Comparison of a single indicator and gravimetric technique for estimation of extravascular lung water in endotoxemic pigs.
OBJECTIVE
To compare the single thermal indicator dilution (STID) technique for measurement of extravascular lung water (EVLW(STID)) with gravimetrically determined EVLW (EVLW(GRAV)) in anesthetized pigs under sham and endotoxemic conditions.


METHODS
Open experimental comparative animal study.


METHODS
University animal research laboratory.


METHODS
Fifteen anesthetized landrace pigs.


METHODS
Endotoxin infusion during 5 hrs in five pigs. Six animals were only anesthetized and rested for 5 hrs. In four additional animals, the impact on EVLW(STID) measurements by changes in pulmonary perfusion, ventilation, and the combination of the two was studied. The alterations in ventilation and perfusion were induced by caval balloon inflation, inflation of the pulmonary artery catheter balloon, and bronchial plugging respectively.


RESULTS
The STID technique, with default settings of the intrathoracic blood volume (ITBV) to global end-diastolic volume (GEDV) (i.e., the extrapulmonary intravascular volume between the point of injection of the indicator, and the point of detection) relationship (ITBV = 1.25GEDV), systematically overestimated the EVLW index compared with the gravimetrical method (mean bias of 5.4 mL/kg). By adapting the ITBV to GEDV relationship to the current model (ITBV = 1.52GEDV + 49.7), the accuracy of the STID technique improved. Moreover, the measurement of EVLW(STID) proved to be reduced by manipulation of pulmonary perfusion and ventilation. However, the STID technique could detect an increase in EVLW during endotoxemia independent of the ITBV/GEDV relationship used.


CONCLUSIONS
Despite technological improvement, the dilution techniques for the measurement of EVLW might still be influenced by changes in perfusion and ventilation. The STID technique, in addition, might demand adjustment of the ITBV/GEDV relationship to the particular condition and species subjected to measurement. The STID technique may, however, be a useful tool for monitoring changes of EVLW over time, but further studies are warranted to confirm this.
Department of Physiology and Pharmacology, Section of Anaesthesiology & Intensive Care Medicine, Karolinska Institute, Stockholm, Sweden.
Patrik
P
Rossi
Michael
M
Wanecek
Anders
A
Rudehill
David
D
Konrad
Eddie
E
Weitzberg
Anders
A
Oldner
D000704:Analysis of Variance; D000818:Animals; D001810:Blood Volume; D015633:Extravascular Lung Water / Q000378:metabolism*; D005260:Female; D008070:Lipopolysaccharides; D008297:Male; D011652:Pulmonary Circulation; D011654:Pulmonary Edema / Q000175:diagnosis*; D012123:Pulmonary Ventilation; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D018805:Sepsis / Q000503:physiopathology*; D013552:Swine; D013815:Thermodilution / Q000379:methods*
D008070:Lipopolysaccharides