Weaning from Ventilatory Support

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Weaning from Ventilatory Support
27th April 2009 Supervisied by Dr ??? Presented
by R2 ???
Current Opinion in Critical Care 2009, 153643
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Contents
Introduction
Readiness testing
Spontaneous breathing trials
Causes of weaning failure
Progressive withdrawal
3
Contents
Weaning protocols
Extubation
Weaning from prolonged mechanical ventilation
Conclusion
4
Introduction
Invasive mechanical ventilation is associated
with risks and complications that prolong the
duration of mechanical ventilation and increase
the risk for death
Epstein S. Complications in ventilator supported
patients. In Tobin M, editor.Principles and
practice of mechanical ventilation, 2nd ed. New
YorkMcGraw Hill 2006. pp. 877902.
Increasing duration of mechanical ventilation
itself is associated with increased mortality
Esteban A, Anzueto A, Frutos F, et al.
Characteristics and outcomes in adultpatients
receiving mechanical ventilation a 28-day
international study. J AmMed Assoc 2002
287345355
5
Introduction
A multisociety consensus conference
characterized the weaning process as a continuum
lasting from intubation until hospital discharge
Weaning from mechanical ventilation. EurRespir J
2007 2910331056. Recommendation of an
international, multisociety consensus conference
onweaning. Boles JM, Bion J, Connors A, et al.
6
Introduction
A minority of patients fail and may need a
more gradual approach, with success ultimately
dependent on Identifying correctable causes for
weaning intolerance. Once spontaneous breathing
is tolerated attention shifts to determining
whether the patient can be extubated
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Introduction
Recognizing that respiratory failure and
respiratory muscle function have improved and the
patient is capable of spontaneous breathing
Readiness Testing
A new classification of weaning
Patient tolerates first spontaneous breathing
trial (SBT) and is successfully extubated (70 of
all patients).
Simple weaning
Patient fails to tolerate initial SBT, successful
weaning requiring up to three SBTs or up to 7
days from first SBT.
Difficult weaning
Prolonged weaning
Patient fails at least three SBTs or takes more
than 7 days after the first SBT.
8
Introduction
A New Classification of Weaning
9
Introduction

• Approximately 1/3 of patients fall into the
  difficult and prolonged categories and experience
  higher ICU mortality (25) than seen with simple
  weaning (5).
• The higher mortality
• Complications of mechanical ventilation
• Underlying illness leading to mechanical
  ventilation.

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Readiness Testing
The patients capacity to breathe spontaneously
is often underestimated. For example, 50 of
patients who self-extubate do not require
reintubation
Patient-initiated device removal in intensive
care units a national prevalence study. Crit
Care Med 2007 3527142720. Mion LC, Minnick AF,
Leipzig R, et al.
30 of patients never satisfying objective
readiness criteria can still be successfully
weaned
The prognostic significance of passing adaily
screen of weaning parameters. Intensive Care Med
1999 25 581587 Ely EW, Baker AM, Evans GW, et
al.
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Readiness Testing
A comprehensive evidence-based medicine
review identified more than 50 objective
physiologic tests (weaning predictors) as tools
for assessing readiness for spontaneous
breathing. Only five were associated with
clinically significant changes in the probability
of weaning success or failure but predictive
capacity was modest

• Epstein SK. Weaning parameters. Respir Care Clin
  N Am 2000 6 253301.
• MacIntyre NR, Cook DJ, Ely EW Jr, et al.
  Evidence-based guidelines for weaning and
  discontinuing ventilatory support a collective
  task force facilitatedby the American College of
  Chest Physicians the American Associationfor
  Respiratory Care and the American College of
  Critical Care Medicine. Chest 2001
  120375S395S.
• Meade M, Guyatt G, Cook D, et al. Predicting
  success in weaning from mechanical ventilation.
  Chest 2001 120400S424S.

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Readiness Testing
Weaning predictors

• Negative inspiratory force (maximal inspiratory
  pressure).
• (2) Minute ventilation.
• (3) Respiratory frequency.
• (4) Tidal volume.
• (5) Frequencytidal volume ratio ( f/VT).

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Readiness Testing
Frequencytidal volume ratio ( f/VT)
How the measurements are made ?
MEASUREMENTS AND RESULTS Respiratory frequency
(f) and tidal volume (VT) were measured during
PS, CPAP, CPAP-R/A, and T-piece in all patients.
RSBI (f/VT) was determined for each patient under
all experimental conditions, and the average RSBI
was compared during PS, CPAP, CPAP-R/A, and
T-piece. RSBI was significantly smaller during PS
(46/-8 bpm/l), CPAP (63/-13 bpm/l) and CPAP-R/A
(67/-14 bpm/l) vs. T-piece (100/-23 bpm/l).
Effect of pressure support ventilation and
positive end expiratory pressure on the rapid
shallow breathing index in intensive care unit
patients. Intensive Care Med 2008
34505510. El-Khatib MF, Zeineldine SM,
Jamaleddine GW
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Readiness Testing
Frequencytidal volume ratio ( f/VT)
The average sensitivity of 0.87 indicates that
f/VT is a reliable screening test for successful
weaning
15
Readiness Testing
Whether the f/VT, or any weaning predictor,
actually facilitates weaning decision-making ?
Interventions Patients were screened daily for
measures of oxygenation, cough and secretions,
adequate mental status, and hemodynamic
stability. Patients were randomized to two
groups in one group the f/Vt was measured but
not used in the decision to wean (n 151), but
in the other group, f/Vt was measured and used,
using a threshold of 105 breaths/min/L (n 153).
Patients passing the screen received a 2-hr
spontaneous breathing trial. Patients passing the
spontaneous breathing trial were eligible for an
extubation attempt.
A randomized, controlled trial of the role of
weaning predictors in clinical decision making.
Crit Care Med 2006 3425302535. Tanios MA,
Nevins ML, Hendra KP, et al.
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Readiness Testing
Whether the f/VT, or any weaning predictor,
actually facilitates weaning decision-making ?
Measurements and Main Results Groups were
similar with regard to gender, age, and Acute
Physiology and Chronic Health Evaluation II
score. The median duration for weaning time was
significantly shorter in the group where the
weaning predictor was not used (2.0 vs. 3.0 days,
p .04). There was no difference with regard to
the extubation failure, in-hospital mortality
rate, tracheostomy, or unplanned extubation.
Conclusions Including a weaning predictor f/Vt)
in a protocol prolonged weaning time. In
addition, the predictor did not confer survival
benefit or reduce the incidence of extubation
failure or tracheostomy. The results of this
study indicate that f/Vt should not be used
routinely in weaning decision making.
A randomized, controlled trial of the role of
weaning predictors in clinical decision making.
Crit Care Med 2006 3425302535. Tanios MA,
Nevins ML, Hendra KP, et al.
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Readiness Testing
One explanation is the demonstrated safety of a
closely monitored SBT.
Am J Respir Crit Care Med 1999 159439446.
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Readiness Testing
Am J Respir Crit Care Med 2003 167120127.
In conclusion, in contrast to our hypothesis,
weaning failure was not accompanied low-frequency
fatigue of the diaphragm, although many weaning
failure patients displayed diaphragmatic weakness.
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Readiness Testing

• Thus a failed SBT should not result in
  respiratory muscle injury as long as patients are
  quickly reconnected to the ventilator when signs
  of weaning intolerance occur.
• Although unproven, structural respiratory muscle
  injury may occur if the failed weaning trial is
  improperly extended.

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Readiness Testing
21
Readiness Testing
These concepts are supported by the ABC trial in
which greater than 50 passed an SBT when
readiness was assessed using liberal oxygenation
criteria (SpO2 88 on FiO2 0.5 and PEEP 8cmH2O)
and weaning predictors were not used
Efficacy and safety of a paired sedation and
ventilator weaning protocol for mechanically
ventilated patients in intensive care (awakening
and breathing controlled trial) a randomised
controlled trial. Lancet 2008
371126134. Girard TD, Kress JP, Fuchs BD, et al.
22
Spontaneous Breathing Trials
Direct extubation after satisfying readiness
criteria alone is unwise, as 40 of such patients
require reintubation
Weaning from mechanical ventilation a model for
extubation. Intensive Care Med 1999
2510771083. Zeggwagh AA, Abouqal R, Madani N,
et al.
Therefore a trial of spontaneous breathing,
carried out on low-level pressure support
(PSV7mmHg), CPAP, or unassisted through a
T-piece, is indicated. Randomized controlled
trials indicate these techniques are equivalent
23
Spontaneous Breathing Trials
Theoretically, PSV more effectively
counterbalances endotracheal tube-related
resistive workload, but a given level may either
overcompensate or under-compensate for imposed
work
24
Spontaneous Breathing Trials
Automatic tube compensation (ATC)
SBTs conducted with either ATC, PSV, or T-piece
to be equivalent
Extubation after breathing trials with automatic
tube compensation, T-tube, or pressure support
ventilation. Acta Anaesthesiol Scand 2002
46973979. Haberthur C, Mols G, Elsasser S, et
al.
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Spontaneous Breathing Trials
Automatic tube compensation (ATC)
Higher SBT success for ATC compared to CPAP
Extubation outcome following a spontaneous
breathing trial with automatic tube compensation
versus continuous positive airway pressure. Crit
Care Med 2006 34682686. Cohen JD, Shapiro M,
Grozovski E, et al.
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Spontaneous Breathing Trials
Automatic tube compensation (ATC)
Patients failing a 30- min T-tube trial,
immediate conversion to PSV 7cmH2O for
additional 30 min led to weaning success in 21 of
31 patients, suggesting the endotracheal tube can
contribute to iatrogenic weaning failure
Weaning from mechanical ventilation with pressure
support in patients failing a T-tube trial of
spontaneous breathing. Intensive Care Med 2006
32165169 Ezingeard E, Diconne E, Guyomarch S,
et al.
27
Spontaneous Breathing Trials
Optimal SBT duration
In two studies suggesting that 30 min is
equivalent to 120 min with either T-piece or PSV
Optimal SBT duration may depend upon the duration
of ventilation or the underlying cause for
respiratory failure.
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Spontaneous Breathing Trials
Optimal SBT duration
75 patients with chronic obstructive pulmonary
disease (COPD), ventilated for 15 or more days,
found a median time to trial failure of 120 min
Comparison of two methods for weaning patients
with chronic obstructive pulmonary disease
requiring mechanical ventilation for more than 15
days. Am J Respir Crit Care Med 2001
164225230. Vitacca M, Vianello A, Colombo D, et
al.
Therefore, in some patients the SBT should be
extended to at least 120 min.
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Causes of Weaning Failure
Imbalance between respiratory load and capacity
(e.g. diaphragmatic strength and endurance)

• Excessive load may be imposed by the
• Endotracheal tube,
• Heat and moisture exchange devices,
• Ventilator tubing and valves

• Intrinsic factors such as
• Increased airways resistance,
• Increased elastance from dynamic hyperinflation,
  
• Reduced respiratory muscle capacity are more
• commonly responsible

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Causes of Weaning Failure
31
Causes of Weaning Failure
An important component of load/capacity imbalance
is reduced respiratory muscle strength.

• Mechanisms include
• Reduced diaphragmatic pressure generation
  secondary
• to dynamic hyperinflation
• Phrenic nerve injury after cardiac surgery
• Other identified causes
• Critical illness neuromyopathy
• Ventilator- induced diaphragmatic dysfunction
  (VIDD)
• Endocrinopathy (e.g. hypothyroidism, adrenal
  insufficiency)
• or malnutrition

32
Causes of Weaning Failure

• Cardiac dysfunction contributes to weaning
  failure especially in patients with coronary
  artery disease or chronic heart failure
• Myocardial ischemia (release in
  catecholamines)
• Pulmonary edema (elevation of transmural
• 
  pulmonaryartery occlusion pressure)

Patients at risk for weaning failure from cardiac
disease can manifest an elevated B-type
natriuretic peptide (BNP) or N-terminal pro-BNP
In one study, a pre-SBT BNP gt275 pg/dl correlated
with a longer duration of weaning
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Causes of Weaning Failure

• The stress of weaning is considerable as it
  results in
• increased levels of plasma insulin,
  cortisol, and glucose .
• Lastly, positive fluid balance has been
  associated with
• weaning failure

The effects of different weaning modes on the
endocrine stress response. Crit Care 2004
8R31R34. Koksal GM, Sayilgan C, Sen O, et al.
Fluid balance and weaning outcomes. Intensive
Care Med 2005 3116431647. Upadya A,
Tilluckdharry L, Muralidharan V, et al.
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Progressive Withdrawal
How long should the patient rest after a failed
weaning effort?
When clinical evidence of respiratory muscle
fatigue is absent, multiple daily SBTs are well
tolerated. Yet, a comparison of two international
studies found declining use of this approach from
1998 to 2004
If unequivocal evidence for fatigue is evident
then clinicians should consider providing 24 h of
rest on full support before preceding with the
next weaning effort
Pattern of recovery from diaphragmatic fatigue
over 24 h. J Appl Physiol 1995
79539546. Laghi F, DAlfonso N, Tobin MJ.
35
Progressive Withdrawal
The clinician must decide whether to perform
daily SBTs or whether to more gradually reduce
ventilatory support (progressive withdrawal).
A randomized trial showed no benefit to using
inspiratory muscle training
Inspiratory muscle training is ineffective in
mechanically ventilated critically ill patients.
Clinics 2005 60479484 Caruso P, Denari SD,
Ruiz SA, et al.
36
Progressive Withdrawal
Two RCTs compared progressive withdrawal
techniques in patients satisfying readiness
criteria but intolerant of a 2-h SBT
Although one study found T-piece superior and the
other observed PSV to be most efficient, both
demonstrated that synchronized intermittent
mandatory ventilation (SIMV) alone delays the
process.
37
Progressive Withdrawal
A more recent investigation randomized patients
to SBTs (120 min) with T-piece or PSV and found
the latter associated with decreased weaning
time, duration of mechanical ventilation, and ICU
length of stay
Comparison of pressure support and T-tube weaning
from mechanical ventilation randomized
prospective study. Croat Med J 2004
45162166 Matic I, Majeric-Kogler V
38
Progressive Withdrawal
Noninvasive ventilation (NIV)
Three published RCTs have explored the use of
noninvasive ventilation (NIV) in patients having
trouble weaning from mechanical ventilation
Studies indicate that NIV can facilitate weaning
in a highly select group of patients with acute
on chronic lung disease

• SBT readiness criteria must be satisfied
• Extubation criteria must be satisfied
• The patient must be a good candidate for NIV
  (able to breathe spontaneously
• for at least 510 min and not be a difficult
  reintubation).

39
Progressive Withdrawal
Can the weaning process be automated?
One multicenter study randomized 144 patients to
Conventional weaning VS Computerized weaning
using a closed loop knowledge- based system
A multicenter randomized trial of computer-driven
protocolized weaning from mechanical ventilation.
Am J Respir Crit Care Med 2006
174894900. Lellouche F, Mancebo J, Jolliet P,
et al.
40
Progressive Withdrawal
The computer-driven ventilator continuously
monitors physiologic parameters

• Respiratory rate
• Tidal volume
• PetCO2

Adjusts pressure support by 24cmH2O to maintain
the patient in a zone of comfort.
When a minimal level of PSV is reached, a SBT is
conducted and the clinician prompted if the SBT
proves successful. Computer-driven ventilation
resulted in decreased duration of weaning, total
duration of ventilation, median ICU stay, without
adverse event or increase in reintubation.
41
Weaning protocols
In certain settings, uncontrolled investigations
and RCTs demonstrate improved outcome with
protocol-driven weaning implemented by physicians
or by respiratory care practitioners and ICU
nurses
Standard care VS Intervention strategy
patients passing the daily screen underwent a 2-h
SBT with a prompt for extubation if the trial was
tolerated
42
Weaning protocols
Observational and randomized trials demonstrate
that protocols directed at minimizing the use of
sedative infusions shorten the weaning process.
Specifically, approaches intended to avoid over
sedation by limiting the use of continuous
infusions either through sedation assessment
scoring or by daily cessation of Sedative
infusions decrease duration of mechanical
ventilation and duration of ICU stay.
43
Extubation
Between 25 and 40 of patients develop signs of
respiratory distress after extubation
Extubation failure, when defined as reintubation
within the subsequent 2472 h, occurs in 520 of
patients, depending on the patient population
Decision to extubate. Intensive Care Med 2002
28535546. Epstein SK.

• Risk is greatest for medical and neurologic
  patients.
• Reintubated patients experience increased
  hospital mortality, prolonged
• ICU and hospital stays, greater need for
  tracheostomy, and more
• frequently require long-term acute care

44
Extubation
Avoidable delays in extubation prolong ICU stay,
heighten the risk for pneumonia, and increase
hospital mortality
Implications of extubation delay in brain-injured
patients meeting standard weaning criteria. Am J
Respir Crit Care Med 2000 16115301536. Coplin
WM, Pierson DJ, Cooley KD, et al.
Measuring blood gases at the end of the SBT ?

• Are blood gases necessary in mechanically
  ventilated patients who have successfully
  completed a spontaneous breathing trial?
• Respir Care 2004 4913161319.
• Pawson SR, DePriest JL.
• The effect of arterial blood gas values on
  extubation decisions.
• Respir Care 2003 4810331037.
• Salam A, Smina M, Gada P, et al.

45
Extubation
In general, traditional weaning predictors
perform poorly in predicting extubation outcome
Risk factors for extubation failure in patients
following a successful spontaneous breathing
trial. Chest 2006 13016641671. Frutos-Vivar
F, Ferguson ND, Esteban A, et al.
46
Extubation
One promising technique has demonstrated that
risk of extubation failure is associated with
greater time needed to return to baseline minute
ventilation after resumption of full ventilatory
support
Serial measurements of f/VT can predict
extubation failure in patients with f/VT lt or
105? J Crit Care 2008 23572576. Teixeira C,
Zimermann Teixera PJ, Hohe r JA, et al.
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Extubation
Measuring the airway occlusion pressure at 0.1 s
(P0.1) and the degree of expiratory flow
limitation
Respiratory failure in chronic obstructive
pulmonary disease after extubation value of
expiratory flow limitation and airway occlusion
pressure after one 0.1 second (P0.1). J Crit
Care 2008 23577584. Vargas F, Boyer A, Bui
HN, et al.
48
Extubation
Extubation failure often results from inability
to protect the airway and manage respiratory
secretions
Recent RCTs demonstrate that systemic
corticosteroids can reduce postextubation
stridor, especially in high-risk patients
Intravenous injection of methylprednisolone
reduces the incidence of postextubation stridor
in intensive care unit patients. Crit Care Med
2006 3413451350. Cheng KC, Hou CC, Huang HC,
et al.
49
Extubation
For example, Cheng et al. Randomized 128
high-risk patients (cuff leak volume lt24 of
tidal volume) to placebo or methylprednisolone
injection (multi-dose or single-dose) during the
24 h prior to extubation. Treatment with
methylprednisolone significantly reduced the risk
for postextubation stridor and need
for reintubation
Intravenous injection of methylprednisolone
reduces the incidence of postextubation stridor
in intensive care unit patients. Crit Care Med
2006 3413451350. Cheng KC, Hou CC, Huang HC,
et al.
50
Extubation
The ability to protect the airway is also
dependent upon cough strength and volume of
respiratory secretions (e.g. suction requirement
gt every 2 h)
Mental status is also important, although studies
looking exclusively at this parameter have come
to conflicting conclusions
51
Extubation

• Measuring
• Peak cough flow rates (cut-off lt60 l/min),
• Secretions (cut-off gt2.5 ml/h),
• Abnormal mental status (inability to complete
  four simple
• commands)
• Highly predictive of extubation outcome.
• Failing all three criteria led to certain
  extubation failure, whereas the absence of all
  three was associated with only a 3 risk for
  reintubation

Neurologic status, cough, secretions and
extubation outcomes. Intensive Care Med 2004
3013341339. Salam A, Tilluckdharry L,
Amoateng-Adjepong Y, et al.
52
Weaning from prolonged mechanical ventilation
10 20 of patients with acute respiratory
failure require 21 or more days of ventilatory
support and thus constitute a subset of prolonged
mechanical ventilation defined earlier
A recent multicenter observational study of more
than 1400 patients transferred to long-term care
hospitals found that 50 could be successfully
weaned from mechanical ventilation
53
Weaning from prolonged mechanical ventilation
Weaning efforts should start as soon as possible
after transfer as 1030 of patients with
prolonged mechanical ventilation will tolerate
their initial SBT and be liberated
The only RCT in prolonged mechanical ventilation
found no difference between PSV weaning and
tracheotomy collar trials of increasing duration
in 52 COPD patients
54
Conclusion

• Determining readiness is best achieved using
  liberal oxygenation criteria
• Does not require routine use of weaning
• predictors
• Can often be conducted using protocols driven by
  
• respiratory therapists or ICU nurses.

55
Conclusion

• SBTs should last at least 30 min and can be
• conducted on low levels of pressure support,
• CPAP, or T-piece.
• Weaning failure often results from an imbalance
  
• between respiratory load and capacity.
• There is increasing appreciation that cardiac
• dysfunction can be a limiting factor.

56
Conclusion

• Randomized trials suggest that NIV (in patients
  
• with COPD) and computer-driven approaches
• show promise as weaning strategies.
• New techniques can identify patients at highest
• risk for extubation failure.
• These include the qualitative cuff leak test
• and an assessment that integrates cough
  strength,
• the volume of respiratory secretions, and
  mental
• status.
• When used in high-risk patients NIV can decrease
  
• extubation failure and the need for
  reintubation.