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Before you can begin mechanical ventilation
your ventilator must be correctly assembled
◦ Step 1: Assemble expiratory and inspiratory filters
on the ventilator. (ventilators vary, so this process
will also vary and be taught during lab)
◦ Step 2:Attach circuit to ventilator. Acute ventilator
circuits will have an inspiratory limb and an
expiratory limb so that the circuit is unbroken and
the patients returned volumes are
assessed on the vent.
(long term vents typically have a inspiratory limb only)
A expiratory filter with H2O trap
for condensation- this is for the
840 ventilator. Attached to the
ventilator, prevents H2O from
entering the machine
A inspiratory filter, attached to
the vent and inspiratory limb,
prevents small particulates
from the machine to the
patient
Pressure line
To pt
Pt exhalation
Subacute/long term vent circuit, the patients
exhalation does not go back into the ventilator.
Uses a separate pressure line
Heater
probe
inlet
Expiratory limb
Extra
tubing for
heater
To Pt
Wye
Inspiratory limb
Heater
probe
inlet
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Step 3: Once circuit is attached, close all open
ports on the circuit. Circuits have ports for
heated humidification temperature probes
If circuit is a heated circuit attach humidifier and
probes
Most adult ventilators are setup with an HME
initially. All neonatal and pediatric circuits are
setup with heated humidifiers with heated
circuits
If you setup a heater, but do not have a heated
circuit, you must use water traps inline to catch
the condensation that will develop
Water trap
Non-heated circuit with
water traps
HME, placed at Wye
Passover
heated
Concha Heater.
Heats up a metal
column water
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Ventilator circuits are age specific. For an
adult you must use an adult circuit, pediatric
and neonates have specific circuits as well
Neonatal and Pediatric circuits are always
heated circuits- meaning they have a coil
inside to maintain temperature during
humidification
Depending on the ventilator used
some circuits will have a pressure
line inlet attached to the machine
and/or a flow sensor adapter
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Ventilator circuits should not be changed
routinely for infection control purposes,
however you can change a circuit if soiled
Circuits are sterile, meaning you should not
insert a younker inside the circuit to remove
secretions.
Once the circuit is attached you can now plug
in the electrical and air/O2 connections to
your ventilator…
Ventilators are electrically powered and
pneumatically driven
Long term vent
Transport vent
with O2/Air
cylinders
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The use of closed suction catheters should be
considered part of a VAP prevention strategy,
and they do not need to be changed daily for
infection control purposes. The maximum
duration of time that closed suction catheters
can be used safely is unknown
Use only inline
suction ballards
on vents. They
make ETT and
Trach sizes
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Once your circuit, filters and humidification is
on and your vent is plugged in to electricity
and Air and O2, you can now do the pre-use
calibration
This varies greatly with all ventilators, but
generally you start by turning on your vent
(remember, most vents you will take off the
stopper at the WYE when you first turn on the
vent)
Once the vent is on you choose SST (short
self test) option to run the calibration
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The calibration will assess the circuits
compliance/elastance, check for leaks and
proper flow
http://www.youtube.com/watch?v=4p0SppVb
GMs
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Once it has been determined a patient
requires a ventilator you must now attach
them and apply the proper settings.
When you first turn on the ventilator you will
press either “new patient” or “same patient”,
verbiage will vary. Most new vents will save
the previous settings in case you transfer a
patient and reattach them
During the setup the patient is typically being
bagged. The MD may or may not give you the
settings.
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Mode is AC, SIMV or CPAP
◦ Assist control (no breathing, or inadequate
breathing, patient sedated…)
◦ SIMV (same reasons as AC, but you expect patient
will breathe spontaneously soon, post ops)
◦ Spontaneous/CPAP: Patient is breathing
spontaneously
◦ http://www.youtube.com/watch?v=IUZ3Plmz_YQ&f
eature=related
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PCV: Used for patients where you want to
control their pressure limit, set on AC or SIMV
◦ Set inspiratory pressure limit, I-time, FIO2, PEEP,
Rate
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VC: Used in most patients, control minute
volume, set on AC or SIMV
◦ Set tidal volume, flow, FIO2, PEEP, rate
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PRVC: Becoming a common mode for most
patients, limits pressure and gives a
minimum volume, set on AC or SIMV
◦ Set minimum VT, pressure limit, FIO2, rate, peep, Itime
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Once you decide what mode and breath type,
next you input the settings.
VT: set in VC mode, based on IBW, normal
range 8-12 ml/kg, restrictive lungs 5-7
ml/kg
Flow: Set to give an appropriate I:E ratio,
typically 40-60 LPM, set higher for COPD
patients, watch for airtrapping
Pressure Limit: set to achieve an acceptable
VT, typically set between 15-25 cmH2O
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I-time: Decrease when rate is set high, otherwise
start around 0.8-1 second
Rate: Initial rates are 8-12 per min. If you
suspect or know patient has high PaCO2 you may
start higher
FIO2: typically set at 100% if it’s a new patient
and you do not know their PaO2, otherwise set
per patients FIO2 before vent if it was acceptable
PEEP: typically started at 0, and added once FIO2
is at 60% and patient has refractory hypoxemia,
then initiate at 5
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Pressure Support: If you started in CPAP or
SIMV mode, you will set a PSV. Typically
around 10-12 cmH2O, but give to increase
spontaneous Vte to acceptable ranges and
give enough to over come RAW
Sensitivity: Set as either flow or pressure. In
either one it is set between 0.5-3, the higher
this number the harder it is for the patient to
trigger the breath, the lower =auto trigger
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Flow pattern: In VC mode you can choose
how the set flow will be delivered to the
patient. Either as a constant flow (Square) or
as a decelerating pattern. In PC and PRVC the
flow is not set, so the pattern in always
decelerating. A constant flow will increase
MAP, this will increase oxygenation but
increase PIP
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Any time it is desired to limit inspiratory
pressure.
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High PIPs
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Low Pa02
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Need high, variable flow rates
Goals in ARDS
 ARDS goal - control/minimize lung
damage
 Literature suggests
– low alveolar pressure / low Vt strategy
– recently more concerned with lung
damage caused by over distention
– preventing repeated collapse and
reopening of alveoli
Treating ARDS
 What are your goals for these patients?
– O2 delivery
– oxygenation is more affected by MAP
– PCV, BiLevel, or APRV may be a better way
to approach these patients
 peak airway pressure and MAP is controlled
 oxygenation is favored
 ventilation is sacrificed if it conflicts with
controlling pressure
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Pressure Control is time cycled.
Rapid rise to set pressure and pressure is
maintained for the duration of the inspiratory
time.
Inspiratory plateau promotes alveolar
recruitment and oxygenation.
F E B 11 1996
W A V E F O R M M O N IT O R IN G
30
30
P A T IE N T
ID 98787987
13:50
Pressure
PressureTime
TimeCurve
Curve
Volume
Pressure
Volume
Expiration
Inspiratory Time
PPawaw
SSec
ec
cm
H 2 020
cmH
11
22
33
.
V
-10
A C C E S S F U N C T IO N 60 T O C H A N G E O R E X IT W A V E FO R M S
44
55
66
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Use the plateau
pressure obtained
during volume
ventilation as a
starting point (if you
started in VC first)
Adjust pressure to
obtain desired Vt in
the range of 5 – 8
cc/kg
“B” Represents Inspiratory Pressure
“A” represents PEEP
T
V
LITERS
.6
A
B
.4
“C” = Upper
Inflection point
.2
aw
P
cmH 0
2
“D” = Lower Inflection Point
60
40
20
0
20
40
60
Setting I-Time in PCV
 Observing the Flow and Tidal
Volume Time curve during PCV
can help determine adequate
inspiratory time.
 Observing the Pressure Time
curve will assist in determining if
the I -Time is too long
450cc
600 cc
VT
SEC
0
-20
120
1
2
3
4
5
6
.
SEC
V
1
LPM
120
2
3
4
5
6
450cc
600 cc
500cc
VT
SEC
0
-20
120
1
2
3
4
5
6
Lost VT
.
SEC
V
1
LPM
120
2
3
4
5
6
30
Assessing correct Inspiratory Time in PCV
Optimal
Paw
Sec
cmH20
1
2
3
4
Too Long
-10
Answer - Inspiratory time set too long
Patient is starting to exhale prematurely.
5
6
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Flow x Time = Volume
Increasing the I time can increase the Vt.
Try this before increasing the inspiratory
pressure.
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Watch for I time too long, causing auto
peep and dyschrony.
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Keep I time constant to maintain more
stable tidal volumes
The Pressure Control Mode
 Pressure Control
– Set high pressure =
PI
 PI is PEEP compensated
and changes as PEEP
level changes
– Set low pressure =
PEEP
– Set breath timing
parameters = TI, TE,
I:E ratio
Pressure Control
Rise TIme
 Commonly referred to as rise %, or
rise time
 Available in all pressure breaths (PC,
PS, and spontaneous)
 Tailors inspiratory rise to match
patient demand. Does not change I
time.
Rise Time %
 Commonly referred to as rise %, or rise
time
 Tailors inspiratory rise to match patient
demand
Rise Time %
Transient Overshoot
FAP = 1
= 100
FAP = 50
FAP
Pressure Relief
Expiratory Sensitivity
(ESens)
Peak Inspiratory Flow
V
40%
20%
5%
T