 28

1. Place the patient on CPAP
2. Allow patient to stabilize
3. Record RR and VT
4. Use formula RSBI = RR/Vt (in liters)
   The standard limit is less than 105, and the smaller the number the better it is

Question 29

What is the CROP index and what is a value that predicts successful extubation?

Answer 29

Combines multiple parameters together to create one summative value to help us predict extubation success. CROP index >13 is likely for successful extubation.

Question 30

How is peak cough flow used to determine readiness for extubation?

Answer 30

The cough is a defensive and protective mechanism that requires the coordination of the respiratory muscles and larynx, so a good peak cough flow can reduce secretion retention and shows us the patient will be able to clear their airway.

Question 31

What should a peak cough flow be when extubating?

Answer 31

If intubated, it should be >60. Once extubated/decannulated the flow should be >160.

Question 32

Describe the process of obtaining a peak cough flow.

Answer 32

1. Explain to patient that they are going to try to cough as hard as they can
2. Hyper-oxygenate if required
3. Have them take a maximal inspiration, then coach to cough as hard as possible
4. On vents that have the freeze screen option (PBs and V500) freeze the screen and scroll back to the biggest expiratory effort to find the flow
5. Repeat three times to ensure consistent results

Question 33

When should you stop a weaning assessment?

Answer 33

If the patient desaturates significantly, RR increases significantly, HR or BP significantly drops or increases, or if dysrhythmias appear

Question 34

What are some benefits of trachs when weaning?

Answer 34

Improved patient comfort, less likely to dislodge, enhanced patient mobility, increased potential for speech, decreased airway resistance, decreased deadspace, decreased laryngeal damage and edema, more options for weaning from ventilator, may be able to talk and swallow.

Question 35

What are some reasons for giving a patient a trach?

Answer 35

Prolonged intubation for mechanical ventilation, improved clearance of secretions, facilitate the weaning process, acute or chronic upper airway obstruction

Question 36

How long should a patient be on a ventilator before getting a trach?

Answer 36

Most are trached after they have been on a vent more than 2 weeks

Question 37

How does having a fenestrated trach tube affect ventilation and extubation?

Answer 37

Because there is an inner and outer cannula, the larger diameter can make plugging and speaking valve trials more difficult, and because the inner cannula is usually smaller it can be harder to ventilate through.

Question 38

When should we consider trach decannulation?

Answer 38

Once the patient can withstand a plugging trial for a minimum of 24 hours straight.