Give Me (Vent) Liberty or Give Me Death

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What is an SBT and how we do them

• Spontaneous Breathing Trials: Spontaneous breathing trials assess the patients ability to breathe while receiving no vent support. A collective task force in 2001 stated you should start weaning by assessing if underlying cause of respiratory failure has been resolved or not

  • Strategy - T-piece (pictured to right) vs CPAP vs PS

  • Time - at least 30 minutes or no longer than 120

  • Pass/Fail

Credit: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.497.2519&rep=rep1&type=pdf

An international consensus was done which stated several minimum conditions for criteria to perform SBT, but no formal recommendations made on how to do a SBT

• Strategy -

  • no current evidence that one approach is superior. A Cochran review was done showing no difference between T-piece and pressure support regarding extubation failure but had low quality; but pressure support was found to be superior in the proportion of patients considered to have simple weaning

• Time -

  • collective task force in 2001; there is some evidence regarding the harmful effects of respiratory muscle fatigue if it occurs early in SBTs

• Judgement -

  • there is no consensus on what is success or failure, but low heart rate, good blood pressure, no anxiety, low RR is used to “pass”

  • Can patient protect airway? Handling secretions well, not too thick?

  • NIF = important in NM disease; otherwise should be a factor but no the deciding factor

  • Each hospital has their own protocols

Weaning Predictors

• Heart Rate Variability - Acrentales et al. -  good sensitivity and specificity, small group of patients

• Oxidative stress - Verona et al. - elevated markers of malondialdehyde and vitamin C, low NO were associated with SBT failure

• Sleep Quality - Chen et al. - cross sectional study that looked at affect of function of respiratory muscles

• Hand Grip Strength - Cottereau et al. - low associated with prolonged weaning but NOT extubation failure

• Diaphragmatic Dysfunction -DiNino et al. - at 30% or more difference in diaphragm thickness could predict extubation failure

• Cuff Leak Test - predictor of stridor after extubation - 24 hours before intubation, they measured amount of air leaking through ETT after deflating cuff; <110 mL = high risk of stridor (although crust around tube may affect this)

  • positive cuff leak is good, negative cuff leak is bad; if cuff leak is negative (<110 mL), steroids

• Mental status - GCS>8 King C.S. et al.

• RSBI - Karl Yang MD and Martin Tobin, MD - university of Texas and Loyola University in Chicago in 2011, low RSBI is associated with successful extubation

  • RSBI = (f/Vt). <105, successful weaning predicted

  • Predictive factors of weaning from mechanical ventilation and extubation outcome: A systematic review. - Journal of Critical Care

But make sure your reintubation rate isn’t too low

• Too low? not being agressive enough, patients are spending longer on the vent = high risk of badness

• Too high? Being too agressive

• Generally shoot for 10-15%

BiPAP or HFNC after Extubation

• Reconnect trial:

  • Giving patients a period of rest following a SBT would lead to higher success rate

• Bipap after extubation - has been studied for a very long time

• blue journal, lancent, ccm, anethesia journals

  • NAVA - Critical Care Medicine

  • Ferrer - Respiratory and Critical Care Medicine

  • Ferrer #2 - The Lancet

  • Ornico - Critical Care Medicine

• HFNC after extubation

  • Maggiore - HFNC vs Venturi Mask after extubation

  • Hernandez - Effect of HFNC vs NIV on extubation failure

summary

• Being on the vent is bad; patient should be reasonably safe for SBT

• You should do SBT/SAT on safe patients every day (wake up and breathe trial)

• One of the most important weaning predictors is RSBI (f/Vt) - <105 has been show to have a reduced reintubation rate

• Always think about why you intubated a patient in the first place before you extubate; and think about expected clinical course

• For high risk patients, consider a period of rest after SBT, HFNC or BiPAP post-extubation

• Track your reintubation rate - it shouldn’t be too high or too low

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