VENTILATOR

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VENTILATOR THE BASIC- COURSE
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HISTORY OF VENTILATOR
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Early History of Ancient times
Old testament there is a mention of Prophet
Elisha Inducing pressure breathing from his
mouth into the mouth of a child who was
dying(Kings 434-35).
Hippocrates (460-375 BC) wrote  the first
description of endotracheal intubation his book
Treatise on Air One should
introduce a cannula into the trachea along
the jaw bone so that air can be drawn
into the lungs.
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Negative Pressure Ventilators
Two successful designs became popular In one -
the body of the patient was enclosed in an iron
box or cylinder and the patients
head protruded out of the end. The second -
design was a box or shell that fitted over the
thoracic area only
(chest cuirass).
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IRON LUNG- DRINKER LUNG (Philip Drinker and Louis
Agassiz Shaw) mid-1900s
The first iron lung was used on October 12, 1928
at
Children's Hospital,
Boston, -used in a
child unconscious from respiratory failure
-her dramatic recovery,
within seconds
popularize the "Drinker Respirator."
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In 1949, John Haven Emerson
Developed a mechanical assister for anesthesia at
Harvard University.
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Iron lung ward filled with Polio patients,
Rancho Los Amigos Hospital, ca. 1953
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Woman lying in negative pressure ventilator (iron
lung).
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During the 1950's
Mechanical ventilators used increasingly in
Anesthesia and
intensive care.
-To treat polio patients and
-The increasing use of
muscle relaxants
during anesthesia
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MODERN VENTILATOR
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THE COURSE DEALS WITH

• INTRODUCTION
• INDICATION FOR MECHANICAL VENTILATION
• MECHANICAL VENTILATOR- WHAT IT IS ?
• MECHANICAL VENTILATORS- CLASSIFICATION
• VENTILATOR MODES
• HOW TO INITIATE MECHANICAL VENTILATION?
• VENTILATOR SETTINGS
• NURSING CARE
• SEDATION AND NEUROMUSCULAR BLOCKADE
• ASSESMENT CRITERIA
• WEANING AND EXTUBATION
• FAILURE TO WEAN
• METHODS OF WEANING
• POST EXTUBATION CARE

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P0ST-TEST EVALUATION HANDS ON VENTILATOR HANDS
ON INTUBATING MANNIQUINE
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WHAT A MOST IMPORTANT THING A DOCTOR SHOULD
KNOW AFTER THIS COURSE ?
MONITORING THE PROGRESS
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WHAT A MOST IMPORTANT THING A ICU STAFF
SHOULD KNOW AFTER THIS COURSE
?
ALARMS AND CARE OF THE PATIENT
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• VENTILATOR THE BASIC

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• Mechanical ventilation is used when a
  patient is unable to breathe adequately on his
  or her own.
• The ventilator can either completely take over
  respiratory function, or it can be used to
  support the patients own respiratory efforts

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MECHANISM OF RESPIRATION A mechanism for
telling the body that it is time to breath This
involves CO2 sensors in the brainstem, which
signal diaphragmatic movement via the cervical
nerves.   The phrenic nerves The diaphragm
contracts it increases the volume of the
thorax, by moving down into the abdomen, making
the intra-pleural and intra-alveolar pressure
more negative, creating a pressure gradient
between the atmospheric and the alveoli, and
allowing air to pass down through a series of
narrowing bronchi into the alveoli.   The
alveoli and the pulmonary capillary network,
Derived from the main pulmonary arteries,
oxygen and carbon dioxide diffuse across the
concentration gradient out of and into the
alveoli respectively. The diffusion of CO2 is
more effective due to its higher solubility.
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Indications for mechanical ventilation Ventila
tion Failure Oxygenation Failure
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Failure to Ventilate Characterized by
reduced alveolar ventilation which manifests
as an increase in the PaCO2 gt 50 mmHg
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Indications for mechanical ventilation  

• Is it failure to ventilate (is the PCO2 gt
  50mmHg), or failure to oxygenate (is the
  PO2 lt50mmHg)?
• Remember that a low O2 is much more significant
  than a high PCO2,
• If it is ventilatory failure, where is the injury
  in the brain (the medulla),
  - in the spinal
  cord,
  - in the peripheral nerves,
  - at the neuromuscular junction,
  - in the muscle
  itself or in the chest cage?
• If the problem is oxygenation failure, where is
  the injury - Is it in the blood supply,
  - at the
  alveolar-capillary interface or
  - in the upper, middle or lower
  airways?

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• Neurological Problems ( Ventilatory failure )
• Central
• Loss of ventilatory drive due to
  sedation, narcosis, stroke or brain injury.
• Spinal
• Spinal cord injury, cervical
  loss of diaphragmatic function,
• thoracic
  loss of intercostals.
• Peripheral Nerve injury (e.g. phrenic nerve in
  surgery), Guillain-Barre syndrome
  (demyelination), poliomyelitis,
  
  motor neurone disease.
• Muscular Problems
• myasthenia gravis, steroid induced
  myopathy, protein malnutrition.
• Anatomical Problems
• Chest Wall rib fractures or flail chest,
  obesity, abdominal hypertension, restrictive
  dressings
• Pleura pleural effusions, pneumothorax,
  hemothorax.
• Airways airway obstruction (in lumen, in
  wall, outside wall), laryngeal
  edema,
  inhalation of a foreign object,
  bronchospasm

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Failure to Oxygenate
Diffusion abnormality Thickening of the
alveoli (fibrosis) Increased extracellular
fluid pulmonary edema. This
obstructs gas exchange.

• Ventilation/Perfusion Mismatch Dead Space
  Ventilation 
• (or high V/Q)
• Alveoli are ventilated but not perfused

Eg pulmonary embolus

• Dead space may be anatomical - the conducting
  airways(150ml)

• physiological, for example in hemorrhage or
  hypotension

Shunt (or low V/Q) where alveoli are perfused
but not ventilated
occurs in airway collapse, pneumonia,
pulmonary hemorrhage (contusion), ARDS/ALI.
Inability to extract O2 at cellular level
sepsis, cyanide or carbon monoxide
poisoning
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• Mechanical Ventilator
• What is it?

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Mechanical Ventilator What is it?
A mechanical ventilator is a machine that
generates a controlled flow of gas
into a patients airways
Two kinds of ventilators
Negative pressure and Positive
pressure.
Negative Pressure
-iron lung, the Drinker respirator, and the chest
shell
-advantage these ventilators didnt require
insertion of an
artificial airway, -disadvantage they were
noisy and made nursing care difficult.
Positive Pressure
-The Emerson Company in Boston developed the
positive pressure ventilator, which was first
used at Massachusetts General Hospital.
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Positive pressure ventilators

• Require an artificial airway (endotracheal or
  tracheostomy tube),
• and use positive pressure to
  force oxygen into a patients lungs

• Inspiration can be triggered either by the
  patient or the machine.

• Four types of positive pressure ventilators

• volume cycled
• pressure cycled

-deliver a preset tidal volume
-ideal for patients with bronchospasm since the
same tidal volume is delivered regardless of
the amount of airway resistance
-deliver gases at preset pressure
-decreased risk of lung damage from high
inspiratory pressures
-disadvantage is that the patient may not receive
the complete tidal volume if he or she has poor
lung compliance and increased airway resistance
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• flow cycled
• time cycled

-deliver a breath until a preset flow rate
These arent used
-deliver a breath over a preset time period
expiration is passive
.
gas flows along a pressure gradient between the
upper airway and the alveoli
Flow is either volume targeted and pressure
variable, or pressure limited and volume
variable.
The pattern of flow may be either sinusoidal
(which is normal), decelerating or constant. Flow
is controlled by an array of sensors and
microprocessors.
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• Mechanical Ventilators
• Classification

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Mechanical Ventilators Classification
1) Control
Either Volume Controlled (volume limited, volume
targeted) and Pressure VariableorPressure
Controlled (pressure limited, pressure targeted)
and Volume VariableorDual Controlled (volume
targeted (guaranteed) pressure limited)
2) Cycling
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
-If an inspiratory pause is added,
then the breath is both
volume and time cycled (contd)
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3) Triggering

• what causes the ventilator to cycle to
  inspiration?
• Ventilators may be
• 
  time triggered,
• 
  pressure triggered or
  
  flow triggered.
• Time the ventilator cycles at a set frequency
  as determined by the
• controlled rate.
• Pressure the ventilator senses the patient's
  inspiratory effort
• by way of a decrease in the
  baseline pressure.

• Flow modern ventilators deliver a constant
  flow around the circuit
• throughout the respiratory cycle
  (flow-by). A deflection in this
• flow by patient inspiration, is
  monitored by the ventilator and
• it delivers a breath.
• This mechanism requires less work by
  the patient than pressure triggering.
• 
  (Contd)

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• 4) Breaths are either
• what causes the ventilator to
  cycle from inspiration?
• Mandatory (controlled) - which is determined by
  the respiratory rate.
• Assisted - (as in assist control, synchronized
  intermittent mandatory
• ventilation,
  pressure support)
• Spontaneous- (no additional assistance in
  inspiration, as in CPAP)

• 5) Flow pattern
• 
  constant, accelerating, decelerating or
  sinusoidal
• Sinusoidal this is the flow pattern seen in
  spontaneous breathing and CPAP
• Decelerating the flow pattern seen in pressure
  targeted ventilation
• inspiration slows down as alveolar pressure
  increases
• (there is a high initial flow).
• 
  (Contd)

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• Constant - flow continues at a constant rate
  until the set tidal volume is delivered
• Accelerating - flow increases progressively as
  the breath is delivered. This should not be used
  in clinical practice.
  Flow Pattern

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KEY-POINTS
1.      The resting point of outward chest spring
and inward lung collapse is the
Functional Residual Capacity (FRC)
this is a reservoir for gas exchange .The FRC is
the lungs physiologic reserve, it is a
reservoir. 2.      Loss of chest wall or lung
compliance causes reduced FRC. 3.      Exhalation
below FRC is active causing dynamic airway
collapse, trapping air in the alveoli
(auto PEEP) 4.      At residual volume it is not
possible to empty alveoli of air further,
due to dynamic airway collapse (airway closure)
5.      The closing volume (CV) is the point at
which dynamic compression of the airways
begins. 6.      Such airway closure occurs
normally within FRC, and it is known as the
closing volume (CV). With age and
disease the CV moves into the tidal breathing
range. 7.      The CV increases with age,
smoking, lung disease, and body position (supine
gt erect). 8.      Airway collapse increases the
work of breathing and leads to ventilation-perfusi
on mismatch 9.      In mechanically ventilated
patients airway collapse is prevented by applying
positive pressure to the airway
throughout the respiratory cycle CPAP/PEEP 10. 
PEEP/CPAP works by increasing FRC, maintaining
alveolar recruitment facilitating gas
exchange (and removal of CO2 and replenishment of
O2), and reducing the workload of
breathing. 11.  The patient requires sufficient
PEEP to prevent alveolar de-recruitment, but not
so much PEEP that alveolar
over-distension, dead space ventilation and
hypotension occurs. 12.  The ideal level of PEEP
is that which prevents de-recruitment of the
majority of alveoli, while causing
minimal over-distension. 13.  Recruitment
maneuvers are used to re-inflate collapsed
alveoli, a sustained pressure above the
tidal ventilation range is applied, and PEEP is
used to prevent de-recruitment. 14.  Auto-PEEP
is gas trapped in alveoli at end expiration, due
to inadequate time for expiration,
bronchoconstriction or mucus plugging. It
increased the work of breathing. 15.  The
increased work of breathing associated with
auto-PEEP can be offloaded by applying CPAP
to the trachea/mouth, and splinting open the
connecting airways. The objective is
to set the CPAP level above the auto-PEEP level.
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• VENTILATOR WAVE FORMS

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Ventilator Waveforms
Airway pressure screen
Step 1 - determine the CPAP level   this is
the baseline position from which there is a
downward deflection on, at least, beginning
of inspiration, and to which the airway pressure
returns at the end of expiration.
Step 2 is the patient triggering? -There will
be a negative deflection into the CPAP line just
before inspiration
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Step 3 what is the shape of the pressure wave?
-If the curve has a flat top, then the breath
is pressure limited, if it has a
triangular or sharks fin top, then it is not
pressure limited and is a volume
breath.
Flow screen
Step 4 what is the flow pattern?
If it is constant flow (square shaped) this must
be volume controlled, if
decelerating, it can be any mode.
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Is the patient gas trapping?  
-expiratory flow does not return to baseline
before inspiration commences (i.e.
gas is trapped in the airways at end-expiration).
Step 4 the patient is triggering
is this a pressure supported  or SIMV or VAC
breath? -This is easy, the pressure supported
breath looks completely differently
than the volume control or synchronized breath
the PS breath has a decelerating
flow pattern, and has a flat topped
airway pressure wave. The synchronized breath
has a triangular shaped pressure
wave.
Airway pressure
Flow pattern
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Step 5 the patient is triggering is this
pressure support or pressure control?
-The fundamental difference between pressure
support and pressure control
is the length of the breath in PC, the
ventilator determined this (the inspired time)
and all breaths have an
equal i time. In PS, the patient determined the
duration of
inspiration, and this varies from breath to
breath.                                         
                                                  
                                                  
                                  
                                                  
                                                
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Step 6 is the patient synchronizing with the
ventilator? -Each time the ventilator
is triggered a breath should be delivered.
If the number of triggering episodes is
greater than the number of breaths,
the patient is asynchronous with the ventilator.
Further, if the peak flow rate of
the ventilator is inadequate, then
the inspiratory flow will be "scooped"
inwards, and the patient appears to be fighting
the ventilator. Both of these
problems are illustrated below
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• Ventilator Modes

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Ventilator Modes

• Control Ventilation (CV)
• Assist-Control Ventilation (A/C)
• Synchronous Intermittent Mandatory Ventilation
  (SIMV)
• Pressure Support Ventilation (PSV)
• Positive End Expiratory Pressure (PEEP)
• Constant Positive Airway Pressure (CPAP)
• Independent Lung Ventilation (ILV)
• High Frequency Ventilation (HFV)
• Inverse Ratio Ventilation (IRV)
• Advanced Pressure Control Modes

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1)Control Ventilation
(CV) -CV delivers the preset volume or
pressure regardless of the patients
own inspiratory efforts. -This mode is
used for patients who are unable to initiate a
breath. -If it is used with
spontaneously breathing patients, they must be
sedated and/or pharmacologically paralyzed so
they dont breathe out of synchrony with
the ventilator.
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2)Assist-Control Ventilation
(A/C) -A/C delivers the preset volume
or pressure in response to the patients
own inspiratory effort but will initiate the
breath if the patient does not do so within the
set amount of time. -This means that
any inspiratory attempt by the patient triggers a
ventilator breath. -The patient
may need to be sedated to limit the number of
spontaneous breaths since hyperventilation can
occur. -This mode is used for patients
who can inititate a breath but who have weakened
respiratory muscles.
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3) Synchronous Intermittent Mandatory
Ventilation (SIMV) -SIMV was
developed as a result of the problem of high
respiratory rates associated with A/C.
-SIMV delivers the preset volume or pressure
and rate while allowing the patient to breathe
spontaneously in between ventilator breaths.
-Each ventilator breath is delivered in
synchrony with the patients breaths, yet the
patient is allowed to completely control the
spontaneous breaths. -SIMV is used as a
primary mode of ventilation, as well as a
weaning mode. -The disadvantage of this
mode is that it may increase the work of
breathing and respiratory muscle fatigue.
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4) Pressure Support
Ventilation (PSV) -PSV is preset pressure that
augments the patients spontaneous inspiratory
effort and decreases the work of breathing.
-The patient completely controls the
respiratory rate and tidal volume. -PSV
is used for patients with a stable respiratory
status and is often used with SIMV to
overcome the resistance of breathing through
ventilator circuits and tubing.
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5) Positive End Expiratory Pressure
(PEEP) -PEEP is positive pressure that is
applied by the ventilator at the end of
expiration. -Used as an adjunct to CV, A/C,
and SIMV to improve oxygenation by collapsed
alveoli at the end of expiration.
-Complications decreased cardiac output,
pneumothorax, and increased intracranial
pressure.
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6) Constant Positive Airway Pressure
(CPAP) -CPAP is similar to PEEP except that it
works only for patients who are breathing
spontaneously. -The effect of both is
comparable to inflating a balloon and not letting
it completely deflate before inflating it
again. The second inflation is easier to
perform because resistance is decreased.
-CPAP can also be administered using a mask.
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7) Independent Lung Ventilation (ILV)
-This method is used to ventilate each lung
separately in patients with
unilateral lung disease or with a
different disease process in each lung.
-It requires a double-lumen endotracheal tube and
two ventilators. -Sedation and
pharmacological paralysis are used to facilitate
optimal ventilation and increased comfort
for the patient.
8) High Frequency Ventilation (HFV) -HFV
delivers a small amount of gas at a rapid rate
(as much as 60-100 breaths per minute.)
-This is used when conventional mechanical
ventilation would compromise hemodynamic
stability, during short-term procedures, or for
patients who are at high risk for
pneumothorax. -Sedation and pharmacological
paralysis are required.
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9) Inverse Ratio Ventilation (IRV) -The normal
inspiratoryexpiratory ratio is 12 but this is
reversed during IRV to 21 or greater (the
maximum is 41). -This mode is used for
patients who are still hypoxic even with the use
of PEEP. -The longer inspiratory time
increases the amount of air in the lungs at the
end of expiration (the functional residual
capacity) and improves oxygenation by
reexpanding collapsed alveoli. -The shorter
expiratory time prevents the alveoli from
collapsing again. -Sedation and
pharmacological paralysis are required since its
very uncomfortable for the patient.
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MODE
FUNCTION
CLINICAL
USE Control Ventilation (CV)
Delivers preset volume or
pressure Usually used for
patients who are apneic



regardless of
patients own


inspiratory efforts


Assist-Control
Ventilation (A/C)
Delivers breath in response to
Usually used for spontaneously


patient effort and if patient fails to
breathing patients with weakened

do so
within preset amount of time
respiratory muscles














Synchronous Intermittent Mandatory
Ventilator breaths are synchronized
Usually used to wean patients
from



mechanical ventilation

with patients respiratory
effort Ventilation (SIMV) Pressure Support
Ventilation (PSV) Preset
pressure that augments the
Often used with SIMV during



weaning




patients inspiratory effort and

decreases the
work of breathing Positive End Expiratory
Pressure (PEEP)
Positive pressure
applied at the end Used
with CV, A/C, and SIMV to



Improve oxygenation by opening collapsed




alveoli

of expiration



Constant Positive Airway Pressure
Similar to PEEP but used only
with Maintains
constant positive pressure



in airways so resistance is decreased

spontaneously
breathing patients (CPAP)
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• MODE
  FUNCTION
  
  CLINICAL USE
• Independent Lung Ventilation (ILV)
  Ventilates each lung separately
  Used for patients with unilateral lung
• 
  
  
  disease or different disease process
• 
  
  
  In each lung
• 
  requires two
  ventilators and
• 
  sedation/paralysis
• High Frequency Ventilation (HFV)
  Delivers small amounts of gas at a
  Used for hemodynamic
  instability,
• 
  
  
  during short-term procedures,
  or if
• 
  
  
  patient is at risk for
  pneumothorax
• 
  rapid rate (60-100
  breaths/minute)
• 
  requires
  sedation/paralysis
• Inverse Ratio Ventilation (IRV)
  IE ratio is reversed to allow longer
  Improves oxygenation in patients
• 
  
  
  who are still hypoxic even with PEEP

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Volume Control Ventilation
Anesthesiologists use mechanical ventilators in
the operating room. These are bag in bottle
mechanical bellows which are controlled by three
factors 1) tidal volume, 2) respiratory rate,
3) IE ratio.
Conventional anesthesia ventilator the patient
is delivered mandatory breaths from a bag in
bottle ventilator. He can also draw unsupported
spontaneous breaths from an in-line reservoir
bag
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-Longer inspiratory times and faster respiratory
rates predispose to alveolar gas trapping
Pressure-assist ventilation
Pressure assist ventilation is pressure control
without a set rate. Patients
take pressure controlled breaths at the rate of
their choosing, and the
volumes derived are determined by the pressure
preset level, the Ti and the
flow demanded. This is a very
comfortable mode, and is used
in weaning from pressure control (the pressure
limit is weaned).
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Pressure Controlled Ventilation
controlled (CMV)
pressure control.
assist-controlled
SIMV
The term pressure control refers to an assist
control mode
-A pressure limited breath is delivered at a set
rate. -The tidal volume is determined by the
preset pressure limit. -The flow waveform is
always decelerating in pressure control -Gas
flows into the chest along the pressure
gradient. -As the airway pressure rises with
increasing alveolar volume the rate of flow
drops off (as the pressure gradient narrows)
until a point is reached. when the
delivered pressure equals the airway pressure
flow stops. -The pressure is maintained for the
duration of inspiration . Obviously,
longer inspiratory times lead to higher mean
airway pressures (the i time (Ti) is a
pressure holding time after flow has stopped).
-The combination of decelerating flow and
maintenance of airway pressure over time
means that stiff, noncompliant lung units (long
time con which are difficult to aerate are
more likely to be inflated. -Drawbacks of
pressure control? -Pressure control does not
guarantee minute
ventilation. change in the compliance,
then the
patient may hypoventilate and
become hypoxic.
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Volume Assist Control
In volume assist-control -often labelled volume
control
-patients may receive either controlled or
assisted breaths.
-When the patient triggers the ventilator,

he/she receives a breath .
-The patient receives
a breath of this type irrespective of
actual
minute ventilation requirement, so patients

tend to hyperventilate as they emerge. Assist
control (AC) ventilation involves the use of four
variables -tidal
volume -respiratory
rate - inspiratory
flow (as an alternative to IE ratio)
-trigger sensitivity
If the flow rate is too high, the volume is
rapidly delivered to only the
most compliant lung tissues (and not to the
inelastic diseased tissues), If the
peak flow is too low, the patient will demand
more gas than the ventilator
is set up to supply and dysynchrony with the
machine occurs
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The inspiratory flow rate is measured in liters
per minute, and it determines
how quickly the
breath is delivered. The time required to
complete inspiration is determined by the tidal
volume
delivered and the flow rate
Ti VT/Flow Rate.
controlled breaths
assisted breaths
decelerating flow pattern
tidal volume is identical
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• Ventilation  How to Initiate Mechanical
  Ventilation

58
Ventilation  How to Initiate Mechanical
Ventilation
The ventilation strategy -is determined by
whether the patient has failure to
ventilate or failure to oxygenate. -The
first problem is managed by increasing the
patients minute ventilation, -the second by
recruiting collapsed lung units and
controlling mean airway pressure.
Sedation- fentanyl
or morphine
with lorazepam, midazolam or
propofol For profoundly
hypoxemic patients, the addition of a
neuromuscular blocking agent
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• The Procedure of Rapid Sequence Induction
• Preparation
• Drugs thio/ propofol/ etomidate/ midazolam,
  succinyl choline,
• atropine, ephedrine/phenylephrine.
• Endotracheal tubes a variety of sizes available
  and cuff checked
• (to make sure
  that the cuff is intact -ie. Not punctures)
• Laryngoscopes 2 functioning laryngoscopes with
  a variety of blades.
• Suction on and under the pillow.
• A Gum elastic bougie to railroad the ETT if
  there is difficulty in placing the ett.
• An intravenous cannula, with a free-flowing drip
• Monitoring

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Options 1.       Awake
intubation /- local anesthesia applied
topically. 2.       Sedation with midazolam /-
local anesthetic. 3.       Midazolam
succinylcholine 4.       Ketamine
succinylcholine (small babies). 5.      
Thiopental or propofol succinylcholine 6.      
Etomidate succinylcholine
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• Ventilator Settings

62
Ventilator Settings
Respiratory Rate (RR) -The respiratory
rate is the number of breaths the ventilator
delivers to the patient
each minute. -The rate chosen depends on
the tidal volume
the type of pulmonary pathology
the patients target PaCO2. -Obstructive
lung disease, the rate should be set at 6-8
breaths/minute to avoid
the development of auto-PEEP and
hyperventilation -Restrictive lung disease
usually tolerate a range of 12-20
breaths/minute. - Patients with normal
pulmonary mechanics can tolerate a rate of 8-12
breaths/minute.
Tidal Volume (VT) -The tidal volume is the
volume of gas the ventilator delivers to the
patient with each breath. -The usual
setting is 5-15 cc/kg, based on compliance,
resistance, and type of pathology.
-Patients with normal lungs can tolerate a tidal
volume of 12-15 cc/kg, -Patients with
restrictive lung disease may need a tidal volume
of 5-8 cc/kg.
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To start a patient on
assist-control one must
select -a PEEP (as determined by
lung compliance), -a minute volume (MV
100ml/kg), -a tidal volume (TV
6ml/kg), and a peak flow. -The
respiratory rate is the MV/TV. -The
peak flow is usually four times the minute
ventilation. -The trigger is either
set as flow-by or a negative pressure of
-2cmH2O
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Fractional Inspired Oxygen (FIO2) -The
fractional inspired oxygen is the amount of
oxygen delivered to the patient. It can range
from 21 (room air) to 100. -Oxygen toxicity
causes structural changes at the
alveolar-capillary membrane, pulmonary
edema, atelectasis, and decreased
PaO2. InspiratoryExpiratory (IE) Ratio -The
IE ratio is usually set at 12 or
11.5 Pressure Limit -The pressure limit
regulates the amount of pressure the
volume-cycled ventilator can generate to deliver
the preset tidal volume. -High pressures can
cause lung injury, its recommended that the
plateau pressure not exceed 35 cm H20. -Caused
by airway is obstructed with mucus,the patient
coughing, biting on the ETT, breathing against
the ventilator, or by a kink in the ventilator
tubing.
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• Flow rate
• -The flow rate is the speed with which the tidal
  volume is delivered. The usual setting is 40-100
  liters per minute.
• Sensitivity/Trigger
• -The sensitivity determines the amount of effort
  required by the patient to initiate inspiration.
• It can be set to be triggered by pressure or flow
  
• Sigh
• -The ventilator can be programmed to deliver an
  occasional sigh with a larger tidal volume.
• it prevents collapse of the alveoli (atelectasis)
  
• Minute volume (VE)
• Minute volume is the total volume of air inhaled
  and exhaled in one minute. The patients minute
  volume should be less than 10 liters per minute.

66

Ventilator Settings The following is a summary
of the settings that nurses deal with the
most. SETTING
FUNCTION
USUAL PARAMETERS Respiratory Rate (RR)
Number of breaths delivered usually
4-20 breaths/mt
by the ventilator per minute Tidal Volume
(VT) Volume of gas delivered during
usually 5-15cc/kg
each ventilator
breath Fractional Inspired Amount of
oxygen delivered by 21-100 to
keep Oxygen(FIO2)
ventilator to patient
PaO2gt60mmHg or

SaO2gt90 InspiratoryExpiratory
Ratio Length of inspiration
usually 12 or 11.5 (IE)
compared to length of expiration Pressu
re Limit Maximum amount of
pressure 10-12cm H2O above
the ventilator can use to
PIP maximum35cmH2O
deliver breath
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Alarms and Common Causes

• High Pressure Low Pressure High
  Respiratory Rate Low Exhaled Volume
• Secretions in -vent tubing not
  patient anxiety or -vent
  tubing not
• ETT/airway or connected
  pain
  connected
• condensation in -displaced ETT
  -secreations in ETT/ -Leak
  in cuff or
• tubing or trach tube
  airway
  inadequate cuff seal
• Kink in vent
  - Hypoxia
  
• Tubing
  - Hypercapnia
  -Occurrence of
• Patient biting on
  
  another alarm
• ETT
  
  preventing full
• Patient coughing,
  
  delivery of breath
• gagging, or trying
• to talk

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• Noninvasive Forms of Mechanical Ventilation

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Noninvasive Forms of Mechanical Ventilation
Noninvasive positive pressure ventilation (NIPPV)
include - patients who dont have
oxygenation problems, - who are able
to manage their secretions, and - who
dont have an upper airway obstruction. CPAP
Continuous Positive Airway Pressure (CPAP)
CPAP can also be delivered through
either a nasal mask or a full face mask. Full
face masks - minimize air leaks,
-more claustrophobic- must be removed for
the patient to speak or

expectorate secretions. - a
smaller air leak leads to greater pressure
buildup and gastric

distention Nasal masks - less claustrophic and
dont have to be removed to speak or

expectorate, - they
usually have large air leaks BiPAP
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Bi-level Positive Airway Pressure (Bi-PAP)
- similar to CPAP - BiPAP
maintains positive airway pressure during both

inspiration and
expiration. -The two levels are
referred to as inspiratory
positive airway pressure (IPAP) and
expiratory positive airway pressure (EPAP).
-Benefits of IPAP
increased tidal volume and minute ventilation,
decreased PaCO2 level,
relief of dyspnea, and
reduced use of accessory muscles.
-Benefits of EPAP increased
functional residual capacity,
resulting in an increased PaO2 level.
-Bi-Pap is usually delivered through a nasal
mask, allowing exhalation
through the mouth
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IPPB -Intermittent Positive Pressure
Breathing (IPPB) is used after surgery or for a
short time after mechanical ventilation has been
discontinued. -The IPPB machine is a
pressure-cycled ventilator that delivers
compressed gas under positive
pressure into the patients airway.
-Its triggered when the patient inhales,but it
allows passive expiration. -Usually,
10-20 breaths are given every 1-2 hours for 24
hours. -Benefits of IPPB include
prevention of atelectasis,
promotion of full-lung expansion,
improved oxygenation, and
administration of nebulized
medications.
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• Nursing Care of the
• Mechanically Ventilated Patient

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Nursing Care of the Mechanically Ventilated
Patient
Nursing Care of the Endotracheal Tube (ETT)
ETT management consists of
- ensuring a patent airway,
- suctioning pulmonary and oral
secretions, and -
providing frequent oral and/or nasal care.
-secure ETT in place

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Oral cavity should also be suctioned
separately -oral care
should be provided every eight hours and as
needed. Bite block -If the patient has a
bite block to prevent them from biting on
the tube, it must be removed and
cleaned or replaced every eight
hours. -If the tube is
taped to the patients face, the tape must be
removed and replaced on the opposite side
of the face at least once per day .
-The
amount of air in the cuff should be checked every
eight hours to ensure that the cuff is
not exerting too much pressure on the
trachea walls. -ETT should be
confirmed to be the same as prior to the
procedure
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Endotracheal tube care Tray
This includes -a sterile suction kit
(two
separate suction catheters for oral and ETT)
-a bottle of
sterile 0.9 sodium chloride
-sterile gloves
-a clean bite
block, and
-tape torn into appropriately sized pieces.
Nursing Care of the Tracheostomy Tube
-Tracheostomy (trach) care should
be done every eight hours
and involves cleaning around
the incision,
as well as replacing the inner cannula
if the patient has
a double-lumen tube.
-prevent breakdown of the skin
surrounding the site,
and prevent
infection. -Using
sterile technique, the skin and external portion
of the
tube is cleaned with hydrogen peroxide.
- inner cannula must be cleaned with
hydrogen peroxide, rinsed with
0.9 sodium chloride, and
reinserted using sterile technique
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Sterile suctioning -
Suctioning should be performed only when the
patient needs it the need should be
assessed at least every two hours.
- Pre-oxygenation with 100 O2
- two separate suction catheters for oral
and ETT - size of suction
catheter should be 1/3rd of ETT diameter
- Duration of each suction pass should
be limited to ten seconds
-The number of passes should be limited to three
or less - saline installation
should not be used routinely
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Eyes

• Eyes should be covered with a sterile gauze after
  applying a eye ointment.
• This is to avoid dryness of cornea subsequent
  development of any ulceration.

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Naso gastric tubes

• Instituted for gastric decompression
• Administration of medications.
• Nutritional support
• Should be irrigated every 4 hours.
• Position should be verified before administration
  of any fluids.
• After administration flush with 10ml of water.

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Care of Bladder

• Continuous bladder drainage
• Catheter should changed once in 72 hours check
  patency

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GIT Care

• Oral cavity examination
• Abdominal Examination
• Per Rectal Examination

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Care to avoid development of bed sore

• Constant changing position of patient
• Avoid pressure points
• Alpha bed or Water bed

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Psychological care

• Good communication
• Alleviate anxiety and promote emotional well
  being
• Orientation of patient to surrounding, Time and
  Persons

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• Sedation Neuromuscular
  Blockade

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Sedation Neuromuscular Blockade
-Patients require sedation in order to tolerate
mechanical ventilation Common
Medications
- sedatives
decrease anxiety and produce amnesia
- neuroleptics,
- analgesics, and
- paralytics SEDATIVES
Lorazepam
Midazolam Propofol Dexmedetomidine Onset
of action 5-15 minutes 1-3 minutes 1
minute Immediately Half-life
6-15 hours 1 hour lt 30
minutes 1.5-3 hours Loading Dose 0.05
mg/kg 0.03 mg/kg 0.5 mg/kg 1
mcg/kg Infusion rate 0.5-5 mg/hr
1-20 mg/hr 0.5-3mg/kg/hr 0.2-0.7
mcg/kg/hr
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NEUROLEPTICS -Given to
patients who are experiencing delirium or
ICU
psychosis. Symptoms -disorganized
thinking, - audio and
visual hallucinations, and
- disorientation. Haloperidol -
intravenously in 2-10 mg doses every 2 to 4
hours ANALGESICS Intravenous narcotics
Morphine,fentanyl or hydromorphone PARALYTICS
AGENTS or neuromuscular blocking agents (NMBs)
- must always be administered with
other sedatives and narcotics Two classes of
NMBs - Nondepolarizing (Succinylcholine
for intubation)
- Depolarizing ( Atracurium,Pancuranium,Vec
uranium)
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• Assessment Criteria

87
Assessment Criteria
Breath Sounds - Breath sounds should be
assessed at least every four hours
Crackles (rales) Rhonchi
Wheeze Pleural friction
rub Spontaneous Respiratory Rate and Tidal
Volume -If the spontaneous tidal
volume is low -the
patient may not do well with weaning attempts.
-If the respiratory rate is high,
particularly with weaning modes indicate
-the patient isnt tolerating the mode,
-needs suctioning,
-or he or she is anxious or trying to
communicate. Pulse Oximetry -The
machine detects the percent of hemoglobin that is
fully saturated. -pulse oximetry can be a
helpful guide when titrating FIO2
-In general, a SpO2 of 92 in white patients, and
95 in black patients indicates adequate
oxygenation (PaO2 gt 60 mmHg).
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(Capnography) End Tidal CO2 -Capnography, also
called end tidal CO2, is CO2 measured at the
end of exhalation -a
display where a waveform (capnogram) is created,
along with a number that closely approximates
the PaCO2 -In a
hemodynamically stable patient with a normal
ventilation/perfusion relationship, the end
tidal CO2 (also called PetCO2) is generally 1-5
mmHg less than the PaCO2
-The most useful function of end tidal CO2
measurement is to confirm ETT placement in
the lungs.
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Arterial
Blood Gases (ABG) pH Normal pH of
body fluids 7.35-7.45 pH lt 7.35
acidosis pH gt 7.45 alkalosis PaCO2
PaCO2 is the partial pressure of
dissolved CO2 in blood. Normal
35-45 mmHg PaCO2 is directly related
to rate and depth of respiration.
Its a direct indicator of the effectiveness of
ventilation. As PaCO2 rises, the
blood becomes more acidic and pH drops.
As PaCO2 decreases, the blood becomes more
alkaline and pH rises. If a change in
PaCO2 is the primary alteration, then a
respiratory problem

exists. HCO3 Bicarbonate (HCO3) is the
primary buffer in the body and is able to take up
and release H. Normal
22-26 mmHg As HCO3 rises, the blood
becomes more alkaline and pH increases.
As HCO3 drops, the blood becomes more acidic
and pH decreases. If a change in HCO3
is the primary alteration, then a metabolic
problem exists.
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CO2 Considered a measure of
bicarbonate concentration includes total of
bicarbonate and carbonic acid.
Normal 23-27 mEq/L Base Excess/Deficit
Measures excess amount of acid or base
present in blood. This is independent of
changes in PaCO2 therefore, its a measure of
metabolic acid-base balance.
Increased HCO3 base excess (alkalosis)
Decreased HCO3 base deficit
(acidosis) PaO2 The amount of
oxygen dissolved in plasma (about 3 of total
the other 97 is bound to hemoglobin).
Normal is 80-100 mmHg in healthy young people
breathing room air at sea level this
decreases with age and altitude. PaO2
gt 60 mmHg is considered acceptable in critically
ill, mechanically ventilated adults
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Figure out the ABG results

• pH 7.30, PaCO2 40, HCO3 18
• Metabolic acidosis (pH , PaCO2 ok, HCO3 )
• 2. pH 7.48, PaCO2 30, HCO3 24
• Respiratory alkalosis (pH , PaCO2 , HCO3 ok)
• 3. pH 7.25, PaCO2 54, HCO3 26
• Respiratory acidosis (pH , PaCO2 , HCO3 ok)
• 4. pH 7.50, PaCO2 42, HCO3 33
• Metabolic alkalosis (pH , PaCO2 ok, HCO3 )

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• Weaning and Extubation

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Indications for weaning and extubation The
patient is able to ventilate The patient is
able to oxygenate The patient is able to
protect his/her airway
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Suitability for Weaning
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• INTOLERENCE TO WEANING
• Increased HR
• Increasrd RR (gt30/mt)
• Increased work breathing
• Sweating (Hypercapnia)
• Hypertension
• Hypoxia

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Does the patient meet criteria?
How do I know if the patient is tolerant
intolerant of the trial?
Is the patient suitable for extubation?
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Other Factors
Is the patient suitable for extubation?
No
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Weaning
Extubation Partial Ventilation Support
Normalization of inspiratory times
Driving pressure is targeted to a tidal volume
of 4 - 6ml/kg.
Mean airway pressure, the CPAP level and the
FiO2 are reduced to targeted PaO2
As PaCO2 reduces reduce the controlresp.rate
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• Failure to Wean

102
Failure to Wean Is the patient able to
ventilate? Is the patient able to oxygenate?
What other factors influence weaning?
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• Is the patient able to ventilate?
• FACTORS THAT MAY INTERFERE WITH WEANING 
• Neurological
• Anatomical Problems

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Is the patient able to oxygenate?

• Diffusion abnormalities,
• ventilation-perfusion mismatch,
• dead space and shunt.
• Certain factors may limit successful weaning
• - persistent lower respiratory tract
  infection,
• -alveolar edema,
• -airway/lobar collapse,
• -lung fibrosis.

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What other factors influence weaning?
Cardiovascular pulmonary edema,fluid overload
Gastroinestinal recurrent aspiration
pneumonitis, ascites
or abdominal wounds leading to
diaphgramatic splinting
Nutrition -protein malnutrition leading to
muscular atrophy, which affects
the diaphragm and intercostals Acid base
metabolic alkalosis reduces respiratory drive.
Conversely, muscles perform
poorly in an acidic environment Electrolytes
hypophosphatemia, hypomagnesemia, hypokalemia,
hypocalcemia these all
affect muscular function and protein metabolism.
Endocrine muscle weakness due to
hypothyroidism or steroid induced myopathy.
Oxygen delivery capacity the circulating
hemoglobin concentration
anemia increases respiratory
drive and cardiac output Pain control it is
very difficult to wean patients who are in pain
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Weaning Discontinuation Algorithm

• Removing a patient from a ventilator involves
  discontinuation of mechanical ventilation
  and extubation.
• There are two parts to weaning weaning to
  partial ventilator support and
  weaning to discontinuation.
• The single most traumatic event for the patient
  is conversion from positive pressure to negative