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Measuring end-expiratory lung volume. Giacomo Bellani , M.D., Ph.D . University of Milano-Bicocca Monza, Italy giacomo.bellani1@unimib.it. Conflicts of interest. Personal: Lecturing fees from GE Institutional , research grants from: Draeger Maquet Chiesi Farmaceutici. - PowerPoint PPT Presentation
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Measuring end-expiratory lung volume
Giacomo Bellani, M.D., Ph.D.University of Milano-Bicocca
Monza, Italygiacomo.bellani1@unimib.it
Conflicts of interest
Personal:• Lecturing fees from GE
Institutional, research grants from:• Draeger• Maquet• Chiesi Farmaceutici
Which «lung volume» ?
Functional Residual Capacity (FRC)Functional Residual Capacity (FRC)Volume of gas in the lung at the end of a physiologic Volume of gas in the lung at the end of a physiologic
expiration expiration Relaxation volume of respiratory systemRelaxation volume of respiratory system
End Expiratory Lung Volume (EELV)End Expiratory Lung Volume (EELV)Volume of gas in the lung at end expiration during Volume of gas in the lung at end expiration during mechanical ventilation with PEEPmechanical ventilation with PEEP
EELV @ 0 cmH2O= FRC
• How do we measure End-expiratory lung volume?
• Why should we measure end-expiratory lung volume?
TechniquesCT scan
• Precise quantitative assessment• Radiological exposure+patient transfer
Closed circuit• Need for a dedicated tracer+closed system• No need for «fast» response concentration
measurements - offline measurementOpen circuit muti-breath washin/washout
• Potentially no need for a gas tracer• Fast response measurement, synchrony with tidal
ventilation
TechniquesCT scan
• Precise quantitative assessment• Radiological exposure+patient transfer
Closed circuit• Need for a dedicated tracer+closed system• No need for «fast» response concentration
measurements - offline measurementOpen circuit muti-breath washin/washout
• Potentially no need for a gas tracer• Fast response measurement, synchrony with tidal
ventilation
Closed Dilution Technique
VVff = V = Vii + EELV + EELV
Mass conservation
CiCiViVi
FRC ?FRC ?
CfCfVfVf
ViViCfCfCiCi
ViViEELVEELV -=
VVii* C* Cii = V = Vff* C* Cff
TechniquesCT scan
• Precise quantitative assessment• Radiological exposure+patient transfer
Closed circuit• Need for a dedicated tracer+closed system• No need for «fast» response concentration
measurements - offline measurementOpen circuit muti-breath washin/washout
• Potentially no need for a gas tracer• Fast response measurement, synchrony with tidal
ventilation
70 %
30 %O2
N2
50 %
50 %
FiN2=70%
Vt
FeN2
600 ml
1400 ml
1000 ml
1000 ml ml.
ml
..
Nml2000
20
400
5070
400 2
Multibreath nitrogen washout
Wrigge H et al Intensive Care Med 1998; 24: 487
Off-line correction of viscosity effect on sidestream delay time and pneumothacografic measurments
Derives N2 concentration from: 100%- [CO2]- [CO2]
Uses end-tidal concentration (no need for synchronization)
What about Pressure Support ?
0
1000
2000
3000
4000
0 1000 2000 3000 4000
EELV by He dilution (ml)
EE
LV
by
GE
En
gst
rom
(m
l)Volume Control
R2 = 0.8353
Pressure Support
Using a 20% variation in FiO2:
Bellani G, unpublished
FRC INview (Engstrom carestation)
• How do we measure End-expiratory lung volume?
• Why should we measure end-expiratory lung volume?
EELV is profoundly reduced in ARDS• Estimate of alveolar
recruitment• Determinant of VILI
Why should we measure end-expiratory lung volume?
EELV is profoundly reduced in ARDS
• Estimate of alveolar recruitment
• Determinant of VILI
Why should we measure end-expiratory lung volume?
Alveolar recruitment by P-V curve
Maggiore S. et al, Am J Resp Crit Care Med, 2001
Effect of recruitment on FRC (0 cmH2O)
Patroniti N et al., CCM 2010
A simplified approachAssessing alveolar recruitment by EELV
PEEP = 0
Compliance=30 ml/cmH2OEELV= 1000 ml
PEEP=10
Expected EELV increase: 30 * 10= 300 ml
No recruitmentEELV= 1300 ml
RecruitmentEELV = 1600 ml
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
4 14
PEEP (cmH2O)
EE
LV
(l)
0
5
10
15
20
25
30
35
Crs
(m
l/cm
H2O
)
6 8 10 12
1350 ml
Crs 29 expected EELV increase 174 ml
1524 l
1950 l
true EELV increase 600 ml
∆EELV / PEEP change = 600 / 6 = 100 ml/cmH2O
EELV is profoundly reduced in ARDS• Estimate of alveolar
recruitment• Determinant of VILI
Why should we measure end-expiratory lung volume?
EELV
VE (L/min)
RATIO
NORMAL
ARDS
2500 < 7 < 2.8
1000 > 15 > 15
SPECIFIC HYPERVENTILATION
Vt/F
RC
End-expiration End-inspiration PETEELVnormally-aerated
Vtnormally-aerated
Kinormally-aerated
High activity
Low activity
- 1000
100
-500
Regional distension and inflammation
Bellani G et al., Am J Resp Crit Care Med, 2011
The role of tidal volume/EELV
Bellani G et al., Am J Resp Crit Care Med, 2011
Conclusions:o Measurement of end-expiratory lung volume is
now available:RESEARCH TOOL → CLINICAL TOOL
o Useful in estimating lung recruitmentoCan it help in setting PEEP? Yeso Is it being used to set PEEP? Don’t know
o Possible role in adjusting tidal volume?
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