Assessing Patient Readiness for Extubation
Assessing Patient Readiness for Extubation
Chris NicksonNov 3, 2020
OVERVIEW
The criteria used to assess a patient to determine whether they are ready for extubation is complex and multi-factorial.
- Ventilator weaning and extubating are two distinct processes
- Identifying patients for extubation based solely on clinical gestalt is inaccurate
- Predicting patient readiness is based upon many different physiologic variables
- No single parameter can accurately predict which patients are ready to resume spontaneous breathing
OPTIMAL RATE OF FAILED EXTUBATION
- About 15% of patients overall fail extubation in ICU
- the optimal rate is unknown, but is probably 5-10%
- higher rates are likely to lead to unnecessary prolongation of intubation at the population level
APPROACH
- determine disease resolution and consider other factors
- identify candidates for spontaneous breathing trial
- perform spontaneous breathing trial
- identify candidates for extubation
- extubation and post-extubation care
1. DETERMINE DISEASE RESOLUTION
- Begins with the resolution of respiratory failure and/or the disease that prompted initiation of mechanical ventilation
- Criteria to define disease resolution are not defined nor prospectively validated
- A systemic approach emphasising objective surrogate markers of recovery:
A+B
- Adequate oxygenation and gas exchange
- PaO2 >60mmHg on FiO2 <40%
- PEEP 5–8cmH2O
- CXR stable or improving
C
- absent or only low dose vasopressors/inotropes
- with SBP>90mmHg or MAP>60mmHg
- Stable cardiac rhythm
- No tachycardia
- No evidence of myocardial ischemia
D
- Adequate mentation
- Rousable (this is controversial: some advise GCS>8 equivalent, some able to follow commands, some neither!)
- No continuous sedative infusion or neuromuscular blockade
- no significant weakness (e.g. can lift head off pillow, raise arms in air for 15 seconds, clap hands)
- pain controlled
E
- No significant acidosis
- No electrolytes disturbance (e.g. normal K, PO4 >0.4)
- adequate fluid status (not overloaded)
F G
- abdominal pain/ distention controlled
- tolerating feeds
- Adequate hemoglobin
- Afebrile/ sepsis controlled
H I
Consider other factors:
- difficulty of intubation
- need for further procedures
- skill level of junior staff in unit overnight
- time of day
2. IDENTIFY CANDIDATES IN THE ICU FOR A SPONTANEOUS BREATHING TRIAL (SBT)
See Spontaneous Breathing Trial
3. PERFORM SPONTANEOUS BREATHING TRIAL
See Spontaneous Breathing Trial
4. IDENTIFY PATIENTS READY FOR TRIAL OF EXTUBATION
Indices to reliably predict extubation do not exist!
Key questions
Awake or easily rousable?
Able to follow commands?
Minimal volume of respiratory secretions?
Intact gag and cough reflex to prevent aspiration? (absent gag is normal in many people)
Consider a cuff leak test to check for laryngeal oedema:
Laryngeal edema reported in as many as 40% of prolonged intubations
5% patients experience severe upper airway obstruction following extubation
can be detected by ‘cuff leak’ test
Remember to consider other factors:
- difficulty of intubation
- need for further procedures
- skill level of junior staff in unit overnight
- time of day
5. EXTUBATION AND POST-EXTUBATION CARE
- Monitor closely for Laryngospasm and Post-extubation stridor — reintubation is not always need
- Consider high flow nasal prongs or non-invasive ventilation to treat or prevent post-extubation respiratory failure