Magic is in the air: Monitoring the respiratory system

Magic is in the air:Monitoring the respiratory system

C. PutensenDepartement of Anesthesiology and

Intensive Care Medicine

Estimation of thetransvascular volumeflux

increased permeability ?

volume overload/hydrostatic

•  ITBV ↓⊥ , EVLW ↑

•  ITBV ↑, EVLW ↑

edema ?

Am J Cardiol 1999;84:1158–1163

4h

Fluid restriction in ARDS

PaO12h2/FiO2

Baseline74±6 85±6

92±518 ± 2 18 ± 2PEEP; cm H2O

18 ± 2Pei; cm H2O 28 ± 3 28 ± 3

28 ± 33,8 ± 0,7 3,6 ± 0,6CI, l/min/m2

2,8 ± 0,7101 ± 7HR; /min

110 ± 7 122 ± 818 ± 3

34 ± 3

19 ± 3

17 ± 4

31 ± 5

18 ± 3

CVP; mm Hg13 ± 3

PAP; mm Hg31 ± 4

PAOP; /min18 ± 3

EVLW

I (m

l/kg)

ITBVI (ml/m2)200 400 600 800 1000 1200

28

26

24

22

20

18

16

14

12

10

Fluid restriction in ARDS

R = 0.75 R2 = 0.57

What is evidence based?

O.3

O.4

O.4

O.5

O.5

O.6

O.7

O7

O.7

O.8

O.9

O.9

O.9

1.0

1.0

1.0

1.0

5 5 8 8 10 10 10

12

14 14 14 16 18 18

20

22

24 cm H2O

FiO2

PEEP

What is evidence based?

ARDS Network. NEJM 2004

PEEP/FiO2titration

VTPei

RRpH

=≤

≤→

6 ml/kg pBW30 cm H2O

35 /min> 7,15

SaO2 > 90%

Distension of the lungs

Sres

s (m

bar)

The mechanical distension of thelungsCollagen and Elastin

≈100

50

40 80

Strain (%)

FRC

Stress and strain of the lungs

Stress ≈ transpulmonal pressure (PTP)

Strain ≈ VT / FRC

The linkage is specific regional compliance

PTP = Espec *

Barotrauma

VT

FRC

Volotrauma

Chiumello D, Carlesso E, Cadringher P, Caironi P, Valenza F, Polli F, Tallarini F, Cozzi P, Cressoni M, Colombo A, Marini JJ, Gattinoni L.Lung stress and strain during mechanical ventilation for acute respiratory distress syndrome.Am J Respir Crit Care Med. 2008;178:346-55.

FT

min maxMead J et al. J. Appl. Physiol. 28(5):596-6081970

Stress distribution - homogenous system

min maxMead J et al. J. Appl. Physiol. 28(5):596-6081970

Spannungsverteilung - inhomogenes System

25

EL EW

ETOT

5

EL EW

15 15

ETOT

PulmonalLung injury

Compliance Lungs(CL) ↓↓

Compliance Thoraxic wall(CW) ⊥

Extra-pulmonalLung injury

Compliance Lungs (CL) ⊥ ↓

Compliance Thoraxic wall(CW) ↓↓

Transpulmonal pressure (PTP) = EL/ETOT* PAW

Elastance (E) =1

Compliance (C)

PAW

Che

st W

all E

last

ance

(cm

H2O

/L)

N=21R=0.83P<0.0001

3,6 7,2 10,8 14,4 21,618,0 25,2 28,8

Pulmonary und extrapulmonary induced ARDS –intraabdominal pressure

Intraabdominal Pressure (cmH2O)

Gattinoni L, Pelosi P, Suter PM, Pedoto A, Vercesi P, Lissoni A.Acute respiratory distress syndrome caused by pulmonary and extrapulmonarydisease. Differentsyndromes?Am J Respir Crit Care Med. 1998;158:3-11.

Transpulmonary pressure

PTP = PAW - Ppl

Paw = 30 cmH2O

PTP = 18 cm H2O

PTP = 12 cm H2O

Low Ppl

High Ppl

EL/Etot = 0.6

EL/Etot = 0.4

PTP = EL/ETOT * PAW

BouhuysA.Physiology and musical instruments. Nature 1969;221(187):1199–1204

Tidal Volumex ETOT

Plateau Pressure

x EL/ ETOT

TranspulmonalPressure

VILI

?

Lung

vol

ume

Putensen C., Baum M., Hörmann C.Selecting ventilator settings according to variables derived from the quasi-static pressure/volume relationship in patients with acute lung injury.Anesth Analg 1993; 77:436-447.

0

250

500

1750

1500

1250

1000

750

0 5 10 15 20 25 30 35 40 45 50

Paw

55 cm H2O

mL

PEEP

VT

PEI

Biotrauma BarotraumaAtelecttrauma

* p<0.05

VT ml/kg

PEI cm H2O

PEEP cm H2O

PaO2/FiO2

PaCO2 mm Hg

Adjustemen of ventilator settingsaccording V/P-curve

prior10,1±0,8

30±27±1

180±2534±4

after7,5±0,8 *28±112±1 *

265±19 *38±3

FRC

N=24

-2.SD

+2.SD

MW

N=24

FRC in assisted mechanical ventilation N2-washouttechnique versus CT

Zinserling J, Wrigge H, Varelmann D, Hering R, Putensen C.Measurement of functional residual capacity by nitrogen washout during partial ventilatory support.Intensive Care Med. 2003; 29:720-6

R = 0.78

Lung

stre

sstra

nspu

lmon

al p

ress

ure

(cm

H2O

)

PEEP 5 cmH2O

0

44 50 33 50 22 50 11 505

PEEP 15 cmH2O

P<0.001

P=0.001

patients with healthyPatients with ALI/ARDS

P<0.001

P<0.01

lungs

6 ml/kg 12 ml/kg6 ml/kg 12 ml/kg

Lung stresslow vs.high VTandlow vs. high PEEP

Chiumello D, Carlesso E, Cadringher P, Caironi P, Valenza F, Polli F, Tallarini F, Cozzi P, Cressoni M, Colombo A, Marini JJ, Gattinoni L.Lung stress and strain during mechanical ventilation for acute respiratory distress syndrome.Am J Respir Crit Care Med. 2008;178:346-55.

Do we need to measure Ppl?

Esophageal Pressure

•  Technique:–  Balloon catheter filled with 0.5 ml gas

–  in the milde third of the esophagus – heart beat artifacts

•  Limitations of Pes :–  P/V characteristics und filling of the balloon

–  In the supine position: assumption is questionable becauseof the weight of the lungs and the mediastinum

–  No calibration – occlusion test ?

–  Artifacts caused by swallowing, heart interactions,…–  Displacement by swallowing,

Assumption: Pes= mean Ppl

Inspection of the Pes curve is essential

ΔPes ≈ ΔPpl

Benditt, Respir Care 2005; 50:68

Esophageal-Balloon-Catheter

Postioning

Patient in supine position30 degree upright.

60cm

40cm

positivepressureventilation

spontaneousbreathing

Inhalation

Exhalation

Chest wall compliance

Inhalation Exhalation

Inspiratory muscleeffort

Respir Physiol 1977;31:63Eur Respir J 1988;1:51

mm Hg18

10

mm Hg18

10

Br J Anaesth 1976;48:474Crit Care Med 1983;11:271Chest 2002; 21:533-538

•  PEEP levels were set to achieve atranspulmonary pressure of 0 to 10 cm ofwater at end expiration

•  Keep transpulmonary pressure <25 cm ofwater at end inspiration.

Conclusion - PTP

•  Determination of PTP is complex and requiresmeasurement of PES

•  Despite of PTP varies regionally we only determin anaverage PES

•  PTPvaries with equal PPLAT caused by changes in thethoraxic wall compliance and during spontaneousbreathing

•  PTP is the major force contributing to VILI•  Ventilatory setting targeting PTP may be favorable

•  Easier monitoring would be required

hyperinflated

poorly aerated

normally aerated

not aerated-900 -500

EI

EE

40

0-1000

-20

Protective mechanical ventilationdelta vol (ml)

120

60

-100

Hounsfield Units

Terragni PP, Rosboch G, Tealdi A, Corno E, Menaldo E, Davini O, Gandini G, Herrmann P, Mascia L,Quintel M, Slutsky AS, Gattinoni L, Ranieri VM.Tidal Hyperinflation during Low Tidal Volume Ventilation in Acute Respiratory Distress Syndrome.Am J Respir Crit Care Med 2007;175:160-6

EI

EE

hyperinflated

poorly aerated

normally aerated

not aerated

-500

120

80

40

-100

Hounsfield Units

0-1000 -900

-20

Terragni PP, Rosboch G, Tealdi A, Corno E, Menaldo E, Davini O, Gandini G, Herrmann P, Mascia L,Quintel M, Slutsky AS, Gattinoni L, Ranieri VM.Tidal Hyperinflation during Low Tidal Volume Ventilation in Acute Respiratory Distress Syndrome.Am J Respir Crit Care Med 2007;175:160-6

Non protective – protective mechanical ventilationDelta vol (ml)

Disadvantage of current measurementsof lung mechanics

•  global measurements•  no measurements of absolute FRC/EELV•  does not give any information on specificlung regions

•  recruitment and overdistension may occursimultaneously

Regional ventilationimaging technology

CTNot at the bedside

radiationIntermittently applicable

EITat the bedsidenon invasive

continously applicable

-

Regional GascontentComputertomography andElectroimpedance Tomography

Ventilation

+

Electrical conductiv performance ofthe chest

J. Malmivuo and R. Plonsey, „Bioelectromagnetism“, Oxford Press, 1995 (modified)

CHEST 1999; 116:1695–1702

Electrical Impedance Tomoraphy- EIT -

EIT-device

16

5

78910

11

13

15 3

4

21

I

U

U

U

6

U

U

UU

12

U

U

U

U

14

UU


16

78910

11

15 3

4

21

IU

U

U5

6

U

U

UUU

13

12

U

U

U

U

14

U

16 x 13 =208measurements

per„Frame“➔at 50Hz➔10400

measurements/s


Different EIT reconstruction algorithms

Moerer O, Hahn G, Quintel M.Lung impedance measurements to monitor alveolar ventilation.Curr Opin Crit Care 2011; 17:260-7

Multiple plane EIT measurements

Bikker et al. Critical Care 2011, 15:R193

Influence of PEEP on regionaldistribution of ventilation

Contribution of impedance with increasingdistance from the cross-section

defined by the position of the electrode belt.

5 10 15 250

5

10

30 cmDiaphragmatic cupolaApex

Regional distribution of PEEP-induced overinflation in 32Patients with Acute Lung Injury ( 6 « focal » and 26 « diffuse »)

Overinflated lung volume ( % of total pulmonary volume )

15

Nieszkowska et al., Critical Care Medicine, 32: 1496, 2004

What does the image tell us?

Image display

•  Display of differences of impedancewith respect to end-expiratoryreference level

•  Colour coded display

ΔZpositive

ΔZ = 0:reference level

new

• 

• 

• 

Image display

Tidal images or standard deviation of ventilation

Colour coding

Display of ventilation, not the lung itself!

Expiration

Ventilation cycle duringspontaneous breathing

Inspiration

Image display as movie

Display of local time courses

Globalventilation

Localventilationat cursorposition

Validation studies

Local lung air content with EIT andelectron beam tomography

Frerichs I, Hinz J, Herrmann P, Weisser G, Hahn G, Dudykevych T, Quintel M, Hellige G.Detection of local lung air content by electrical impedance tomography compared with electron beamCT.J Appl Physiol. 2002;93(2):660-6.

Local lung air content with EIT andelectron beam tomography

Change of lung density and impedance difference with tidal volume variation

Frerichs I, Hinz J, Herrmann P, Weisser G, Hahn G, Dudykevych T, Quintel M, Hellige G.Detection of local lung air content by electrical impedance tomography compared with electron beamCT.J Appl Physiol. 2002;93(2):660-6.

Regional ventilationEIT vs. single photon emission tomography

Hinz J, Neumann P, Dudykevych T, Andersson LG, Wrigge H, Burchardi H, Hedenstierna G.Regional ventilation by electrical impedance tomography: a comparison with ventilation scintigraphy inpigs.Chest. 2003 Jul;124(1):314-22.

Gas

geha

lt C

T [%

]G

asge

halt

CT

[%]

Regional Gascontent Electroimpedance Tomographyvs. Computertomography

ventral

dorsal

right lung left lung

0 10 20 30 40 50

10

0

50

40

30

20

0 10 20 30 40 50

10

0

50

40

30

20

Gasgehalt EIT [%]0 10 20 30 40 50

10

0

30

20

50

40

0 10 20 30 40 50

10

0

30

20

50

40

Gasgehalt EIT [%]

Wrigge H, Zinserling J, Muders T, Varelmann D, Günther U, Groeben C, Magnusson A, Hedenstierna G, Putensen C.Electrical impedance tomography compared to thoracic computed tomography during a slow inflation maneuver in experimental models of lung injury.Crit Care Med 2008;36:903-9

R=0,78

R=0,71R=0,70

R=0,79

BA

A

C D

Regional Gascontent Electroimpedance Tomographyvs. Computertomography

B

ventral

dorsal

right lung left lung


Information provided by EIT

30 %

35 % 15 %

20 %

Pleural effusion due to rupture of diaphragm

Information provided by EIT1.  Continuous quantification of regional distribution

of tidal volumesmax.

min.

Information provided by EIT2.  Assess the impact of therapeutic interventions

before recruitment immediately after recruitment

max.

min.

Patient ventilated with same tidal volumes before and afterrecruitment (both images with same color scale)

Information provided by EIT3.  Quantification of changes of end-expiratory

lung volume

Tidal volume: 500 ml dEELV: + 350 ml

Electric impedance tomography tracing duringPEEP optimization

Erlandsson K, Odenstedt H, Lundin S, Stenqvist O.Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obesepatients during laparoscopic gastric bypass surgery.Acta Anaesthesiol Scand. 2006;50(7):833-9

Two recruitment maneuvers in seriesFirst maneuver Second maneuver

Volume recruited no further volume recruited

Information provided by EIT4. Localization of regional end-expiratory

lung volume - changes

Present and futureapplications

Meier T, Luepschen H, Karsten J, et al.Assessment of regional lung recruitment and derecruitment during a PEEP trial based on electrical impedance tomography. Intensive Care Med2008; 34: 543-550

ventilationgain

ventilationloss

ΔVT+9ml

TVG

TVL

PEEP 15 ➔ PEEP 10

Tidal immage 1

Tidal immage 2

GlobalImpedancecurve

Trend parameterof the ventilator

Differenceimmage

Trend

Information provided by EIT

Differenceimmage

Trend

ΔEELI global

Global Impedancecurve

Regionale changein end-exspiratorylung impedance

Regionalimpedance curve

Trend parametersof thr ventilator

Information provided EIT

Costa EL, Borges JB, Melo A, et al.Bedside estimation of recruitable alveolar collapse and hyperdistension by electrical impedance tomography.Intensive Care Med 2009; 35: 1132-1137

Collapse and hyperinflation- regional compliance -

Collapse and hyperinflation- Regional compliance -

Costa EL, Borges JB, Melo A, et al.Bedside estimation of recruitable alveolar collapse and hyperdistension by electrical impedance tomography.Intensive Care Med 2009; 35: 1132-1137

Frak

tion

of re

crui

tied

atel

ecta

ses

0 200 400 600 800 1000 1200 1400

EIT ventilation delay [ms]

0.5

0.4

0.3

0.2

0.1

0.0

r2=0.60

N=24

Regional VentilationRegional Recruitment

Recruitment maneuver withlow gas flow

VL0.6

100%

45%

25%

15%

15%


Homogeneity of regional ventilationRegionalVentilation Delay Index

Ventilation

Regionalventilation distribution

RVD pixel for pixel RVD Map

early late

Start of the global impedance change

PEEP 0 PEEP 5 PEEP 10 PEEP 15 PEEP 20 PEEP 25

RVD in Quadrants

right ventral:r2=0.81

left ventral:r2=0.48

right dorsal:r2=0.32

left dorsal:r2=0.98

Cyclic alveolar collapse

Vent

ilatio

nRV

D M

apHomogenity of ventilation – recruitment/cyclic alveolar collapse

early

PEEP 0 PEEP 5 PEEP 10 PEEP 15 PEEP 20 PEEP 25max

min

late

potential for alveolar recruitment

cyclic alveolar collapse (tidal recruitment)

EIT, SDRVD maping, CT at different PEEP levels

Muders T, Luepschen H, Putensen C.Impedance tomography as a new monitoring technique.Curr Opin Crit Care. 2010 Jun;16(3):269-75.

PEEP

20

cmH

2OPE

EP 2

5 cm

H2OEnd-expiratory

CTDelay map (EIT)

late

RVD

early

late

RVD

early

Is of SDRVDclinical relevance ?

What is the goal of a EIT directedventilator setting?

regionalV/Q determination using SPECT

ARDSnetPEEP

EITPEEP

OLPEEP ANOVA

VT[ml]VE[l/min

215(±18)7.3(±0.8)

210(±15)7.1(±0.9)

209(±21)7.4(±0.9)

nsns

PEEP[cmH2O]Ppeak[cmH2O]Pmean[H2O]

10.1(±2.7)§$34.7(±6.9)§$32.7(±6.4)§$

22.1(±2.1)#$39.0(±5.2)#$37.3(±5.6)#$

25.0(±3.8)#§42.8(±7.1)#§40.1(±7.3)#§

P<0.001P<0.001P<0.001

PaO2/FiO2[mmHg] 141(±40)§$ 417(±114)# 388(±120)# P<0.001

CO[l/min] 6.3(±1.2)§$ 4.8(±1.3)# 4.3(±1.0)# P<0.001

ITBV[ml]MAP[mmHg]

520(±66)97(±17)

515(±95)94(±21)

499(±107)92(±18)

nsns

HR[bpm] 120(±25)§$ 105(±20)# 109(±17)# P<0.05

Data are average values ± SD. p<0.05 (post hoc), # vs ARDSnet-PEEP, § vs. EIT-PEEP, $ vs. OL PEEP

ResultsVentilatory and cardio-vascular variables

dorsal

ventral

dorsal

ventral

dorsal

ventral

ARDSnet PEEP

PEEP 10 cm H2O

Total lungPerfused lung

Resultsregional perfusion

EIT PEEP

PEEP 20 cm H2O


Open Lung PEEP

PEEP 24 cm H2O


Pulm

onal

er B

lutfl

uss [

ml/m

in]

[ml/m

in]

Perf

usio

n

niedriges

ventral

dorsal

[%]

pulmonaler Blutfluss [ml/min] § $ &

ANOVA: p<0.05 for factor „V/Q “, „ventilatory modality“ and interactions. Post hoc (Newman-Keuls):p<0.05 # vs ARDSnet-PEEP, § vs. EIT-PEEP, $ vs. OL PEEP

#

#

# #

§$§$

# #

§$

Shunt

V/Q

normalesV/Q hohes

V/Q

Totraum

ARDSnet PEEP

Resultsregionale perfusion

EIT PEEP Open Lung PEEP

1.6

1.0

0.4

dorsal

ventral

dorsal

ventral

dorsal

ventral

ARDSnet PEEP

PEEP 10 cm H2OTotal lungVentilated lung

Resultsregional ventilation

EIT PEEP

PEEP 20 cm H2O

Total lungVentilated lung

Open Lung PEEP

PEEP 24 cm H2OTotal lungVentilated lung

Pulm

onal

er G

asflu

ss [m

l/min

]

[ml/m

in]

Vent

ilatio

n

niedriges

ANOVA: p<0.05 for factor „V/Q “, „ventilatory modalities“ and interactions.Post hoc (Newman-Keuls): p<0.05 # vs ARDSnet-PEEP, § vs. EIT-PEEP, $ vs. OL PEEP

# #

§$

# #

§$

Shunt

V/Q

normalesV/Q hohes

V/Q

Totraum

ventral

dorsal

[%]

pulmonaler Gasfluss [ml/min] $&

ARDSnet PEEP

Resultsregional ventilation

EIT PEEP Open Lung PEEP

2.5

1.5

0.5

dorsal

ventral

d

v

d

v

>10

<0.1

1

ARDSnet PEEP

PEEP 10 cm H2O

Resultsregional V/Q

EIT PEEP

PEEP 20 cm H2O

Open Lung PEEP

PEEP 24 cm H2O

The future

Supine

Prone

Regionale Ventilation/Perfusion-Verteilung bestimmt mit 81mKr/99mTc-MAA SPECT ScansLamm W.J.E. et al. Am J Respir Crit Care Med 1994; 150:184-193.

Regional Ventilation/Perfusion-Distribution

EIT-Ventilation

EIT-Perfusion

EIT-Ventilation/Perfusion

The goal

Visualizing cardiac relatedimpedance changes

•  Separation of respiratory andcardiac related impedancechanges

•  ATTENTION: Perfusion isdefined as flow in a certaindirection

•  Interpretation of cardiacimpedance changes is stilldifficult

•  Temporal and spatialinformation may help

•  Contrast agents:–  Saline

–  Glucose

Cardiacimpedance

changesRespiratoryimpedance

changes

Curves knownfrom thermodilution

measurements

Three components

Time

Right Heart (RH), Lung (L), Left Heart (LH)

Validation

•  SPECT/CT (in pigs)

Muders T, Luepschen H, Putensen C. Curr Opin Crit Care, 2010

Costa EL, Lima RG, Amato MB.Electrical impedance tomography.Curr Opin Crit Care. 2009 Feb;15(1):18-24

Advantages of EIT

•  Noninvasive method

•  Application at bedside

•  Regional ventilation changes can bemonitored

–  over time

–  after maneuvers

–  used to adjust mechanical ventilation (e.g. PEEP)

Currently, no clinical data areavailable that advanced

respiratory monitoring (e.g. PPT, EIT)improve outcome in the overall or in a

selected critical care population

Documents

Magic is in the air: Monitoring the respiratory system