Weaning, Extubation and Weaning Failure Flashcards
Weaning is defined as process of __ from ____
Spontaneous breathing trial (SBT) is a trial under ______. Patient is put on __ with PEEP __ + PS __ for __ and observed
Weaning failure is defined as (3)
Extubation failure is defined as __
Liberating from mechanical support and endotracheal tube
SBT: work of breathing without assistance
Placed on PSV: PEEP 0 + PS 5-10
Duration: 30 minutes
Weaning failure
1. SBT failure
2. Reintubation need
3. NIV support within 48-72 hours following extubation
Extubation failure - need for reintubation
What is the duration typically needed for resumption of unsupported breathing?
What are the complications of prolonged intubation?
75% of patients are able to resume unsupported breathing within 7 days
Complications of prolonged ventilation:
1. Ventilator acquired infection
2. Ventilator induced lung injury
3. Tracheobronchomalacia and ventilator dependence
4. Vocal cord palsy
Outline the protocol for assessment for extubation
- Cause requiring intubation controlled/treated
- Initial screening for SBT and CAALMS
- Readiness assessment and RSBI < 120 (or 105)
- SBT
- Extubation - to NIV or unsupported
What are the initial criterias for SBT and ventilator discontinuation?
What is CAALMS?
- Lung issues stable or resolving
- Haemodynamically stable - no/weaning of inotropes, no arrhythmias
- Spontaneous inspiratory efforts, not in distress
- Calm, awake and alert (except stroke patients)
- Adequate gas exchange with low PEEP (<5-8 cmH2O) and low FiO2 (< 0.4-0.5)
CAALMS
CNS: mentation, follows commands
Airway: patency, previous difficult intubation, risk for laryngeal oedema (cuff leak)
Abdomen: normal abdominal compliance, stomach decompressed, NBM (off feeding)
Lungs: oxygenation, resolving respiratory failure
Meds: off opiates, benzodiazepines, paralysis
Secretions: no weak cough and no difficult to clear copious secretions
Readiness assessment and RSBI
- Closely monitor 1-5 minutes while on minimal to no support
- Put on CPAP 5-10cm H2O - Rapid shallow breathing index (RSBI)
- Identifies patient at risk of failed extubation
- Positive (<105 or 120) predicts success and negative (>105 or 120) predicts failure
RSBI (breaths/min/L) = **RR / VT**
Spontaneous breathing trial
What are its failure rate?
- PS mode 5-8cm H2O, PEEP 0-5 cmH2O
- Monitor for:
- Respiratory distress (RR, sats)
- Haemodynamic instability (BP, HR, arrhythmias)
- Gas exchange problem (ABG)
- Discomfort
Successful SBT does not indicate readiness for extubation
Re-intubation rate: 10-15%
- Higher in: ETT > 48 hours, elderly, severe illness, anaemia, cardiac failure
Criterias for successful SBT
- RR < 35/min
- Good tolerance to SBT
- HR < 140/min, or HR variability > 20%
- Sats > 90% or PaO2 > 60mmHg on Fi 0.4
- SBP > 80 and < 180 (or < 20% change from baseline)
- No signs of increased WOB or distress
- Accessory muscle, paradoxical/asynchronous rib cage movement, intercostal retraction, nasal flaring, profuse diaphoresis, agitation
When is patient considered not ready / failed SBT requiring reinitiation of full support?
- Worsening acid base abnormalities
- Increasing PaCO2 > 10mmHg without increase in effort or rate - narcotics, sedatives, hypothyroidism, brain injury
- Metabolic alkalosis due to contraction alkalosis from diuresis, nasogastric suctioning
- Respiratory acidosis pH < 7.32
- PaO2 < 60mmHg on Fi 0.4
- Fall in sats > 5% - Impaired central drive - tachypnoea, tachycardia, distress
- Impaired neuromuscular function
- Fatigue from prolonged high load, inadequate rest, ventilator asynchrony
- Hypothyroidism
- Electrolytes: hypoK, hypoPhos, hypoMg
- Critical illness myopathy/polyneuropathy
- Steroid myopathy
- Aminoglycosides, NM antagonists
- Diaphragmatic paralysis (phrenic nerve injury)
- Malnutrition - Excessive respiratory load
- Airway resistance - asthma, COPD, secretions
- Air trapping - COPD
- Poor compliance - pulmonary oedema, fibrosis, pneumonia, abdomen distention, thoracic cage abnormalities, PE
- High minute ventilation - fever, sepsis, met acidosis, dead space, PE - Left ventricular dysfunction - MI, APO
- Psychological intolerance - delirium, anxiety
NIV post-extubation
- Useful in COPD, cardiogenic pulmonary oedema
- Prophylaxis in high re-intubation risk
- Reduces mortality and VAP, length of ICU and hospital stay
Prolonged mechanical ventilatory support (PMV) is defined as ventilator support need for __ days and at least __ hours per day.
Incidence of ____
These patients will require __
One-year survival rate ranges from ____
Elderly and poor baseline functional status predicts worse prognosis
At least 21 days, at least 6 hours/day
Incidence 3-7%
Requires tracheostomy
Survival rate 23-76%
PMV weaning strategy
- Multidisciplinary rehabilitation
- Respiratory rehab
- Nutrition
- Physical therapy
- Psychosocial support - Gradual reduction in ventilator support
- Progressive wean to 50% of maximal support
- Daily cyclical trachy collar and SBTs, progressively longer duration, with nocturnal NIV support
(Success rate of 50-60%) - Re-explore causes of failed weaning
HFNC in post-extubation respiratory failure
High flow nasal cannula
- Reduces dead space
- Reduces work of breathing
- Humidification aids to clear secretions
Overcomes nasopharyngeal resistance
Hagen-Poiseuille equation
Spain study: HFNC re-intubation within 72 hours lower (4.9% vs 12%) than conventional oxygen group
No effect in time to intubation
ROX Index for HFNC failure requiring intubation
ROX Index = SpO₂/FiO₂ / Respiratory rate Sats in decimals (ie: 95% is 0.95) Fi in decimals (ie: 40% is 0.4)
ROX <3.85: risk of HFNC failure is high
- Intubation should be discussed.
ROX 3.85 to <4.88: repeat scoring one or two hours later for further evaluation
ROX Index ≥4.88: lower risk for intubation.
