Ppt for ventilator machine

1. Institute of Technology
Department of Biomedical Engineering
BIOMEDICAL INSTRUMENTATION LAB-II
BMEG 3154
LECTURE ON – MECHANICAL VENTILATOR
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2. Content
Introduction
Type of ventilation
Block diagram
Components of Ventilator
Basic Settings of Ventilator
Modes of Ventilation: The Basics
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3. Objective
After the end of this lecture the student will able to:-
Understand the working principle of mechanical ventilator
Differentiate parts of mechanical ventilator machine
Draw the pneumatic and electrical schematics of mechanical
ventilator
Demonstrate mechanical ventilator at lab
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4. Introduction
Mechanical ventilator is a machine that
helps a patient breathe (ventilate) when he
or she is recovering from surgery or critical
illness, or cannot breathe on his or her own
for any reason.
A ventilator delivers gas to the lungs with
either negative or positive pressure.

5. Ventilator
Machine designed to move breathable air into
and out of the lungs.
Provide breathing for a patient who is
physically unable to breathe, or breathing
insufficiently.

6. Why Ventilator?
Maintain or improve O2/CO2 levels in the blood
Rest the respiratory muscles
Improve sleep quality
Decrease the work of breathing
Inflate the lungs more fully
Prevent respiratory complications

7. Types of Ventilation
Positive-pressure ventilation: means that airway pressure is applied at
the patient's airway through an endotracheal or tracheostomy tube.
The positive nature of the pressure causes the gas to flow into the lungs
until the ventilator breath is terminated.
Negative pressure ventilation: such as the "iron lung", support
ventilation by exposing the surface of the chest wall to subatmospheric
pressure allows thorax expansion and causes inhalation.
 The release of the negative pressure allows the thorax to relax and thus
the lungs to exhale.

8. Block Diagram of Ventilator

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11. Components of Ventilator
 Gas Air Mixer/ Blender
 Pneumatic System (with valves and solenoids)
 Pressure Regulator
 Pressure Sensor
 Flow Sensor
 Air generating System (Piston/Turbine)
 Filters and Tubings
 Humidifier

12. Basic Settings of Ventilator
Trigger mode and sensitivity
Respiratory rate
Tidal Volume
Positive end-expiratory pressure (PEEP)
Flow rate
Inspiratory time
Fraction of inspired oxygen

13. Trigger
There are two ways to initiate a ventilator-delivered breath: pressure
triggering or flow-by triggering
 When pressure triggering is used, a ventilator-delivered breath is
initiated if the demand valve senses a negative airway pressure
deflection (generated by the patient trying to initiate a breath) greater
than the trigger sensitivity.
 When flow-by triggering is used, a continuous flow of gas through
the ventilator circuit is monitored. A ventilator-delivered breath is
initiated when the return flow is less than the delivered flow, a
consequence of the patient's effort to initiate a breath

14. Tidal Volume
The tidal volume is the amount of air delivered with each breath.
The appropriate initial tidal volume depends on numerous
factors, most notably the disease for which the patient requires
mechanical ventilation.

15. Respiratory Rate
The number of breaths the ventilator will deliver/minute (12-16
b/m).
Total respiratory rate equals patient rate plus ventilator rate.

16. Positive End-Expiratory Pressure (PEEP)
Applied PEEP is generally added to mitigate end-expiratory
alveolar collapse. A typical initial applied PEEP is 5 cmH2O.
However, up to 20 cmH2O may be used in patients undergoing
low tidal volume ventilation for acute respiratory distress
syndrome (ARDS)

17. Flow Rate
The peak flow rate is the maximum flow delivered by the
ventilator during inspiration.

18. Inspiratory Time: Expiratory Time Relationship
(I:E Ratio)
During spontaneous breathing, the normal I:E ratio is 1:2,
indicating that for normal patients the exhalation time is about
twice as long as inhalation time.
If exhalation time is too short “breath stacking” occurs resulting
in an increase in end-expiratory pressure also called auto-PEEP.
Depending on the disease process, such as in ARDS, the I:E ratio
can be changed to improve ventilation

19. Fraction of Inspired Oxygen(FiO2)
Fraction of inspired oxygen (FiO2) is the fraction or percentage
of oxygen in the volume being measured.

20. Minute Volume
The volume of expired air in one minute .
Respiratory rate times tidal volume equals minute ventilation
VE = (VT x F)

21. Sensitivity
The sensitivity function controls the amount of patient effort
needed to initiate an inspiration.
Increasing the sensitivity (requiring less negative force)
decreases the amount of work the patient must do to initiate a
ventilator breath.
Decreasing the sensitivity increases the amount of negative
pressure that the patient needs to initiate inspiration and
increases the work of breathing

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SETTING FUNCTION USUAL PARAMETERS
Respiratory Rate (RR) Number of breaths delivered by
the ventilator per minute
Usually 4-20 breaths
per minute
Tidal Volume (VT) Volume of gas delivered during
each ventilator breath
Usually 5-15 cc/kg
FiO2 Amount of oxygen delivered by
ventilator to patient
21% to 100%; usually set to keep
SpO2 > 90%
Inspiratory: Expiratory (I:E)
Ratio
Length of inspiration compared to
length of expiration
Usually 1:2 or 1:1.5 unless inverse
ratio ventilation is required
Pressure Limit Maximum amount of pressure the
ventilator can use to deliver breath
10-20 cm H2O above peak
inspiratory pressure; maximum is 35
cm H2O

24. Modes of Ventilation: The Basics
Control Mode Ventilation(PCV,VCV)
Assist-Control Ventilation Volume Control(PCV,VCV)
Pressure Support Ventilation
Pressure Regulated Volume Control (PRVC)
Synchronized Intermittent Mandatory Ventilation Volume
Control(PCV,VCV)
CPAP
BiPAP

25. Control Mode Ventilation
Control Mode ventilation is a mode of ventilation in which
the respirator delivers the preset volume or pressure regardless
of the patient's own inspiratory efforts.

26. Assist Control Ventilation
A set tidal volume (if set to volume control) or a set pressure
and time (if set to pressure control) is delivered at a minimum
rate.
The patient may initiate a breath on his own, but the ventilator
assists by delivering a specified tidal volume to the patient. Client
can initiate breaths that are delivered at the preset tidal volume.

27. Pressure Support Ventilation
Allows the patient to determine inflation volume and respiratory
frequency.
The patient controls the respiratory rate and exerts a major
influence on the duration of inspiration, inspiratory flow rate and
tidal volume
The patient initiates every breath and the ventilator delivers
support with the preset pressure value. With support from the
ventilator, the patient also regulates his own respiratory rate and
tidal volume.

28. Pressure Regulated Volume
Control
A volume target backup is added to a pressure assist-control
mode

29. The ventilator provides the patient with a pre-set number of
breaths/minute at a specified tidal volume and FiO2.
In between the ventilator-delivered breaths, the patient is able to
breathe spontaneously at his own tidal volume and rate with no
assistance from the ventilator.
However, unlike the A/C mode, any breaths taken above the set
rate are spontaneous breaths taken through the ventilator circuit.
Breaths are given are given at a set minimal rate, however if the
patient chooses to breath over the set rate no additional support is
given.
Synchronized Intermittent
Mandatory Ventilation

30. BIPAP(Bilateral Positive Airway
Pressure Ventilation)
BiPAP is a noninvasive form of mechanical ventilation provided
by means of a nasal mask or nasal prongs, or a full-face mask.
The system allows the clinician to select two levels of positive-
pressure support:
An inspiratory pressure support level (referred to as IPAP)
An expiratory pressure called EPAP (PEEP/CPAP level).

31. CPAP
Constant positive airway pressure during spontaneous
breathing
CPAP allows the nurse to observe the ability of the patient to
breathe spontaneously while still on the ventilator.
CPAP can be used for intubated and nonintubated patients.
It may be used as a weaning mode and for nocturnal ventilation
(nasal or mask CPAP)

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MODE FUNCTION CLINICAL USE
Control Ventilation (CV) Delivers preset volume or
pressure regardless of
patient’s own inspiratory
efforts
Usually used for
patients who are apneic
Assist-Control Ventilation
(A/C)
Delivers breath in response to
patient effort and if patient
fails to do so within preset
amount of time
Usually used for
spontaneously breathing
patients with weakened
respiratory muscles
Synchronous Intermittent
Mandatory Ventilation
(SIMV)
Ventilator breaths are
synchronized with patient’s
respiratory effort
Usually used to wean patients
from mechanical ventilation

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MODE FUNCTION CLINICAL USE
Pressure Support
Ventilation (PSV)
Preset pressure that augments the
patient’s inspiratory effort and
decreases breathing work
Often used with SIMV during
weaning
Positive End Expiratory
Pressure (PEEP)
Positive pressure applied at the
end of expiration
Used with CV, A/C, and
SIMV to improve
oxygenation by opening
collapsed alveoli
Continuous Positive
Airway Pressure (CPAP)
Similar to PEEP but used only
with spontaneously breathing
patients
Maintains constant positive
pressure in airways so
resistance is decreased

34. Cont….

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