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Weaning Modes and Protocol. 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. Stages of Mechanical Ventilation. 2. - PowerPoint PPT Presentation
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Weaning Modesand Protocol
• 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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2
Stages of Mechanical Ventilation
Causes of Ventilator Dependence
Who is the “ventilator dependent’?
• Mechanical ventilation > 24 h
or• Failure to respond during discontinuation
attemps
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Causes Description
Neurologic controller Central drivePeripheral nerves
Respiratory system Mechanical loadsVentilatory muscle propertiesGas exchange properties
Cardiovascular system Cardiac tolerance of ventilatory muscle workperipheral oxygen demands
Psychological issues
Causes of Ventilator Dependence
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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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
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Criteria Used in Weaning/Discontinuation in different studies
Assessment for Discontinuation Trial
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Measurements used To Predict the Outcome of a Ventilator Discontinuation Effort in More Than One Study
Assessment for Discontinuation 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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Spontaneous Breathing Trial
Criteria Used in Several Large Trials To Define Tolerance of an SBT*
*HR heart rate; Spo2 hemoglobin oxygen saturation.
Spontaneous Breathing Trial
• The tolerance of SBTs lasting 30 to 120 min should prompt consideration for permanent ventilator discontinuation
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Spontaneous Breathing Trial
Frequency of Tolerating an SBT in Selected Patients and Rate of Permanent Ventilator Discontinuation
Following a Successful SBT*
*Values given as No. (%). Pts patients.†30-min SBT.‡120-min SBT.
Spontaneous Breathing Trial
Do Not Wean To Exhaustion
Weaning to Exhaustion
• RR > 35/min• Spo2 < 90%• HR > 140/min• Sustained 20% increase in HR• SBP > 180 mm Hg, DBP > 90 mm Hg• Anxiety• Diaphoresis
Daily SBT
<100
Mechanical Ventilation
RR > 35/minSpo2 < 90%HR > 140/minSustained 20% increase in HRSBP > 180 mm Hg, DBP > 90 mm HgAnxietyDiaphoresis
30-120 min
PaO2/FiO2 ≥ 200 mm HgPEEP ≤ 5 cm H2OIntact airway reflexesNo need for continuous infusions of vasopressors or inotrops
RSBI
ExtubationNo
> 100
Rest 24 hrs
Yes
Stable Support StrategyAssisted/PSV
24 hours
Low level CPAP (5 cm H2O), Low levels of pressure support (5 to 7 cm H2O)“T-piece” breathing
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
Extubation Criteria
Post Extubation Stridor • 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
Extubation Criteria
Post Extubation Stridor • 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.
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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Extubation Criteria
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
Respiratory Increased resistanceDecreased complianceIncreased WOB and exhaustionAuto-PEEP
Cardiovascular Backward failure: LV dysfunctionForward heart failure
Metablic/Electrolytes Poor nutritional statusOverfeedingDecreased Mg and PO4 levelsMetabolic and respiratory alkalosis
Infection/fever
Major organ failure
Stridor
• 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
Failure of SBT
Failure of SBT
Factors affecting ventilator demands
Failure of SBTTherapeutic measures to enhance weaning progress
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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Modes of Partial Ventilator Support
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*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.
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
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 Modes
• 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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Weaning Protocols
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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• 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
36
Role of Tracheotomy
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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• 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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Long-term Facilities
Thank You
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
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)
Oxygenation Status
• PaO2 ≥ 60 mm Hg
• FiO2 ≤ 0.40
• PEEP ≤ 5 cm H2O
Ventilation Status
• Intact ventilatory drive: ability to control their own level of ventilation
• Respiratory rate < 30
• Minute ventilation of < 12 L to maintain PaCO2 in normal range
• Functional respiratory muscles
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
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
Predictors of Weaning Outcome
PredictorPredictor ValueValueEvaluation of ventilatory drive:Evaluation of ventilatory drive:
P 0.1P 0.1 < 6 cm H2O< 6 cm H2O
Ventilatory muscle capability:Ventilatory muscle capability: Vital capacityVital capacity Maximum inspiratory pressureMaximum inspiratory pressure
> 10 mL/kg> 10 mL/kg < -30 cm H< -30 cm H22OO
Ventilatory performanceVentilatory performance Minute ventilationMinute ventilation Maximum voluntary ventilationMaximum voluntary ventilation Rapid shallow breathing indexRapid shallow breathing index Respiratory rateRespiratory rate
< 10 L/min< 10 L/min > 3 times V> 3 times VEE
< 105< 105 < 30 /min< 30 /min
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)
Frequency/Volume Ratio
• Index of rapid and shallow breathing RR/Vt• Single study results:
– RR/Vt>105 95% wean attempts unsuccessful– RR/Vt<105 80% successful
• One of the most predictive bedside parameters.
Measurements Performed Either While Patient Was Receiving Ventilatory Support or During a Brief
Period of Spontaneous Breathing That Have Been Shown to Have Statistically Significant LRs To Predict the
Outcome of a Ventilator Discontinuation Effort in More Than One Study*
Weaning to Exhaustion
• RR > 35/min• Spo2 < 90%• HR > 140/min• Sustained 20% increase in HR• SBP > 180 mm Hg, DBP > 90 mm Hg• Anxiety• Diaphoresis
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
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
0
-5
Gradient
-5
0
Auto PEEP +10
-5
Gradient
-15
PEEP10
Auto PEEP +10
5
Gradient
-5
Preparation: Factors Affecting Ventilatory Demand
Integrative Indices Predicting Success
Measured Indices Must Be Combined With Clinical Observations
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.
Thank You