The document outlines indications and contraindications for mechanical ventilation, detailing various ventilation modes such as volume and pressure-controlled, and spontaneous ventilation. It discusses the advantages and disadvantages of each mode, complications related to invasive ventilation, and management of breath delivery and monitoring. Additionally, it emphasizes the importance of PEEP and considerations for weaning patients off ventilators.

1. Mechanical
Ventilation

2. INDICATIONS
 Respiratory Failure
 Cardiopulmonary arrest
 Trauma Events
 Cardiovascular impairment
 Neurological impairment
 Pulmonary impairment
 Procedures requiring sedation/paralysis

3. CONTRA-INDICATIONS
 Risks outweigh benefits, for example
Neutropenia
 Non-invasive deemed preferable to invasive
ventilation
 Invasive ventilation considered medically
futile
 Contrary to the expressed wishes of the
patient

4. VENTILATORS
A machine that generates a controlled
flow of blended air and oxygen into a
patient’s airway.

5. VENTILATION
Two categories Volume or Pressure
This refers to the mode of breath
delivery rather than the mode itself

6. VOLUME
In volume category modes of ventilation the machine
generates flow to achieve a set volume known as
TIDAL VOLUME

7. TIDAL VOLUME
VT
Definition –
‘the volume of air
that is inspired or
expired in a single
breath during
regular breathing’

8. VOLUME MODES
Advantages
Guaranteed Minute
Ventilation (Mv).
Disadvantages
Increased
monitoring of airway
pressures.
Airway pressures
will increase if lung
compliance
decreases.
Risk of barotrauma.

9. MINUTE VENTILATION
MV
Definition –
‘The total volume of
gas in litres expelled
from the lungs per
minute’

10. PRESSURE
In pressure modes of ventilation a pressure limit is
set, the machine generates flow until the peak
pressure limit is achieved-
PAP or PIP
Peak Airway
(inspiratory) Pressures

11. PEAK AIRWAY (INSPIRATORY) PRESSURES
Pip
Pap
Ppeak
Definition –
‘Peak Airway
(Inspiratory) Pressure
is the highest level of
pressure applied to the
lungs during inhalation
expressed in cmh2o’

12. PRESSURE MODES
Advantages
Greater control of
airway pressure.
Less risk of
barotrauma.
Disadvantages
No guaranteed minute
ventilation.
Increased monitoring of
VT required.
Rapid changes in the
compliance can cause
hypoventilation/hypoxia
.

13. INSPIRATION
FLOW TRIGGER - a breath is generated when the
patient’s respiratory effort causes flow to reach a set level.
PRESSURE TRIGGER - a breath is generated by
measuring pressure and starting assisted ventilation when
pressure reaches a given level.
TIME TRIGGER - a breath is generated by measuring
frequency of respirations and starting ventilation when
respirations frequency is at a given.

14. EXPIRATION
 TIME CYCLED - such in in pressure controlled
ventilation
 FLOW CYCLED - such as in pressure support
 VOLUME CYCLED - the ventilator cycles to expiration
once a set tidal volume has been delivered: this occurs in
volume controlled ventilation.

15. IPPV
 Set: TV, rate, Fi02, PEEP,
 No capacity for the patient
to trigger a breath
 Uncomfortable if patient
not fully sedated &/
paralysed
 Suitable only for patients
who have no ability to
breathe spontaneously

16. SIMV
SYNCHRONIZED INTERMITTENT
MANDATORY VENTILATION
 Provides a set TIDAL VOLUME at a set RATE (F)
 Patient can breathe in-between mandatory ventilation
 Spontaneous breaths are supported with pressure
support
 Ventilator synchronises mandatory breaths and
spontaneous breaths for increased patient comfort
NB
Usually volume targeted but some machines offer SIMV(pc)

17. SIMV
 Guaranteed Minute
Ventilation
 Increased monitoring
of airway pressures.
 Airway pressures will
increase if lung
compliance
decreases.
 Risk of barotrauma.
Advantages Disadvantages

18. SPONTANEOUS MODES OF
VENTILATION

19. SPONTANEOUS MODES OF VENTILATION
Spontaneous modes
are-
Triggered
Cycled
-By the patient

20. PRESSURE SUPPORT OR ASB
The patient triggers the ventilator and receives a
supported breath at a pre-set pressure.
This helps overcome the increased work of
breathing or resistance of breathing through an
endotracheal tube.

22. COMPLICATIONS OF INVASIVE VENTILATION
 Airway:
 Aspiration pneumonia
 Trauma to trachea during
intubation
 Hypoxia prior to / during
intubation
 Laryngeal oedema
 Occlusion of blood supply to
trachea (if cuff pressures to
high)
 Sinus infection

23. COMPLICATIONS OF INVASIVE VENTILATION
 Mechanical:
 Ventilator malfunction.
 Ventilator circuit: occlusion,
kinks, bronchospasm,
disconnection & biting.
 Barotrauma / Volutrauma
can rupture alveoli, causing
pneumothorax.

24. COMPLICATIONS OF INVASIVE VENTILATION
 Decreased cardiac output:
 Induction agents
 Changes intrathoracic
pressure & reduces venous
return
 Cardiac output falls, BP
drops
 CVP and LV preload rise
 This has implications for the
perfusion of all vital organs:
brain, kidneys, GI tract

25. COMPLICATIONS

26. PEEP
 Maintains pressure within the
breathing circuit at a pre-set
level at the end of expiration
 When used during
spontaneous respiration it is
called CPAP
 A degree of PEEP should be
applied on all ventilation
modes to minimise risk of
atelectasis

27. INSPIRATION TIME : EXPIRATION TIME
 I:E ratio is 1:2
 Can be reversed – 1:1 or less:
2:1
 Some machines automatically
alter I:E ratios when the set
resp rate is altered.

28. REVERSING THE I:E RATIO
 Air trapping from
increased
intrathoracic
pressure
 Hypercarbia ( Î C02)
 Breath stacking
 Extreme discomfort
for the pt
 Reduction in cardiac
return
 Advantages or
reversing the I:E ratio:
 Alveolar recruitment
 Reduced alveolar
collapse due to shorter
expiratory times
 Increased mean airway
pressure without
increasing PAP
Disadvantages Advantages

29. WEANING OFF VENTILATOR

30. THANK YOU