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
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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
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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 PEEP≤5 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
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6. Weaning predictors
• Can be divided into those that assess the
following indices:
– the oxygenating capabilities of the patient’s lungs
– the strength and stamina of the respiratory
muscles
– respiratory drive and the work of breathing
– Composite indices draw from these categories-
RSBI
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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?
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10. Parameters that Assess Respiratory
Muscle Performance
• PI max-measures of inspiratory muscle
strength
• Gives no information about the diaphragm’s
ability to sustain ventilation
• Relatively poor in predicting weaning success
and failure
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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
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14. • U/S parameteres of diaphragmatic functions
for predicting success of weaning
DIE-
TPIAdia-
DT-
DTF-
DTD-
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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
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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?
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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 1–3 b/min at each step
then after 30min take ABG sample
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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
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20. NIPPV
• decrease the intubation rate & high weaning
rate
• success compromised if leaks are allowed to
occur
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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
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24. • After the patient’s 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
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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
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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
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27. Technique of Extubation
• sitting position (Fowler’s or semi-Fowler’s)
• 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
• patient’s condition,breathing pattern, vitals, ECG and SpO2 are closely
monitored
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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.
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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
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
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
Cutt off value for the P:F ratio determined in one study to separate weaning success from failure was 238
In normal lungs, the A-a DO2 is <12–15 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.
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
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
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 of“rest” on the ventilator are optimal between attempts at spontaneou breathing,but again clinical experience points to a range of 1–3 h as sufficient
T-piece method serves quite well in patients without significant lung disease
Deplete respiratory reserve in pt with a compromised cardiorespiratory status.
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.
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
decrease the intubation rate in acute type II respiratory failure in COPD patients, but also achieves a high weaning rate
Weaning is not synonymous with extubation
Steroid for anything that swells-philosophy
High flow nasal prongs are better tolerated and provide some PEEP
Laryngeal edema tends to be clinically significant only when vocal cord mobility is impaired
