Weaning Modes and Protocol

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Weaning Modesand Protocol
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• Causes of Ventilator Dependence
• Assessment for Discontinuation Trial
• Spontaneous Breathing Trial (SBT)
• Extubation Criteria
• Failure of SBT
• Weaning Modes
• Weaning Protocols
• Role of Tracheostomy
• Long-term Facilities

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Stages of Mechanical Ventilation
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Causes of Ventilator Dependence

• Who is the ventilator dependent?
• Mechanical ventilation gt 24 h
• or
• Failure to respond during discontinuation attemps

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Causes of Ventilator Dependence
Description Causes
Central drive Peripheral nerves Neurologic controller
Mechanical loads Ventilatory muscle properties Gas exchange properties Respiratory system
Cardiac tolerance of ventilatory muscle work peripheral oxygen demands Cardiovascular system
Psychological issues
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Assessment for Discontinuation Trial

• Criteria for discontinuation trial
• Evidence for some reversal of the underlying
  cause for respiratory failure
• Adequate oxygenation and pH
• Hemodynamic stability and
• The capability to initiate an inspiratory effort

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Assessment for Discontinuation Trial

• Extubation failure
• 8-fold higher odds ratio for nosocomial pneumonia
  
• 6-fold to 12-fold increased mortality risk
• Reported reintubation rates range from 4 to 23
  for different ICU populations

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Assessment for Discontinuation Trial
Criteria Used in Weaning/Discontinuation in
different studies
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Assessment for Discontinuation Trial
Measurements used To Predict the Outcome of a
Ventilator Discontinuation Effort in More Than
One Study
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Spontaneous Breathing Trial

• Formal discontinuation assessments should be
  performed during spontaneous breathing
• An initial brief period of spontaneous breathing
  can be used to assess the capability of
  continuing onto a formal SBT.

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Spontaneous Breathing Trial

• How to assess patient tolerance?
• the respiratory pattern
• the adequacy of gas exchange
• hemodynamic stability, and
• subjective comfort.

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Criteria Used in Several Large Trials To Define
Tolerance of an SBT
Spontaneous Breathing Trial
HR heart rate Spo2 hemoglobin oxygen
saturation.
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Spontaneous Breathing Trial

• The tolerance of SBTs lasting 30 to 120 min
  should prompt consideration for permanent
  ventilator discontinuation

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Frequency of Tolerating an SBT in Selected
Patients and Rate of Permanent Ventilator
DiscontinuationFollowing a Successful SBT
Spontaneous Breathing Trial
Values given as No. (). Pts patients. 30-min
SBT. 120-min SBT.
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Do Not Wean To Exhaustion
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Weaning to Exhaustion

• RR gt 35/min
• Spo2 lt 90
• HR gt 140/min
• Sustained 20 increase in HR
• SBP gt 180 mm Hg, DBP gt 90 mm Hg
• Anxiety
• Diaphoresis

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Mechanical Ventilation
Low level CPAP (5 cm H2O), Low levels of
pressure support (5 to 7 cm H2O) T-piece
breathing
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Extubation Criteria

• Ability to protect upper airway
• Effective cough
• Alertness
• Improving clinical condition
• Adequate lumen of trachea and larynx
• Leak test to identify patients who are at risk
  for post-extubation stridor

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Post Extubation Stridor
Extubation Criteria

• The Cuff leak test during MV
• Set a tidal Volume 10-12 ml/kg
• Measure the expired tidal volume
• Deflated the cuff
• Remeasure expired tidal volume (average of 4-6
  breaths)
• The difference in the tidal volumes with the cuff
  inflated and deflated is the leak
• A value of 130ml ? 85 sensitivity
• 95 specificity

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Post Extubation Stridor
Extubation Criteria

• Cough / Leak test in spontaneous breathing
• Tracheal cuff is deflated and monitored for the
  first 30 seconds for cough.
• Only cough associated with respiratory gurgling
  (heard without a stethoscope and related to
  secretions) is taken into account.
• The tube is then obstructed with a finger while
  the patient continues to breath.
• The ability to breathe around the tube is
  assessed by the auscultation of a respiratory
  flow.

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Extubation Criteria

• The risk of postextubation upper airway
  obstruction increases with
• the duration of mechanical ventilation
• female gender
• trauma, and
• Repeated or traumatic intubation

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Failure of SBT

• Correct reversible causes for failure
• adequacy of pain control
• the appropriateness of sedation
• fluid status
• bronchodilator needs
• the control of myocardial ischemia, and
• the presence of other disease processes
• Subsequent SBTs should be performed every 24 h

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Failure of SBT
Increased resistance Decreased compliance Increased WOB and exhaustion Auto-PEEP Respiratory
Backward failure LV dysfunction Forward heart failure Cardiovascular
Poor nutritional status Overfeeding Decreased Mg and PO4 levels Metabolic and respiratory alkalosis Metablic/Electrolytes
Infection/fever
Major organ failure
Stridor

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Failure of SBT

• Left Heart Failure
• Increased metabolic demands
• Increases in venous return and pulmonary edema
• Appropriate management of cardiovascular status
  is necessary before weaning will be successful

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Failure of SBT
Factors affecting ventilator demands
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Failure of SBT
Therapeutic measures to enhance weaning progress
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Weaning Modes

• Patients receiving mechanical ventilation for
  respiratory failure who fail an SBT should
  receive a stable, nonfatiguing, comfortable form
  of ventilatory support

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Weaning Modes

• Modes of Partial Ventilator Support

SIMV synchronized intermittent mandatory
ventilation PSV pressure support ventilation
VS volume support VAPS(PA) volume assured
pressure support (pressure augmentation) MMV
mandatory minute ventilation APRV airway
pressure release ventilation.
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Weaning Modes

• PSV Pressure Support
• Gradual decrease in the level of PSV on regular
  basis (hours or days) to minimum level of 5-8 cm
  H2O
• PSV that prevents activation of accessory muscles
• Once the patient is capable of maintaining the
  target ventilatory pattern and gas exchange at
  this level, MV is discontinued

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Weaning Modes

• SIMV synchronized intermittent mandatory
  ventilation
• Gradual decrease in mandatory breaths
• It may be applied with PSV
• Has the worst weaning outcomes in clinical trials
• Its use is not recommended

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Weaning Modes

• New Modes
• VS, Volume support
• Automode
• MMV, mandatory minute ventilation
• ATC, automatic tube compensation
• ASV, adaptive support ventilation

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Weaning Protocols

• With the assisted modes, to achieve patient
  comfort and minimize imposed loads, we should
  consider
• sensitive/responsive ventilator-triggering
  systems
• applied PEEP in the presence of a triggering
  threshold load from auto-PEEP
• flow patterns matched to patient demand, and
• appropriate ventilator cycling to avoid air
  trapping are all important to

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Weaning Protocols

• Weaning protocols
• Developed by multidisciplinary team
• Implemented by respiratory therapists and nurses
  to make clinical decisions
• Results in shorter weaning times and shorter
  length of mechanical ventilation than
  physician-directed weaning
• Sedation protocols should be developed and
  implemented

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Role of Tracheotomy

• Candidates for early tracheotomy
• High levels of sedation
• Marginal respiratory mechanics
• Psychological benefit
• Mobility may assist physical therapy efforts.

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Role of Tracheotomy

• The benefits of tracheotomy include
• improved patient comfort
• more effective airway suctioning
• decreased airway resistance
• enhanced patient mobility
• increased opportunities for articulated speech
• ability to eat orally, and
• more secure airway

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Role of Tracheotomy

• Concerns
• Risk associated with the procedure
• Long term airway injury
• Costs

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Long-term Facilities

• Unless there is evidence for clearly
  irreversible disease (e.g., high spinal cord
  injury or advanced amyotrophic lateral
  sclerosis), a patient requiring prolonged
  mechanical ventilatory (PMV) support for
  respiratory failure should not be considered
  permanently ventilator-dependent until 3 months
  of weaning attempts have failed.

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Long-term Facilities

• Critical-care practitioners should familiarize
  themselves with specialized facilities in
  managing patients who require prolonged
  mechanical ventilation
• Patients who failed ventilator discontinuation
  attempts in the ICU should be transferred to
  those facilities

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Long-term Facilities

• Weaning strategies in the PMV patient should be
  slow-paced and should include gradually
  lengthening SBTs
• Psychological support and careful avoidance of
  unnecessary muscle overload is important for
  these types of patients

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• Thank You

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Introduction

• 75 of mechanically ventilated patients are easy
  to be weaned off the ventilator with simple
  process
• 10-15 of patients require a use of a weaning
  protocol over a 24-72 hours
• 5-10 require a gradual weaning over longer time
• 1 of patients become chronically dependent on MV

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Readiness To Wean

• Improvement of respiratory failure
• Absence of major organ system failure
• Appropriate level of oxygenation
• Adequate ventilatory status
• Intact airway protective mechanism (needed for
  extubation)

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Oxygenation Status

• PaO2 60 mm Hg
• FiO2 0.40
• PEEP 5 cm H2O

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Ventilation Status

• Intact ventilatory drive ability to control
  their own level of ventilation
• Respiratory rate lt 30
• Minute ventilation of lt 12 L to maintain PaCO2 in
  normal range
• Functional respiratory muscles

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Intact Airway Protective Mechanism

• Appropriate level of consciousness
• Cooperation
• Intact cough reflex
• Intact gag reflex
• Functional respiratory muscles with ability to
  support a strong and effective cough

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Function of Other Organ Systems

• Optimized cardiovascular function
• Arrhythmias
• Fluid overload
• Myocardial contractility
• Body temperature
• 1? degree increases CO2 production and O2
  consumption by 5
• Normal electrolytes
• Potassium, magnesium, phosphate and calcium
• Adequate nutritional status
• Under- or over-feeding
• Optimized renal, Acid-base, liver and GI
  functions

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Predictors of Weaning Outcome
Predictor Value
Evaluation of ventilatory drive P 0.1 lt 6 cm H2O
Ventilatory muscle capability Vital capacity Maximum inspiratory pressure gt 10 mL/kg lt -30 cm H2O
Ventilatory performance Minute ventilation Maximum voluntary ventilation Rapid shallow breathing index Respiratory rate lt 10 L/min gt 3 times VE lt 105 lt 30 /min
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Maximal Inspiratory Pressure

• Pmax Excellent negative predictive value if less
  than 20 (in one study 100 failure to wean at
  this value)
• An acceptable Pmax however has a poor positive
  predictive value (40 failure to wean in this
  study with a Pmax more than 20)

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Frequency/Volume Ratio

• Index of rapid and shallow breathing RR/Vt
• Single study results
• RR/Vtgt105 95 wean attempts unsuccessful
• RR/Vtlt105 80 successful
• One of the most predictive bedside parameters.

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Measurements Performed Either While Patient Was
Receiving Ventilatory Support or During a
BriefPeriod of Spontaneous Breathing That Have
Been Shown to Have Statistically Significant LRs
To Predict theOutcome of a Ventilator
Discontinuation Effort in More Than One Study
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Weaning to Exhaustion

• RR gt 35/min
• Spo2 lt 90
• HR gt 140/min
• Sustained 20 increase in HR
• SBP gt 180 mm Hg, DBP gt 90 mm Hg
• Anxiety
• Diaphoresis

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Work-of-Breathing

• Pressure Volume/compliance flow X resistance
• High airway resistance
• Low compliance
• Aerosolized bronchodilators, bronchial hygiene
  and normalized fluid balance assist in
  normalizing compliance, resistance and
  work-of-breathing

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Auto-PEEP

• Increases the pressure gradient needed to inspire
• Use of CPAP is needed to balance alveolar
  pressure with the ventilator circuit pressure
• Start at 5 cm H2O, adjust to decrease patient
  stress
• Inspiratory changes in esophageal pressure can be
  used to titrate CPAP

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0
-5
-5
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0
Auto PEEP 10
-5
-15
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PEEP 10
Auto PEEP 10
5
-5
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Preparation Factors Affecting Ventilatory Demand
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The frequency to tidal volume ratio (or rapid
shallow breathing index, RSBI) is a simple and
useful integrative indicator of the balance
between power supply and power demand. A rapid
shallow breathing index lt 100 generally indicates
adequate power reserve. In this instance, the
RSBI indicated that spontaneous breathing without
pressure support was not tolerable, likely due in
part to the development of gas trapping.
Even when the mechanical requirements of the
respiratory system can be met by adequate
ventilation reserve, congestive heart failure,
arrhythmia or ischemia may cause failure of
spontaneous breathing.
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Integrative Indices Predicting Success
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Measured Indices Must Be Combined With Clinical
Observations
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Three Methods for Gradually Withdrawing
Ventilator Support
Although the majority of patients do not require
gradual withdrawal of ventilation, those that do
tend to do better with graded pressure supported
weaning than with abrupt transitions from
Assist/Control to CPAP or with SIMV used with
only minimal pressure support.
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• Thank You