Post on 26-May-2018
Recognizing Patient-Ventilator
dyssynchrony
D. Georgopoulos, Professor of Medicine,
Intensive Care Medicine Department,
University Hospital of Heraklion,
University of Crete,
Heraklion, Crete, Greece
Using the ventilator screen
(flow, volume, airway pressure)
PmusI
V’I
Alveoli
Airway
Pres=V’I x Rrs (Resistive pressure)
Pel = ΔV1 x Ers (Elastic pressure)
ΔV1
PmusΙ = ΔVxErs + V’xRrs
Pel
(elastic pressure)
Pres
(resistive pressure)
Paw (Ventilator pressure)
Paw
+
-PmusE
Passive FRC
Pel = -ΔV2xErs
ΔV2
Pres = -VE’xR
V’E
PmusI
V’I
Alveoli
Airway
Pres=V’I x Rrs (Resistive pressure)
Pel = ΔV1 x Ers (Elastic pressure)
ΔV1
Paw + PmusΙ = ΔVxErs + V’xRrs
Paw (Ventilator pressure)
-PmusE
Passive FRC
Pel = -ΔV2xErs
ΔV2
Pres = -VE’xR
V’E
Think the applied pressures
as well as their directions
and observe Paw, flow and volume
Positive values
PmusI, Pel above FRC, Pres (V’I)
Negative values
PmusE, Pel below FRC, Pres (V’E)
Equation of motion with common
modes of assisted mechanical
ventilation
• Assist volume control
(AVC, VT constant)
• Pressure support or pressure control
(PS, PC, Pressure constant)
Pventilator + Pmus = V’xRs + VxErs
Equation of motion
Mechanical ventilation
Volume control
Independent variablesDependent variable
-1
-0,5
0
0,5
1
1,5
2
0 0,1 0,2 0,3 0,4 0,5
0
10
20
30
40
50
60
0 0,1 0,2 0,3 0,4 0,5
-8
-6
-4
-2
0
2
4
6
8
10
12
0 0,1 0,2 0,3 0,4 0,5
Pm
us
(cm
H2O
)P
aw (
cmH
2O
)F
low
(l/
sec)
Time (sec)
Independent variable
Dependent variableTo identify non-synchrony
phenomena
observe Paw
Volume control
Inspiratory phase
Active
Passive
Pventilator + Pmus = V’xRs + VxErs
Equation of motion
Mechanical ventilation
Pressure control
Independent variableDependent variables
-2
3
8
13
18
23
0 0,2 0,4 0,6 0,8 1 1,2
-1
-0,5
0
0,5
1
1,5
0 0,2 0,4 0,6 0,8 1 1,2
0
0,1
0,2
0,3
0,4
0,5
0,6
0 0,2 0,4 0,6 0,8 1 1,2
-6
-4
-2
0
2
4
6
8
10
0 0,2 0,4 0,6 0,8 1 1,2
Pm
us
(cm
H2O
)P
aw (
cmH
2O
)F
low
(l/
sec)
Vo
lum
e (l
)
Time (sec)
Independent variable
Dependent variable
Dependent variable
Pressure control/support
Inspiratory phase
To identify non-synchrony
phenomena
observe flow (mainly)
and volume
Active Passive
1 sec
Flo
w (
l/se
c)
0
0
20
0.2
Paw
(cm
H2O
)
Time
Independent of the mode, observe expiratory flow
(not Paw) for dyssynchrony identification
ΔPaw during expiration
= ΔV’E x Rrscircuit
During expiratory
phase
Rrscircuit ≈ 0
Better signal in flow waveform
ΔV’E mainly depends on ΔPalv
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering Entrainment
(Reverse
triggering) Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
-0,8
-0,6
-0,4
-0,2
0
0,2
0,4
0,6
0,8
-2 3 8 13 18
-5
0
5
10
15
20
25
30
35
-2 3 8 13 18
-5
0
5
10
15
20
-2 3 8 13 18
Time (sec)
Flo
w (
l/se
c)P
aw (
cmH
2O
)P
es (
cmH
2O
)
5 sec
Fr = 33 b/min
Vent. rate = 12 b/minc
Do we need Pes?
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-4
-2
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6
Time (sec)
Flo
w (
l/se
c)P
es (
cmH
2O
)
5 sec
Ventilator pressure
PmusIPmusI
Pel
↑ driving pressure for V’I ↓ driving pressure for V’E
Rapid decrease
in V’E
Rapid decrease
in V’E
1 sec
Flo
w (
l/se
c)
0
0
20
0.2
Paw
(cm
H2O
)
Time
During expiration:
Better signal in flow waveform
Ineffective
efforts
Ineffective
efforts
Be careful!
These are not
ineffective efforts
Pel
PmusE
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering Entrainment
(Reverse
triggering) Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
-0,80
-0,40
0,00
0,40
0,80
1,20
0 2 4 6 8 10
0
10
20
30
0 2 4 6 8 10
-5
-4
-3
-2
-1
0
0 2 4 6 8 10
Flo
w (
l/se
c)P
aw (
cmH
2O
)P
es (
cmH
2O
)
Time (sec)
No dynamic hyperinflation
Absence of Paw/flow distortion
before triggering
Alveolar pressure distortion
↑Triggering sensitivity
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering Entrainment
Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
• Expiratory asynchrony is the inability of the
ventilator to synchronize the end of mechanical
inflation with the end of neural inspiration
Types of
Expiratory asynchrony
Premature opening Delayed opening
Paw or V’I PmusPaw or V’I
Pmus
Expiratory asynchrony
Premature opening
Paw or V’I Pmus
Flo
w P
aw P
ga
Pes
Pdi
Georgopoulos et al. Intensive Care Med 2006;32:34-47
Be careful!!
These are not ineffective efforts
-1,8
-1,4
-1
-0,6
-0,2
0,2
-2
0
2
4
6
8
10
0
5
10
15
20
25
0 0,2 0,4 0,6 0,8 1
Pel(t) = ΔV(t)xErs
PmusI(t)
Pm
us
(cm
H2O
)
Paw
(cm
H2O
) F
low
(l/
sec)
Expiratory time (sec)
V’EPassive expiration
Valve opens
Risk of double triggering
(during the delay time Pmus
may trigger the ventilator again)
Kondili et al. Br J Anaesth 2003;91:106
Volume control: Double triggering (breath stacking)
Flow
Paw
Pga
Pes
Pdi
Expiratory asynchrony
Delayed opening
Tassaux et al. Am J Respir Crit Care Med 2005;172:1283
Paw
Risks:
Triggering delay
Ineffective efforts
(since mechanical inflation
extents into neural expiration)
Paw or V’IPmus
Ineffective efforts
may indicate
expiratory asynchrony
of delayed opening type
0 1 2 3
0
0
0
4
8
12
16
10
20
1.5
-1.5
Time (sec)
Paw
Flo
wP
mu
sEnd of neural inspiration
Palv
Pel(t) = ΔV(t)xE
PmusI(t)
Prinianakis et al. Intensive Care Med 2008
In PS mode a sudden
increase in Paw during
inspiration is usually due
to relaxation of inspiratory
muscles (end of neural
inspiration) and indicates
expiratory asynchrony
of delayed opening of the
valve
0 1 2 3
0
0
0
4
8
12
16
10
20
1.5
-1.5
Time (sec)
Paw
Flo
wP
mu
s
Prinianakis et al. Intensive Care Med 2008
In PS mode a sudden
increase in Paw during
inspiration is usually due
to relaxation of inspiratory
muscles (end of neural
inspiration) and indicates
expiratory asynchrony
of delayed opening of the
valve
End of neural inspiration
Palv
Pel(t) = ΔV(t)xE
PmusI(t)
-1
-0,5
0
0,5
1
1,5
2
0 0,1 0,2 0,3 0,4 0,5
0
10
20
30
40
50
60
0 0,1 0,2 0,3 0,4 0,5
-8
-6
-4
-2
0
2
4
6
8
10
12
0 0,1 0,2 0,3 0,4 0,5
Pm
us
(cm
H2O
)P
aw (
cmH
2O
)F
low
(l/
sec)
Time (sec)
Independent variable
Dependent variableTo identify non-synchrony
phenomena
observe Paw
Volume control
Inspiratory phase
ActivePassive
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering
Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
Entrainment
(Reverse
triggering)
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
The ventilator breath triggers inspiratory effort
(vagal feedback – cortical influence)
Entrainment (Reverse triggering) implies a resetting of the
respiratory rhythm such that a fixed temporal relationship exists between
the onset of inspiratory activity and the onset of a mechanical breath.
Simon et al. J Appl Physiol 2000
Simon et al. Am J Respir Crit Care Med 1999
Akoumianaki et al. Chest. 2013;143(4):927-938.
Akoumianaki et al. Chest. 2013;143(4):927-938.
1:1
2:1
3:1
Dres et al. Current Opinion in Critical Care. 22(3):246-253, June 2016
Signs of
inspiratory
muscles
contraction
in the absence
of patient
triggered
breaths
a fixed temporal relationship
with the onset of mechanical breath
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering Entrainment
Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
Patient’s effort
Nilsestuen and Hargett Respir Care 2005
Volume control
Negative relationship between
Paw and PmusI
Pventilator + Pmus = V’xRs + VxErs
PEEP
Premature opening (Expiratory asynchrony)
Assist volume
Large drop in Pes
(strong effort)
Demands are not met
-1
-0.5
0
0.5
1
-0.5 0 0.5 1 1.5 2 2.5 3
0
5
10
15
20
25
30
-0.5 0 0.5 1 1.5 2 2.5 3
-1
0
1
2
3
4
5
-0.5 0 0.5 1 1.5 2 2.5 3
-0.6
-0.4
-0.2
0
0.2
0.4
-0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4
-4
0
4
8
12
16
20
-0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4
0
5
10
15
20
-0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4
Paw
Flow
Pdi
Pt. no. 1 Pt. no. 2
Demands
are metDemands may or
may not be met
Look for clinical
Signs of high drive
Expiratory muscle
activity toward the
end of expiration
may indicate unmet
demands
Be careful!
These are not
ineffective efforts
Breath stacking may also indicate
unmet demands
Beitler et al. Intensive Care Medicine 2016Kondili et al. Br J Anaesth 2003;91:106
15 cmH2O
drop in Pes
Patient-ventilator dyssynchrony
Cycling of the ventilator
is not in phase with
patient’s effort
The patient instantaneous
ventilatory demands are
not met by the gas
delivered by the ventilator
The ventilator assist is
such that predisposes to
apnea or periodic
breathing (PB)
Triggering delay
Ineffective efforts
Expiratory
asynchrony
Autotriggering Entrainment
Georgopoulos et al. Intensive Care Med 2006
Gilstrap and MacIntyre Am Rev Respir Crit Care Med 2013
Akoumianaki et al. Chest 2013
Apnea Apnea Apnea
It is very common and underestimated
PB increases morbidity (poor sleep)
Parthasarathy and Tobin Am J Respir Crit Care Med 2000;166:1423
Delisle, S. et al. Respir Care 2013;58:745-753
Alexopoulou et al. Intensive Care Med 2007;33:1139
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Stable
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Stable Stable
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Stable Stable Stable
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Paw
Stable Stable Stable
Apnea Apnea Apnea
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Paw
Stable Stable Stable
Apnea Apnea Apnea
Arousals
Message:
Periodic breathing is
produced by excessive
assist (lowers PaCO2
below apneic threshold)
Sleep quality is poor
characterized by
severe sleep
fragmentation and low
levels of deep sleep
(REM and N3)
PmusI
V’I
Alveoli
Airway
Pres=V’I x Rrs (Resistive pressure)
Pel = ΔV1 x Ers (Elastic pressure)
ΔV1
PmusΙ = ΔVxErs + V’xRrs
Pel
(elastic pressure)
Pres
(resistive pressure)
Paw (Ventilator pressure)
Paw
+
-PmusE
Passive FRC
Pel = -ΔV2xErs
ΔV2
Pres = -VE’xR
V’E
Think the applied pressures
as well as their directions
and observe Paw, flow and volume
Which is the commonest cause of
patient-ventilator dyssynchrony?
Patient brain Physician brain
Dyssynchrony between patient and ventilator
Pmus Paw
Dyssynchrony
between brains
Education
-1
-0,5
0
0,5
1
1,5
2
0 0,1 0,2 0,3 0,4 0,5
0
10
20
30
40
50
0 0,1 0,2 0,3 0,4 0,5
-2
0
2
4
6
8
10
12
0 0,1 0,2 0,3 0,4 0,5
Pm
us
(cm
H2O
)P
aw (
cmH
2O
)F
low
(l/
sec)
Time (sec)
Independent
variable
Dependent
variable
Ineffective effort
With volume-control observe Paw for ineffective efforts during inflation
Georgopoulos et al. Intensive Care Med 2006
Passive: Black
Active: Red
Ineffective effort
↓Paw
Assist volume
control
(constant flow)
Paw
V
V’
Pes
0
30
0
1
Georgopoulos et al. Intensive Care Med 2006
Active Passive
Data from Mitrouska et al. Eur Respir J 1999;13:873
Low ventilatory
demands
High ventilatory
demands
Georgopoulos et al. Intensive Care Med 2006
Be careful!
These are not
ineffective efforts
PmusE
Pel
↑ driving pressure
for V’E
Breath stacking
1. Consecutive inspiratory cycles
2. Expiratory time < 1s between cycles
3. Expiratory volume < 2 ml/kg of
inspiratory volume of 1st cycle
4. Inspiratory time (Pressure modes)
>120% set time
5. Final Volume >2 ml/kg PBW of set VT
Beitler et al. Intensive Care Medicine 2016
2 sec
Flo
w (
l/se
c)
0
0
20
0.2
Paw
(cm
H2O
)
Time
Independent of the mode, observe expiratory flow
(not Paw) for ineffective efforts during expiration
Paw during expiration
is mainly affected by
resistance of the circuit (≈0)
Carteaux et al. Chest. 2012;142(2):367-376
Autotriggering is the commonest cause of asynchrony during
NIMV (most probably due to leaks)
Use of Ventilator with
efficient leak compensation
system
Flow
Paw
Pga
Pes
Pdi
Paw
V
V’
Pes
0
30
0
1
Abrupt increase in Paw toward
the end of mechanical inflation
indicates the end of neural inspiration
Volume control
Meza et al. J Appl Physiol 1998;85:1928
0 3 6
8
Paw
Paw
Stable Stable Stable
Apnea Apnea Apnea
Message:
Periodic breathing is
produced by excessive
assist (lowers PaCO2
>apneic threshold)