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Weaning Modes and Protocol. Causes of Ventilator Dependence Assessment for Discontinuation Trial Spontaneous Breathing Trial (SBT) –Extubation Criteria.

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Presentation on theme: "Weaning Modes and Protocol. Causes of Ventilator Dependence Assessment for Discontinuation Trial Spontaneous Breathing Trial (SBT) –Extubation Criteria."— Presentation transcript:

1 Weaning Modes and 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 2

3 2 Stages of Mechanical Ventilation

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

5 5 DescriptionCauses 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 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 6

7 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 7 Assessment for Discontinuation Trial

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

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

10 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. 10 Spontaneous Breathing Trial

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

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

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

14 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

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

18 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

19 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

20 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

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

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 22

23 :::::: 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 PO 4 levels Metabolic and respiratory alkalosis Metablic/Electrolytes Infection/fever Major organ failure Stridor

24 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

25 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 27

28 Modes of Partial Ventilator Support 28 *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

29 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

30 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 30 Weaning Modes

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

32 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 32 Weaning Protocols

33 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 33 Weaning Protocols

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

35 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 35 Role of Tracheotomy

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

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. 37

38 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 38 Long-term Facilities

39 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 39 Long-term Facilities

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 Pa O2 ≥ 60 mm Hg Fi O2 ≤ 0.40 PEEP ≤ 5 cm H 2 O

44 Ventilation Status Intact ventilatory drive: ability to control their own level of ventilation Respiratory rate < 30 Minute ventilation of < 12 L to maintain Pa CO2 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 PredictorValue Evaluation of ventilatory drive:  P 0.1  < 6 cm H2O Ventilatory muscle capability:  Vital capacity  Maximum inspiratory pressure  > 10 mL/kg  < -30 cm H 2 O Ventilatory performance  Minute ventilation  Maximum voluntary ventilation  Rapid shallow breathing index  Respiratory rate  < 10 L/min  > 3 times V E  < 105  < 30 /min

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 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*

51 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

52 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

53 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

54 0 -5 Gradient -5

55 0 Auto PEEP +10 -5 Gradient -15

56 PEEP 10 Auto PEEP +10 5 Gradient -5

57 Preparation: Factors Affecting Ventilatory Demand

58

59 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 < 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.

60 Integrative Indices Predicting Success

61 Measured Indices Must Be Combined With Clinical Observations

62 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.

63 Thank You


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