Mechanical ventilation

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MECHANICAL
VENTILATION
BY:
Mrs. Keerthi Samuel
Assistant Professor
Vijay MarieCON

 “Mechanical ventilation is the use of a
ventilator to move room air or oxygen
enriched air into and out of the lungs
mechanically to maintain proper
levels of oxygen and carbon dioxide
in the blood.”
DEFINITION

GOALS
Improve gas exchange
Relive respiratory distress
Improve pulmonary mechanics
Permit lung and airway healing
Avoid complication
Reverse hypoxemia/Relieve acute respiratory acidosis
Reverse respiratory muscle fatigue Prevent and reverse atelectasis
Improve lung compliance/Maintain lung and airway function
Prevent disuse respiratory muscle dystrophy

 To maintain gas exchange in case of
acute and chronic respiratory failure.
 To maintain ventilator support after CPR.
 To reduce pulmonary vascular resistance.
 To excrete increased CO2 production.
 To give general anesthesia with
muscle relaxants.
PURPOSES

Acute respiratory failure
Apnoea or impending inability
to breath
Severe Hypoxia/Hypoxemia
Respiratory muscle fatigue
Cardiac Insufficiency
Neurological problems
Therapeutic and prophylactic
INDICATIONS

 Respiratory failure: An inability of the heart and lungs to provide
adequate tissue oxygenation or removal of carbon dioxide.
 Hypoxemic respiratory failure – lung failure
 Hypercapnic respiratory failure – pump failure
 Neuromuscular diseases : Myasthenia Gravis, Guillain-Barre
Syndrome, and Poliomyelitis (failure of the normal respiratory
neuromuscular system)
 Musculoskeletal abnormalities : Such as chest wall trauma .
 Infectious diseases :of the lung such as
pneumonia, tuberculosis.
INDICATIONS

 Obstructive lung disease in the form of asthma,
chronic bronchitis or emphysema.
 Conditions such as pulmonary edema,
atelectasis, pulmonary fibrosis.
 Patients who has received general anesthesia as
well as post cardiac arrest patients requires
ventilatory support until they have recovered from the
effects of the anesthesia or out from a Danger.
INDICATIONS

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PARAMETERS VENTILATOR INDICATED NORMAL RANGE
A- Pulmonary function studies:
• Respiratory rate (breaths/min).
• Tidal volume (ml/kg body wt.)
• Vital capacity (ml/kg body wt.)
• Maximum Inspiratory Force (cm HO2)
ARTERIAL BLOOD GAS:
• PH
• PaO2 (mmHg)
• PaCO2 (mmHg)
>35
<5
<15
<-20
< 7.25
< 60
> 50
15-20
5-7
65-75
75-100
7.35-7.45
75-100
35-45

TERM MEANING
Independent variables The parameters that are set by clinician.”
Dependent variables “The parameters measured by the ventilators.”
Fraction of inspired oxygen
(FiO2):
“The concentration of O2 in the inspired gas, usually between
21% and 100% O2. The lowest possible fraction of inspired
oxygen (FiO2) necessary to meet oxygenation goals should
be used. “
Tidal volume (TV):  “The amount of air delivered to the patient per
breath. It is expressed in milliliters.”
 A starting point for the VT setting is 8 to 10ml/kg of
ideal weight.
Respiratory rate/frequency (f):  “The number of breaths per minute. This can be from the
ventilator, the patient, or both. “
 The RR is set as near to physiological rates (14 to 20
breaths/min) as possible.

TERM MEANING
Minute ventilation (V E):  “The product of V and respiratory frequency (VT * f). It is
usually expressed in liters/minute.”
Exhaled Tidal Volume:(E TV):  “It is the amount of gas that comes out of the patients
lungs on exhalation.”
 This is the most accurate measure of the volume
received by the patient
 If the ETV deviates from the set TV by 50ml or more,
troubleshoot the system to identify the source of gas loss.
Fraction of inspired oxygen
(FiO2):
“The concentration of O2 in the inspired gas, usually between
21% and 100% O2. The lowest possible fraction of inspired
oxygen (FiO2) necessary to meet oxygenation goals should
be used. “
Sigh : A deep breath , A breath that has a greater volume
than the tidal volume.
It provides hyperinflation and prevents atelectasis

TERM MEANING
 Inverse Inspiratory to
Expiratory ratio:
 “I:E ratios such as 1:1,2:1 and 3:1 arecalled inverse
I:E ratios”
 Inverse I:E ratio allows unstable alveoli time to fill and also
prevents collapse by shortened expiratory phase.
Sigh volume :  Usual volume is 1.5 –2 times tidal volume.
Positive end-expiratory pressure
(PEEP):
 ““The amount of positive pressure that is maintained at
end-expiration.”
 Typical settings for PEEP are 5 to 20 cm H2O
 PEEP increases oxygenation by preventing
collapse of small airways
 It increases the functional residual capacity of the lungs
 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)

TERM MEANING
 Auto PEEP: “  Auto PEEP is the spontaneous development of PEEP
caused by gas trapping in the lung resulting from insufficient
expiratory time and incomplete exhalation.”
 Causes of auto PEEP formation include rapid RR, high VE
demand, airflow obstruction and inverse I:E ratio ventilation.
 Auto PEEP = Total PEEP - Set PEEP
Inspiratory to Expiratory ratio
(I:E):
 “The I:E ratio is usually set to mimic the pattern of
spontaneous ventilation.”
 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.

TERM MEANING
 Peak airway pressure (Paw):  The pressure that is required to deliver the TV to the
patient. It has a unit of centimeters of water (cm H2O).”
Plateau pressure (Pplat):  “The pressure that is needed to distend the lung. This
pressure can only be obtained by applying an end
inspiratory pause. It also has a unit of cm H2O.”
Mean airway pressure:  “The time-weighted average pressure during the respiratory
cycle. It is expressed in cm H2O.”
Peak inspiratory Pressure
(PIP):
 In adults if the peak airway pressure is persistently above
45 cmH2O, the risk of barotrauma is increased and efforts
should be made to try to reduce the peak airway pressure.
 “Increasing PIP is also sign of Blockage of airway and
needed to suctioning or changeEt
/TT.”
Sensitivity ( Trigger Sensitivity)
:
: “The sensitivity function controls the amount of patient
effort needed to initiate an inspiration.”

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• Inspiration: Inspiratory valve opens and expiratory
valve is closed
• Inspiratory pause: inspiratory valve and expiratory
valve closed
• Expiration: Inspiratory valve closed and expiratory
valve open
• Expiratory Pause: Inspiratory valve and expiratory
(PEEP) valve closed at the end of expiration
PHASES OF VENTILATOR

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 Mode denotes interplay b/w patient and the ventilator
 Describes the style of breath support based on relationship between
the various possible types of breath and inspiratory – phase variables
MODES OF VENTILATOR

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MODES OF VENTILATOR
PRESSURE CYCLED
VENTILATION MODES
CPAP
BiPAP
PSV
PCV
PCIRV
VOLUME CONTROLLED
MODES
ACV
IMV
SIMV
3. TIME CYCLED
VENTILATION

 CPAP is positive pressure applied throughout the
respiratory cycle to the spontaneously breathing
patient.
 A continuous level of elevated pressure is provided
through the patient circuit to maintain adequate
oxygenation, decrease the work of breathing.
 CPAP may be used invasively through an
endotracheal tube or tracheostomy or
noninvasively with a face mask or nasal
prongs.
CONTINOUS POSITIVE AIRWAY
PRESSURE

 provides pressure at end expiration, which
prevents alveolar collapse and improves the
functional residual capacity and oxygenation.
 CPAP allows the nurse to observe the ability
of the patient to breath spontaneously while
still on the ventilator.
 It may used as a Weaning Mode.

• Similar to CPAP
• Non invasive mechanical ventilation.
• Indicated for sleep apnea patients with high pressure
settings
• Used when CPAP fails
• Effective for CHF patients and often prescribed for
patients with lung disorders or neuromuscular disorders.
• CPAP offers constant singular pressure difficult to exhale
against.
• For patients with higher pressure strengths exhaling
against an incoming air can feel difficult as
•
BILEVEL POSITIVE AIRWAY PRESSURE

• For patients with higher pressure strengths exhaling against
an incoming air can feel difficult as if they are having to
force their breathing out.
• Bipaps can also be set to include a breath timing feature
that measures the amount of breaths per minute a person
should be taking . If the time between the breaths exceeds
the set limit , the machine can force the person to breath by
temporarily increasing the air pressure.
• BiPAP has two pressure settings: a prescribed pressure for
inhalation -Ipap and a lower pressure for exhalation Epap.
This dual settings allow the patient to get more air into the
lungs
BILEVEL POSITIVE AIRWAY PRESSURE

 In pressure controlled ventilation the breathing
gas flows under constant pressure into the
lungs during the selected inspiratory time.
 The flow is highest at the beginning of
inspiration( i.e when the volume is lowest in
the lungs).
 As the pressure is constant the flow is
initially high and then decreases with
increasing filling of the lungs.
PRESSURE CONTROLLED
VENTILATION

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 Pressure (or Pressure above PEEP) is the setting variable
 No mandatory breaths
 Applicable on Spontaneous breaths
 Patient effort determines size of breath and flowrate.
 It augments spontaneous VT, decreases spontaneous rates and WOB.
 Used in conjunction with spontaneous breaths in any mode of
ventilation
 No back up ventilation in the event of apnea.
 Provides pressure support to overcome the increased work of
breathing imposed by the disease process, the endotracheal tube, the
inspiratory valves and other mechanical aspects ofventilatory support.
 Allows for titration of patient effort during weaning.
PRESSURE SUPPORT
VENTILATION

• Inverse ratio ventilation (IRV) mode reverses this
ratio so that inspiratory time is equal to, or longer
than, expiratory time (1:1 to 4:1).
• Inverse I:E ratios are used in conjunction with
pressure control to improve oxygenation by
expanding stiff alveoli by using longer distending
times, thereby providing more opportunity for gas
exchange and preventing alveolar collapse.
PC-INVERSE RATIO VENTILATION

Synchronized
Intermittent Mandatory
Ventilation (SIMV)
Intermittent
Mandatory Ventilation
(IMV)
Assist/Controlled
Ventilation
II.VOLUME CONTROLLED
VENTILATION

 The ventilator provides the patient with a pre-
set tidal volume at a pre-set 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 breathe at a higher rate than the
preset number of breaths/minute
ASSIST /CONTROLLED VENTILATION

 The total respiratory rate is determined by the
number of spontaneous inspiration initiated by
the patient plus the number of breaths set on
the ventilator.
 If the patient wishes to breathe faster, he or she
can trigger the ventilator and receive a full-volume
breath.
 Often used as initial mode of ventilation When the
patient is too weak to perform the work of
breathing (e.g. when emerging from anesthesia)

 The preset RR ensures that the patient
receives adequate ventilation, regardless of
spontaneous efforts.
 The patient can breath faster than the
preset rate but not slower.

 Elongated tank, which encases the patient up to the
neck. The neck is sealed with a rubber gasket, the
patient's face are exposed to the room air.
 These exert negative pressure on the external chest
decreasing the intra-thoracic pressure during
inspiration, allows air to flow into the lungs, filling its
volume.
 The cessation of the negative pressure causes the
chest wall to fall and exhalation to occur.
NEGATIVE PRESSURE VENTILATORS

 A mode of mechanical ventilation in which the
patient is allowed to breath independently
except during certain prescribed intervals,
when a ventilator delivers a breath either
under positive pressure or in a measured
volume.
 This mode is not use mostly in clinical practice
due to many new tech. Modes.
INTERMITTENT MANDATORY
VENTILATION

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PROS CONS
• Freedom for natural
spontaneous breaths
even on the machine
• Asynchrony
• Lesser chances of
hyperventilation
• Random chances of
breath stacking
• Increased work of
breathing
• Random barotrauma and
volutrauma
VENTILATION

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 Ventilator delivers either patient triggered assisted
breaths or time triggered mandatory breath in a
synchronized fashion so as to avoid breath stacking
 If the patient breathes between mandatory breaths, the
ventilator will allow the patient to breathe a normal
breath by opening the demand (inspiratory) valve but
not offering any inspiratory assistance.
 If patient does not make an inspiratory effort then ventilator will
deliver a time triggered mandatory breath
SYNCHRONIZED INTERMITTENT
MANDATORY VENTILATOR

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 3 types of breathing:
1. Patient initiated assisted ventilation,
2. Ventilator generated controlled ventilation,
3. Unassisted spontaneous breath.

 The SIMV mode of ventilation delivers a set number of
breaths of a set TV, and between these mandatory
breaths the patient may initiate spontaneous breaths.
 If the patient initiates a breath near the time a mandatory
breath is due, the delivery of the mandatory breath is
synchronized with the patient’s spontaneous effort to prevent
patient ventilator dys synchrony.
 In between the ventilator-delivered breaths , the patient is
able to breath spontaneously at his own tidal volume and rate
with no assistance from the ventilator.
 Ventilators breaths are synchronized with the patient
spontaneous breath.

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 Machine breaths are delivered at a set rate (volume or
pressure limit)
 Patient is allowed to breath spontaneously from
either a demand valve or a continuous flow of
gases but not offering any inspiratory assistance.
 Patient’s capability determines Tidal volume of
spontaneously breaths
 Some freedom to breath naturally even on
mechanical ventilator
VENTILATION

Non Invasive
Ventilation
Invasive
Ventilation
Positive pressure
Negative
pressure
TYPES OF VENTILATORS

 Non Invasive Ventilation: “Ventilatory
support that is given without establishing
endotracheal intubation or tracheostomy is
called Non invasive mechanical ventilation.”
 Invasive Ventilation: “Ventilatory support that
is given through endotracheal intubation or
tracheostomy is called as Invasive mechanical
ventilation.”
TYPES OF VENTILATORS

Negative pressure:
• Producing Neg. pressure intermittently in the pleural
space/ around the thoracic cage.
• e.g.: Iron Lung
• Delivering air/gas with positive pressure to the
airway.

 The patient’s body was encased in an iron cylinder and negative
pressure was generated
 The iron lung are still occasionally used today.
 These are simple to use and do not require intubations of the
airway; consequently, they are especially adaptable for home
use.
 It is used mainly in chronic respiratory failure associated with
neuromuscular conditions such as poliomyelitis, muscular
dystrophy and myasthenia gravis.
 The use of negative-pressure ventilators is restricted in clinical
practice, however, because they limit positioning and movement
and they lack adaptability to large or small body torsos (chests).

 POSITIVE PRESSURE VENTILATION:
 inflate the lungs by exerting positive pressure on the
airway forcing the alveoli to expand during inspiration.
 Expiration occurs passively.
 Positive-pressure ventilators require an artificial airway
(Endotracheal or tracheostomy tube) in invasive ventilation
and in NIV includes BiPAP Mask , O2 mask , Nasal
mask/cannula , O2 high concentrated reservoir mask etc.
 Inspiration can be triggered either by the patient
or the machine.

 “Ventilator Alarms defined as a Voice or sound to alert
Nurse/Doctor and caused by any abnormal value of
either in client or in Ventilator.”
 Check for bucking the vent
 These Alarms have 3main Types as below:
 (i)Pressure alarms
 (ii)Volume alarms
 (iii)Apnea alarms
VENTILATOR ALARMS

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PRESSURE ALARMS
 They are triggered when
there is increased airway
resistance or decreased
lung compliance.
 Low pressure alarms
and high pressure
alarms
VOLUME ALARMS
 Volume alarms are
valuable for ensuring
adequate alveolar
ventilation, particularly in
the patient receiving a
pressure mode of
ventilation
VENTILATOR ALARMS
APNEA ALARMS
 This alarm is very
important when the
patient is on a
spontaneous breathing
mode such as PS or
CPAP, and no
mandatory breaths are
set.

 An alarm should never be silenced until the
cause has been investigated and corrected.
 If the source of the alarm cannot be determined,
disconnect the client from the ventilator and use a
hand-held resuscitation bag for manual ventilation
with 100% oxygen until the problem can be
resolved
TWO RULES….

Airway
Mechanical
Physiological
Artificial
Airway
COMPLICATIONS

 Aspiration
 Decreased clearance of secretions
 Nosocomial or ventilator-acquired pneumonia
(VAP)
I.AIRWAY COMPLICATIONS

• Hypoventilation with atelectasis with respiratory
acidosis or hypoxemia.
• Hyperventilation with hypocapnia and respiratory
alkalosis
• Barotrauma
• Closed pneumothorax,
• Tension pneumothorax,
• Subcutaneous emphysema.
• Alarm “turned off”
• Failure of alarms or ventilator
• Inadequate nebulization or humidification
• Overheated inspired air, resulting in hyperthermia
MECHANICAL COMPLICATONS

 Fluid overload with humidified air and sodium
chloride (NaCl) retention
 Depressed cardiac function and
hypotension
 Stress ulcers
 Paralytic ileus
 Gastric distension
 Starvation
 Dyssynchronous breathing pattern
PHYSIOLOGICAL COMPLICATIONS

(A) IN ENDOTRACHEAL TUBE :
 Tube kinked or plugged
 Tracheal stenosis or
tracheomalacia
 Main stem intubation with
contralateral (located on or
affecting the opposite side of the
lung)
 lung atelectasis
 Cuff failure
 Sinusitis
 Otitis media
 Laryngeal edema
ARTIFICIAL AIRWAY COMPLICATIONS
(B) IN TRACHEOSTOMY TUBE :
 Acute haemorrhage at the site
 Air embolism
 Aspiration
 Tracheal stenosis
 Failure of the tracheostomy cuff
 Laryngeal nerve damage
 Obstruction of tracheostomy tube
 Pneumothorax
 Subcutaneous and mediastina
emphysema
 Infection
 Accidental decannulation with loss of
airway

SYSTEM WISE COMPLICATIONS
SYSTEM COMPLICATIONS
CARDIIOVASCULA
R SYSTEM
◦ Increased intrathoracic pressure
◦ Reduced CO2
PULMONARY ◦ Barotrauma (trauma r/t pressure)
 Pneumothorax
 Subcutaneous emphysema
Alveolar
hypoventilation
 Cuff leak
 Ventilator settings
 Secretions
 Atelectasis
Alveolar
hyperventilation
 Due to hypoxemia, fear, pain, anxiety → alkalosis
 RX: sedate, analgesia, communication, correct
hypoxemia
 Due to inappropriate ventilator settings
 high tidal volume
 High rate
◦ Pulmonary Infection

SYSTEM COMPLICATIONS
NEUROLOGICAL ◦ Positive pressure ventilation → increased
intrathoracic pressure
◦ interferes with venous drainage; increased ICP
 GI: ◦ Stress ulcers and GI bleeds; Rx with H2
receptor blockers
Gastric and bowel dilation
 Musculoskeletal:  Muscle atrophy r/t immobilisation
 Mobilise
 ROM
 Psychologic:  Stress
 Communication very important
 Sedate, explain, family visits, pain management
 Facilitate expression of needs

High Peak Pressures Low Plateau
Pressures
High Peak Pressures High Plateau
Pressures
• Mucus Plug • ARDS
• Bronchospasm • Pulmonary Edema
• ET tube blockage • Pneumothorax
• Biting • ET tube migration to a single
bronchus
• Effusion

 Weaning is the process of withdrawing
mechanical ventilator support and
transferring the work of breathing from
the ventilator to the patient which is done
only when patient is free from the cause
to be kept on mechanical ventilation.
 “Weaning success is defined as effective
spontaneous breathing without any
mechanical ventilation for 24 hours or
more.” or “The process of going OFF
from ventilator dependence to
spontaneous breathing”
WEANING

From
Ventilator
From
Tube
From
Oxygen
STAGES OF WEANING

Tidal volume greater than 5 ml/kg),
Respiratory frequency less than 30
breaths/min
Oxygen partial pressure be above PaO2
greater than 60mm Hg and FIO2 <40%
Vital capacity 10 to 15 ml/kg.
CRITERIA FOR WEANING

 It consists of removing the patient from the ventilator and
having him / her breathe spontaneously on a T-piece
connected to oxygen source.
 During T-piece weaning, periods of ventilator support are
alternated with spontaneous breathing.
 The goal is to progressively increase the time spent of f the
ventilator.
1.T-PIECE TRIAL

Observe for signs & Symptoms of….
 Hypoxia,
 increasing fatigue,
 Tachy cardia- Ischemic ECG changes
 Restlessness
 RR > 35/min
 Use of accessory muscles for breathing
 Paradoxical chest movement
1.T-PIECE TRIAL

 ET/TT removed only if following criterion
met…
 Spontaneous ventilation is adequate
 Pharyngeal and laryngeal reflexes are active
 Pt maintain adequate airway and can swallow,
move the jaw clench teeth , voluntary cough is
effective to bring out secretion
 Before the tube is removed—a trail with
nose/mouth breathing is done – Deflating cuff,
using fenestrated tube etc
1.T-PIECE TRIAL

 SIMV is the most common method of
weaning.
 It consists of gradually decreasing the number of
breaths delivered by the ventilator to allow the
patient to increase number of spontaneous
breaths.
 In pt’s who – satisfies all criteria for weaning
but cannot have spontaneous breathing for long
time.
2.WEANING FROM VENTILATOR-SIMV

 When placed on CPAP, the patient does all the
work of breathing without the aid of a back up
rate or tidal volume.
 No mandatory (ventilator-initiated) breaths are
delivered in this mode i.e. all ventilation is
spontaneously initiated by the patient.
 Weaning by gradual decrease in
pressure value
2.WEANING FROM VENTILATOR-CPAP

 The patient must initiate all pressure support
breaths.
 During weaning using the PSV mode the level of
pressure support is gradually decreased based on
the patient maintaining an adequate tidal volume (8
to 12 mL/kg) and a respirator y rate of less than 25
breaths/minute.
 PSV weaning is indicated for :-
- Difficult to wean patients
- Small spontaneous tidal volume.
2.WEANING FROM VENTILATOR-PSV

 Diaphoresis
 Dyspnea & Labored respirator y pattern
 Increased anxiety ,Restlessness, Decrease in
level of consciousness
 Dysrhythmia , Increase or decrease in heart rate
of > 20 beats /min. or heart rate > 110b/m ,
Sustained heart rate >20% higher or lower than
baseline.
 Tidal volume ≤5 mL/kg, Sustained minute
ventilation <200 mL/kg/minute
SIGNS OF WEANING INTOLERANCE

 Pt successfully weaned---- and has adequate
respiratory function – weaned from O2
 FIO2 is gradually reduced until SPO2 is in
range of 80-100 mmHg while breathing in
Room air
 If air SPO2 less than 70 supplementary O2
recommended
2.WEANING FROM OXYGEN

 Ineffective breathing pattern
 Potential for pulmonary infection
 Impaired water and fluid regulation
 Oral hygiene
 Potential altered nutritional status: less than
body requirement related to NPO status
 Potential for complications related to
immobility
NURSING DIAGNOSIS

 Knowledge deficit related to intubation and
mechanical ventilation
 Elimination care
 Promoting coping ability
 Preventing trauma and infections
 Promoting rest and sleep
 Safety and security needs.
NURSING DIAGNOSIS

1.LINK“http://www.nhlbi.nih.gov/health/health
topics
/topi cs/VENT/”
2.LINK http://www.mmcwm.com/BiPAP
3.LINK:“wwwappskc.lonestar.edu/programs/m
odes.p pt”
4.WEBPAGE : WWW.WIKIPEDIA.COM &
WWW. ENCYCLOPEDIA.COM , TOPIC
OF MECHANICAL VENTILATOR & THEIR
MODES
REFERENCES

Mechanical ventilation

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