Vol. 274, Issue 1, H209-H216, January 1998
PEEP only partly restores disturbed distribution of regional
pulmonary blood flow in lung injury
M.
Kleen1,2,
B.
Zwissler2, and
K.
Messmer1
1 Institute for Surgical
Research and 2 Institute of
Anesthesiology, Klinikum Grosshadern,
Ludwig-Maximilians-University, 81366 Munich, Germany
The effects of lung injury, positive
end-expiratory pressure (PEEP), and norepinephrine on heterogeneity of
regional pulmonary blood flow (rPBF, radioactive microspheres) were
investigated. We hypothesized that lung injury increases heterogeneity
of rPBF and that PEEP ventilation reduces these effects. Heterogeneity of rPBF is scale dependent and was therefore assessed in detail. Local
correlation (
), relative dispersion (RD), fractal dimension (D),
perfusion gradients, and histograms of rPBF each measures a different
aspect of heterogeneity. In eight anesthetized dogs, lung injury was
induced with oleic acid and glass bead injection. Afterward, PEEP of
10-20 cmH2O was instituted.
Norepinephrine was infused at 20 cmH2O PEEP. Heterogeneity
increased upon lung injury (, 0.44 ± 0.09 vs. 0.24 ± 0.09;
RD, 0.36 ± 0.06 vs. 0.64 ± 0.12; both
P 
0.05), but fractal dimension
remained constant. PEEP did not change , RD, or D. Perfusion
gradients were reversed after lung injury (right, 
27 ± 18 vs. 196 ± 115%; left, 24 ± 18 vs. 282 ± 184%;
P 0.05). PEEP (10 cmH2O) reduced gradients (116 ± 73 and 143 ± 62%, respectively;
P 0.05). Norepinephrine, in part,
further reduced gradients (right, 50 ± 58%;
P 0.05; left, 102 ± 94%;
P = NS). We conclude that oleic acid-
and glass bead-induced lung injury produces abnormal distribution of
rPBF. Of these changes, application of PEEP only reverses perfusion gradients.
positive end-expiratory pressure; acute respiratory distress
syndrome; microspheres; regional blood flow; oleic acid; dogs
