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Journal of
eISSN: 2376-0060

Lung, Pulmonary & Respiratory Research

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Received: January 01, 1970 | Published: ,

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Objectives

Discuss the variables that are used to indicate readiness to wean from mechanical ventilation Discuss the use of protocols to wean patients from ventilatory support Discuss the criteria used to indicate readiness for extubation Describe the most common reasons why patients fail to wean from mechanical ventilation.

Predicted success rate

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 24-72hours 5-10% require a gradual weaning over longer time 1% of patients become chronically dependent on MV

Assessment criteria for weaning

    1. Neurological: (No sedation, GCS>8,Pain controlled)
    2. Respiratory: (No­WOB, PS <10,PEEP 5,FIO2-40%,sat >90%, PF >200)
    3. Cardiovascular : (Stable Hemodynamics, Hb >7, Normal ECG)

Ventilation status

    1. Intact ventilatory drive: ability to control their own level of ventilation
    2. Respiratory rate <30
    3. Minute ventilation of <10 L to maintain PaCO2 in normal range
    4. VD/VT <60% (Vd/Vt=0.320+0.0106 (PaCO2 - end-tidal carbon dioxide measurement)+0.003 (RR per minute)+0.0015 (age in years )
    5. Functional respiratory muscles

Intact airway protective mechanism

    1. Intact ventilatory drive: ability to control their own level of ventilation
    2. Respiratory rate <30
    3. Minute ventilation of <10 L to maintain PaCO2 in normal range
    4. VD/VT <60% (Vd/Vt=0.320+0.0106 (PaCO2 - end-tidal carbon dioxide measurement)+0.003 (RR per minute)+0.0015 (age in years )
    5. Functional respiratory muscles

Approaches to weaning

    1. Spontaneous breathing trials
    2. Pressure support ventilation (PSV) SIMV
    3. New weaning modes

Maximal inspiratory pressure

    1. Negative Expiratory pressure must be more than -20cmH2o
    2. Assures ability to mobilize secretions

Shallow breathing index

Index of rapid and shallow breathing=RR/Vt in litre

Single study results

    1. RR/Vt>105 95% wean attempts unsuccessful
    2. RR/Vt<105 80% successful
    3. One of the most predictive bedside parameters

Spontaneous Breathing Trial (SBT)

    1. Explore Exclusion Criteria
    2. Assess Readiness for SBT
    3. If passed proceed sedation vacation for 30min
    4. Initiate SBT for 30minutes
    5. Assess the tolerance to SBT
    6. If SBT passed assess Readiness for Extubation

Exclusion Criteria for SBT

    1. GCS <8 unsedated use of Neuro muscular drugs
    2. Neuro Muscular Disease with VC <20ml/kg or NIP <20
    3. RASS sedation and agitation scale +1 and higher, -3 and lower
    4. Immediate pending Invasive procedure
    5. ICP >20 or needing RX in last 12hours
    6. Ongoing Cardiac Ischemia
    7. Uncontrolled seizures

Failure to wean

    1. Weaning to exhaustion
    2. Auto-PEEP
    3. Excessive work of breathing
    4. Poor nutritional status
    5. Overfeeding
    6. Left heart failure
    7. Infection/fever
    8. Major organ failure
    9. Technical limitation

Appendix

Protocols

    1. Developed by multidisciplinary team
    2. Implemented by respiratory therapists and nurses to make clinical decisions
    3. Results in shorter weaning times and shorter length of mechanical ventilation than physician-directed weaning

Points to remember

    1. The primary prerequisite for weaning is reversal of the indication of mechanical ventilation
    2. Adequate gas exchange should be present with minimal oxygenation and ventilatory support before weaning is attempted
    3. The function of all organ systems should be optimized, electrolytes should be normal, and nutrition should be adequate before weaning is attempted
    4. The most successful predictor of weaning is RSBI <100
    5. Maximum inspiratory pressure is the best predictor of weaning failure
    6. Ventilatory discontinuation should be done if patient tolerates SBT for 30-120minutes
    7. Use of liberation and weaning protocol facilitates the process and decreases the ventilator length of stay.1–4

Acknowledgements

None.

Conflict of interest

The author declares no conflict of interest.

References

  1. J bras. pneumol.  São Paulo Sept./Oct. 2011;37(5). 
  2. http://dx.doi.org/10.1590/S1806-37132011000500016  
  3. Journal  Brasileirode Pneumologia
  4. AARC
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