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Optical measurement of isolated canine lung filtration coefficients after alloxan infusion
Ist Teil von
Journal of applied physiology (1985), 1998-04, Vol.84 (4), p.1381-1387
Ort / Verlag
Bethesda, MD: Am Physiological Soc
Erscheinungsjahr
1998
Link zum Volltext
Quelle
MEDLINE
Beschreibungen/Notizen
1 Department of Biomedical
Engineering and 2 Center for
Pulmonary Research, Vanderbilt University, Nashville, Tennessee
37235
In this study, lung filtration coefficient
( K fc ) was
measured in eight isolated canine lung preparations by using three
methods: standard gravimetric (Std), blood-corrected gravimetric (BC), and optical. The lungs were held in zone III conditions and were subjected to an average venous pressure increase of 8.79 ± 0.93 (mean ± SD) cmH 2 O. The
permeability of the lungs was increased with an infusion of alloxan (75 mg/kg). The resulting
K fc values (in
milliliters · min 1 · cmH 2 O 1 · 100 g dry lung weight 1 )
measured by using Std and BC gravimetric techniques before vs. after
alloxan infusion were statistically different: Std, 0.527 ± 0.290 vs. 1.966 ± 0.283; BC, 0.313 ± 0.290 vs. 1.384 ± 0.290. However, the optical technique did not show any statistical
difference between pre- and postinjury with alloxan, 0.280 ± 0.305 vs. 0.483 ± 0.297, respectively. The alloxan injury, quantified by
using multiple-indicator techniques, showed an increase in permeability and a corresponding decrease in reflection coefficient for albumin ( f ). Because the optical
method measures the product of
K fc and f , this study shows that
albumin should not be used as an intravascular optical filtration
marker when permeability is elevated. However, the optical technique,
along with another means of measuring
K fc (such as BC),
can be used to calculate the f
of a tracer (in this study, f
of 0.894 at baseline and 0.348 after injury). Another important finding
of this study was that the ratio of baseline-to-injury K fc values was
not statistically different for Std and BC techniques, indicating that
the percent contribution of slow blood-volume increases does not change
because of injury.
Evans blue; permeability; gravimeteric techniques