Mechanical ventilator notes

1. Mechanical Ventilation

2. Contents
 Anatomy and Physiology Of Respiratory System
 Introduction About Mechanical Ventilation
 History
 Meaning of Mechanical Ventilation
 Indications for use
 Types or Forms Of Mechanical Ventilation
 Settings of Mechanical Ventilation
 Modes of Mechanical Ventilation
 Complications associated with Mechanical Ventilation
 Nursing Management of ventilator patients

3. Anatomy and Physiology Of
Respiratory System

4. Introduction About Mechanical
Ventilation
Mechanical ventilation is typically used after an
invasive intubation, a procedure wherein an
endotracheal or tracheostomy tube is inserted into
the airway. It is used in acute settings such as in
the ICU for a short period of time during a serious
illness. It may be used at home or in a nursing or
rehabilitation institution if patients have chronic
illnesses that require long-term ventilation
assistance.

5. History
The roman physician Galen may have been the
first to describe mechanical ventilation: "If you take
a dead animal and blow air through its larynx
[through a reed], you will fill its bronchi and watch
its lungs attain the greatest distention.” Vesalius
too describes ventilation by inserting a reed or
cane into the trachea of animals. In 1908 George
Poe demonstrated his mechanical respirator by
asphyxiating dogs and seemingly bringing them
back to life.

6. Meaning of Mechanical
Ventilation
In medicine, mechanical ventilation is
a method to mechanically assist or
replace spontaneous breathing.

7. Indications for use
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Common medical indications for use include:
Acute lung injury (including ARDS, trauma)
Apnea with respiratory arrest, including cases from intoxication
Chronic obstructive pulmonary disease (COPD)
Acute respiratory acidosis with partial pressure of carbon dioxide
(pCO2) > 50 mmHg and pH < 7.25, which may be due to paralysis of
the diaphragm due to Guillain-Barré syndrome, Myasthenia Gravis,
spinal cord injury, or the effect of anaesthetic and muscle relaxant
drugs
Increased work of breathing as evidenced by significant tachypnea,
retractions, and other physical signs of respiratory distress
Hypoxemia with arterial partial pressure of oxygen (PaO2) with
supplemental fraction of inspired oxygen (FiO2) < 55 mm Hg
Hypotension including sepsis, shock, congestive heart failure
Neurological diseases such as Muscular Dystrophy Amyotrophic
Lateral Sclerosis

8. Types or Forms Of Mechanical
Ventilation
The two major types of Mechanical Ventilation are
Negative pressure and positive Pressure
ventilation
The main form of mechanical ventilation is
positive pressure ventilation, which works by
increasing the pressure in the patient's airway
and thus forcing air into the lungs. Less common
today are negative pressure ventilators (for
example, the "iron lung") that create a negative
pressure environment around the patient's
chest, thus sucking air into the lungs.

9. Types or Forms Of Mechanical Ventilation
Negative Pressure
Ventilator
Positive Pressure
Ventilator

10. Settings of Mechanical
Ventilation
• Mechanical Ventilator Settings
regulates the rate, depth and
other characteristics of ventilation.
Settings are based on the
patient’s status (ABGs, Body
weight, level of consciousness
and muscle strength)

11. PARAMETERS OF MECHANICAL
VENTILATION ARE
Respiratory Rate (f) :-Normally 10-20b/m
Tidal Volume (VT) :-5-15ml/kg
Oxygen Concentration(FIO2):-b/w 21-90%
I:E Ratio:-1:2
Flow Rate:-40-100L/min
Sensitivity/Trigger:- 0.5-1.5 cm H2O
Pressure Limit:-10-25cm H2O
PEEP :- Usually, 5-10 cmH2O

12. Connection to Ventilators
• Face Mask
• Airway
• Laryngeal Mask
• Tracheal Intubation
• Tracheostomy

13. Modes of Mechanical
Ventilation
• Controlled Mandatory Ventilation (CMV)
• Asst-Control Mandatory Ventilation (ACV)
• Synchronized Intermittent Mandatory
Ventilation(SIMV)
• Positive Expiratory End Pressure(PEEP)
• Continuous Positive Airway Pressure
(CPAP)
• Pressure Support Ventilation (PSV)

14. Modes of Mechanical Ventilation

15. Controlled Mandatory
Ventilation (CMV)
• Controlled Mechanical Ventilation (CMV).
In this mode the ventilator provides a
mechanical breath on a preset timing.
Patient respiratory efforts are ignored.
This is generally uncomfortable for
children and adults who are conscious
and is usually only used in an
unconscious patient. It may also be used
in infants who often quickly adapt their
breathing pattern to the ventilator timing

16. Asst-Control Mandatory
Ventilation (ACV)
• Assist Control (AC). In this mode the ventilator provides a
mechanical breath with either a pre-set tidal volume or peak
pressure every time the patient initiates a breath. Traditional assist-
control used only a pre-set tidal volume--when a preset peak
pressure is used this is also sometimes termed Intermittent Positive
Pressure Ventilation or IPPV. However, the initiation timing is the
same--both provide a ventilator breath with every patient effort. In
most ventilators a back-up minimum breath rate can be set in the
event that the patient becomes apnoeic. Although a maximum rate
is not usually set, an alarm can be set if the ventilator cycles too
frequently. This can alert that the patient is tachypneic or that the
ventilator may be auto-cycling (a problem that results when the
ventilator interprets fluctuations in the circuit due to the last breath
termination as a new breath initiation attempt)

17. Synchronized Intermittent
Mandatory Ventilation(SIMV)
• Synchronized Intermittent Mandatory Ventilation (SIMV). In this
mode the ventilator provides a pre-set mechanical breath (pressure
or volume limited) every specified number of seconds (determined
by dividing the respiratory rate into 60 - thus a respiratory rate of 12
results in a 5 second cycle time). Within that cycle time the ventilator
waits for the patient to initiate a breath using either a pressure or
flow sensor. When the ventilator senses the first patient breathing
attempt within the cycle, it delivers the preset ventilator breath. If the
patient fails to initiate a breath, the ventilator delivers a mechanical
breath at the end of the breath cycle. Additional spontaneous
breaths after the first one within the breath cycle do not trigger
another SIMV breath. However, SIMV may be combined with
pressure support (see below). SIMV is frequently employed as a
method of decreasing ventilatory support (weaning) by turning down
the rate, which requires the patient to take additional breaths
beyond the SIMV triggered breath.

18. Positive End Expiratory
Pressure(PEEP)
• PEEP) is functionally the same as CPAP, but refers to
the use of an elevated pressure during the expiratory
phase of the ventilatory cycle. After delivery of the set
amount of breath by the ventilator, the patient then
exhales passively. The volume of gas remaining in the
lung after a normal expiration is termed the functional
residual capacity (FRC). The FRC is primarily
determined by the elastic qualities of the lung and the
chest wall. In many lung diseases, the FRC is reduced
due to collapse of the unstable alveoli, leading to a
decreased surface area for gas exchange and
intrapulmonary shunting (see above), with wasted
oxygen inspired. Adding PEEP can reduce the work of
breathing (at low levels) and help preserve FRC.

19. Continuous Positive Airway
Pressure (CPAP)
• (CPAP). A continuous level of elevated pressure
is provided through the patient circuit to maintain
adequate oxygenation, decrease the work of
breathing, and decrease the work of the heart
(such as in left-sided heart failure — CHF). Note
that no cycling of ventilator pressures occurs
and the patient must initiate all breaths. In
addition, no additional pressure above the CPAP
pressure is provided during those breaths.
CPAP may be used invasively through an
endotracheal tube or tracheostomy or non-
invasively with a face mask or nasal prongs.

20. Pressure Support Ventilation
• Pressure Support Ventilation (PSV). When a
patient attempts to breath spontaneously
through an endotracheal tube, the narrowed
diameter of the airway results in higher
resistance to airflow, and thus a higher work of
breathing. PSV was developed as a method to
decrease the work of breathing in-between
ventilator mandated breaths by providing an
elevated pressure triggered by spontaneous
breathing that "supports" ventilation during
inspiration

21. Complication
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Hypotension
Pneumothorax
Decreased Cardiac Output
Nosocomial Pneumonia
Positive Water Balance
Increased Intracranial Pressure (ICP)
Alarms turned off or nonfunctional
Sinusitis and nasal injury
Mucosal lesions
Aspiration, GI bleeding, Inappropriate ventilation (respiratory
acidosis or alkalosis, Thick secretions, Patient discomfort due to
pulling or jarring of ETT or tracheostomy, High PaO2, Low
PaO2, Anxiety and fear, Dysrhythmias or vagal reactions during
or after suctioning, Incorrect PEEP setting, Inability to tolerate
ventilator mode.

22. MECHANICAL
VENTILATOR
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• A mechanical ventilator is a machine that
generates a controlled flow of gas into a
patient’s airways. Oxygen and air are received
from cylinders or wall outlets, the gas is
pressure reduced and blended according to
the prescribed inspired oxygen tension (FiO2),
accumulated in a receptacle within the
machine, and delivered to the patient using
one of many available modes of ventilation.

23. Types of Mechanical
ventilators
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• Transport ventilators
• Intensive-care ventilators
• Neonatal ventilators
• Positive airway pressure ventilators for NIV

24. Classification of positive-pressure
ventilators
• Ventilators are classified according to how the
inspiratory phase ends. The factor which terminates
the inspiratory cycle reflects the machine type.
• They are classified as:
Pressure cycled ventilator
Volume cycled ventilator
Time cycled ventilator
24

25. 1- Volume-cycled
ventilator
• Inspiration is terminated after a preset tidal
volume has been delivered by the ventilator.
• The ventilator delivers a preset tidal volume
(VT), and inspiration stops when the preset
tidal volume is achieved.
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26. 2- Pressure-cycled ventilator
• In which inspiration is terminated when a
specific airway pressure has been reached.
• The ventilator delivers a preset pressure;
once this pressure is achieved, end
inspiration occurs.
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27. 3- Time-cycled
ventilator
• In which inspiration is terminated when a
preset inspiratory time, has elapsed.
• Time cycled machines are not used in adult
critical care settings. They are used in
pediatric intensive care areas.
27

28. Mechanical Ventilators
Different Types of Ventilators Available:
Will depend on your place of employment
Ventilators in use in MCH
Servo S by Maquet
Savina by Drager

29. MODES OF
VENTILATION

30. Ventilator
mode
• The way the machine ventilates the patient
• How much the patient will participate in his
own ventilatory pattern.
• Each mode is different in determining how
much work of breathing the patient has to
do. 30

31. A- Volume
Modes
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• 1. CMV or CV
• 2. AMV or AV
• 3. IMV
• 4. SIMV

32. B- Pressure
Modes
1 Pressure-controlled ventilation (PCV)
2 Pressure-support ventilation (PSV)
3 Continuous positive airway pressure
(CPAP)
4 Positive end expiratory pressure (PEEP)
5 Noninvasive bilevel positive airway pressure
ventilation (BiPAP) 32

33. Control Mode
Delivers pre-set volumes at a pre-set rate and
a pre-set flow rate.
The patient CANNOT generate spontaneous
breaths, volumes, or flow rates in this mode.

34. Control Mode

35. Assist/Control Mode
•Delivers pre-set volumes at a pre-set
rate and a pre-set flow rate.
•The patient CANNOT generate
spontaneous volumes, or flow rates in
this mode.
•Each patient generated respiratory effort
over and above the set rate are delivered at
the set volume and flow rate.

36. Assist Control
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• Volume or Pressure control mode
• Parameters to set:
– Volume or pressure
– Rate
– I – time
– FiO2

37. Assist Control
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• Machine breaths:
– Delivers the set volume or pressure
• Patient’s spontaneous breath:
– Ventilator delivers full set volume or pressure &
I-time
• Mode of ventilation provides the most
support

38. Negative deflection,
triggering assisted
breath
Assist Control

39. Delivers a pre-set number of breaths at a
set volume and flow rate.
Allows the patient to generate
spontaneous breaths, volumes, and flow
rates between the set breaths.
Detects a patient’s spontaneous breath
attempt and doesn’t initiate a ventilatory
breath – prevents breath stacking
SYCHRONIZED
INTERMITTENT
MANDATORY
VENTILATION (SIMV):

40. SIMV
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Synchronized intermittent mandatory ventilation
• Machine breaths:
– Delivers the set volume or pressure
• Patient’s spontaneous breath:
– Set pressure support delivered
• Mode of ventilation provides moderate amount of
support
• Works well as weaning mode

41. SIMV cont.
Machine Breaths
Spontaneous Breaths
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42. IMV
57
Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB, Scmidt GA, & Wood
LDH(eds.): Principles of Critical Care

43. Volume
Modes
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44. PRESSURE REGULATED VOLUME
CONTROL (PRVC):
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• This is a volume targeted, pressure limited
mode. (available in SIMV or AC)
• Each breath is delivered at a set volume with
a variable flow rate and an absolute pressure
limit.
• The vent delivers this pre-set volume at the
LOWEST required peak pressure and adjust
with each breath.

45. PRVC (Pressure regulated volume control)
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A control mode, which delivers a set tidal volume
with each breath at the lowest possible peak
pressure.
Delivers the breath with a decelerating flow
pattern that is thought to be less injurious to the
lung…… “the guided hand”.

46. PRCV: Advantages
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Decelerating inspiratory flow pattern
Pressure automatically adjusted for changes in
compliance and resistance within a set range
Tidal volume guaranteed
Limits volutrauma
Prevents hypoventilation

47. PRVC: Disadvantages
Pressure delivered is dependent on tidal volume achieved on
last breath
Intermittent patient effort  variable tidal volumes
Pressur
e
Flo
w
Volum
e
Set tidal volume
47
© Charles Gomersall 2003

48. Pressur
e
Flo
w
Volum
e
Set tidal volume
PRVC: Disadvantages
48
© Charles Gomersall 2003
Pressure delivered is dependent on tidal volume achieved on
last breath
Intermittent patient effort  variable tidal volumes

49. PRVC
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50. POSITIVE END EXPIRATORY PRESSURE
(PEEP):
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• This is NOT a specific mode, but is rather an
adjunct to any of the vent modes.
• PEEP is the amount of pressure remaining in
the lung at the END of the expiratory phase.
• Utilized to keep otherwise collapsing lung
units open while hopefully also improving
oxygenation.
• Usually, 5-10 cmH2O

51. 51

52. Pplat
• Measured by occluding the ventilator 3-5 sec at
the end of inspiration
• Should not exceed 30 cmH2O
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53. Peak Pressure (Ppeak)
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• Ppeak = Pplat + Pres
Where Pres reflects the resistive element of
the respiratory system (ET tube and airway)

54. Ppeak
• Pressure measured at the end of inspiration
• Should not exceed 50cmH2O?
54

55. Auto-PEEP or Intrinsic PEEP
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– Normally, at end expiration, the lung volume is
equal to the FRC
– When PEEPi occurs, the lung volume at end
expiration is greater than the FRC

56. Auto-PEEP or Intrinsic PEEP
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• Why does hyperinflation occur?
– Airflow limitation because of dynamic collapse
– No time to expire all the lung volume (high RR or
Vt)
– Decreased Expiratory muscle activity
– Lesions that increase expiratory resistance

57. Auto-PEEP or Intrinsic PEEP
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• Adverse effects:
– Predisposes to barotrauma
– Predisposes hemodynamic compromises
– Diminishes the efficiency of the force generated by
respiratory muscles
– Augments the work of breathing
– Augments the effort to trigger the ventilator

58. • This is a mode and simply means that a pre-
set pressure is present in the circuit and lungs
throughout both the inspiratory and
expiratory phases of the breath.
• CPAP serves to keep alveoli from collapsing,
resulting in better oxygenation and less WOB.
• The CPAP mode is very commonly used as a
mode to evaluate the patients readiness for
extubation.
58
Continuous Positive Airway
Pressure (CPAP):

59. Combination “Dual Control” Modes
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Combination or “dual control” modes combine features
of pressure and volume targeting to accomplish
ventilatory objectives which might remain unmet by
either used independently.
Combination modes are pressure targeted
Partial support is generally provided by pressure support
Full support is provided by Pressure Control

60. Thank You
(Save the life Safely)