Download Mechanical Ventilator What is it?

VENTILATOR
THE BASICCOURSE
HISTORY OF
VENTILATOR
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 4:34-35).
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”.
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 patient’s head protruded out of the end.
The second - design was a box or shell that fitted over the thoracic area only
(chest cuirass).
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."
In 1949, John Haven Emerson
Developed a mechanical assister for anesthesia at Harvard University.
Iron lung ward filled with Polio patients,
Rancho Los Amigos Hospital, ca. 1953
Woman lying in negative pressure ventilator (iron lung).
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
MODERN VENTILATOR
THE COURSE DEALS WITH
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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
WHAT A MOST IMPORTANT THING
A DOCTOR SHOULD KNOW
AFTER THIS COURSE ?
MONITORING THE PROGRESS
WHAT A MOST IMPORTANT THING
A ICU STAFF SHOULD KNOW
AFTER THIS COURSE ?
ALARMS AND CARE OF THE PATIENT
VENTILATOR
THE BASIC
•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
patient’s own respiratory efforts
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 it’s higher solubility.
Indications for mechanical ventilation:
Ventilation Failure
Oxygenation Failure
Failure to Ventilate
Characterized by reduced alveolar ventilation
which manifests
as an increase in the PaCO2 > 50 mmHg
Indications for mechanical ventilation:
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Is it
failure to ventilate (is the PCO2 > 50mmHg), or
failure to oxygenate (is the PO2 <50mmHg)?
Remember that a low O2 is much more significant than a
high PCO2,
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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?
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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?
Neurological Problems ( Ventilatory failure )
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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
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
Mechanical Ventilator
What is it?
Mechanical Ventilator What is it?
A mechanical ventilator is a machine that generates a controlled flow of gas
into a patient’s airways
Two kinds of ventilators:
Negative pressure and Positive pressure.
Negative Pressure :
-iron lung, the Drinker respirator, and the chest shell
-advantage these ventilators didn’t 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.
Positive pressure ventilators
• Require an artificial airway (endotracheal or tracheostomy tube),
and use positive pressure to force oxygen into a patient’s lungs
• Inspiration can be triggered either by the patient or the machine.
• Four types of positive pressure ventilators:
volume 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
pressure cycled
-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
flow cycled -deliver a breath until a preset flow rate
 time cycled -deliver a breath over a preset time period
expiration is passive
These aren’t
used
.
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.
Mechanical Ventilators
Classification
Mechanical Ventilators Classification
1) Control
Either
Volume Controlled (volume limited, volume targeted) and Pressure Variable
or
Pressure Controlled (pressure limited, pressure targeted) and Volume Variable
or
Dual 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)
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)
4) Breaths are either:
what causes the ventilator to cycle from inspiration?
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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)
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Constant - flow continues at a constant rate until
the set tidal volume is delivered
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Accelerating - flow increases progressively as
the breath is delivered. This should not be used in
clinical practice.
Flow Pattern
KEY-POINTS
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12.
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14.
15.
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 lung’s physiologic reserve, it is a reservoir.
Loss of chest wall or lung compliance causes reduced FRC.
Exhalation below FRC is active causing dynamic airway collapse,
trapping air in the alveoli (auto PEEP)
At residual volume it is not possible to empty alveoli of air further,
due to dynamic airway collapse (airway closure)
The closing volume (CV) is the point at which dynamic compression of the airways begins.
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.
The CV increases with age, smoking, lung disease, and body position (supine > erect).
Airway collapse increases the work of breathing and leads to ventilation-perfusion mismatch
In mechanically ventilated patients airway collapse is prevented by applying positive pressure
to the airway throughout the respiratory cycle – CPAP/PEEP
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.
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.
The ideal level of PEEP is that which prevents de-recruitment of the majority of alveoli,
while causing minimal over-distension.
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.
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.
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.
VENTILATOR
WAVE FORMS
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
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 shark’s 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.
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
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.
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
Ventilator
Modes
Ventilator Modes
•Control Ventilation (CV)
•Assist-Control Ventilation (A/C)
•Synchronous Intermittent Mandatory Ventilation (SIMV)
• Pressure Support Ventilation (PSV)
•Positive End Expiratory Pressure (PEEP)
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•Constant Positive Airway Pressure (CPAP)
•Independent Lung Ventilation (ILV)
•High Frequency Ventilation (HFV)
• Inverse Ratio Ventilation (IRV)
• Advanced Pressure Control Modes
-Inverse Ratio Ventilation (IRV) and
-Airway Pressure Release Ventilation (ARPV),
-Bilevel and Proportional Assist Ventilation?
1)Control Ventilation (CV)
-CV delivers the preset volume or pressure regardless of the
patient’s 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 don’t
breathe out of synchrony with the ventilator.
2)Assist-Control Ventilation (A/C)
-A/C delivers the preset volume or pressure in response to the
patient’s 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.
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 patient’s
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.
4) Pressure Support Ventilation (PSV)
-PSV is preset pressure that augments the patient’s 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.
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.
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 i
easier to perform because resistance is decreased.
-CPAP can also be administered using a mask.
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.
9) Inverse Ratio Ventilation (IRV)
-The normal inspiratory:expiratory ratio is 1:2 but this is reversed during IRV to
2:1 or greater (the maximum is 4:1).
-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 it’s very
uncomfortable for the patient.
MODE
Control Ventilation (CV)
Assist-Control Ventilation (A/C)
FUNCTION
CLINICAL USE
Delivers preset volume or pressure
regardless of patient’s own
inspiratory efforts
Usually used for patients who are apneic
Delivers breath in response to
patient effort and if patient fails to
do so within preset amount of time
Synchronous Intermittent Mandatory
Ventilation (SIMV)
Pressure Support Ventilation (PSV)
Ventilator breaths are synchronized
with patient’s respiratory effort
Preset pressure that augments the
patient’s inspiratory effort and
decreases the work of breathing
Positive End Expiratory Pressure
(PEEP)
Positive pressure applied at the end
of expiration
Constant Positive Airway Pressure
(CPAP)
Similar to PEEP but used only with
spontaneously breathing patients
Usually used for spontaneously
breathing patients with weakened
respiratory muscles
Usually used to wean patients from
mechanical ventilation
Often used with SIMV during
weaning
Used with CV, A/C, and SIMV to
Improve oxygenation by opening collapsed
alveoli
Maintains constant positive pressure
in airways so resistance is decreased
MODE
Independent Lung Ventilation (ILV)
FUNCTION
Ventilates each lung separately;
requires two ventilators and
sedation/paralysis
High Frequency Ventilation (HFV)
Delivers small amounts of gas at a
rapid rate (60-100 breaths/minute);
requires sedation/paralysis
Inverse Ratio Ventilation (IRV)
I:E ratio is reversed to allow longer
inspiration; requires sedation/
paralysis
CLINICAL USE
Used for patients with unilateral lung
disease or different disease process
In each lung
Used for hemodynamic instability,
during short-term procedures, or if
patient is at risk for pneumothorax
Improves oxygenation in patients
who are still hypoxic even with PEEP;
keeps alveoli from collapsing
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) I:E 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:
-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).
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.
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 I:E 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
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
decelerating flow pattern
assisted breaths
tidal volume is identical
Ventilation How
to Initiate
Mechanical
Ventilation
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
For profoundly hypoxemic patients, the addition of a
neuromuscular blocking agent
propofol
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:
blood pressure, ECG, pulse oximetry, end tidal CO2 (if available).
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
Ventilator
Settings
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 patient’s 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.
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
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.
Inspiratory:Expiratory (I:E) Ratio
-The I:E ratio is usually set at 1:2 or 1:1.5
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, it’s 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.
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
patient’s minute volume should be less than 10 liters per minute.
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
by the ventilator per minute
usually 4-20 breaths/mt
Tidal Volume (VT)
Volume of gas delivered during
each ventilator breath
usually 5-15cc/kg
Fractional Inspired
Oxygen(FIO2)
Amount of oxygen delivered by
ventilator to patient
21%-100% to keep
PaO2>60mmHg or
SaO2>90%
Inspiratory:Expiratory
(I:E)
Ratio Length of inspiration
compared to length of expiration
usually 1:2 or 1:1.5
Pressure Limit
Maximum amount of pressure
the ventilator can use to
deliver breath
10-12cm H2O above
PIP; maximum35cmH2O
Alarms and Common Causes
High Pressure
Low Pressure
• Secretions in
ETT/airway or
condensation in
tubing
-vent tubing not
connected
-displaced ETT
or trach tube
• Kink in vent
Tubing
• Patient biting on
ETT
• Patient coughing,
gagging, or trying
to talk
• Increased airway
pressure from
bronchospasm or
pneumothorax
High Respiratory Rate
–patient anxiety or
pain
-secreations in ETT/
airway
- Hypoxia
- Hypercapnia
Low Exhaled Volume
-vent tubing not
connected
-Leak in cuff or
inadequate cuff seal
-Occurrence of
another alarm
preventing full
delivery of breath
Noninvasive Forms
of Mechanical
Ventilation
Noninvasive Forms of Mechanical Ventilation
Noninvasive positive pressure ventilation (NIPPV) include
- patients who don’t have oxygenation problems,
- who are able to manage their secretions, and
- who don’t 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 don’t have to be removed to speak or
expectorate,
- they usually have large air leaks BiPAP
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
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 patient’s airway.
-It’s 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.
Nursing Care of the
Mechanically Ventilated Patient
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
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 patient’s 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
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
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
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.
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.
Care of Bladder
Continuous bladder drainage
Catheter should changed once in
72 hours – check patency
GIT Care
Oral cavity examination
 Abdominal Examination
 Per Rectal Examination

Care to avoid development of
bed sore
 Constant
changing position of
patient
 Avoid pressure points
 Alpha bed or Water bed
Psychological care
 Good
communication
 Alleviate anxiety and promote
emotional well being
 Orientation of patient to
surrounding, Time and Persons
Sedation &
Neuromuscular
Blockade
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
Half-life
6-15 hours
1 hour
Loading Dose
0.05 mg/kg
0.03 mg/kg
0.5 mg/kg
Infusion rate
0.5-5 mg/hr
1-20 mg/hr
0.5-3mg/kg/hr 0.2-0.7
mcg/kg/hr
< 30 minutes
Immediately
1.5-3 hours
1 mcg/kg
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,Vecuranium)
Assessment
Criteria
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 isn’t 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 > 60 mmHg).
(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.
Arterial Blood Gases (ABG)
pH
• Normal pH of body fluids = 7.35-7.45
• pH < 7.35 = acidosis
• pH > 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.
It’s 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.
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, it’s 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 > 60 mmHg is considered acceptable in critically ill, mechanically
ventilated adults
Figure out the ABG results
1. 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 )
Weaning and
Extubation
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
Suitability for Weaning
Criteria
Objective measurements
Subjective clinical
assessments
Description
•
Adequate oxygenation (eg, PO2 >60 mm Hg on FIO2 > 0.4; PEEP <5–10 cm H2O;
PO2/FIO2 >150–300);
•
Stable cardiovascular system (eg, HR <140; stable BP; no (or minimal) pressors)
•
Afebrile (temperature < 38°C)
•
No significant respiratory acidosis
•
Adequate hemoglobin (eg, Hgb >8–10 g/dL)
•
Adequate mentation (eg, arousable, GCS >13, no continuous sedative infusions)
•
Stable metabolic status (eg, acceptable electrolytes)
•
Resolution of disease acute phase; physician believes discontinuation possible;
adequate cough
INTOLERENCE TO WEANING
•
Increased HR
•
Increasrd RR (>30/mt)
•
Increased work breathing
•
Sweating (Hypercapnia)
•
Hypertension
•
Hypoxia
I wish to evaluate the patient for
discontinuation from the ventilator
Does the patient meet criteria?
Place the patient on a Spontaneous
Breathing Trial
How do I know if the patient is tolerant
intolerant of the trial?
Watch for 5 or 10 minutes
If acute distress does not occur, continue
for a maximum of 2 hours
Is the patient suitable for extubation?
Weaning / Discontinuation
of Mechanical Ventilation
Is the patient suitable for extubation?
Weaning / Discontinuation
of Mechanical Ventilation
No
Yes
Sit the patient up in the bed, suction out the
endotracheal tube, explain what you are
going to do and extubate the patient.
Failure to Ventilate
Failure to Oxygenate
Other Factors
Rest the patient on the ventilator
Ensure optimal analgesia and
sedation
Reassess failure to wean/discontinue
Attempt Spontaneous Breathing Trial
ONCE every 24 hours
Recurrent Failure
Consider Tracheostomy:

requiring excessive sedation to
tolerate
ETT

marginal mechanics

psychological dependence on
ventilator

mobility

airway trauma.
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
Failure to Wean
Failure to Wean:
Is the patient able to ventilate?
Is the patient able to oxygenate?
What other factors influence weaning?
Is the patient able to ventilate?
FACTORS THAT MAY INTERFERE WITH WEANING
Neurological
Anatomical Problems
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.
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
Weaning & Discontinuation Algorithm
1. Removing a patient from a ventilator involves discontinuation of mechanical
ventilation and extubation.
2. There are two parts to weaning: weaning to partial ventilator support and
weaning to discontinuation.
3. The single most traumatic event for the patient is conversion from positive
pressure to negative pressure ventilation.
4. To extubated a patient, they need to be awake, able to cough and protect
their airway.
5. If it is possible to wean a patient to extubation, but the patient cannot protect
his/her airway, it is best to perform tracheotomy.
6. For a patient to self ventilate, many body systems must be functioning:
-the cardiopulmonary apparatus,
-the central nervous system,
-the nerves that supply the diaphragm (including the neuromuscular junctions),
-the muscles themselves.
-Moreover the patient must be willing to breath and maintain their own
functional residual capacity (not if there is diaphragmatic splinting due to pain).
-There must be room in the abdomen for the diaphragm and lungs to move into.
-There must be adequate hemoglobin to deliver oxygen to the tissues.
7. Difficult to wean a patient if ongoing inflammatory processes persist in the lungs:
consolidation, fibrosis, auto-PEEP, diffusion defects
8. Muscles must be trained and nourished, and patient-ventilator interaction encouraged
9. most effective method of weaning to discontinuation is spontaneous breathing trials
(SBT). SBTs should not be performed more than once daily.
Methods of
weaning
Methods of weaning
There are three primary methods
• T piece/CPAP trials,
• Synchronized Intermittent Mandatory
Ventilation (SIMV),
• Pressure Support Ventilation (PSV).
PSV is often used with SIMV to decrease the work of
breathing.
T-piece/CPAP trials
-T-piece trials consist of alternating intervals of time on the ventilator with
intervals of spontaneous breathing.
CPAP
-T-shaped tube is attached
- endotracheal or tracheostomy tube.
- tubing is attached to an oxygen flowmeter
-the other end is open
-watch for signs of hypercapnia
Tachycardia
Tachypnoea
Sweating
Hypertension
- With CPAP, the patient breathes spontaneously, but has the benefit of the
ventilator alarms if he or she has difficulty.
- CPAP maintains constant positive pressure in the airways, which facilitates gas
exchange in the alveoli.
SIMV
-SIMV is a ventilator mode that delivers a preset number of breaths to the
patient but coordinates them with the patient’s spontaneous breaths.
-The ventilator may be set to deliver 12 breaths per minute, but the patient’s
respiratory rate may be 16 (12 ventilator breaths plus 4 patient-initiated
breaths).
-The ventilator rate is usually decreased by one to three breaths at a time and
an arterial blood gas (ABG) is obtained 30 minutes after the change
Pressure support
- Placing the patient on the pressure support mode at a level that allows the
patient to achieve a spontaneous tidal volume of 10-12 ml/kg.
- During weaning, the level of PS is decreased by 3-5 cm H2O as long as the
patient maintains the desired tidal volume.
Weaning criteria
Simple bedside pulmonary function tests
Vital capacity (VC)
-The vital capacity is the maximal amount of air that can be exhaled
after a maximal inhalation.
-The patient’s vital capacity should be at least 10-15 cc/kg.
Negative inspiratory force (NIF)
-Negative inspiratory force is the ability to take a deep breath and to
generate a cough strong enough to clear secretions.
-The patient’s NIF should be at least –20 cm H20.
Tidal volume (VT)
-Tidal volume is the volume of air inspired and expired during a normal
respiratory cycle.
-The patient’s tidal volume should be at least 5 ml/kg
Minute volume (VE)
-Minute volume is the total volume of air inhaled and exhaled in one
minute.
-The patient’s minute volume should be less than 10 liters per minute.
Respiratory rate (RR)
-The respiratory rate is the number of breaths per minute. The
patient’s RR should be less than 25 breaths/minute.
Arterial blood gas (ABG)
-An ABG should be done before the patient is extubated. The PaO2
should be at least 50 mmHg on less than 50% oxygen
and with no more than 5 cm H20 PEEP.
Post - Extubation
Care
Post-Extubation Care
Humidified oxygen
-Supplemental oxygen requires humidification to prevent drying and
irritation of the respiratory tract and to facilitate removal of secretions.
-oxygen delivered through a mask for a few hours after extubation.
Respiratory exercises
-coughing and deep breathing.
-incentive spirometry exercises.
IPPB
-is used in some institutions to assist patients to take deeper breaths,
especially after surgery.
-The IPPB machine is a pressure-cycled ventilator that delivers compressed
gas under positive pressure into the patient’s airway.
-It’s triggered when the patient inhales, but it allows passive expiration.
-10-20 breaths are given every 1-2 hours for 24 hours.
-Benefits of IPPB
-prevention of atelectasis,
-promotion of full-lung expansion,
-improved oxygenation, and
-administration of nebulized medications
Assessment and monitoring
- Breath sounds, pulse oximetry, and vital signs should be assessed and
recorded every 15 minutes x 1 hour, every 30 minutes x 1 hour, then
every hour until stable
- ABG to be done 30-60 minutes after extubation
-Don’t forget to ask the patient how his or her breathing feels
Thanks to your expert nursing care