Mechanisms of Patient-Ventilator Dyssynchrony

Laurent Brochard

Toronto

Conflicts of interest

• Our clinical research laboratory has received equipment

or research grants for clinical research projects from the

following companies: – Covidien (PAV+)

– Air Liquide (CPR)

– Sentec (tcPCO2)

– Philips (Sleep)

– Fisher Paykel (Optiflow)

ICU ventilators…

…ICU ventilators

Maquet Getinge

EngströmHamilton

Draeger

Air Liquide

Avea

MedtronicPB

Pes

Paw

Good Synchrony: Paw follows Pes

time

Clinical consequences of asynchronies

•Dynamic hyperinflation

•Excessive or insufficient ventilatory assistance

•2)

•1)

•3) •Sedation

•4)

•5) •Errors in assessing weaning readiness

•6) •Prolonged duration of ventilation

•Sleep fragmentation

•7) •Respiratory sequelae...

PSV (with Edi monitoring)

Pes during controlled ventilation Vs. spontaneous breathing

From Murias G… Blanch L Crit Care 2016

From Younes M, Brochard L… ICM 2007

Assistance in excess

• Auto-triggering

• Apneas

• Ineffective Efforts or Missed Cycles

Short cycle and distortion of flow signal

No airway pressure drop at the beginning of the cycle

No effort

When to suspect

auto-triggering ?

During controlled ventilation:

• RR > adjusted RR

• Respiratory alkalosis

During assisted ventilation:

• Sudden increase or persistently

high respiratory rate

•Absence of an airway pressure

drop at beginning of the cycle

• PSV: short cycle with a flow

signal distortion

• ACV: abrupt airway pressure

increase

Imanaka H, et al. Crit Care Med 2000; 28:402-407

Pressure support ventilation

Pressure support ventilation

1 min Parthasarathy. AJRCCM 2002;166:1423

C4-A1

O3-A2

ROC

LOC

Chin

Leg

VT

RC

ABSpO2

EKG

Assist-Control Pressure SupportArousal

-2

0

2

4

6

0 2 4 6 8

Wasted Effort: Ineffective breath

Esophageal

Pressure

(cmH2O)

0

5

10

15

20

25

Airway

Pressure

(cmH2O)

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8Pressure drop

Flow increase

Time (s)

Flow

(L/s)

Intrinsic

PEEP

Ineffective triggering

Start of patient’s effort

Start of ventilator insufflation

-0,6

-0,4

-0,2

0

0,2

0,4

0,6

0,8

0 2 4 6 8 10 12

-10

-5

0

5

0 2 4 6 8 10 12

0

5

10

15

20

25

0 2 4 6 8 10 12

Weak effort

Flow

(L/min)

Airway

Pressure

(cmH2O)

Esophageal

Pressure

(cmH2O)

-1

-0.5

0

0.5

1

0 3 6 9 12

0

10

20

30

40

0 3 6 9 12

Time (s)

-1

-0,5

0

0,5

1

1,5

0 3 6 9 12 15

0

10

20

30

0 3 6 9 12 15

Airway

Pressure

Flow

PSV

ACV

Flow

Airway

Pressure

0

5

10

15

20

25

0 1 2 3

0

5

10

15

20

25

0 1 2

0

5

10

15

20

25

0 1 2 3

0

5

10

15

20

25

0 1 2

Airway Pressure (cmH2O)

Baseline PS-ZEEP

Baseline PS-PEEP

Optimal PS Optimal Ti

Time (s)

Intensive Care Med 2008

0

10

20

30

40

50

60

PS basal PS optimal

Asynchrony Index (%)

Baseline PS-PEEP

Optimal PS

Thille et al., Intensive Care Med 2008

Insufficient Assistance

• Air hunger or flow starvation

• Double triggering, breath stacking and short cycles

Ventilation assistée-contrôlée

Ventilation assistée-contrôlée

Ventilation assistée-contrôlée

-5

0

5

10

0 2 4 6 8 10

-5

0

5

10

0 1 2 3

0

5

10

15

20

0 1 2 3

-0,8

-0,4

0

0,4

0,8

1,2

0 1 2 3

-0.8

-0.4

0

0.4

0.8

1.2

0 2 4 6 8 10

0

5

10

15

20

25

30

0 2 4 6 8 10

Flow

(L/min)

Airway

Pressure

(cmH2O)

Esophageal

Pressure

(cmH2O)

Beginning of patient’s effort

End of patient’s effort

Double Triggering

Continuation of

patient’s effort

AB

Under Assistance

-5

0

5

10

0 2 4 6 8 10

-5

0

5

10

0 1 2 3

0

5

10

15

20

0 1 2 3

-0,8

-0,4

0

0,4

0,8

1,2

0 1 2 3

-0.8

-0.4

0

0.4

0.8

1.2

0 2 4 6 8 10

0

5

10

15

20

25

30

0 2 4 6 8 10

Flow

(L/min)

Airway

Pressure

(cmH2O)

Esophageal

Pressure

(cmH2O)

Beginning of patient’s effort

End of patient’s effort

Double Triggering

Continuation of

patient’s effort

AB

Under Assistance

Ward M et al. Anesthesiology 1988;69:29-35

Peak Flow and Work of Breathing

Volume Assist-Control

Passive Active

PL

VT

mL

Paw

cmH20

Pes

cmH20

0-

0-

Pressure Assist-Control

Passive Active

PL

Akoumianaki E et al AJRCCM 2014

Excessive Sedation?

• Respiratory Entrainement or Reverse Triggering

Paw (cm H2O)

Flow (L/sec)

EAdi (µV)

Accidental observation…

A

EAdi (µV)

Paw (cm H2O)

Flow (L/sec)

Respiratory Entrainment

Akoumianaki E et al Chest 2012

Flow

Paw

Pes

VT

Clinical consequences: VT increase

Clinical consequences: double cycle

Reverse triggering dyssynchrony 24 hours after initiation of mechanical ventilationRicard Mellado Artigas, L. Felipe Damiani, Thomas Piraino, …Laurent BrochardIn revision

40%( 1mV) or 26% (3 mV) patients have > 10% RT

Variable RT>8% RT≤8%

Median Peak Eadi,

µV1.7 (0.8-4.3) 0.7 (0.7-0.8)***

Patient-triggered

breaths over the 1

hour recording, %

12 (8-26) 1 (0-3)***

Assisted mode/extubation within 24h

13 (68) 7 (35)*

ACV

CoEMV.ca