Christian Putensen - Monitoring the respiratory system - IFAD 2012

Magic is in the air:
Monitoring the respiratory system
C. Putensen
Departement of Anesthesiology and
Intensive Care Medicine

Estimation of the
transvascular volumeflux
• ITBV  , EVLW   increased permeability ?
• ITBV  EVLW  volume overload/
hydrostatic edema ?

Am J Cardiol 1999;84:1158–1163

ITBVI (ml/m2)
200 400 600 800 1000 1200
EVLWI(ml/kg)
10
12
14
16
18
20
22
24
26
28
R = 0.75 R2 = 0.57
Fluid restriction in ARDS

O.3
5
O.4
5
O.4
8
O.5
8
O.5
10
O.6
10
O.7
10
O7
12
O.7
14
O.8
14
O.9
14
O.9
16
O.9
18
1.0
18
1.0
20
1.0
22
1.0
24 cm H2O
FiO2
PEEP
What is evidence based?
ARDS Network. NEJM 2004
PEEP/FiO2 titration
VT = 6 ml/kg pBW
Pei ≤ 30 cm H2O
RR ≤ 35 /min
pH → > 7,15
SaO2 > 90%

The mechanical distension of the lungs
Collagen and Elastin
100
50
Sress(mbar) Strain (%)
40 80
FRC

Stress and strain of the lungs
Stress  transpulmonal pressure (PTP)
Strain  VT / FRC
The linkage is specific regional compliance
PTP
VT
FRC
= *Espec
Barotrauma 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 max
Mead J et al. J. Appl. Physiol. 28(5):596-608 1970
Stress distribution - homogenous system

min max
Mead J et al. J. Appl. Physiol. 28(5):596-608 1970
Spannungsverteilung - inhomogenes System

Pulmonal
Lung injury
Extra-pulmonal
Lung injury
25
EL EW
ETOT
5
EL EW
15 15
ETOT
Compliance Lungs (CL) ↓↓
Compliance Thoraxic wall (CW) ⊥
Compliance Lungs (CL) ⊥ ↓
Compliance Thoraxic wall (CW) ↓↓
Transpulmonal pressure (PTP) = EL/ETOT * PAW
Elastance (E) =
Compliance (C)
1
PAW

N=21
R=0.83
P<0.0001
Intra-Abdominal Pressure (cmH2O)
0 5 10 15 20 25 30 35 40
Chest-WallElastance(cmH2O/L))
0
2
4
6
8
10
12
14
16
18
20
ARDSp
ARDSexp
Gattinoni L, Pelosi P, Suter PM, Pedoto A, Vercesi P, Lissoni A.
Acute respiratory distress syndrome caused by pulmonary and extrapulmonarydisease. Different syndromes?
3,6 7,2 10,8 14,4 21,6 28,818,0 25,2
Pulmonary und extrapulmonary induced ARDS –
intraabdominal pressure
ChestWallElastance(cmH2O/L)
Intraabdominal Pressure (cmH2O)

Transpulmonary pressure
PTP = PAW - Ppl
Paw = 30 cmH2O
PTP = 18 cm H2O
PTP = 12 cm H2O
Low Ppl EL/Etot = 0.6
High Ppl EL/Etot = 0.4
PTP = EL/ETOT * PAW

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

Tidal Volume
Plateau Pressure
Transpulmonal
Pressure
VILI
x ETOT
x EL/ ETOT
?

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
750
1000
1250
1500
1750
0 5 10 15 20 25 30 35 40 45 50 55
Paw
cm H2O
mL
Lungvolume
PEEP
VT
PEI
Biotrauma
Barotrauma
Atelecttrauma
* p<0.05
VT ml/kg 10,1±0,8 7,5±0,8
PEI cm H2O 30±2 28±1
PEEP cm H2O 7±1 12±1
PaO2/FiO2 180±25 265±19
PaCO2 mm Hg 34±4 38±3
Adjustemen of ventilator settings
according V/P-curve
prior after
*
*
*
FRC

(FRCAuswasch+FRCCT)/2 / ml
0 200 400 600 800 1000 1200 1400
FRCAuswasch-FRCCT/ml
-600
-400
-200
0
200
400
600
N=24 +2.SD
-2.SD
MW
FRCCT
0 200 400 600 800 1000 1200 1400
FRCAuswasch 0
200
400
600
800
1000
1200
1400
N=24
FRC in assisted mechanical ventilation
N2-washout technique 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

PEEP 5 cmH2O
Lungstress
transpulmonalpressure(cmH2O)
0
5
10
15
20
25
30
35
40
45
PEEP 15 cmH2O
P<0.01
P<0.001
P<0.001
P=0.001
Patients with ALI/ARDS
patients with healthy lungs
6 ml/kg 12 ml/kg6 ml/kg 12 ml/kg
Lung stress
low vs.high VT and low 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.

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 because
of 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

Postioning
Patient in supine position
30 degree upright.
60cm
40cm

Inhalation Exhalation
Inhalation Exhalation
positive
pressure
ventilation 18
10
mm Hg
Chest wall compliance
spontaneous
breathing
18
10
mm Hg
Inspiratory muscle effort
Br J Anaesth 1976;48:474 Respir Physiol 1977;31:63
Crit Care Med 1983;11:271 Eur Respir J 1988;1:51
Chest 2002; 21:533-538

• PEEP levels were set to achieve a
transpulmonary pressure of 0 to 10 cm of
water at end expiration
• Keep transpulmonary pressure <25 cm of
water at end inspiration.

Conclusion - PTP
• Determination of PTP is complex and requires
measurement of PES
• Despite of PTP varies regionally we only determin an
average PES
• PTP varies with equal PPLAT caused by changes in the
thoraxic wall compliance and during spontaneous
breathing
• PTP is the major force contributing to VILI
• Ventilatory setting targeting PTP may be favorable
• Easier monitoring would be required

hyperinflated normally aerated
poorly aerated not aerated
-1000 -900 -500 -100
EI
EE
-20
40
60
120
0
Protective mechanical ventilation
delta vol (ml)
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 normally aerated
poorly aerated not aerated
-1000 -900 -500 -100
-20
40
80
120
Hounsfield Units
Delta vol (ml)
0
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 ventilation

Disadvantage of current measurements
of lung mechanics
• global measurements
• no measurements of absolute FRC/EELV
• does not give any information on specific
lung regions
• recruitment and overdistension may occur
simultaneously

Regional ventilation
imaging technology

Regional Gascontent
Computertomography and Electroimpedance Tomography
CT
Not at the bedside
radiation
Intermittently applicable
EIT
at the bedside
non invasive
continously applicable
Ventilation
-
+

Electrical conductiv performance of
the chest
J. Malmivuo and R. Plonsey, „Bioelectromagnetism“, Oxford Press, 1995 (modified)

Electrical Impedance Tomoraphy
- EIT -
EIT-device

16
5
6
7
8910
11
12
13
14
15 3
4
21
I
U
U
U
U
U
UUUU
U
U
U
U U
U
U
U
UUUU
U
U
U
U
U
- EIT -

16
5
6
7
8910
11
12
13
14
15 3
4
21
IU
U
U
U
U
UUUU
U
U
U
U
U
U
U
UUUU
U
U
U
U
U
U
16 x 13 = 208
measurements
per„Frame“
at 50Hz
10400
measurements/s
- 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 regional
distribution of ventilation

Contribution of impedance with increasing
distance from the cross-section
defined by the position of the electrode belt.

Overinflated lung volume ( % of total pulmonary volume )
5 10 15 25 30
0
5
10
15
cm
Diaphragmatic cupolaApex
Regional distribution of PEEP-induced overinflation
in 32 Patients with Acute Lung Injury ( 6 « focal » and 26 « diffuse »)
Nieszkowska et al., Critical Care Medicine, 32: 1496, 2004

Image display
• Display of differences of impedance
with respect to end-expiratory
reference level
• Colour coded display
DZ positive
DZ = 0:
reference level
new

Image display
• Tidal images or standard deviation of ventilation
• Colour coding
• Display of ventilation, not the lung itself!

Ventilation cycle during
spontaneous breathing
Expiration
Inspiration

Display of local time courses
Global
ventilation
Local
ventilation
at cursor
position

Local lung air content with EIT and
electron 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 beam CT.
J Appl Physiol. 2002;93(2):660-6.

Local lung air content with EIT and
electron 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 beam CT.
J Appl Physiol. 2002;93(2):660-6.

Regional ventilation
EIT 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 in pigs.
Chest. 2003 Jul;124(1):314-22.

Regional Gascontent
Electroimpedance Tomography vs. Computertomography
ventral
dorsal
right lung left lung
GasgehaltCT[%]
0 10 20 30 40 50
0
10
20
30
40
50
0 10 20 30 40 50
0
10
20
30
40
50
Gasgehalt EIT [%]
0 10 20 30 40 50
0
10
20
30
40
50
0 10 20 30 40 50
0
10
20
30
40
50
GasgehaltCT[%]
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=0,71
R=0,70
R=0,79

0 10 20 30 40
aircontentdifferenceCT-EIT[%]
-30
-20
-10
0
10
20
30
+2SD
mean
-2SD
0 10 20 30 40
-30
-20
-10
0
10
20
30
+2SD
mean
-2SD
mean air content [%]
-10 0 10 20 30 40
aircontentdifferenceCT-EIT[%]
-30
-20
-10
0
10
20
30
+2SD
mean
-2SD
mean air content [%]
-10 0 10 20 30 40
-30
-20
-10
0
10
20
30
+2SD
mean
-2SD
A B
A B
C D
Regional Gascontent
Electroimpedance Tomography vs. Computertomography
ventral
dorsal
right lung left lung

30 %
35 % 15 %
20 %
Pleural effusion due to rupture of diaphragm
Information provided by EIT
1. Continuous quantification of regional distribution
of tidal volumes
max.
min.

2. Assess the impact of therapeutic interventions
before recruitment immediately after recruitment
max.
min.
Patient ventilated with same tidal volumes before and after
recruitment (both images with same color scale)

3. Quantification of changes of end-expiratory
lung volume
Tidal volume: 500 ml dEELV: + 350 ml

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

Two recruitment maneuvers in series
First maneuver Second maneuver
Volume recruited no further volume recruited

4. Localization of regional end-expiratory
lung volume - changes

Present and future
applications

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 Med
2008; 34: 543-550
ventilation
gain
ventilation
loss
ΔVT
+9ml
TVG
TVL
PEEP 15  PEEP 10

Tidal immage 1
Tidal immage 2
Global
Impedance
curve
Trend parameter
of the ventilator
Difference
immage
Trend

Trend parameters
of thr ventilator
Global Impedance
curve
DEELI global
Difference
immage
Trend
Regional
impedance curve
Regionale change
in end-exspiratory
lung impedance
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

Regional Ventilation
Regional Recruitment
EIT ventilation delay [ms]
0 200 400 600 800 1000 1200 1400
Fraktionofrecruitiedatelectases
0.0
0.1
0.2
0.3
0.4
0.5
0.6
r2=0.60
N=24
Recruitment maneuver with
low gas flow
VL
100%
45%
25%
15%
15%

Homogeneity of regional ventilation
Regional Ventilation Delay Index
Ventilation
Regional
ventilation 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
0 5 10 15 20 25
1000
2000
3000
4000
5000
6000
7000
rechts ventral
links ventral
rechts dorsal
links dorsal
RVD in Quadrants
1000 2000 3000 4000 5000 6000 7000
-10
0
10
20
30
40
50
60
70
RVD index
[%ROI]
r2=0.59
right ventral:
r2=0.81
left ventral:
r2=0.48
right dorsal:
r2=0.32
left dorsal:
r2=0.98
Cyclic alveolar collapse

0 5 10 15 20 25
200
400
600
800
1000
1200
1400
1600
SD of pixel-RVD
Potential for recruitment
0 250 500 750 1000 1250 1500 1750
0
100
200
300
400
500
SD of pixel-RVD
ml
Potential for recruitment
r2=0.93
Homogenity of ventilation – recruitment/cyclic alveolar collapse
late
early
RVDMap
PEEP 0 PEEP 5 PEEP 10 PEEP 15 PEEP 20 PEEP 25
max
min
Ventilation
0 5 10 15 20 25
0
100
200
300
400
potential for alveolar recruitment
0 5 10 15 20 25
0
100
200
300
400
Potential für Rekrutierung
zyklischer Kollapscyclic alveolar collapse (tidal recruitment)
potential for alveolar recruitment
Cyclic alveloar collapse
r2=0.98
0 250 500 750 1000 1250 1500 1750
0
5
10
15
20
25
SD of pixel-RVD
[%lung]

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.

End-expiratory
CT
Delay map (EIT)
late
early
RVD
late
early
RVD
PEEP20cmH2OPEEP25cmH2O
Is of SDRVD clinical relevance ?

What is the goal of a EIT directed
ventilator setting?
regionalV/Q determination using SPECT

Data are average values ± SD. p<0.05 (post hoc), # vs ARDSnet-PEEP, § vs. EIT-PEEP, $ vs. OL PEEP
Results
Ventilatory and cardio-vascular variables
ns92 (±18)94 (±21)97 (±17)MAP [mmHg]
P < 0.05109 (±17) #105 (±20) #120 (±25) §$HR [bpm]
ns499 (±107)515 (±95)520 (±66)ITBV [ml]
P < 0.0014.3 (±1.0) #4.8 (±1.3) #6.3 (±1.2) §$CO [l/min]
P < 0.001388 (±120) #417 (±114) #141 (±40) §$PaO2/FiO2 [mmHg]
P < 0.00140.1 (±7.3) #§37.3 (±5.6) #$32.7 (± 6.4) §$Pmean [H2O]
P < 0.00142.8 (±7.1) #§39.0 (±5.2) #$34.7 (±6.9) §$Ppeak [cmH2O]
P < 0.00125.0 (±3.8) #§22.1 (±2.1) #$10.1 (±2.7) §$PEEP [cmH2O]
ns7.4 (±0.9)7.1 (±0.9)7.3 (±0.8)VE [l/min
ns209 (±21)210 (±15)215 (±18)VT [ml]
ANOVA
OL
PEEP
EIT
PEEP
ARDSnet
PEEP

Results
regional perfusion
PEEP 10 cm H2O PEEP 20 cm H2O PEEP 24 cm H2O
dorsal
ventral
dorsal
ventral
dorsal
ventral
ARDSnet PEEP EIT PEEP Open Lung PEEP
Total lung
Perfused lung Total lung
Perfused lung
Total lung
Perfused lung

Results
regionale perfusion
PulmonalerBlutfluss[ml/min]
Q
0 100 200 300 400 500
lung
dorsal---------------------------------------------ventral
0
20
40
60
80
100
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
0
1000
2000
3000
4000
5000
ARDS net
EIT
Open Lung
#
#
# #
§ $
§ $
# #
§ $
Shunt
niedriges
V/Q
normales
V/Q hohes
V/Q
Totraum
1.6
0.4
1.0
Perfusion[ml/min]

Results
regional ventilation
dorsal
ventral
dorsal
ventral
dorsal
ventral
Total lung
Ventilated lung Total lung
Ventilated lung
Total lung
Ventilated lung

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
0
1000
2000
3000
4000
5000
6000
ARDS net
EIT
Open Lung
# #
§ $
#
#
§ $
PulmonalerGasfluss[ml/min]
Shunt
niedriges
V/Q
normales
V/Q hohes
V/Q
Totraum
Results
regional ventilation
V
0 100 200 300 400
lung
dorsal---------------------------------------------ventral
0
20
40
60
80
100
ventral
dorsal
[%]
pulmonaler Gasfluss [ml/min] $&
2.5
0.5
1.5
Ventilation[ml/min]

dorsal
ventral
d
v
d
v
>10
<0.1
1
Results
regional V/Q

Supine Prone
Regionale Ventilation/Perfusion-Verteilung bestimmt mit 81mKr/99mTc-MAA SPECT Scans
Lamm 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 related
impedance changes
• Separation of respiratory and
cardiac related impedance
changes
• ATTENTION: Perfusion is
defined as flow in a certain
direction
• Interpretation of cardiac
impedance changes is still
difficult
• Temporal and spatial
information may help
• Contrast agents:
– Saline
– Glucose
Respiratory
impedance
changes
Cardiac
impedance
changes
Curves known
from thermodilution
measurements

Three components
Right Heart (RH), Lung (L), Left Heart (LH)
TTime

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 be
monitored
– over time
– after maneuvers
– used to adjust mechanical ventilation (e.g. PEEP)

Currently, no clinical data are
available that advanced
respiratory monitoring (e.g. PPT, EIT)
improve outcome in the overall or in a
selected critical care population

Christian Putensen - Monitoring the respiratory system - IFAD 2012

Christian Putensen - Monitoring the respiratory system - IFAD 2012

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