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Weaning Modes and Protocol

Weaning Modes and Protocol

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Weaning Modes and Protocol

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  1. Weaning Modesand Protocol

  2. 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

  3. Stages of Mechanical Ventilation 2

  4. Causes of Ventilator Dependence Who is the “ventilator dependent’? • Mechanical ventilation > 24 h or • Failure to respond during discontinuation attemps

  5. Causes of Ventilator Dependence

  6. 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

  7. 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

  8. Assessment for Discontinuation Trial Criteria Used in Weaning/Discontinuation in different studies

  9. Assessment for Discontinuation Trial Measurements used To Predict the Outcome of a Ventilator Discontinuation Effort in More Than One Study

  10. 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.

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

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

  13. Spontaneous Breathing Trial • The tolerance of SBTs lasting 30 to 120 min should prompt consideration for permanent ventilator discontinuation

  14. 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.

  15. Do Not Wean To Exhaustion

  16. 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

  17. Rest 24 hrs PaO2/FiO2 ≥ 200 mm Hg PEEP ≤ 5 cm H2O Intact airway reflexes No need for continuous infusions of vasopressors or inotrops > 100 RSBI <100 Stable Support Strategy Assisted/PSV Daily SBT 24 hours 30-120 min RR > 35/min Spo2 < 90% HR > 140/min Sustained 20% increase in HR SBP > 180 mm Hg, DBP > 90 mm Hg Anxiety Diaphoresis Extubation No Yes Mechanical Ventilation Low level CPAP (5 cm H2O), Low levels of pressure support (5 to 7 cm H2O) “T-piece” breathing

  18. 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

  19. 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

  20. 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.

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

  22. 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

  23. Failure of SBT • : • : • :

  24. 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

  25. Failure of SBT Factors affecting ventilator demands

  26. Failure of SBT Therapeutic measures to enhance weaning progress

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

  28. 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.

  29. 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

  30. 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

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

  32. 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

  33. 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

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

  35. 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

  36. Role of Tracheotomy • Concerns: • Risk associated with the procedure • Long term airway injury • Costs

  37. 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.

  38. 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

  39. 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

  40. Thank You

  41. 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

  42. 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)

  43. Oxygenation Status • PaO2≥ 60 mm Hg • FiO2 ≤ 0.40 • PEEP ≤ 5 cm H2O

  44. 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

  45. 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

  46. 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

  47. Predictors of Weaning Outcome

  48. 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)

  49. 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.

  50. 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*