weaning and discontinuation from mechanical ventilation

1. Presented by
Ann Mary Jose,

2. OBJECTIVES
 Rationale for weaning
 Predictors of Weaning success or failure
 Methods of weaning
 Weaning failure

3. WEANING
The transition process from total ventilatory support to
spontaneous breathing trial.
This period may take many forms ranging from abrupt
withdrawal to gradual withdrawal from
ventilatory support.

4. CATEGORIES
• First SBT trial successful, extubation successful.
SIMPLE
WEANING
• Fails first SBT, requires upto 3 SBTs before successful
(7 days or less from 1st SBT to successful SBT)
DIFFICULT
WEANING
• Fails atleast 3 SBTs or requires > 7 days from 1st
SBT to successful SBT
PROLONGED
WEANING

5. WHEN SHOULD WEANING
COMMENCE ?
• Evaluation of weanability should commence with decision to
intubate, ventilate.
• Patient should be tested for reduced support when it is safe.
• Physicians must relay on clinical judgement.
• Consider when the reason for IPPV is stabilized and the patient is
improving and haemodynamically stable
• Daily screening may reduce the duration of MV and ICU cost

6. DOUBLE EDGED SWORD !!
!! Unnecessary delays in this discontinuation process
increase the complication rate from mechanical
ventilation (e.g., pneumonia, airway trauma) as well
as the cost
!! Premature discontinuation carries its own set of
problems, including difficulty in re-establishing
artificial airways and compromised gas exchange.

7. DAILY SCREENING
• Resolution/improvement of patient’s underlying
problem
• Patient able to initiate an inspiratory effort.
• Normal state of consciousness
• Absence of fever, temperature < 38C
• Correction of metabolic and electrolyte disorders
• Adequate hemoglobin concentration, > 8-10 g/dl

9. PHYSIOLOGICAL PARAMETERS
Ventilatory
performance and
muscle strength
VC > 15mL/kg
VE < 10 to 15 l/min
VT > 4 to 6 ml/kg
f < 35 breaths per min
f/VT < 60 to105
breaths/min/L
PImax < -20 to -30 cm
H2O
Measure of drive to
breath
P0.1 > -6cm H20
Measure and
estimation of WOB
WOB < 8J/L
Cdyn > 25mL/cm H2O
VD/VT < 0.6
CROP index > 13
mL/breaths/min

10. Measurement of
adequacy of
oxygenation
PaO2 > 60 mm Hg
PEEP < 5 to 8 cm H2O
PaO2/FiO2 > 250 mm Hg
PaO2/PAO2 > 0.47
P(A-a)O2 < 350 mm Hg
%QS/QT < 20% to 30%

11. Patients receiving MV for respiratory failure should
undergo a formal assessment of discontinuation potential
if the criteria are satisfied.
Reversal of cause, adequate oxygenation, haemodynamic
stability, capability to initiate respiratory effort. The
decision must be individualized.

12. Search for all the causes that may contribute to
ventilator dependence in all patients with longer than
24hrs of MV support, particularly who has fail
attempts. Reversing all possible causes should be an
integral part of discontinuation process.

13. PREDICTORS OF THE OUTCOME OF
WEANING
 Patient parameters
 Awake, alert and cooperative
 Haemodynamically stable
 RR < 30/min
 No effect of sedation/neuromuscular blockade
 Minimal secretions
 Nutritional status good
Burton GG Respir Care 1997, Caruso P 1999 Chest
Girault C. 1994 Monaldi Arch Chest Dis,TobinMJ. 1990 Eur Respir J,Yang KL.1991 N Engl J Med

14.  Ventilator parameters
 Spontaneous TV > 5 - 8 ml/kg ,
 VC > 10 - 15 ml/kg ,
 PEEP requirement < 5 mm of H2O
 Static compliance > 30 ml/cm of H2O
 MV < 10 L
 VD/VT < 60 %
 MIP < -30 cm H2O
 NIF Burton GG Respir Care 1997, Caruso P 1999 Chest
Girault C. 1994 Monaldi Arch Chest Dis,TobinMJ. 1990 Eur Respir J,Yang
KL.1991 N Engl J Med

15.  Oxygenation criteria
 PaCO2 < 50 mm of Hg with Normal pH
 PaO2 > 60 at FiO2 0.4 or less
 SaO2 > 90 % at FiO2 0.4 or less
 PaO2/FiO2 > 200
 Qs/QT < 20 %
 P(A-a)O2 < 350 mm of Hg at FiO2 of 1.0
Burton GG Respir Care 1997, Caruso P 1999 Chest
Girault C. 1994 Monaldi Arch Chest Dis,TobinMJ. 1990 Eur Respir J,Yang
KL.1991 N Engl J Med

16. The removal of the artificial airway from a patient
who has successfully been discontinued from
ventilatory support should be based on assessment of
airway patency and the ability of the patient to
protect the airway.

17. PARAMETERS THAT ASSESS
AIRWAY PATENCY AND
PROTECTION
1. Maximal expiratory
pressure
2. Peak expiratory flow rate
3. Cough strength
4. Secretion volume
5. Suctioning frequency
6. Cuff leak test
7. Neurological function
(GCS)

18. METHODS
OF
WEANING
Spontaneo
us
breathing
with t-
piece
SIMV
Newer
Modes
PSV

19. GRADUAL V/S SUDDEN
WEANING ???
 No data available
 Most trials have used sudden
weaning using Spontaneous
breathing trial with T-piece,
PSV or CPAP
 However if a patient fails
recurrent weaning attempts
gradual weaning strategy is
advocated
Respir Care 2002; 47: 69-
90

20. SPONTANEOUS BREATHING
TRIAL
• Communicate with patient, weaning is about to begin, allow patient
to express fear whenever possible
• Obtain baseline value and monitoring clinical parameters; vital
signs, distress, gas exchange, arrhythmia
• Ensure a calm atmosphere, avoid sedation
• Fit T-tube with adequate flow, observe for 2 hrs.

21. Esteban et al compared a 30 min to a 120min T-piece trial
No reported difference in the
rate of re-intubation between
groups.
Patients who were randomized
to the shorter T-piece trial
benefited from statistically
significant reductions in ICU
and hospital lengths of stay (2
days and 5 days shorter,
respectively)

22. The criteria to assess patient tolerance during SBTs
are respiratory pattern, gas exchange, hemodynamics
stability and patient comfort. The tolerance of SBTs
lasting 30 to 120 minutes should prompt for permanent
ventilator discontinuation.

23. PRESSURE SUPPORT
PROTOCOL
Esteban et al compared 2-h trials of unassisted
breathing
using PS of 7 cm H2O v/s a T-piece
A smaller proportion of patients in the PS group
(14%)
failed to tolerate the weaning and to achieve
extubation
at the end of the 2-h trial than in the T-pieceReintubation rates were similar

24. A superior weaning technique among the three
most popular modes, T-piece, pressure support
ventilation, or synchronized intermittent mandatory
ventilation cannot be identified
SIMV may lead to a longer duration of the
weaning process than either T-piece or PSV
The most effective mode of ventilation for
weaning still needs to be determined and
more work is required in this area.

25. FAILED TO WEAN
Patients receiving MV who fail an SBT should have the cause
determined. Once causes are corrected, and if the patient still
meets the criteria , subsequent SBTs should be performed
every 24 hours.

26. Early
detection
Record vs.
physical
exam
Obtain an
ABG if
possible
Put back
previous
settings
Identify
causes

28. SIGNS AND SYMPTOMS OF
WEANING FAILURE
Subjective Indices
• Agitation and anxiety
• Diaphoresis
• Cyanosis
• Accessory muscle use
• Facial sign of distress
• Dyspnea
Objective Measurements
• PaO2 ≤50-60 mmHg on FiO2 ≥
0.5
• SaO2 < 90%
• PaCO2 > 50mm Hg
• pH < 7.3
• f/Vt > 105 breaths/min/L
• RR > 35bpm
RR > 10
breaths/min
HR > 20 beats/min
SPB > 30 mmHg

29.  Associated with intrinsic lung disease
 Associated with prolonged critical illness
 Incidence approximately 20%
 Increased risk in patient with longer duration of mechanical
ventilation
 Increased risk of complications, mortality

30. Patients receiving MV for respiratory failure who fail
an SBT should receive a stable, non fatiguing,
comfortable form of ventilatory support.
Rest 24 hours
Correct the
causes
Retry weaning
Retry with
gradual
modes
Tracheostomy
long term
ventilation

31. ROLE OF
TRACHEOSTOMY

32. Tracheostomy should be considered after period of
stabilization on the ventilator when it becomes apparent that
the patient will require prolonged MV. Tracheostomy should be
performed when the patient appears likely to gain one or more
benefits from the procedure

33. • Improved patient comfort
• More effective airway suctioning
• Decreased airway resistance
• Enhanced patient mobility
• Increased opportunities for articulated speech
• Ability to eat orally, a more secure airway
• Accelerated weaning from mechanical ventilation
• Ability to transfer ventilator-dependent patients from ICU

34. Unless there is evidence for clearly irreversible disease, a
patient requiring prolonged MV should not be considered
permanently ventilator-dependent until 3 months of weaning
attempts have failed.

35. SUMMARY
• The ventilator discontinuation process is a critical component of ICU care.
• Daily wean screen and subsequent SBT should be done in all patients
recovering from respiratory failure.
• Early extubation with backup ventilation of NIPPV is usefull especially in COPD
• Role of newer modes unclear – require more studies.
•Managing the patients who fails the SBT - determine the reasons for failure.

36. REFERENCE
1. Neil R. Maclntyre, Mechanical Ventilation: 2nd edition; Chapter 18,
Discontinuing Mechanical Ventilation; pg.no. 317-322.
2. Lynelle N. B. Pierce, Management of the mechanically ventilated Patient: 2nd
edition; Chapter 11, Weaning from Mechanical Ventilation; pg.no. 378-398.
3. Susan P. Pilbeam, Mechanical Ventilation: 5th edition; Part 7: Discontinuation
from Ventilation and Long term Ventilation; pg.no. 402 – 452

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