Recognizing Patient-Ventilator...

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



ΔV1

Paw + PmusΙ = ΔVxErs + V’xRrs


-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


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)


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’s effort

Triggering delay

Ineffective efforts

Expiratory

asynchrony


(Reverse

triggering) Georgopoulos et al. Intensive Care Med 2006





not met by the gas




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’s effort

Triggering delay

Ineffective efforts

Expiratory

asynchrony


Georgopoulos et al. Intensive Care Med 2006





not met by the gas




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


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


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


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


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)


Dependent variableTo identify non-synchrony

phenomena

observe Paw

Volume control

Inspiratory phase

ActivePassive




patient’s effort

Triggering delay

Ineffective efforts

Expiratory

asynchrony

Autotriggering




Entrainment

(Reverse

triggering)



not met by the gas




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’s effort



not met by the gas


Triggering delay

Ineffective efforts

Expiratory

asynchrony







apnea or periodic

breathing (PB)

Patient’s effort

Nilsestuen and Hargett Respir Care 2005

Volume control

Negative relationship between

Paw and PmusI


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’s effort



not met by the gas




apnea or periodic

breathing (PB)

Triggering delay

Ineffective efforts

Expiratory

asynchrony





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


0 3 6

8

Paw

Stable Stable


0 3 6

8

Paw

Stable Stable Stable


0 3 6

8

Paw

Paw


Apnea Apnea Apnea


0 3 6

8

Paw

Paw


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



ΔV1

PmusΙ = ΔVxErs + V’xRrs

Pel

(elastic pressure)

Pres

(resistive 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


Passive: Black

Active: Red

Ineffective effort

↓Paw

Assist volume

control

(constant flow)

Paw

V

V’

Pes

0

30

0

1


Active Passive

Data from Mitrouska et al. Eur Respir J 1999;13:873

Low ventilatory

demands

High ventilatory

demands


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


0 3 6

8

Paw

Paw


Apnea Apnea Apnea

Message:

Periodic breathing is

produced by excessive

assist (lowers PaCO2

>apneic threshold)

Recognizing Patient-Ventilator...

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