This slide is on weaning of patients from Ventilators.

1. Weaning from ventilator
Presenter: Dr. Tapan Biswas
Moderator: Dr.Samir Samal

2. What is weaning
• Liberation from mechanical ventilation is a three-step process that
involves readiness testing, weaning, and extubation
• Readiness testing — Readiness testing uses objective clinical
criteria (and occasionally physiological tests) to determine whether a
patient is ready to begin weaning from mechanical ventilation
• Weaning — Weaning is the process of decreasing the degree of
ventilator support and allowing the patient to assume a greater
proportion of their own ventilation
• Extubation — Extubation is the removal of the endotracheal tube
and is the final step in liberation from mechanical ventilation support.
Extubation is performed when the patient is successful at weaning
• And both airway patency and airway protection are measured

3. Importance
• Delayed weaning can lead to
complications- VILI,VAP,VIDD, Incease
ICU length
• Premature weaning can lead to
complications like loss of the airway, re-
intubation, defective gas exchange,
aspiration and respiratory muscle fatigue.

4. Goal of Readiness testing
• Identifying those who are ready to wean.
• Identifying patients who are not ready to wean.
• has the underlying condition improved?
• is the patient's general condition optimal?
• have potential airway problems been identified
and remedied?
• is breathing adequate?

5. Weaning criteria

6. Subjective assessment
• Adequate cough
• No neuromuscular blocking agents
• Absence of excessive trachea-bronchial
secretion
• Reversal of the underlying cause for
respiratory failure
• No continuous sedation infusion or
adequate mentation on sedation

7. Objective measurements
• Stable cardiovascular status
• Heart rate ≤ 140 beat/minute
• No active myocardial ischemia
• Adequate hemoglobin level ( ≥ 7 g/dl)
• Systolic blood pressure 90–160 mmHg
• Afebrile (36° C < temperature < 38° C)
• No or minimal vasopressor or inotrope (< 5
µg/kg/minute dopamine or dobutamine)

8. Respiratory criteria(oxygenation)
• Tidal volume > 5 mL/kg
• Vital capacity >10 mL/kg
• Respiratory rate ≤ 35/minute
• PaO2 ≥ 60 and PaCO2 ≤ 60 mmHg
• PEEP ≤ 8 cmH2O
• No significant respiratory acidosis (pH ≥ 7.30)
• Maximal inspiratory pressure (MIP) ≤ -20 – -25 cmH2O
• O2 saturation > 90% on FIO2 ≤ 0.4 (or PaO2/FIO2 ≥ 200)
• Rapid Shallow Breathing Index (respiratory Frequency/Tidal
Volume) < 105

9. SBT
• A recent Cochrane systematic review
concluded that there is no difference
between T-piece trials and pressure
support trials regarding extubation failure.
• Duration of SBT should be at least 30
minutes and not longer than 120 minutes

10. Criteria of successful SBT
• Respiratory rate < 35 breaths/minute
• Good tolerance to spontaneous breathing trials
• Heart rate < 140 /minute or heart rate variability of >20%
• Arterial oxygen saturation >90% or PaO2 > 60 mmHg on
FiO2<0.480 <
• SBP < 180 mmHg or <20% change from baseline
• No signs of increased WOB
• Impending sign of respiratory failure will be absence-
----Accessory muscle use, paradoxical or asynchronous rib
cage-abdominal movements, intercostal retractions,
nasal flaring, profuse diaphoresis, agitation

11. Outcome
• Simple :Successful SBT after the first
attempt
• Difficult: Failed SBT at first attempt
or Required up to three trials
or Required <7days to reach successful
SBT
• Prolonged: Required >7days to reach
successful SBT

12. Weaning Failure
• Respiratory causes
• Cardiac causes
• Neuromuscular competence (central and
peripheral),
• Critical illness neuromuscular abnormalities
(CINMA),
• Neuropsychological factors
• Metabolic
• Endocrine disorders

13. Causes of difficult weaning(central
causes)
• Drive to breathe reduced by Sedatives
• Direct insults to the respiratory centre (Brain
stem injury)
• Central hyperventilation- seen in CVA with
raised ICP
• Metabolic alkalosis (commonly exacerbated by
hypokalaemia)—precipitator of hypercapnea
• Loss of hypoxic drive (COPD) – low o2 is
indicate.

14. Causes of difficult
weaning(neuromuscular causes)
1.Primary neurological disorders :Guillain–Barré
syndrome, Myasthenia Gravis ,Botulism, cervial
injury
2.Critical illness polyneuropathy (more common
with steroids and neuromuscular blocking
agents)
3.Critical care myopathy/malnutrition
4.Electrolyte: K+,PO4-,Mg+,Ca++
5.Hypothyroidism, hypoadrenalisom

15. Increased respiratory load(lung
causes)
• Increased resistance
:Bronchospasm,Increased or thick
secretions
• Reduced compliance: Pneumonia,
Pulmonary oedema, Intrinsic PEEP,Pleural
effusions,Pneumothorax, Paralytic ileus or
abdominal distension

16. Cardiac causes
• Many patients will have identified as IHD, valvular heart
disease, systolic or diastolic dysfunction prior to, or
identified during, their critical illness.
• More subtle and less easily recognised are myocardial
dysfunction, which is only apparent when exposed to the
workload of weaning.
• Positive pressure ventilation to spontaneous ventilation
is associated with increased venous return, negative
intra-thoracic--- increased left ventricular afterload and
increased myocardial oxygen consumption.

17. Increased ventilation
• Hypermetabolism (sepsis is a common
cause)
• Overfeeding
• Metabolic acidosis
• Shock
• Pulmonary embolism

18. Extubation
• It is the final step in liberating a patient from
mechanical ventilation
Extubation should not be performed
---until it has been determined that the patient's
medical condition is stable,
---a weaning trial has been successful,
--the airway is patent
---any potential difficulties in reintubation have
been identified.
Most patients are extubated during daytime hours,

19. Weaning failure(SBT and
Extubation)
• Weaning failure is defined as either the failure of SBT or
the need for reintubation within 48 h following extubation
• Failure of SBT is defined by: 1) objective indices of
failure, such as tachypnoea, tachycardia, hypertension,
hypotension, hypoxaemia or acidosis, arrhythmia;
• 2) subjective indices, such as agitation or distress,
depressed mental status, diaphoresis and evidence of
increasing effort
• Vallverdu et al. reported that weaning failure occurred in
as many as 61% of COPD patients, 41% of neurological
patients 38% of hypoxaemic patients, brain-injured
patients demonstrated that 80%.

20. Extubation Failure and importance
• . Extubation failure is defined as re-
intubation within 48 hours of extubation.
• Number of re-intubated patients divided
by total number of extubated patients.
• A value too high suggests that weaning is
done too early, and a value too low
suggests unnecessary conservative
practices.
• Value of 5-20% is generally accepted

21. Cuff leak test and stridor
• Cuff leak test has been introduced as a predictor of
stridor after extubation
• The amount of air leaking through the airway after
deflating the cuff of the endotracheal tube is measured.
The average of three values of 6 consecutive breaths
during continuous mandatory ventilation 24 hours before
extubation is taken.
• A value of <110 ml is considered to identify patients at
high risk for stridor after extubation
• Steroids and/or epinephrine can treat post extubation
stridor.
• It is also possible to give steroids and/or epinephrine 24
hours before extubation for patients with low cuff leak
values

22. How to over come
• Correction of elecrtolyte-
K+,Mg++,Ca++,Po4-
• Avoid of Neuromuscular weakness drugs-
steroid, amino glycosides, Polymixin, NM
blocker
• Nutrition- adequate protein and calories.
• Regular physiotherapy
• Use of bronchodilator
• Tapping of pleural/peritoneal fluid

23. How to overcome
• Optimisation of sedation
• De-escalation of fluid/ reduce lung oedema
• Correction of anaemia
• Treat the ischemia
• Albumin reduce chest wall oedema/RRT
• Correction of acidosis or alkalosis
• Reduction of dead space by tracheotomy
• Use of newer mode of ventilator—proportional
assist ventilation,ASV, NAVA,APRV

24. Methods of Weaning From
Mechanical Ventilation in Adult
https://www.frontiersin.org ›
fmed.2021.752984 › full
• Conclusion: In general consideration, our study
provided evidence that weaning with proportional assist
ventilation(PAV) has a high probability of being the most
effective ventilation mode for patients with mechanical
ventilation regarding a higher rate of weaning success, a
lower proportion requiring reintubation, and a lower
mortality rate than other ventilation modes.

25. Critical illness
neuropathy/Myopathy(ICU-AW)
• It is a type of skeletal muscle dysfunction due to
sepsis, mobility restriction, hyperglycemia,
steroid, NM block
• Pathophysiology remains incompletely
understood but comprises complex
structural/functional alterations within myofibers
and neurons
• Risk factors include age, weight, comorbidities,
illness severity, organ failure, exposure to drugs
• Incidence is 25-45%, Diagnosed by MRC
score(48/60)

26. Management of ICU-AW
• Avoid specific drugs
• Nutritional support
• Antioxidant therapy
• Early mobilisation
• Physiotherapy
• Electrical muscle stimulation
• The impact of early mobilization, neuromuscular
electrical stimulation and of pharmacological
interventions were inconsistent, with recent
systematic reviews/meta-analyses revealing no
or only low-quality evidence for benefit.

27. https://www.ncbi.nlm.nih.gov ›
articles › PMC7224132
• Critically ill patients frequently acquire muscle weakness
while in the ICU, which adversely affects short- and long-
term outcomes.
• No effective treatments are currently available whereas
partial prevention of ICU-acquired weakness is possible
by avoiding hyperglycemia, by postponing parenteral
nutrition to beyond the first ICU week, and by minimizing
sedation.
• Further mechanistic research is warranted in order to
identify novel preventive and/or therapeutic strategies
that can be tested in adequately powered RCTs.

28. How to overcome
• NIV with standard medical therapy in extubation failure
• It showed that NIV when used prophylactically in patients with high
risk for extubation failure was associated with lower risk for re-
intubation and ICU mortality.
• The role of high flow nasal cannula (HFNC)
• Modern HFNC devices provide gas flow with a high rate up to 70
Litter/min and thus can provide oxygen with a high FiO2 up to 100%.
• Maggiore et al. conducted an RCT of HFNC versus conventional
venture mask for oxygen delivery after extubation and found that
HFNC was associated with better oxygenation and lower re-
intubation rate .
• Bortfain et al. found that HFNC was associated with better
oxygenation, more ventilator free days and lower re-intubation rate

29. TAKE HOME
• Identifying those who are ready to wean and
who are not. Clinical judgement is essential.
• No difference between T-piece trials and
pressure
• Use of newer mode of ventilator(proportional
assist ventilation,ASV, NAVA,APRV) can be
used in weaning difficulty.
• SAT and SBT every day
• No effective treatments are currently
available for ICU-AW