What is EVLW and how is it measured by the PiCCO system?

26th International Symposium of
Intensive Care and Emergency Medicine
Brussels 21
-24 March 2006
21-24
What is EVLW and
how is it measured by
the PiCCO system?
Dr. F Javier Belda
Servicio de Anestesiología y Reanimación
Hospital Clínico Universitario
Valencia (SPAIN)
Q#1 Extra-vascular lung water (EVLW) is
1. The amount of water in the alveoli
2. A qualitative term describing pulmonary edema
3. The amount of water that is present in the lungs
outside of the pulmonary vasculature
4. The amount of total water contained within the lungs
Please vote now!
EVLW is the amount of water that is present in the lungs
outside of the pulmonary vasculature.
The abnormal accumulation of EVLW is a frequent
phenomenon in critically ill patients.
Normal lung
Floor tile
Edema
Advanced ARDS
The normal values of EVLW are 3-7 ml/kg
Although its clinical and physiological manifestations
can be quite variable, increased EVLW is always
a potential threat to life!
EVLW is not well detected by:
Chest radiograph / Blood gas analysis
Halperin BD, et al (1985). Chest 88: 649±652
Baudendistel L, et al (1982) J Trauma 22: 988-983
Lungs
CVC
V. cava
sup.
PAOP
Sibbald WJ, et al (1985). Chest 87:585-592
RA
Measuring EVLW
by transpulmonary
thermo-dye dilution
CV bolus injection
cold indocynine green
(ICG) dye
RAEDV
Fiberoptic arterial catheter
EVLW
RVEDV
Aorta
PBV
Arterial measurement of
dye- and thermo-dilution
curves
LAEDV
LVEDV
Dye-dilution curve: (Indocyanin green) Intra Thoracic Blood Volume
ITBV = CO * MTtICG
Intrathoracic Blood Volume
MTt
MTt: Mean transit time ≈ half of the indicator passed the point of detection
ITTV = CO * MTtcold
Intrathoracic Thermal Volume
MTt
Thermo-dilution curve: (8ºC) Intra Thoracic Thermal Volume
ITTVcold
EVLW
ITBVdye (ICG)
-
=
ITTV - ITBV = EVLW
From double dye-cold indicator to single (cold) indicator
c (I)
injection
recirculation
ln c (I)
e-1
At
DSt
MTt
MTt: Mean transit time
DSt: Downslope time
ITTV = CO * MTtTD
PTV = CO * DStTD
t
For several mixing chambers in series with identical flow, the decay of the
dilution curve is predominantly determined by the largest compartment
n = 209 pts
Bias = -0.2 ml/kg
SD = 1.4 ml/kg
r = 0.96
EVLW measurement by the single transpulmonary
thermodilution correlates very well with the double
indicator technique
Sources of error
in single TP-TD
Relationship GEDV - ITBV
(n = 57 pts, r = 0.96)
ITBV= 1.25 • GEDV
Factors influencing:
Sakka S et al, Intensive Care Med 2000
- Overall volume status
- Compensatory vasoconstriction (redistribution to central compartments)
Large-wite pigs: 9 control
10 hypovolemic (1ml/kg/min)
EVLW: Single TP-TD (Picco) vs gravimetry
Hypovolemia:
Reduction >30% CO
Reduction >BP 30%
SvO2 <40%
Lactate > 3 mmol
Conclusion
EVLW can be measured at
the bedside using central
venous and arterial line
only!