How To Ventilate ICU
Patient
Dr Mohammed Bahzad
MBBS.FRCPC,FCCP,FCCM
Head Of Critical Care Department
Mubarak Alkbeer Hospital
Aims
Get oxygen in
 Get carbon dioxide out
 Minimize adverse effects
 Maximize patient comfort

Case A
60 kg male
 Post operative – complicated wipel
procedure
 No previous lung or heart disease
 Still paralyzed

Make the ventilator fit the
patient
Mode
Non-invasive
 Invasive

–
–
–
–

Assist control
Pressure control
SIMV
(Pressure support)
Pick a mode you understand and are
familiar with
Assist control
Set tidal volume
 Inspiratory-expiratory cycling

– Time cycled
Time is set
 Ventilator adjusts flow to deliver set tidal volume in
the set time

– Volume cycled
Assist control

Breaths:
– Ventilator initiated (control breaths)
– Patient initiated (assist breaths)
– Set minimum frequency

Characteristics of each inspiration are the
same
– Not affected by whether breath is control breath
or an assist breath
Assist control
T
50 cmH2O
Pressure
70 l/min
Flow
-70
700 ml
Volume
Assist control
T
50 cmH2O
Pressure
70 l/min
Flow
-70
700 ml
Volume
Assist control

Set
– Minimum respiratory rate
Patient’s spontaneous respiratory rate < set rate 
ventilator gives additional control breaths to make
up difference
 Patient’s spontaneous rate > set rate  no control
breaths

Volume control

Set
– Minimum respiratory rate
– Tidal volume
Volume control

Set
–
–
–
–
Minimum respiratory rate
Tidal volume
Inspiratory time or I:E ratio
Inspiratory pause time
Volume control

Longer inspiratory time
– Improved oxygenation


Higher mean airway pressure
Re-distribution
– Lower peak airway pressure


More time available to deliver set tidal volume
Shorter inspiratory time
– Less risk of gas trapping and PEEPi
– Less effect on cardiovascular system
Setting I:E, inspiratory flow time,
pause time
Nomenclature
Volume

Time
Setting I:E, inspiratory flow time,
pause time

Nomenclature
Volume
Inspiratory flow time
Time
Setting I:E, inspiratory flow time,
pause time

Nomenclature
Volume
Inspiratory pause time
Time
Setting I:E, inspiratory flow time,
pause time

Nomenclature
Volume
Inspiratory time
Time
Setting I:E, inspiratory flow time,
pause time

Nomenclature
Volume
Inspiratory time
Time
Expiratory time
Setting I:E, inspiratory flow time,
pause time

Nomenclature
Volume
Respiratory cycle time
Time
I:E as a ratio & inspiratory pause time
as a percentage
6 secs
1
2
Volume
10%
Time
I:E as a ratio & inspiratory pause time
as a percentage
3 secs
1
2
 Respiratory rate
Volume
10%
Time
Absolute inspiratory time, inspiratory
flow time as a function of flow rate
6 secs
2 secs
4 secs
Volume
0.5 s
Time
Absolute inspiratory time, inspiratory
flow time as a function of flow rate
3 secs
2 secs
 Respiratory rate without
changing Inspiratory time or
inspiratory flow
1 sec
Volume
0.5 s
Time
Absolute inspiratory time, inspiratory
flow time as a function of flow rate
3 secs
2 secs
 inspiratory flow
1 sec
Volume
1.5 s
Time
Absolute inspiratory time, inspiratory
flow time as a function of flow rate
3 secs
1 sec
 Absolute inspiratory time
2 sec
Volume
0.5 s
Time
Inspiratory flow time as a function of
flow rate, absolute pause time
3 secs
2 secs
 Respiratory rate without
changing inspiratory flow or
inspiratory pause time
1 sec
Volume
0.5 s
Time
Inspiratory flow time as a function of
flow rate, absolute pause time
3 secs
1 sec
 inspiratory flow
2 sec
Volume
0.5 s
Time
Inspiratory flow time as a function of
flow rate, absolute pause time
3 secs
0.8 sec
 inspiratory pause time
2.2 sec
Volume
0.3 s
Time
Volume control

Set
– Minimum respiratory rate
– Tidal volume
– Inspiratory time or I:E ratio

Directly/indirectly
– Inspiratory pause time

Directly/indirectly
– PEEP
Assist control

Advantages
– Relatively simple to set
– Guaranteed minimum
minute ventilation
– Rests muscles of
respiration (if properly
set)

Disadvantages
– Not synchronized
– Patient may “lead”
ventilator
– Inappropriate triggering
may result in excessive
minute ventilation
–  lung compliance  
alveolar pressure with risk
of barotrauma
– Often requires sedation to
achieve synchrony.
Pressure control
Pressure preset assist/control ventilation
 Similar to volume control except pressure is
preset

Pressure
PC above PEEP
PEEP
Time
Volume
Flow
Time
Time
Pressure
Normal inspiratory time
Short inspiratory time
PC above PEEP
PEEP
Time
Volume
Flow
Time
Time
Pressure control

Advantages
– Relatively simple
– Avoids high
inspiratory pressures
– Rests muscles of
respiration
– Improved oxygenation

Disadvantages
– Not synchronized
– Inappropriate triggering
may  excessive minute
ventilation
– Change in lung compliance
or resistance  change in
tidal volume
– Often requires sedation
Pressure support

Nomenclature
– Inspiratory assist
– Assisted spontaneous breathing
Pressure
Pressure support
PS above PEEP
Volume
Flow
Maximum
inspiratory
flow
PEEP
Set % of max
inspiratory flow
Pressure support

Advantages
– Simple to set
– Avoids high
inspiratory pressures
– Better patientventilator synchrony
– Unloads respiratory
muscles

Disadvantages
– No apnoea back-up in
older ventilators
– Change in lung
compliance or
resistance  change in
tidal volume
Pressure support
Pressure support of 3.5-14.5 cmH2O
required to overcome the additional work
of breathing due to breathing through ETT
and demand valve
 Patients who require pressure support of <
6 cmH2O can probably be extubated

SIMV (& pressure support)

SIMV almost always combined with
pressure support
SIMV
Patient receives a minimum number of
mandatory breaths
 Able to breath in between these breaths

– ± pressure support breaths
SIMV
Mandatory
breath
Pressure
PEEP
Time
Flow
Time
Trig
Trig
SIMV
Pressure
support breath
Pressure
PEEP
Time
Flow
Time
Trig
Trig
Mandatory breaths

Volume control breaths
– Set tidal volume

Pressure control breaths
– Set pressure
Mandatory breaths

Synchronized with patients inspiratory
efforts
Triggering

Effect of triggering depends on its timing
– Close to time that a mandatory breath is due
(during SIMV period)

⇒synchronized mandatory breath
– Other times (during spontaneous period)

⇒pressure support breath
SIMV period
T
Spontaneous period
T
SIMV period
Spontaneous period
Settings


FiO2
SIMV rate
– =mandatory breath rate





SIMV period (some ventilators)
Tidal volume (or inspiratory pressure)
I:E ratio
Pressure support
PEEP
Volume control

Set
– Minimum respiratory rate
– Tidal volume
– Inspiratory time or I:E ratio

Directly/indirectly
– Inspiratory pause time

Directly/indirectly
– PEEP
SIMV & PS

Advantages
– Better patientventilator synchrony
– Guaranteed minimum
minute ventilation

Disadvantages
– Complicated mode
What mode?

Largely apnoeic patient
– Control of minute ventilation important

Assist control
– Control of peak pressure important


Pressure control
Intermittent spontaneous breaths
– SIMV

Regular spontaneous breaths, improving condition
– Pressure support
Case A
60 kg male
 Post operative – complicated wipel
procedure
 No previous lung or heart disease
 Still paralyzed

Mode
Volume Control
Admit
patient
Automode
Nebulizer
Set ventilation mode
Volume control
I:E
500
1:2.0
Resp. Rate
T. pause
12
10
5
Ti =1.33 s (33%)
Save
I:E
Tidal volume
PEEP
Alarm
profile
12-25 15:32
Automode
Basic
Status
Trends
i
Trigger
.
Trigger sensitivity
V
Quick
start
T. Insp. rise
5
Menu
Main
screen
O2 conc.
100
.
Cancel
Accept
Additional
values
!
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
54
Assess
Chest movement
 Breath sounds
 Saturation

pH
7.23
PaCO2
8.1 kPa (61 mmHg)
PaO2
54.9 kPa (413 mmHg)
HCO3-
26 mmol/l
Base excess
+3
Saturation
100%
Alveolar ventilation  RR x (V - V )
T
D
Increasing alveolar ventilation

Increase tidal volume
Flow x resistance

(Volume/compliance)
+ PEEP
Increase respiratory rate
– Increase risk of gas trapping
Mode
Volume Control
Automode
Admit
patient
Nebulizer
Status
12-25 15:32
Recording
50 cmH2O
Ppeak
Pplat
Pmean
Basic
70 l/min
Alarm
profile
I:E
Trigger
PEEP
34
28
12
5
Save
i
12
100
0
1:2.0
RR
O2
Vee
I:E
Moderately high
Pplat
Quick
start
-70
700 ml
MVe
MVi
VTi
VTe
Additional
settings
Trends
6.0
6.1
501
471
Menu
Main
screen
.
Additional
values
!
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
58
Mode
Volume Control
Admit
patient
Automode
Nebulizer
Set ventilation mode
Volume control
 Resp
rate
I:E
500
1:2.0
Resp. Rate
T. pause
15
10
5
Ti =1.33 s (33%)
Save
I:E
Tidal volume
PEEP
Alarm
profile
12-25 15:32
Automode
Basic
Status
Trends
i
Trigger
.
Trigger sensitivity
V
Quick
start
T. Insp. rise
5
Menu
Main
screen
O2 conc.
50
.
 FiO2
Cancel
Accept
Additional
values
!
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
59
Case A
Patient starts to wake up
 Triggering ventilator frequently

– some breath stacking

Change to pressure support mode
Mode
Volume Control
Admit
patient
Automode
Nebulizer
Set ventilation mode
Status
Alarm
profile
12-25 15:32
Pressure support
Save
Basic
I:E
PS above PEEP
T. Insp. rise
15
5
Trends
i
Trigger
.
Trigger sensitivity
V
PEEP
Insp. cycle off
5
5
Quick
start
O2 conc.
40
Menu
Main
screen
.
Cancel
Accept
Additional
values
!
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
61
Other settings

Trigger sensitivity
–  sensitivity preferable
Flow triggering generally more sensitive than
pressure triggering
  flow or  pressure   sensitivity

Assess
Chest movement
 Respiratory rate & effort
 Saturation

Mode
Volume Control
Automode
Admit
patient
Assess
Nebulizer
Status
Ppeak (cmH2O)



Respiratory rate
Tidal volume
Synchrony
Blood gases
Additional
settings
Save
40
20
Pmean

Alarm
profile
i
12
5
PEEP
Trends
RR (b/min)
10
O2 (%)
46
40
MVe (l/min)
7.1
34
Quick
start
8.5
Menu
VTi
701
VTe
693
Main
screen
.
Additional
values
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
Case B
72 year old, 60 kg man with history of
asthma
 Presents with severe bilateral pneumonia

Mode
Pressure Control
Automode
Admit
patient
Nebulizer
Case B
Status
Ppeak (cmH2O)




Pressure control mode
FiO2 1.0
Insp pressure 10 above PEEP 5
RR 20
I:E= 1:2
Additional
settings
Save
40
15
Pmean

Alarm
profile
i
12
5
PEEP
Trends
RR (b/min)
20
O2 (%)
100
100
MVe (l/min)
4.1
94
Quick
start
8.5
Menu
VTi
201
VTe
193
Main
screen
.
Additional
values
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
Mode
Pressure Control
Automode
Admit
patient
Nebulizer
Case B
Status
Ppeak (cmH2O)




Pressure control mode
FiO2 0.6
Insp pressure 20 above PEEP 5
RR 20
I:E= 1:2
Additional
settings
Save
40
25
Pmean

Alarm
profile
i
12
5
PEEP
Trends
RR (b/min)
20
O2 (%)
66
60
MVe (l/min)
8.1
54
Quick
start
8.5
Menu
VTi
501
VTe
493
Main
screen
.
Additional
values
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
Case B
pH
7.43
PaCO2
5.1 kPa (38 mmHg)
PaO2
6.9 kPa (52 mmHg)
HCO3-
22 mmol/l
Base excess
-2
Saturation
84%
Look for causes of desaturation
Chest movement
 Breath sounds
 Ventilator malfunction
 CXR

Mode
Pressure Control
Automode
Admit
patient
Nebulizer
Improving oxygenation
Status
Ppeak (cmH2O)
Options ?
–
–
–
–
Additional
settings
 FiO2
 inspiratory pressure
 inspiratory time
 PEEP
Save
40
25
Pmean

Alarm
profile
i
12
5
PEEP
Trends
RR (b/min)
20
O2 (%)
66
Mean alv pre 60
MVe (l/min)
8.1
54
Quick
start
8.5
Menu
VTi
501
VTe
493
Main
screen
.
Additional
values
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
Mode
Pressure Control
Automode
Admit
patient
Nebulizer
Status
Improving oxygenation
Alarm
profile
Ppeak (cmH2O)
25
Pmean

Options ?
–
–
–
–
Additional
settings
 FiO2
 inspiratory pressure
 inspiratory time
 PEEP
Save
40
i
12
5
PEEP
Trends
RR (b/min)
20
O2 (%)
66
60
MVe (l/min)
8.1
54
Quick
start
8.5
Menu
VTi
501
VTe
493
Main
screen
.
Additional
values
Start
breath
O2
breaths
Exp.
hold
Insp.
hold
Re-assess
Pulse oximetry
 Arterial blood gas

Summary
Chose the mode that fits the patient
 Set the ventilator to achieve your aims
 Often more than one way to achieve your
aims

– Select the method with the least adverse effects
Thank You