1. Weaning and Extubation:
A Pediatric Perspective
Ira M. Cheifetz, MD, FCCM, FAARC
Professor of Pediatrics
Chief, Pediatric Critical Care
Medical Director, PICU & Peds Resp Care
Duke Children’s Hospital

2. Weaning and Extubation
‘The separation of a patient from his
ventilator is very nearly pure art.’
– Donald F. Egan, 1977
‘Fundamentals of Respiratory Therapy’

3. Definitions
 Weaning: transition from ventilatory support
to complete spont breathing
 Success: maintaining effective gas
exchange with complete spont breathing
 Failure: inability to sustain effective gas
exchange w/o mechanical support within
48 hours of extubation

4. Definitions
 Spontaneous breathing trial (SBT)
– test of the ability to maintain complete
spontaneous breathing (i.e., extubation
readiness)
– failure is the inability to maintain effective gas
exchange with a RR within acceptable limits

5. Indications for Weaning
 Improving underlying disease process
 ‘Adequate’ gas exchange
 No undue burden on respiratory muscles
– cardiac insufficiency
– significant hyperinflation
– severe malnutrition
– multiorgan system dysfunction / failure
 Patient is capable of sustaining spontaneous
ventilation as ventilator support is decreased.

6. Effort of Breathing
 Respiratory rate
 Spontaneous tidal volume
 WOB
– paradoxical breathing / retractions
– esophageal manometry
 Inspiratory pressure of a spont breath (Pi)
 Maximal negative insp pressure (NIF)
 O2 cost of breathing

7. Factors that Contribute to Insp WOB
 ETT size / ventilator circuit deadspace
 Demand valves in the circuit
 Patient - ventilator dys-synchrony
 Trigger: pressure vs. flow
 Distal vs. proximal sensing (??)
 Any additional load on resp muscles

8. Adequacy of Gas Exchange
 Oxygenation
– PaO2/FiO2
– Oxygenation index: (FiO2 x Paw) / PaO2
– alveolar-arterial O2 gradient
– venous admixture; intrapulm shunt fraction
 Ventilation
– PaCO2
– physiological dead space
– EtCO2 - PaCO2 difference
– Fraction of ventilation provided by the vent

9. Vent Mode and Weaning Outcome
 PSV decreased duration of weaning
– Brochard, Am J Resp Crit Care Med, 1994
 Multicenter center study in adults:
– Esteban, N Engl J Med, 1995
– daily SBT led to extubation 3x faster than
IMV and 2x faster than PSV
– multiple daily SBTs were as successful as
a daily trial

10. Prolonged Ventilation
– ↑ nosocomial pneumonia
– ↑ airway injury
– ↑ VILI
– ↑ LOV & LOS
– ↑ cost
– ↓ patient & family satisfaction

11. Failed Extubation
– ↑ nosocomial pneumonia
– ↑ airway injury
– ↑ VILI
– ↑ LOV & LOS
– ↑ cost
– ↓ patient & family satisfaction
– mortality
 Children requiring reintubation within 48 hrs
had significantly  mortality than patients
successfully extubated (20% vs. 2%, p < 0.001)
Esteban, AJRCCM, 2001.

12. % spont breathing
% spont breathing
100
0
Time of extubation
Optimal Balance
Weaning time
100
% ventilator support
0

13. Should all adult pts be gradually
withdrawn from mech ventilation?
 No!
 Majority of adult patients who pass a SBT
are extubated within 24 hours
– Esteban, NEJM, 1995
– Brochard, AJRCCM, 1994

14. Should all peds pts be gradually
withdrawn from mech ventilation?
 Answer remains: No!
 PALISI: 58% of pts initially tested with a
minimal PS trial passed and were extubated
– Randolph, JAMA 2002
 77% of pts who underwent a SBT passed &
were extubated without weaning
– Farias, Inten Care Med, 1998

15. Weaning Protocols
Study Date N ↓ LOV p
Kollef 1997 357 1.4 d 0.029
Ely 1996 300 1.5 d 0.001
Marelich 2000 253 2.3 d 0.0001
Kollef, CCM, 1997
Ely, AJRCCM, 1996
Marelich, Chest, 2000

16. On the other hand….
 No differences between protocol & non-protocol
weaning for children.
 Duration of weaning (n = 182; p=0.75)
– 2.9 days in the ‘protocol’ groups
(median 1.7 d)
– 3.2 days in the ‘no protocol’ group
(median 2.0 d)
 Weaning protocols for ventilated pediatric pts
with ALI do NOT shorten LOV.
Randolph, JAMA, 2002.

17. Weaning & Sedation
Randolph, JAMA, 2002.

18. Extubation Criteria in Adults
 Respiratory frequency to tidal volume ratio
– Yang, NEJM, 1991
– Tahvanainen, CCM, 1983
 T-piece trials
– Sahn, Chest, 1973
 Negative insp effort measurements
– Sahn, Chest, 1973
 CROP index
(compliance, rate, oxygenation, pressure)
– Yang, NEJM, 1991

19. Extubation Criteria in Peds
 No widely accepted criteria for predicting
successful extubation for pediatric pts.
 Successful extubation predictors:
 Low Risk Value High Risk Value
 Vtspont 6.5 ml/kg 3.5 ml/kg
 FiO2 0.30 > 0.40
 Paw < 5 cm H2O > 8.5 cm H2O
 OI 1.4 > 4.5
 FrVe 20% 30%
 PIP 25 cm H2O 30 cm H2O
 Cdyn 0.9 ml/kg/cm H2O < 0.4 ml/kg/cm H2O
Khan, CCM, 1996.

20. Vd/Vt and Successful Extubation
n=3 n=2 n=7
100%
n=13
90% Hubble, CCM, 2000
80%
70%
n=8
60% n=2
50%
40% n=3
30% n=4
20%
10%
n=2
0%
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Vd / Vt

21. Vd/Vt and Extubation
 Elevated physiologic dead space predicts
 Elevated physiologic dead space predicts
extubation failure
extubation failure
 Successful extubation in a heterogeneous
 Successful extubation in a heterogeneous
PICU population (p < 0.001)
PICU population (p < 0.001)
– Vd/Vt < 0.5: 24/25 (96%)
– Vd/Vt < 0.5: 24/25 (96%)
– Vd/Vt 0.5-0.65: 6/10 (60%)
– Vd/Vt 0.5-0.65: 6/10 (60%)
– Vd/Vt > 0.65: 2/10 (20%)
– Vd/Vt > 0.65: 2/10 (20%)
Hubble, CCM, 2000

22. General indications and
contraindications for extubation
 Indications  Contraindications
– alert or easily – obtunded
arousable – poor or absent cough
– good cough and gag or gag
– thin secretions easily – thick or copious
cleared from airway secretions requiring
– nl cardiac function frequent suctioning
– no MOSF – cardiac insufficiency
– MOSF

23. Causes for Extubation Failure
Excessive resp effort 42%
Poor resp effort 24%
Inadequate gas exchange 18%
Cardiovasc insufficiency 10%
Neurologic 6%

24. SBT Recommendations
 Perform a SBT when
– FiO2 ≤ 0.40 PEEP ≤ 6 PIP ≤ 25
– sedation has been decreased or stopped
– adequate insp drive
– improvement or resolution of underlying cause
– pharmacological control of bronchoconstriction
– absence of significant resp acidosis

25. Weaning and Extubation:
Conclusions
 Not all patients require weaning
 Extubation readiness testing decreases
LOV
 Ideal timing of extubation may still
remain more clinical art than science –
although this is changing with ERT