Lung lymph response to overinfusion with hydroxyethyl starch in sheep. Comparative studies of high and low molecular weight compounds.
BACKGROUND
Several hydroxyethyl starch (HES) solutions are available clinically. We performed comparative studies of low and high molecular weight HES to evaluate the effects on lung lymph flow in sheep, to see the difference in the types of HES.


METHODS
We prepared awake sheep with vascular monitorings and lung lymph fistulas. We measured systemic artery pressure (Psa), pulmonary artery pressure (Ppa), and left atrial pressure (Pla) continuously. Cardiac output (CO) was measured every 30 min. Lung lymph flow (Qlym) was collected every 15 min. After baseline measurements, two HES solutions were infused over 2 h, respectively. Experiment 1 (n=6): low molecular weight HES (MW 70 000, substitution ratio 0.5-0.55), Experiment 2 (n=5): high molecular weight HES (MW 450 000, substitution ratio 0.7).


RESULTS
Both low and high molecular HES behaved similarly as a volume expander, increasing Psa, CO, Pla and Ppa, and decreasing hematocrit. In addition, the actual oncotic pressure gradient (plasma - lymph) was widened after the start of either low or high molecular HES, but the value for high molecular HES was significantly higher than that for low molecular HES. Qlym of low molecular HES rose significantly from the baseline and the percent increase in Qlym for low molecular HES was significantly higher than that for high molecular HES.


CONCLUSIONS
These data suggest that low molecular HES is as useful a plasma substitute as high molecular HES, but may increase lung fluid filtration in the overinfused state.
Koizumi
T
T
First Department of Medicine, Shinshu University School of Medicine, Japan.
Kaneki
T
T
Yamamoto
H
H
Ri-Li
G E
GE
Drome
Y
Y
Kubo
K
K
Shibamoto
T
T
D000818:Animals; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects*; D008196:Lymph / Q000187:drug effects*; D008970:Molecular Weight; D009997:Osmotic Pressure; D010952:Plasma Substitutes / Q000494:pharmacology*; D012756:Sheep
D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes