Weaning of MV.pptx
- 1. Discontinuing of MV Presenter-Dr Alemu(EMCC-II) Adviser-DR Tesfaye(EMCC Specialist ) 3/28/2022 1
- 2. Objective At the end of this seminar residents are expected to Define weaning and extubation Describe different weaning parameters Describe weaning methods and Describe prerequesite and techniques extubation 3/28/2022 2
- 3. outline Introduction Weaning parameters Methods of Weaning Extubation 3/28/2022 3
- 4. Introduction 2 step process:readiness testing and weaning Weaning-libration vs extubation Weaning is the process of decreasing ventilator support and allowing patients to assume a greater proportion of their ventilation Crucial milstone in ventilated patient:timing of weaning is vital 3/28/2022 4
- 5. Weaning clinical criteria Required criteria 1. The cause of the respiratory failure has improved 2. PaO 2 /FiO 2 150* or SpO 2 90 percent on FiO 2 40 percent and PEEP5 cmH 2 O 3. pH >7.25 4. Hemodynamic stability (no or low dose vasopressor medications) 5. Able to initiate an inspiratory effort Additional criteria (optional criteria) 1. Hemoglobin 8 to 10 mg/dL 2. Core temperature 38 to 38.5 degrees Centigrade 3. Mental status awake and alert or easily arousable 3/28/2022 5
- 6. Weaning predictors Can be divided into those that assess the following indices: the oxygenating capabilities of the patients lungs the strength and stamina of the respiratory muscles respiratory drive and the work of breathing Composite indices draw from these categories- RSBI 3/28/2022 6
- 8. Parameters that Assess Adequacy of Oxygenation 3/28/2022 8
- 9. A-a DO2 Gradient This parameter reflects the ease of oxygen movement from the lungs to the pulmonary capillaries A high A-a DO2 indicates that the lungs are poorly capable of oxygenating the blood A-a DO2 physiologically rises with an increase in FIO2 What is normal ?weaning threshold? 3/28/2022 9
- 10. Parameters that Assess Respiratory Muscle Performance PI max-measures of inspiratory muscle strength Gives no information about the diaphragms ability to sustain ventilation Relatively poor in predicting weaning success and failure 3/28/2022 10
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- 12. RSBI the ratio of respiratory frequency to tidal volume (f/VT normal ratio 40-50/L one of the best studied and most commonly used weaning predictors Rapid & shallow breathing intolerant to spontanous breathing 3/28/2022 12
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- 14. U/S parameteres of diaphragmatic functions for predicting success of weaning DIE- TPIAdia- DT- DTF- DTD- 3/28/2022 14
- 15. Method of weaning SBT,PSV,IMV/SIMV either be accomplished by SBT on the ETT for progressively longer periods of time or by gradually decreasing the level of support on IMV, SIMV+PS or PSV 3/28/2022 15
- 16. SBT(T-Piece Weaning) patient is disconnected from MV, a T-piece is attached to the ETT and O2 is administered via one limb of the T-piece Trials of 30-120min of spontaneous breathing effective in predicting weaning success When to discontinue SBT?to repeat? 3/28/2022 16
- 17. Indication to terminate SBT 3/28/2022 17
- 18. SIMV Burden of breathing is initially shared between the patient and ventilator gradually transferred to the patient Enough mandatory breaths are given so that the targeted PaCO2 is achieved mandatory breaths are reduced by 13 b/min at each step then after 30min take ABG sample 3/28/2022 18
- 19. PSV certain level of PS is preset and this level of pressure is sustained throughout the inspiratory breath till the airflow falls to about 25% of its peak value Preset PS level is gradually reduced patient is considered ready for extubation when SB occurs without any sign of distress at a PS level of 3 5 cm H2O 3/28/2022 19
- 20. NIPPV decrease the intubation rate & high weaning rate success compromised if leaks are allowed to occur 3/28/2022 20
- 21. Mechanism of weaning failure Respiratory pump failure Imbalance b/n capacity & load in critical illnes Cardiovascular dysfuntion 3/28/2022 21
- 23. Extubation Prior to extubation Airway protection & patency Assessment of the strength of cough Pretreatment with steroid During extubation Post-extubation Outcome-planned vs unplanned 3/28/2022 23
- 24. After the patients ability to protect the airway is assured, GCS >8 Good cough reflex is also vital; the strength of cough may be assessed by using an index card or a blotting paper or by spirometry 3/28/2022 24
- 25. Assessment of airway patency Qualitative-ETT cuff deflated,leak-squeak during ventilator delivered positive pressure breath adequate space around ETT Lack of a leak-squeak implies the presence of laryngeal edema 3/28/2022 25
- 26. Quantiitative assessment ETT cuff deflated The inpiratory tidal volume and the expiratory tidal volume are both noted for each of six successive breaths The difference between the inpiratory tidal volume and the expiratory tidal volume is in essence the cuff leak volume The average of lowest three readings of the cuff leak volume is calculated 3/28/2022 26
- 27. Technique of Extubation sitting position (Fowlers or semi-Fowlers) Preoxygenation with 100% O2 The mouth and throat are thoroughly suctioned The tapes securing the ET tube are loosened As the cuff is deflated, a fairly large breath is provided The patient is instructed to cough vigorously as the tube is withdrawn The ET cuff is completely deflated The tube is withdrawn in a single swift The patient is made to cough once more after the withdrawal of the tube The mouth and throat are suctioned once again Oxygen is administered through a facemask patients condition,breathing pattern, vitals, ECG and SpO2 are closely monitored 3/28/2022 27
- 28. Pretreatment-start 12-24hr prior to extubatio Methylprednisolon-20mg Q4hr(start 12hr prior) Dexamethasone-5mg Q6hr(4doses) 3/28/2022 28
- 29. Post-extubation closely monitored following extubation early aggressive management can prevent reintubation suctioning,bronchodilator therapy,diuresis,or NPPV significantly hypoxemic either high flow face mask or high flow nasal prongs. 3/28/2022 29
- 30. Extubation failure Reintubation and the reinstitution of ventilatory assistance within 24-48 hours of extubation. 3/28/2022 30
- 31. Postextubation laryngeal edema 5-13% Stridor in 30 minutes of extubation PES accompanied by sign of respiratory insufficiency- immediate reintubation Aerosolized epinephrine-2.5ml of 1% Epi promotes vasocnstriction Steroid-dexa 5mg IV Q6hrs for 24hrs NIV-not advised 3/28/2022 31
- 32. Reference Understanding of MV UPTODATE 21.6 Text book of critical care medicine ICU BOOKS Marinos 3/28/2022 32
- 33. 3/28/2022 33
Editor's Notes
- #5: Sequential process
- #6: Clinical criteria used to determine readiness for trials of spontaneous breathing Can unconscous pt wened? Certain factors may hamper the weaning process, either by imposing an excessive load upon the respiratory system, or by depressing the neural output from the respiratory center M.Alkalosis Gastric distension Drug-sedative,NM paralaytic & AMINOglycosides Sleep deprevation noisy ICU
- #7: Since the timing of weaning is so crucial, it is necessary to have reliable information that can help determine the success of the weaning trial Predictors also have the potential for identifying specific physiological derangements responsible for weaning failure Weaning criteria are numerically almost identical to those for intubation and ventilation
- #8: P:F ratio (PaO2/FIO2 ratio) has been shown to predict weaning successfully in 90% of the patients,it was demonstrably less effective in predicting whether a patient would fail a weaning attempt (i.e., its positive predictive value was good, but the negative predictive value poor). Oxygenation-poor weanig predictors
- #9: Cutt off value for the P:F ratio determined in one study to separate weaning success from failure was 238
- #10: In normal lungs, the A-a DO2 is <1215 mmHg on room air and <70 mmHg on 100% oxygen A-a DO2 physiologically rises with an increase in FIO2 and this makes it difficult to interpret on intermediate ranges of FIO2 For a patient on the threshold of weaning, A-a DO2 of less than 350 on 100% oxygen implies weanability from the oxygenation standpoint.
- #11: PImax is measured when the patient exhales completely to residual volume and then makes a maximum inspiratory effort against an occluded airwayA PImax of less than minus 30 cmH2O (the ability of the respiratory muscles to generate a negative pressure of at least 30 cm H2O) is believed to predict successful weaning. Likewise, an inability of respiratory muscles to generate a negative pressure of more than 20 cm H2O is considered to be predictive of weaning failure
- #13: Patients who cannot tolerate independent breathing tend to breathe rapidly (high frequency) and shallowly (low tidal volume). Thus, they generally have a high RSBI. 95% AND 80% Respiratory muscle fatigue is associated with falling TV along with a rise in RR , as the patient strives to sustain a minute volume appropriate to his needs
- #17: patient is encouraged to breathe on his own through the endotracheal tube, initially for brief intervals of time Neither has it been resolved what intervals ofrest on the ventilator are optimal between attempts at spontaneou breathing,but again clinical experience points to a range of 13 h as sufficient
- #18: T-piece method serves quite well in patients without significant lung disease Deplete respiratory reserve in pt with a compromised cardiorespiratory status.
- #19: blood gas sample obtaining after 30 min of reducing the IMV frequency on each occasion enables close monitoring of the PaCO2 and the PH If the Ph continues to remain at a level above 7.35, gradual reduction of the mandatory breaths is continued with blood gas monitoring at each step, until an IMV rate of zero is arrived at When the patient is able to breathe comfortably at this level for 24 h, extubation is carried out.
- #20: PSV is an entirely more comfortable mode of ventilation (or of weaning). The patient is afforded much more flexibility in the sense that the rate, depth, and flow of the inspired breath can be controlled by the patient according to his or her needs
- #21: decrease the intubation rate in acute type II respiratory failure in COPD patients, but also achieves a high weaning rate
- #24: Weaning is not synonymous with extubation
- #29: Steroid for anything that swells-philosophy
- #30: High flow nasal prongs are better tolerated and provide some PEEP
- #32: Laryngeal edema tends to be clinically significant only when vocal cord mobility is impaired