Discontinuing Mechanical Ventilation - 30

Question 1

How can you help the preserve the strength of the diaphragm?

Answer 1

Allowing pt to trigger ventilator breaths

Question 2

Describe the sedation recommendations for vent-dependent pts

Answer 2

1. Maintain light sedation, can be easily aroused

2. Avoid or minimize benzos - use propofol and dexmedetomidine

Question 3

Describe the readiness criteria for spontaneous breathing trial

Answer 3

Resp
- PaO2/FiO2 >150-200 w/ FiO2 13

No fever
No sig electrolyte abn

Question 4

Measurements for successful spontaneous breathing during 1-2 minute trial

Answer 4

Tv 4-6ml/kg
RR 30-38
RR/Tv ratio 60-105 bpm/L
Max insp pressure -15 to -30 cmH2O

Question 5

Describe a spontaneous breathing trial using the ventilator circuit

Answer 5

1. Can monitor Tv and RR as shallow rapid breathing which commonly means failure is easy to spot
2. Can, however, inc work of breathing - 5cm pressure support can help but level is insignificant and irrelevant

Question 6

Describe spontaneous breathing trial with the vent disconnected

Answer 6

1. T-piece circuit with high flow O2 improves O2 and carries away CO2 w/ low work of breathing
2. Disadvantage is can’t monitor RR and Tv
3. Closer to normal breathing conditions and better for pts w/ inc vent demands but NO proven advantage of one method over another

Question 7

How do you know if a SBT fails?

Answer 7

1. RDS - agitation, diaphoresis, rapid breathing
2. Muscle weakness - paradoxical inward mvmt of abd during insp
3. Poor O2 sat, PaO2/FiO2 ratio, rising PaCO2, gradient b/2 et and PaCO2
4. Inadequate systemic oxygenation (central venous O2)

Question 8

How do you distinguish b/w anxiety and ventilatory failure in rapid breathing?

Answer 8

Anxiety = inc Tv

Question 9

How can rapid breathing during SBT be bad?

Answer 9

1. Asthma, COPD –> hyperinflation/auto-PEEP –> dec CO, inc dead space, dec compliance, diaphragm dysfxn d/t flattening
2. Infiltrative/ARDS –> red ventilation in diseased parts –> alveolar collapse, hypoxemia
3. ARF –> inc whole body O2 consumption

Question 10

How do you manage rapid breathing during a SBT?

Answer 10

Anxiety = opioid

Failure = vent

Question 11

What are the cardiac sources of failed SBT?

Answer 11

1. (-) intrathoracic pressures inc LV afterload
2. Hyperinflation and auto-PEEP impair VR and resistance ventricular distensibility/filling
3. Silent MI

Question 12

How do you monitor or detect cardiac dysfxn following multiple SBT failures?

Answer 12

1. Cardiac ultrasound - diastolic dysfxn = high failure rate
2. Dec in central or mixed venous O2 saturation as a result of dec in CO
3. Sig inc BNP

Question 13

What are some potential source of respiratory muscle weakness in vented patients during SBT?

Answer 13

1. Mechanical ventilation - esp when not triggering breaths BUT diaphragm weakness has NOT been demonstrated to prolong vent dependency
2. Neuropathy - severe sepsis, MOF
3. Mag and phosphorous depletion
4. Max insp pressure -15 to -30

Question 14

What are 2 factors you need to address and how do you address them prior to extubation?

Answer 14

1. Airway protective reflexes - make paper 1-2cm away wet with cough
2. Laryngeal edema - cuff-leak test (no leak = high risk for obstruction), methyl-prednisolone 20-40mg q4-6hrs for 12 to 24 hourse

Question 15

How do you manage post-extubation stridor?

Answer 15

Most occur w/in 30 minutes but can be 2hrs

1. Epinephrine neb 2.5ml 1% - unproven in adults
2. Noninvasive ventilation when used as a preventative measure early after extubation NOT if they have resp failure