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
Electrical Impedance Tomoraphy- EIT -
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
Electrical Impedance Tomoraphy- EIT -
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
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
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%
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
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
Total lungPerfused lung
Open Lung PEEP
PEEP 24 cm H2O
Total lungPerfused lung
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