This document discusses liberation from mechanical ventilation and the criteria for removing a patient from a ventilator. It outlines several key points: 1) Liberation involves gradually withdrawing ventilator support and allowing the patient to breathe spontaneously on their own. Readiness is determined by ventilatory, oxygenation, and other physiological criteria. 2) Weaning can be either abrupt for some patients or more gradual over time for others requiring long-term ventilation support. Successful weaning relies on evaluating factors like respiratory function, gas exchange, and other organ system stability. 3) Specific criteria are used to gauge a patient's ability to tolerate a spontaneous breathing trial without ventilator assistance, including acceptable vital signs and gas

1. LIBERATION FROM VENTILLATOR
DR Vishwa Reddy

2. Definition
 Liberation from the ventilator is the process of withdrawing mechanical
ventilatory support and transferring the work of breathing from ventilator to
the patient.
 The ability to breathe spontaneously is the criterion to gauge the success or
failure of weaning attempts .

3. objectives
 Discuss the physiologic variables used to indicate readiness to wean from
mechanical ventilation
 Discuss the use of protocols to wean patients from mechanical ventilation.
 Describe the most common reasons responsible for failure to wean from
mechanical ventilation .
 Discuss the criteria used to indicate readiness for extubation .

4. Weaning may be accomplished :
abruptly with the patient being directly transitioned from full ventilatory
support to unassisted spontaneous breathing Eg : Post anaesthesia ,drug
overdose .
or
For other patients successful weaning requires a more gradual withdrawal of
mechanical ventilatory support , generally longer the patient on ventilator
more gradual is the weaning process .

5. Criteria for liberation from ventilator
The weaning criteria is used to evaluate the readiness of a patient for weaning
trial and the likelihood of weaning success .
It includes :
Ventilatory Criteria
Oxygenation Criteria
Pulmonary reserve
Pulmonary measurements

6. Ventillatory criteria Oxygenation Criteria
 Spontaneous breathing trial
- Tolerates 30-120 min
 PaCo2 - <50mmHg with
normal Ph
 Vital Capacity - >10 to 15
ml/Kg
 Spontaneous Vt - >5 to
8ml/Kg
 Minute Ventillation < 10 L
 Pao2 without PEEP > 60 mmHg at
Fio2 up to 0.4
 Pao2 with PEEP >100mmHg at Fio2
up to o.4
 SaO2 > 90% at Fio2 up to 0.4
 Qs/Qt <20 %
 P(A-a)O2 <350mmHg at Fio2 of 1.0
 PaO2/Fio2 >200mmHg

7. Function of Other Organ Systems
 Optimized cardiovascular function
Arrythmias , 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

8. Intact Airway Protective Mechanism
 Appropriate level of consciousness and Cooperation
 Intact Cough reflex
 Intact Gag reflex
 Functional respiratory muscles with ability to support a strong and
effective cough .

10. Pulmonary Mesurements
 Pulmonary Reserve : Vital Capacity(VC) > 10 -15 ml/Kg
(Effort Dependant) ( IRV +ERV+ TV )
Maximum Inspiratory pressure(MIP) -30 cm
( Negative inspiratory force is the amount of negative pressure that the patient
can generate in 20 sec when inspiring against an occluding measuring device ).
 Pulmonary Measurements : Static Compliance
Airway resistance
Vd/Vt ratio

11. Combined Weaning Indices
 Rapid Shallow breathing Index :(RSBI) - f/Vt <100 breaths/min/L
 Simplified Weaning Index (SWI) < 9/min
SWI = f(PIP-PEEP) PaCo2
MIP 40
 Compliance Rate Oxygenation and Pressure –
 (CROP) Index -13mL/ breaths /min

16. Liberation Methods
 Spontaneous Breathing Trial :
SBT to assess extubation readiness
Let patient breathe spontaneously for up to 5 min every 30 to 120 min
Return patient to mechanical ventilation to rest
Increase duration of spontaneous breathing gradually for up to 2 hrs each time .
Periods of rest between trials and at day time and night
If all steps are tolerated well consider extubation when blood gasses and vital signs
are satisfactory.
Common Weaning Procedures :

17. Criteria Used in Several Large Trials To Define
Tolerance of an SBT
Objective measurements
indicating tolerance/success
Gas exchange aacceptibility (Spo2>85-905,Po2 >50-
60mmHg, pH.>7.32 increase in Paco2<10mmHg
Haemodynamic stability(HR<120-140 beats/min HR not
changed>20%, systolic BP<180-200and >90mmHg: BP not
changed>20%, no pressors required.
Stableventilatory pattern(RR<30-35 breaths/min,RR not
changed>50%
Subjective clinical
assessments indicating
intolerance/failure
Change in mental status (somnolence ,coma , agitation,
anxiety)
Onset or worsening of discomfort
Diaphoresis
Signs of increased work of breathing(use of accessory
respiratory muscles and thoracoabdominal paradox)

18. Frequency of Tolerating an SBT and Rate of
permanent ventilator discontinuation following a
successful SBT
Study name Pts receiving
SBT
Pts tolerating
SBT
Pts
Discontinuing
Ventillation
Pts Having
Ventillation
Reinstituted
Esteban et
al107
546 416(76) 372 58(16)
Ely et al106 113 88(78) 65 5(4)
Dojat et al110 38 22(58) 22 5(23)
Esteban et
al101
246 192(78) 192 36(19)

19.  SIMV : Synchronised Intermittent mandatory ventilation
Reduce rate by 1 to 3 breaths per min
Monitor Spo2 , obtain ABG ,consider extubation when vital signs are satisfactory .
 PSV : Pressure support ventilation
It may be used in conjunction with spontaneous breathing or SIMV mode
Start PSV at a level of 5 to 15 cm( up to 40 cm H20) to augment spontaneous Vt until a
desired high Vt or low spontaneous RR is obtained .
Decrease PS by 3 to 6 cm H2O intervals until a level close to zero is reached .
The weaning outcomes in clinical trials for SIMV mode is less and its use is not recommended
.
Newer Modes of partial ventilatory support include Volume support , Volume assured
pressure support(VAPS),Mandatory minute ventilation(MMV).

20. Weaning Protocol
Step 1 :
1. Does the patient show
 Evidence of some reversal of underlying cause for ventilatory failure
 Presence of inspiratory effort
 Haemodynamic stability
(absence of myocardial ischemia ,hypotension ,use of vasopressor )
 Adequate oxygenation and acid base status
Pao2/Fio2 > 150mmHg, PEEP< 8cm H20 and Ph>7.25
Light sedation or better( brief eye contact to voice command )
( If yes to all five questions proceed weaning to step 2 , if NO postpone weaning till next
day)

21. Weaning Protocol
Step 2 :
Perform and measure rapid shallow breathing index (RSBI or f / vt) with
mandatory rate and pressure support at 0, PEEP<5 cm H20 measurements taken
>3 min of spontaneous breathing .
RSBI or f/Vt < 100 cycles/min/L
(If yes proceed weaning to step 3, if NO postpone weaning till next day)

22. Weaning Protocol (Contd)
Step 3 :
 Can patient tolerate
 Spontaneous breathing trial for up to 30 min and gradually up to 120 min
without termination can proceed for extubation .
Termination Criteria :
 Spontaneous rate >35/min for 5 min;
 Spo2 <90%
 Heart rate >140/min or 120% of baseline
 Systolic pressure >180 mmHg or <90 mmHg
Signs of anxiety or use of accessory muscles .

23. Causes of Weaning Failure
Weaning failure occurs when work of spontaneous breathing becomes great
for the patient to sustain .
 Increase of Air Flow Resistance
Airway obstruction , Bronchospasm
 Decrease of Compliance
ARDS , Refractory hypoxemia , Obesity
 Respiratory Muscle Fatigue
Muscular atrophy , Insufficient nutrition , Electrolyte imbalance

24. EXTUBATION
 Extubation refers to removal of the endotracheal tube (ETT)N, which is th final
step of liberating the patient from mechanical ventilation .
 At the end of the weaning process it may be apparent that a patient no longer
requires mechanical ventilation to maintain sufficient ventilationand
oxygenation.
 Extubation should not be ordered until it has been determined that the
patientis able to protect the airway and airway is patent.

25. Routine Extubation Criteria
 Awake ,alert , able to follow
commands
Sustained eye opening for paediatric
patients or patients unable to understand
commands
Vitals signs Stability
 Protective reflexes returned
(Cough , Gag ,Swallow )
 Adequate reversal of neuromuscular
blockade
Train of 4 stimulation 4/4, sustained
tetany at 50 Hz
Strong Hand grip
Unassisted head tilt(>5sec)
 Arterial blood gases reasonable with Fio2-40
Ph >7.30
Pao2 > 60 mmHg
PaC02 < 50 mmHg
 Respiratory mechanics adequate
Tidal volume >5ml/Kg
Vital capacity>15 ml/kg, Negative Inspiratory
force >-20 cm H20
 For patients at risk of laryngeal edema,
consider cuff leak test and airway inspection
.

26. Cuff leak Test
 Assessment of Upper airway patency is challenging in the intubated patient .
 Qualitative and quantitative cuff- leak tests have been described to assess
the degree of laryngeal oedema and subsequent risk of reintubation .
 An association between the absence of an audible development of post
extubation stridor has been demonstrated(qualitative cuff leak test)
 Patients with a cuff leak volume of<110 ml or of 20% tidal volume may be at
high risk for the presence of laryngeal edema and subsequently for
reintubation .

28. Complications of Routine Extubations
 Unintended extubation
 Fixation of endotracheal tube
 Hypertension ,tachycardia
 Coughing ,breath holding
 Laryngeal injury
 Laryngospasm or vocal card
paralysis
 Stridor, airway obstruction
 Negative pressure pulmonary
edema
 Laryngeal incompetence
 Aspiration

29. Post Extubation Adjuncts
 Measures taken to avert complications in the post
extubation period include :
NIV may be used to provide respiratory support
without need for tracheal intubation :
As an aid to early extubation
As a prophylactic measure in high risk extubations
Finally as a treatment for post extubation respiratory
distress
The ACCP ,ATS and BTS suggest NIV as a stratergy for
weaning in patients with COPD and Chronic
respiratory disease and also advice to use it
prophylactically in patients with high risk of
extubation failure .
 Following extubation the conventional method
of preventing hypoxia is application of
controlled oxygen therapy via a face mask with
variable levels of oxygen delivery dependent
upon the users peak inspiratory flow.
 HFNOT is a new development in adult
populations offering humidified warmed oxygen
at flow rates <60L/min particularly in patients
deemed at a low risk of developing extubation
failure .

30. THANK YOU