10. The mechanical distension of the lungs
Collagen and Elastin
100
50
Sress(mbar) Strain (%)
40 80
FRC
11. 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.
12. FT
min max
Mead J et al. J. Appl. Physiol. 28(5):596-608 1970
Stress distribution - homogenous system
13. min max
Mead J et al. J. Appl. Physiol. 28(5):596-608 1970
Spannungsverteilung - inhomogenes System
23. 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
28. • 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.
29.
30.
31.
32. 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
33. 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
34. 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
35. 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
37. Regional Gascontent
Computertomography and Electroimpedance Tomography
CT
Not at the bedside
radiation
Intermittently applicable
EIT
at the bedside
non invasive
continously applicable
Ventilation
-
+
44. 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
45. Bikker et al. Critical Care 2011, 15:R193
Influence of PEEP on regional
distribution of ventilation
46. Contribution of impedance with increasing
distance from the cross-section
defined by the position of the electrode belt.
47. 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
55. 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.
56. 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.
57. 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.
58. 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
59. 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
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
61. 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.
62. Information provided by EIT
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)
63. Information provided by EIT
3. Quantification of changes of end-expiratory
lung volume
Tidal volume: 500 ml dEELV: + 350 ml
64. 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
65. Two recruitment maneuvers in series
First maneuver Second maneuver
Volume recruited no further volume recruited
66. Information provided by EIT
4. Localization of regional end-expiratory
lung volume - changes
68. 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
69.
70. Tidal immage 1
Tidal immage 2
Global
Impedance
curve
Trend parameter
of the ventilator
Difference
immage
Trend
Information provided by EIT
71. 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
72. 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 -
73. 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
74. 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%
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
75. 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
76. 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
77. 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]
78. 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.
80. What is the goal of a EIT directed
ventilator setting?
regionalV/Q determination using SPECT
81. 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
82. 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
83. 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
ARDSnet PEEP EIT PEEP Open Lung PEEP
1.6
0.4
1.0
Perfusion[ml/min]
84. Results
regional ventilation
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
Ventilated lung Total lung
Ventilated lung
Total lung
Ventilated lung
85. 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] $&
ARDSnet PEEP EIT PEEP Open Lung PEEP
2.5
0.5
1.5
Ventilation[ml/min]
88. 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
89. 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
92. Costa EL, Lima RG, Amato MB.
Electrical impedance tomography.
Curr Opin Crit Care. 2009 Feb;15(1):18-24
93. 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)
94. 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