DR RAMI ADEL ALQUDSI ICU , WEANING PATIENT FROM MECHANICAL VENTILATION IN ICU

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
Weaning from mechanical ventilation
Dr Rami Adel Alqudsi
CONSULTANT OF ANESTHESIOLOGY (KKGH)
MD
JORDAN BOARD IN ANESTHESIOLOGY

2. MECHANICAL VENTILATION
Despite early intervention and appropriate respiratory
care, patients with critical illness will often
require mechanical ventilation. Mechanical ventilation
can replace or supplement normal spontaneous
ventilation. In most instances, the problem
is primary that of impaired CO 2 elimination
(ventilatory failure)

3. Tracheal Intubation
Tracheal intubation for mechanical ventilation is
most commonly undertaken in ICU patients to
manage pulmonary failure

4. Indicators of the need for mechanical ventilation

5. Ventilator settings
Fraction of inspired oxygen (FiO2):
Target Sao2 90 % means Pao2< 60mmHg.
keep FiO2 <50% to avoid O2 toxicty.
Tidal volume (Vt):
 Is constant in volume-cycled modes and variable with
in pressure-limited modes.
In patients without lung disease Vt of 8 - 10 mL/kg .
Lower Vt 6 ml/kg are recommended for ARDS, &
Vt 8 mL/kg is recommended in patients with asthma,
COPD(as long as no increase in plateau presure).

6. Ventilator settings
Respiratory rate (RR):
12 to 20 breaths per minute is reasonable.
Minute ventilation (VE):
Is the product of the Vt and RR.
VE is based on PaCO2 as a marker of ventilatory
requirements.
VE of approximately 5 L/min maintain
normocapnea.

7. Ventilator settings
Inflation pressure limit:
High inflation pressures cause barotruama.
 Inspiratory pressure > 30 cm H2O is recommended.
Inspiratory Sensitivity :
It is the drop in airway pressure that is required before
the ventilator senses the patient's effort.
0.5 to 1 cm H2O allow very weak patients to initiate a
breath, Higher values make triggering more difficult.

8. Ventilatory Modes
Ventilatory mode is defined by the method by
which the ventilator cycles from expiration to
inspiration as well as whether the patient is
able to breathe spontaneously

9. Ventilatory Modes
Continuous Mandatory Ventilation (CMV)
Assist-Control (AC) Ventilation
Intermittent Mandatory Ventilation (IMV)
Mandatory Minute Ventilation (MMV)
Pressure Support Ventilation (PSV)
Pressure Control Ventilation (PCV)
Inverse I:E Ratio Ventilation (IRV)
Airway Pressure Release Ventilation (APRV)
High-Frequency Ventilation (HFV)
Differential Lung Ventilation

10. Continuous Mandatory Ventilation (CMV)
In this mode, the ventilator cycles from expiration
to inspiration after a fixed time interval. The
interval determines the ventilatory rate. Typical
settings on this mode provide a fixed V T and
fixed rate (and, therefore, minute ventilation)

11. Assist-Control (AC) Ventilation
Incorporation of a pressure sensor in the breathing
circuit of AC ventilators permits the patient’s
inspiratory effort to be used to trigger inspiration
A sensitivity control allows selection of the inspiratory
effort required. The ventilator can be set for
a fixed ventilatory rate, but each patient effort of
sufficient magnitude will trigger the set V T . If
spontaneous inspiratory efforts are not detected, the
machine functions as if in the control mode.

12. Intermittent Mandatory Ventilation (IMV)
IMV allows spontaneous ventilation while the
patient is on the ventilator. A selected number
of mechanical breaths (with fixed V T ) is given to
supplement spontaneous breathing. At high mandatory
rates (10–12 breaths/min), IMV essentially
provides all of the patient’s ventilation; at low rates
(1–2 breaths/min), it provides minimal mechanical
ventilation and allows the patient to breathe
spontaneous

13. Mandatory Minute Ventilation (MMV)
With MMV, the patient is able to breathe spontaneously
(with pressure support) and also receive
SIMV mechanical breaths, while the machine monitors
the exhaled minute ventilation. In this mode,
the machine continuously adjusts the number of
SIMV mechanical breaths so that the sum total of
spontaneous and mechanical ventilation equals the
desired set minute ventilation.

14. Pressure Support Ventilation (PSV)
Pressure support ventilation was designed to augment
the V T of spontaneously breathing patients and
overcome any increased inspiratory resistance from
the tracheal tube, breathing circuit and ventilator

15. Pressure Control Ventilation (PCV)
Pressure control ventilation is similar to PSV in that peak
airway pressure is controlled but is different in that a mandatory
rate and inspiratory time are selected . The disadvantage of
conventional PCV is that V T is not guaranteed Any change in
compliance or resistance will affect the delivered V T . This is a
major issue in patients with acute lung injury because if the
compliance decreases and the pressure limit is not increased,
adequate V T may not be attained..

16. Inverse I:E Ratio Ventilation (IRV)
IRV reverses the normal inspiratory:expiratory time
ratio of 1:3 or greater to a ratio of greater than 1:1.
This may be achieved by adding an end-inspiratory
pause, by decreasing peak inspiratory flow during
volume-cycled ventilation (CMV), or by setting an
inspiratory time such that inspiration is longer than
expiration during PCV (PC-IRV).

17. Airway Pressure Release Ventilation (APRV)
APRV or bilevel ventilation is a mode in which a
relatively high PEEP is used, despite the patient
being allowed to breathe spontaneously.
Intermittently, the PEEP level decreases to help
augment the elimination of CO 2 Initial settings
include a minimum PEEP of 10–12 cm H 2 O and a
release level of 5–10 cm H 2 O.

18. High-Frequency Ventilation (HFV)
High-frequency positive-pressure ventilation involves
delivering a small “conventional” V T at a rate of 60–
120 breaths/min. High-frequency jet ventilation (HFJV)
utilizes a small cannula in the airway with high-pressure
gas is delivered at a set frequency of 120–600
times/min

19. Differential Lung Ventilation
This technique, also referred to as independent
lung ventilation, may be used in patients with
severe unilateral lung disease or those with
bronchopleural fistulae.

20. Discontinuing Mechanical Ventilation
((Weaning
There are two phases to discontinuing mechanical
ventilation. The First : preparing for weaning
from mechanical ventilator support.
The second phase, extubation or“weaning” or
“liberation,”
Before weaning Complicating
.

21. Before weaning complicating factors such
as bronchospasm, heart failure,infection,
malnutrition, metabolic acidosis or
alkalosis, anemia, increased CO 2, altered
mental status and sleep deprivation
should be adequately treated.
.

22. Weaning (or liberation) from mechanical
ventilation should be considered when
patients no longer meet general criteria
for mechanical ventilation

23. Mechanical criteria for weaning
Normal

24. The common techniques for weaning include:
 SIMV,
 pressure support
 periods of spontaneous breathing alone
on a Τ -piece or on low levels of CPAP

25. Weaning with SIMV
With SIMV the number of mechanical breaths is progressively
decreased (by 1–2 breaths/min) as long as the arterial CO 2
tension and respiratory rate remain acceptable (generally <45–
50 mm Hg and <30 breaths/min). If pressure support
is used, it should generally be reduced to 5–8 cm H 2 O. In
patients with acid–base disturbances or chronic CO 2 retention,
arterial blood pH (>7.35) is more useful than CO 2 tension.
Blood gas measurements can be checked after a minimum of
15–30 min at each setting. When an IMV of 2–4 breaths is
reached, mechanical ventilation is discontinued if arterial
oxygenation remains acceptable.

26. Weaning with PSV
Weaning with PSV : is by gradually decreasing the
pressure support level by 2–3 cm H 2 O while V T ,
arterial blood gas tensions, and respiratory rate are
monitored (using the same criteria as for IMV). The goal
is to try to ensure a V T of 4–6 mL/kg and an f of less
than 30 with acceptable Pa O 2 and Pa CO 2 . When a
pressure support level of 5–8 cm H 2 O is reached, the
patient is considered weaned

27. Weaning with a T-Piece
Τ -piece trials allow observation while the
patient breathes spontaneously without
any mechanical breaths. The Τ -piece
attaches directly to the tracheal tube or
tracheostomy tube

28. REMEMBER
No guarantee 100% after extubation that the patient no needs
reintubation so all instruments and equipment Should be ready for
reintubation
Ask three questions before extubation :
1- the patient can maintain normal minute volume and protect
airway after extubation ? (No respiratory problems ?)
2- can I provide ventilation if needed after extubation ? (No difficult
ventilation? )
3- can I intubate the patient if needed after extubatient ? (No
difficult intubation? )
If three answers are yes : extubate the patient
If any answer is no : don’t extubate the patient

29. THANK YOU