2000 ventilator made easy aglan

VENTILATOR MADE EASY
BY
DR.A. AGLAN MD.
CRITICAL CARE DEPARTEMENT
ALEXANDRIA UNIVERSITY


CONTRIBUTING AUTHERS


*** CONTENTS
* Introduction--------------------------------------------------------------- p.

Chapter 1* What is a ventilator? ---------------------------------------p.

Chapter 2* The respiratory system-------------------------------------p

Chapter 3* Ventilation---------------------------------------------------p.

Chapter 4* Patient – ventilator inter action--------------------------p.
Chapter 5* Complications of invasive ventilation---------------------p.
Chapter 6* Monitoring the patient on a ventilator---------------------P.

Chapter 7* Ventilation of special cases----------------------------------p.

Chapter 8* Endo tracheal entubation---------------------------------p.

Chapter 9* Drugs used during ventilation------------------------------p.
Chapter 10* Care of ventilated patient---------------------------------------p
Chapter 11* Nutrition of mechanically ventilated patient……………..P
Chapter 12* In- hospital transport of mechanically ventilated paient..

Chapter 1

WHAT IS A VENTILATOR?


WHAT IS A VENTILATOR

** Definition;
It is a machine designed to alter, transmit, and direct applied energy in a
predetermined manner to augment or replace the patient s muscles in performing the
work of breathing.

**Composition;
*It is formed of 5 parts:1- Power input : - a – Electricity 220 v or 110 v
b – Gases O2 & air 3~ 5 bar
2- Power transmission to down regulate electric and gases load to the control
circuit
3-Controle circuits,. It may be mechanical, pneumatic, fluid, electric, and or
electronic.
** All the above three parts are engineering problems.
4- Control variables.
* The main function of the ventilator is to deliver air to the patient,
and the physical characters of air which are changeable are called variables. These are
the flow, the volume, the time, the pressure, and the oxygen concentration (FiO2)
* These variables are preset by the operator as value and shape
depending on the mode and the type of the ventilator.
Pressure
.

5 – Phase variable
Limit or Target
Cycle off
Flow- Volume- Pressure- Time

Baseline
PEEP or Atmospheric

Rising time

Inspiratory pause

Trigger
Flow- Pressure- Time - Volume
*
The ventilator does not know the pattern of respiration, so it has been
programmed to understand the phases of respiration which has been divided into 4
phases as follow:-


1- Change from expiration to inspiration = triggering
2- Inspiration = limits or target
3- Change from inspiration to expiration = cycle off
4- Expiration = baseline
* With each phase of the cycle any of the variables can be used
(Time, Volume, Flow, or Pressure.)

**Let us go and sea how the ventilator reacts and responds to the patient
efforts.
1- The patient starts to take inspiration by making change in the flow,

pressure, or volume which is sensed by the demand valve of ventilator which opens
whenever it reached the preset value
* Sure each ventilator has its own demand valve system which responds
to flow, pressure or volume.
*If the patient is paralyzed the ventilator will start inspiration
automatically by time (60/RR) /min.
2- Then after opening the demand valve air flows to the patient , but the
machine asks you please how fast you need this flow? .This means that you have to
preset the flow ( peak flow ) or the rising time.
3- Then the ventilator asks again please the flow to the patient developed
pressure as a result of the resistance and compliance please would you set a limit to
this pressure as an alarm or would put a maximum not to be exceeded this means you
have to put the p. limit or the p. max.
4- A good question comes from the ventilator; please this phase should be
terminated (cycled) please can you set a time or a flow or a pressure or a volume..
a- You can inform (set) the ventilator please close the inspiratory limb after
a set VT. and keeps this VT in for some time ( inspiratory pause ) and then later open
the expiratory valve, or open the expiratory valve immediately after the closure of the
inspiratory limb ( no inspiratory pause ) ( volume targeted type as BENNET )
b- Please close the inspiratory limb after certain time (Ti), take a pause or
not and then open the expiratory valve ( pressure targeted ,time cycled as ADULT
STAR ) . A question comes from the ventilator what about the VT ? I should answer
that the VT will be adjusted via manipulating the target pressure, the flow ,the rising
time ,and the Ti in addition to the parameters of the lung (compliance & resistance )
c- You have a pressure target which should not be exceeded please close the
inspiratory limb after delivery of the preset VT, and then open the expiratory valve
after the elapse of the Ti. (DRAGER) . What will happen when if?
1- The Ti is longer than the time for the preset VT? An inspiratory
pause will be developed.
2 –The Ti is the same as that for the preset VT? No inspiratory pause

will appear.
3- The Ti is less than that of the preset VT? a volume less than the
preset VT will be delivered and an alarm will signal. So you have to adjust by either
in creasing the Ti, or increasing the target pressure, or increasing the flow.
5- The last question of the ventilator please, shall I allow all the VT to be
exhaled totally and reach the atmospheric pressure or shall I keep some air inside
(above the FRC) to produce a preset pressure above the atmospheric pressure at the
end of expiration (PEEP) . So you have to set the value of the PEEP or not.
** From the phase variable 2 items have emerged;

A- The types of respiration;
** As we have mentioned before that the phase variable is formed of four phases , the
trigger and the cycle phases which could be a patient or a machine function but the


limit and the base phases are only a machine function .Accordingly, we have divided
the respiratory cycle of the ventilator into two types :1- Spontaneous
2- Mandatory
1-SPONTANEOUS CYCLE
** This means that the patient starts (trigger) and terminates (cycle off) the
inspiration.
** This means that the inspiratory time is that of the patient (neural time), which is
determined by the patient and no rule for the machine Ti and accordingly no
mismatching with the ventilator.
** This type of respiration can be supported by the ventilator as in PSV where the
triggering and cycling are of the patient but the limit is aided by the ventilator
** Trigger may be by use of pressure or flow sensor valve according to type of the
ventilator used.
** Termination of inspiration (cycle off) is determined by the device built in the
ventilator and these may be: 1- Increase in expiratory flow 1-2 L/m above the inspiratory flow level

2- Increase in expiratory pressure 1-2 cmH2O above the inspiratory level.
** What are the factors which determine the value of the VT.? ?
* VT is determined by: 1- Patient inspiratory time
2- Pressure support of the ventilator
3- Lung compliance and resistance 4- Patient drive
* So it is the pressure gradient developed between the negative
pressure developed by the drive, inspiratory pump, and lung compliance of the patient
and the pressure support developed by the ventilator.
** Can I make any change in this VT??
* Sure yes, you can adjust VT by adjusting the pressure support in (PSV ) or
(PEEP) IN CPAP ,and the difference between the high PEEP and low PEEP in
BiPAP.
*

2- MANDATORY CYCLE


** There are two types:
1- Triggering and cycling are done by the ventilator as in paralyzed patient
(CMV)

2- The patient triggers but the ventilator terminates (cycle off) the inspiration, so
it is a share between both the patient and the ventilator (ACV)
* How does the ventilator end the cycle?
This is built in device in the machine which may be;
1- Volume, when a preset VT is achieved
2- Flow, when the flow drops to 5L/ m or the flow drops to 25% of
the peak flow.
3- Time, when the machine Ti (preset Ti) is achieved.
* It is clear that the ventilator does not sense the start of the patient

expiration and even is not sensitive to the termination of the patient inspiration.
This means that the neural Ti will not match the machine Ti and so mismatch will
occur leading to a lot of problems
*What about the respiratory rate?
* Sure it is that of the patient which is affected by the set flow, set
VT, and the ventilator Ti.
* What about the VT. ?
* In volume targeted pressure limit, it is the preset VT.
* In pressure targeted, volume controlled, time cycled it is the
preset VT.
*In pressure targeted, time cycled, I/E cycled it will depend on the
target pressure, flow, Ti, I/E, and patient parameters

Ventilator Breaths And Phase Variables
Type Of Ventilation

Trigger

Limit

Cycle


Mandatory
Assisted
Supported
Spontaneous

Machine
Patient

Patient
Patient

Machine
Machine
Machine
Patient

Machine
Machine
Patient
Patient

B- The types of the respiratory cycle (types of ventilator)
** Positive pressure (which supply air with positive pressure through the ETT.),
and negative pressure ventilator (which produces negative pressure around the
chest wall )
**Ventilators have been divided into two types according
to the target undependable fixed variable:2- Pressure targeted
1- Volume targeted
** This division has been built on the relation between the VT, PL., and the
compliance which is controlled by the flowing equation;C = VT / PL
* It is clear from this equation that you will adjust the variables where the parameter
C is fixed, so in one ventilator you will set and change the VT and accordingly the P
will change according to the C (volume targeted), and I the other one you set or
change the P( P max) and accordingly the VT will be determined by the C( pressure
targeted)
** Volume targeted ventilators delivers VT irrespective to the state of C. or the
degree of change in the PL. So when the C is bad the PL, and accordingly the PIP will
be high, but when the C is good the PL, and PIP will not be increased much as in the

following diagram
*


So in cases of bade (low) C. when the preset VT is delivered the PL. will increase
too much and this may expose the alveoli to over distension and volutrauma.
Also, if the patient developed Pneumothorax, the VT will be delivered totally
leading to more increase in the pleural pressure pressing on the cardiac fossa to
produce cardiac tamponade. The patient will die from C.V. collapse
The monitor in such type will be the PL. and the homodynamic
Such ventilators are harmful to infants and children
*.
**PRESSURE TARGETED VENTILATORS:The maximum pressure is preset; this sealing pressure is not exceeded by any mean.
The tidal volume for sure will be determined by the following:1 –the compliance 2- the preset pressure 3- the flow 4 – the inspiratory time
So increase or decrease of any of the above will be associated with increase or
decrease of the VT as is demonstrated by the following diagram

*
In case of Pneumothorax with the same setting of flow, pressure, and time the VT.
will decrease and the patient will develop hypoxia.
So the monitor in such type will be the change in the VT. and blood gases (O2 & CO2)
Such ventilators are safer regarding volutrauma.
In certain ventilators as ADULT STAR the VT is not preset but it is the result of the
empirical values of the preset variables, FLOW, PR., and Ti .which match the
compliance of the patient. So adjustment of these variables is needed to reach to the
desired VT.
In other ventilators as DRAGER the VT is preset so called volume controlled, where
the inspiratory limb of the ventilator is closed after delivery of the preset VT and the
expiratory limb is opened after the lapse of the Ti. This means that you will face one
of three situations:1- The VT is delivered in a time less than Ti so the difference will be

inspiratory pause
2- The VT is delivered in a time equal to the Ti so there will be no inspiratory
pause


3- The Ti is less than the time required to deliver the preset VT. So a part of the
preset VT is delivered and the expiratory limb will open to end the cycle (inspiration).

** THE CONTROL PANEL

** The control panel of any ventilator should contain three items
A- Panel for the set values and this include:
1- Control variables where you set the, VT, F. R., FiO2, Ti, I: E,
Pmax, and R.R
* *VT
* Its value is determined by the lean body weight, BMR, metabolic state, and CNS
activities, and accordingly should be adjusted with RR to define the needed MV for
control of PCO2 or PH
* The value of the VT is usually 10 -15 ml/kg for normal lung, but it is 5 -6 ml/kg for
COPD, bronchial asthma, and ARDS
** F.R.
* Should be adjusted to be the same as the patient drive
* The set value is usually 40 – 60 L/m for adult
*It determines the value of the Ti in volume target and pressure target
volume controlled, and VT in pressure target time controlled
* An increase in the flow rate is associated with an increase in the patient
R.R. and vice versa
* It is the variable for changes in the pressure resistance
* It is used to define the rising time
* Flow triggering and flow by system are important advances to decrease

the work of breathing and to over come the tube resistance
*Decelerating wave form is associated with an improved gas exchange
and a lower peak airway pressure
** FiO2
* Certain important points should be considered and these are;
* When you start ventilation you should start with 100% O2 for 20 -30 min then
decrease gradually every 20 min to be below the toxic threshold 60% with SaO2
.90% or to reach to the least FiO2 with SaO2> 90%
* FiO2 of 100% should be given 3 min before and after suctioning to increase the O2
reserve capacity and avoid desaturation and hypoxia
*Avoid FiO2 of > 60 % to avoid O2 toxicity
* You can calculate the oxygenation indices from the FiO2 and these are; the A- a
gradient, shunt, PaO2 / FiO2, and PaO2 / PAO2
** Ti
*It is determined by the preset VT and FR in the volume target ventilator
* It is preset in the pressure target ventilator
* The total Ti = Ti + inspiratory pause
* You should consider the back up Ti (constant Ti) when you change from CMV
to A / C when the patient takes higher rate to avoid the decrease in the Te
complications and fighting the ventilator
** I: E
*It is the inspiratory and expiratory time ratio


* I: E of about 1: 2 is optimal because it limits gas trapping and mean intra
thoracic pressure
*In the volume target ventilator it is determined by the preset VT and FR ( Ti)
and the RR ( Te)
* In the pressure target it is determined by the preset Ti and RR
* Inversed ratio I: E (2: 1 or more) sometimes used to improve oxygenation by

improving gas distribution and opening atelectatic alveoli, and this can be done
through increase Ti, decrease FR or adding inspiratory pause
** R.R.
* It should be around 20 b/min in adult to decrease the shear force
* It should not exceed 35 b/ min to avoid, CO2 wash out, shallow breathing, or
respiratory fatigue
* Low RR in both COPD and bronchial asthma is important to increase the Te
* The mandatory rate in SIMV is decreased gradually while weaning the patient
** Pmax
*It is set in the pressure target ventilator
* It should not exceed the value of 45 cmH2O
* You should keep in mind that our target pressure is the PLP which should
not exceed 35 cmH2O to avoid volutrauma
* It has a good share in determining the VT in the pressure target ventilator
.
2- Phase variables where you set:
** Trigger value
* The usual value is 2 – 3 cmH2O for the pressure triggering
* In flow triggering its value should be less than the basal flow
* Try to avoid low value of triggering to avoid the outotriggering problems
* High value of triggering will lead to increased working of breathing and
non triggering
** Rising time
* It is the time taken to reach to the target pressure
* Decrease in this time means increase in the flow and vice versa
* It determines the value of the starting flow which should match the patient
drive, and this can adjusted from the P – T curve
* It affects the total Ti
* The starting value is 0.2 sec
** P max

* It is mentioned before
* Cycling
* It may be volume, time, flow, or pressure depending on the ventilator and
the type of the respiration whether mandatory or spontaneous
** PEEP
* You set the desired PEEP which should be 1 – 2 cmH2O, above the lower
inflection point, or the super imposed pressure or to be 85% of the PEEPi
* Keep an eye on the hemodynamic effects of this PEEP
3- Conditioned variables;


** It is the response of the ventilator to certain change in the control variable in a
conditioned way.
** If some changes happened the ventilator responds in a preset way
** Example,
1- apnic ventilation, you preset the condition that if the patient
respiratory rate decreased to 8 b/ m. or the expiratory time exceeded 10 sec. the
ventilator should shift to the controlled(apnic) mode of ventilation. You set the
triggering values and the back up data for CMV
2- Sigh, you preset the condition that after each 15 sec. the VT
should of the value 800 ml. You set the rate (single or multiple) and the value of the
sigh volume
4- Flow wave forms where you select one of them

*
5- Modes of ventilation where you select one as CMV, A/C, SIMV,
BiPAP, CPAP, PAV…

B- Panel for the alarm system as:
* High and low values for the pressure, VT, MV, and R.R.

* Failure of the device, the O2 supply, and the compressed air supply
*


*


*

*


*

C- Out put data (patient data):
1- Variables;
* Expiratory VT
* Patient R.R.
* PIP
* PL.P.
*Mean airway pressure
2- Parameters;
* These parameters are usually calculated from the variables data or might be
calculated automatically by the ventilator and these are;
* Resistance
* Compliance
* Dead space
*Shunt
* Oxygenation indices
* Respiratory drive * Muscle power

* Triggering
* Muscle endurance

** 1- VARIABLES
** Expiratory VT changes;
* VT should be the same as the set one or may be less due to the minimal leak
* VT may be larger than the set value, by the value of the volume loss in the
expansion of the patient circuit as in Adult star where the delivered volume equals the
set VT + the volume loss in the expansion of the patient circuit( PL.P X C. of the
tube)
* VT may be less than the set value due to;
* Leak or disconnection of the patient circuit, ETT and its cuff, and or the
I.C. tube


* Increase in resistance, decrease in the compliance, and closed
pneumothorax in pressure target types of ventilators
* VT in spontaneous and supported breathing is;
A- increased in;
* Increase in compliance
* Decrease in resistance
* Increase in P.S. value
* Increase in respiratory muscle pump
B- decreased in;
* Decrease in compliance
* Increase in resistance
* Decrease in P.S. value
* Decrease in respiratory muscle pump

** PIP (peak inspiratory pressure& plateau pressure)

*
* * A change in the PIP by increase or decrease should direct us to screen the
following four points;
1- The patient circuit, for kink, obstruction, leak, or disconnection
2- The ETT, for disconnection, kink, being bitten by the patient, obstruction by
secretion, cuff leak, cuff herniation, or the tube in the right bronchus
3- The conducting tube for the proximal airway pressure for disconnection,
kink, mal function of the diaphragm, or presence of water in its lumen
4- The patient for, bronchospasm, decrease in compliance, closed
pneumothorax, or I.C.T. leak
* When we keep in mind that P res. = FX R, we can define the causes of its increase
as kink, obstruction, or spasm, and at the same time when know that Pel. =VT/ C, we
can define the causes of its increase as decrease in compliance, hyperinflation, or
PEEPi

** Mean airway pressure (MAP)
* MAP is a formula which is formed from the following equation;


MAP = PIP X Ti / T total + PEEP X Te / T total
* It is a good guide for the adjustment of ventilator setting
* Increase in MAP is associated with an increase in oxygenation not related to I: E
ratio or PEEP
* MAP is increased due to;
* Increase in VT (which causes increase in PLP and accordingly PIP)
* Increase in RR (with decrease in Te leading to air trapping and PEEPi)
* Decrease in FR (with increase in Ti)
* Addition of inspiratory pause (with increase in Ti)
* Employment of decelerating flow (with high starting flow leading to

high PIP)
* Addition of PEEP

** PEEP
* It is meant to keep alveoli open
* Its value should be 1 – 2 cmH2O above the lower inflection point or the super
imposed pressure (> 7.5 cmH2O)
* Take care of its effect on the hemodynamic state
* It should be 85% of the PEEPi to decrease the inspiratory load
* It is an important item to improve oxygenation, so it should be handled carefully
with FiO2
**Respiratory rate (R.R.)
* It is set in the CMV, but changes with the assisted and spontaneous ventilation
**** High R.R. may be due to;
* Central stimulation (chemical) as acidosis, hypoxia, hypercarbia, or
C.N.S lesion
* Mechanical stimulation as
* Increase in spasm
* Obstruction
* Increase in flow
* Increase in sensitivity with auto triggering
* Lung parenchymatus lesion as consolidation
*Non synchronization
**** Low R.R .may be due to;
* Central inhibition as brain lesion, drugs, or CO2 washout to be below
the apnic threshold
* Mechanical causes as;
*High VT
* None triggering due to;
* Decrease patient drive

* Decrease respiratory muscle power
* Hyper inflation
* PEEPi
* High sensitivity of the ventilator trigger
*** R.R. > 35 b / min is a good criteria for weaning failure

** Inspiratory pause
* It is also called inspiratory hold where you close the inspiratory limb but at the same
time the expiratory limb is kept closed for certain time. This time is set by the
operator in the volume target machines, but is developed in the pressure target


ventilators by the difference between the set Ti and the time spent for the delivery of
the set VT
* It should be noted that it is added to the Ti and so can change the I: E ratio
* It can have some share in the development of PEEPi through incomplete exhalation
recoil (expiration) due to loss of inspiration energy as heat during that time
* It is used to study the compliance by measuring the plateau pressure
* Its time should be short (0.2 sec) if not used for I: E changes

** 2- PARAMETERS
* Resistance
*We have two types of resistance, one inspiratory and the second is the expiratory
* The inspiratory resistance measured is the total one which is due to the resistance of
air flow in the tube circuit, the ETT, and the large bronchial tree. This resistance can
be measured from the difference between the PIP and PLP and this is the Pres and
according to the equation P = F X R you can calculate the inspiratory resistance. This
Pres changes will affect the PIP in the volume target ventilator where its increase will
increase PIP and the reverse is correct, but in the pressure target ventilator its increase
will encroach on the PLP and not the Pmax (which is fixed) and accordingly the VT

will be the one to decrease and also the reverse is correct. The increase in such
resistance is usually due to kink, secretions, obstruction, or spasm
* The expiratory resistance is usually due to spasm of the small bronchioles as in
wheezy chest (bronchial asthma). Since P = F X R , the pressure will be the starting
pressure at the beginning of expiration which is the PLP, and the flow will be that
flow measured at the flow time curve recording the starting highest flow, so you can
calculate the expiratory resistance. So the increase in expiratory resistance will not
make change in the Pres but through its hyperinflation effect it will increase PLP with
increase in the PIP in the volume target ventilator but it will decrease the VT in the
pressure target ventilator

* Compliance
* It is a change in volume per unit change in pressure
* It is measured from the equation; C = VT (ml) / (PLP – PEEP) cmH2O
* The normal compliance is;
* Newborns
3 – 5 ml / cmH2O
* Infants
10 -20 ml /cmH2O
* Children
20 -40 ml /cmH2O
*Adults
70 – 100 ml /cmH2O
* Decrease in C will appear as an increase in the PLP in the volume target ventilators,
but VT decreases in the pressure target
* In adults, adjustment of the VT, in volume target ventilator, should be calculated to
avoid PLP > 35cmH2O

* Oxygenation indices
* They are measured to assess the efficacy of the lung for gas exchange

* Alveolo arterial oxygen gradient (A – a), with normal value of FiO2 X age + 2.5
* Arterial – inspired FiO2 ratio (PaO2 / FiO2) which exceeds 400, whatever the FiO2,
but it is < 300 in ALI, and <200 in ARDS and its weaning threshold should be > 350
* Arterial – alveolar O2 tension ratio (PaO2 /PAO2) which is >0 .8 but the weaning
threshold should be > 0.35
* Respiratory index (PAO2 – PaO2 / PAO2)
* Dead space is between 33% and 45% of the VT and the weaning value
should < 60%. It is increased mainly with pulmonary embolism
* Shunt fraction can be measured from the equation = O2 content of
capillary blood – O2 content of arterial blood / O2 content of capillary blood – O2
content of mixed venous blood or can be calculated from the equation of A – a / 20 at
FiO2 100%. The normal value is < 10% and the weaning value should be < 20%
* Neuro- muscular functions
* Respiratory drive can be measured in both conscious and unconscious
patients but not in paralyzed one, by airway occlusion pressure at 100msc (p0.1). Its
normal value = 0.95 cmH2O, and an increase in this value is an indication of the
respiratory distress with encroachment on the reserve capacity which might not be
doubled by inhalation of CO2 of 3% to give failure of weaning at >4 cmH2O
* Muscle power, which can be defined by measuring NIP which should be >
30 cmH2O to wean the patient
* Triggering, can be a good monitor as a parameter when you watch the non
triggering with low sensitivity (equals weak respiratory muscles), in addition to
measuring the P0.1 sec for assessment of the patient drive
* Muscle endurance, is a good monitor for the sustainability of the
respiratory work indefinitely, and this can be measured from the equation PTI which
should be less than 0.15 for weaning (normal value = 0.02)

MODES OF VENTILATION

** It is defined as a particular set of:1- Control variable.
2- Phase variable
3- Conditioned variable
4- Respiratory cycle type
5- Type of respiration


** There are different modes of ventilation which increases with time due to the
advance in technology and the more understanding of the respiratory physiology.
** Some modes are common and present in the majority of ventilators and these will
be dealt with in more details.
** These modes are:* CMV (Controlled Mandatory Ventilation)
* A/ C (Assisted Controlled)
* PSV (Pressure Support Ventilation)
*CPAP (Continuous Positive Airway Pressure)
*BiPAP (Bi-level Positive Airway Pressure)
*SIMV (Synchronized Intermittent Mandatory Ventilation)
*PAV (Proportional Assist Ventilation)
*The data of each mode is selected from each of the above 5 items

**** CMV volume target
Preset flow
PIP is determined by R., C,
and preset VT. Pressure limit
is an alarm
Time triggering
VT is constant and preset
and is delivered whatever R
or C is

*
* Type of the ventilator (respiratory cycle)
Volume T
Pressure T. Volume CON.

Pressure T. Time CY.

* Type of respiration
Spontaneous
Mandatory
Assisted mandatory
*It is used when the patient is apnic or on muscle relaxant
*The job is totally of the ventilator
* Control variables
VT
FLOW
Ti
PR. LIMIT
PR. TARGET
RR
FiO2
*You will set the, VT, flow, the value of the pressure limit, respiratory rate, and
FiO2
* The Ti will be indirectly determined by the set VT and flow
* Phase variables
Trigger
Limit
PR F Time
PR.

Cycle
Insp.Pause
V.
Time +
--

PEEP
+
--


* The trigger will be by time determined by the respiratory rate and you will set the
pressure limit as an alarm, the VT, and you may add inspiratory pause or not, PEEP or
not.
* Conditioned variables
Apnea data
Trigger
CMV

Sigh
Rate/min

Single/Multiple

VT

*No apnea data because this mode is an apnic mode, and you can select the sigh data
or not

***CMV pressure target volume controlled

* Type of the ventilator (respiratory cycle)
Volume T
Pressure T. Volume CON.
** Type of respiration
Spontaneous
Mandatory

Pressure T. Time CY.
Assisted mandatory

** Control variables
VT
FLOW
Ti
PR. LIMIT
PR. TARGET RR
FiO2
*You set the, VT, flow, Ti, PR target, RR, and FiO2
*VT will be determined by the flow, target pressure, and patient compliance.
* Ti you set may be the same time for the set VT, or larger to give an inspiratory
pause, or less than it and in this case the set VT will not be delivered totally
* * Phase variables
Trigger
Limit
Cycle
Insp.Pause
PEEP
PR F Time
PR.
V.

Time +
-+
-* The limit will be a target
* In the cycle the inspiratory limb will closed after delivery of the set VT, but the
expiratory limb will open after the lapse of the Ti
*Inspiratory pause will appear when the Ti is larger than the time consumed for the
delivery of the set VT
•
** Conditioned variables
Apnea data
Trigger
CMV
* The same as before

Sigh
Rate/min

Single/Multiple

VT


*
Pmax

* Increase in the VT is associated with increase in its delivery time to decrease the
inspiratory pause and increase the PLP and accordingly the PIP so long as it is below
the Pmax
*

*Increase in the Ti will be associated with increase in the inspiratory pause


*
* Increase in the flow is associated with decrease in the delivery time of the VT with
an increase in the inspiratory pause, and increase in the Pres and accordingly PIP
Pmax 1
2

Pmax3

*
* When the Pmax -1 is above the PIP the set VT is delivered totally, but when the
Pmax-2 becomes just above the PIP, delivery of the VT will take longer time which
might encroach on the inspiratory pause, and finally when the Pmax 3 is lower than
the PIP the set Ti will not be sufficient to deliver the set VT with loss of the
inspiratory pause
*

***CMV pressure target
*

* Type of the ventilator (respiratory cycle)
Volume T
Pressure T. Volume CON.

Pressure T. Time CY.

** Type of respiration
Spontaneous

Mandatory
Assisted mandatory
*It is used when the patient is apnic or on muscle relaxant
*The job is totally of the ventilator
*** Control variables


VT
FLOW
Ti
PR. LIMIT
PR. TARGET RR
FiO2
*In this ventilator the VT will be determined by manipulation of the, flow, Ti, and
the target pressure in face of the lung compliance
* * * Phase variables
Trigger
Limit
Cycle
Insp.Pause
PEEP
PR F Time
PR.
V.
Time +
-+
-* The pressure is a target
* The inspiratory limb closes and the expiratory limb opens simultaneously at the end
of the set Ti
*Conditioned variables

Apnea data
Sigh
Trigger
CMV
Rate/min
Single/Multiple
VT
The same as before
•

*
•
* The set Pmax is reached according to the set rising time or flow rate.
* The VT is determined by the set Ti, FR, Pmax, and C of the lung
* Increase in the Pmax is associated with increase in the VT as seen in the curve

*** A/C (ASSIST/ CONTROL)