Postgraduates Lecture Thursday 9.3.2017

1. Weaning from mechanical VentilationWeaning from mechanical Ventilation
By.
Alaa metwally
Ass. Prof. chest department
Zagazig university

2. Aim and objectives
• Definition of weaning
• Why weaning ??
• Decision of weaning (indication)
• Trimming of weaning (is he/she weanable?)
• Assessment of steadiness for weaning
• Methods of weaning
• Weaning protocols.
• Assessment of weaning outcome.
• What after weaning.

3. •The process of withdrawing the patient from
dependence and /or assistance on/from the
ventilator.
•Weaning from mechanical ventilation can be
defined as the process of abruptly or gradually
withdrawing the ventilatory support.
•Weaning includes tow separate but closely related
processes, discontinuation of mechanical and
removal of the artificial airway

4. • 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 prolonged weaning plan.
• 1% of patients become dependent on chronic
MV

5. Decision of weaning, indication
• Weaning is started when the patient is recovering
from the acute stage of medical and surgical
problems
or
• When the cause of ventilation is sufficiently or
completely reversed.

6. Why weaning ??

7. Mechanical Ventilation Complications
• GI bleeding, 20% - 30% without prophylaxis
• DVT, 40% - 80% without prophylaxis
• Barotrauma, 4% - 15%, Highest in ARDS
• Reductions in cardiac output
• Impaired right ventricular preload
• Ventilator induced pneumonia, sinusitis, UTI
• Post ETT tracheal stenosis, tracheomalacia
• Cerebral , edema, congestion, increased intracranial
pressure.

8. Trimming of Weaning
• Is the patient able to be disconnected from the
ventilator?

9. • Numerous trials performed to develop criteria for
successful weaning, however, no one criterion can
predict the weaning outcome.
• Physicians must rely on clinical judgment.
• Reversal of initial process that indicated MV.
• Daily screening may reduce the duration of MV.

10. Readiness To Wean
• Improvement of the cause of respiratory failure
• Absence of major system dysfunction
• Appropriate level of oxygenation
• Adequate ventilatory status
• Intact airway protective mechanism (needed for
extubation)

11. Factors to be corrected before weaning
• CNS; Absence of cough, gag, level of consciousness
• Respiratory, rate, volume and color of secretions
• Renal; Correction of acid-base/electrolyte disorders
• Hematologic; correction of anemia, leukocytosis
• Infections; amount and purulence of secretions
• Nutrition; Poor nutritional status, low phosphorus,
excessive nutrition.
• CVS; Arrhythmias (less than 120/m, more than 40/m),
BP (Shock), if supported (max 5 mic/kg/min)

12. Assessment of readiness for weaning
• Respiratory Muscle status:
• NIP (NIF) (; maximum Inspiratory pressure:
• PI max generated by a patient from FRC
approximately 10 sec after occluding the Inspiratory
circuit.
• Rapid Shallow Breathing Index :
• RR/TV (in liters). Inspiratory muscle weakness leads
to rapid shallow breathing

13. Weaning Parameters
• Respiratory Muscle Strength
• Vital Capacity VC >15mL/kg body weight
• The maximum amount of gas that can be inhaled from
residual volume or exhaled from total lung capacity
• Requires patient cooperation

14. Weaning Parameters
• Respiratory Muscle endurance:
• Minute Ventilation VE;
• the amount of air that must be moved in or out of the
lungs over 1 min to maintain a given PaCO2. <10
L/min
• VE will be determined by CO2 production
• Increased on critical care illness, high fever, over
feeding, excess carbohydrate load, Increase death
space.
• RR; Muscle fatigue, patient resorts shallow breathing >35

15. Weaning Parameters
• Respiratory Muscle Demand
• Maximum Voluntary Ventilation; MVV >2 times
the VE
• Requires a motivated and cooperative patient
• The maximum amount of air that can be inhaled or
exhaled over 1 min.
• Respiratory Compliance >33ml/cmH2O
• Work must be performed by inspiratory muscles to
overcome the elastic properties of both the lungs and
chest wall.

16. Weaning Parameters
• Respiratory Gas Exchange
• Significant hypoxemia constitutes a relative
contraindication.
• A PaO2 <60mmHG with and FIO2>.040.
• Arterial to Inspired O2 ratio (PaO2/FIO2)>200

17. Predictors of Weaning Outcome
PredictorPredictor ValueValue
Evaluation of ventilatory drive:Evaluation of ventilatory drive:
 P 0.1P 0.1
 Respiratory complianceRespiratory compliance
 < 6 cm H2O< 6 cm H2O
>33ml/cmH2O
Ventilatory muscle capability:Ventilatory muscle capability:
 Vital capacityVital capacity
 Maximum inspiratory pressureMaximum inspiratory pressure
 > 10 mL/kg> 10 mL/kg
 < -30 cm H< -30 cm H22OO
Ventilatory performanceVentilatory performance
 Minute ventilationMinute ventilation
Rapid shallow breathing indexRapid shallow breathing index
 Respiratory rateRespiratory rate
 < 10 L/min< 10 L/min
< 105< 105
 < 30 /min< 30 /min
•PEEP
•PaO2/FIO2
•FIO2
< 8 cmH2O
> 200
< .50

18. Maximal Inspiratory Pressure
• PI max: Excellent negative predictive value if less
than –20 (in one study 100% failure to wean at this
value)
• An acceptable PImax however has a poor positive
predictive value (40% failure to wean in this study
with a Pmax more than –20)

19. Frequency/Volume Ratio RSBI
• 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.

20. Weaning is a multidisciplinary process :-
Successful weaning
Physician
Nurse
Patient

22. Methods of weaning
• No one or method of weaning has been
definitely found to be superior:
• Initial Trial of Spontaneous Ventilation
• T-piece trial
• Spontaneous trial on ventilator
• Gradual Weaning
• SIMV
• Pressure Support Ventilation (PSV)
• SIMV + PSV
• Extubation + noninvasive ventilation

23. Patient Preparation
Physiological consideration:-
The nurse must consider the patient as a whole, taking into
account factors that impair the delivery of oxygen and elimination
of carbon dioxide as well as those that increase oxygen demand
(sepsis, seizures, thyroid imbalances) or decrease the patient’s
overall strength (nutrition,neuromuscular disease).
Psychological consideration:-
•The nurse explains what will happen during weaning and role the
patient will play in the procedure.
•The nurse emphasizes that someone will be with or near the
patient at all times, and answers any questions simply and
concisely.

24. Weaning trials using a T-piece
• Weaning trials using a T-piece or tracheostomy mask
are normally conducted with the patient disconnected
from the ventilator, receiving humidified oxygen
only, and performing all work of breathing.
• Patients have to overcome the resistance of the
ventilator, may find this mode more comfortable, or
they may become anxious as they breathe with no
support from the ventilator.

25. Nursing role
• The Nurse should : Explain, monitor, and provide
encouragement.
• This method of weaning is usually used when the
patient is awake and alert, is breathing without
difficulty, has good gag and cough reflexes, and is
hemodynamically stable.
• During the weaning process, the patient is maintained
on the same or a higher oxygen concentration than
when on the ventilator.

26. Nursing Assessment:-
• While on the T-piece, the patient should be observed
for signs and symptoms of hypoxia, increasing
respiratory muscle fatigue, or distress. These include:
• Restlessness ,
• Increased RR more than 35 breaths/min,
• Use of accessory muscles,
• Tachycardia with premature ventricular contractions,
• Paradoxical chest movement
• Fatigue or exhaustion is initially manifested by an increased
respiratory rate associated with a gradual reduction in tidal volume;
later there is a slowing of the respiratory rate.

27. If the patient tolerating the T-piece trial, a second
set of arterial blood gas measurements is drawn 20 minutes
after the patient has been on spontaneous ventilation at a constant
FiO2 pressure support ventilation. (Alveolar–arterial equilibration
takes 15 to 20 minutes to occur.)
Signs of exhaustion and hypoxia correlated with deterioration in the
blood gas measurements indicate the need for ventilatory support. The
patient is placed back on the ventilator each time signs of fatigue or
deterioration develop.
If clinically stable, the patient usually can be extubated within 2 or 3
hours of weaning and allowed spontaneous ventilation by means of a
mask with humidified oxygen.

28. Pressure Support Ventilation (PSV)
• Depends on supplying a fixed (pushing) pressure
during inspiration
• Patient initiated and terminated
• More comfortable, depth & length of breath
controlled by patient
• Counteract work/resistance of ETT & ventilator
circuit, airway obstruction.

29. PSV + SIMV
• The pressure support ventilation (PSV) mode
assists the patient by applying pressure to the
airway throughout the patient triggered
inspiration to decrease resistance by the endo-
tracheal tube and ventilator tubing.
• Pressure support is reduced gradually as the
patient’s strength increases.

30. Nurse role in PSV
• The nurse must closely observe the patient’s
respiratory rate and tidal volumes on initiation
of PSV.
• It may be necessary to adjust the pressure
support to avoid tachypnea or large tidal
volumes.

31. Synchronized intermittent mandatory
ventilation (SIMV)
• Synchronized intermittent mandatory ventilation (SIMV) delivers
a preset tidal volume and number of breaths per minute.
• Between ventilator-delivered breaths, the patient can breathe
spontaneously with no assistance from the ventilator on those
extra breaths.
• As the patient’s ability to breathe spontaneously increases, the
preset number of ventilator breaths is decreased and the patientpatient
do more of the work of breathingdo more of the work of breathing.
• SIMV is indicated if the patient satisfies all the criteria for
weaning but cannot sustain adequate spontaneous ventilation for
long period.

32. SIMV Protocol
• Switch to SIMV from assist mode or decrease RR
• Begin with RR 8/min decrease SIMV rate by two
breaths per hour unless clinical deterioration
• If assume to fail, increase SIMV rate to previous level,
until stable
• If stable at least 1 hour of rate 0/ min extubate
• In patient without respiratory disorders, decrease rate
with half an hour interval, 2 hr extubate

33. Nursing role in SIMV:-
Nursing interventions include:-
1.Monitoring progress by recording respiratory
rate, minute volume, spontaneous and
machine-generated tidal volume, FiO2,
2. Arterial blood gas levels.

34. Weaning outcome
• How often will the patient need to be re-
intubated?
• Accepted rate: 5% - 15%

35. Failed to Wean
• Associated with intrinsic lung disease
• Associated with prolonged critical illness
• Increased risk in patient with longer
duration of mechanical ventilation
• Increased risk of complications, mortality

36. Weaning Failure Criteria
• Rapid shallow breathing
• RR > 35/min or > 10/min increase
• Tachycardia
• > 120 bpm or > 20 bpm increase
• BP change > 20%
• Mental status change

37. Weaning Failure Criteria
• Clinical signs of distress:
• Increased dyspnea
• Diaphoresis
• Accessory muscle use
• Paradoxical breathing
• Hypoxemia and/or hypercapnea

38. •Hypoxia (PaO2 < 60, SpO2 <90%) 11 (31%)
•Hypercarbia (PaCO2 > 50 mmHg) 9 (25%)
•Pulse rate > 120/min 17 (47%)
•SBP > 180 or < 90 mmHg 2 (6%)
•Respiratory rate > 30/min 33 (92%)
•Clinical respiratory distress 27 (75%)
Fatigue Criteria

39. Evidence-based medicine
• Patients receiving MV who fail an SBT
should have the cause determined.
• Once causes are corrected, and if the patient
still meets the criteria of DS, subsequent
SBTs should be performed every 24 hours.

40. Failure to Wean
• Unresolved cause of mechanical ventilation
• Auto-PEEP
• Cardiac disease, CHF, ischemic heart disease
• Nutrition and electrolyte imbalance
• Inadequate rest following previous trial
• May need up to 24 hours
• Muscle weakness
• Paralysis or polyneuropathy of critical illness

41. Successful weaning should be followed by the
following:
• Oxygen therapy
• Close monitoring: ABGs evaluation, Pulse oximetry
• Bronchodilator therapy
• Chest physiotherapy
• Adequate nutrition, hydration, and humidification
• Incentive spirometry
What after weaning,

42. Weaning From the Tube:-
•Weaning from the tube is considered when the
patient can breathe spontaneously, maintain an
adequate airway by effectively coughing up
secretions, swallow, and move the jaw.
•If frequent suctioning is needed to clear secretions,
tube weaning may be unsuccessful (Ecklund, 1999)

43. Thank you