ISSN:
1432-2013
Schlagwort(e):
Pulmonary Vascular Resistance
;
Isolated Lung
;
Blood Viscosity
;
Hematocrit
;
Pressure-Flow Relations
;
Lungengefäßwiderstand
;
Isolierte Lunge
;
Blutviscosität
;
Druck-Strombeziehung
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Summary The effect of hematocrit on pressure-flow relations for the pulmonary circulation was studied by means of an isolated lung preparation. Lobes taken from mongrel dogs were perfused with autologous blood of hematocrits ranging from 23 to 75. The apparatus was of a closed circuit type, consisting of the lobe being perfused by means of a roller pump so that a series of steady flows could be obtained. Transpulmonary pressure was imposed by positive inflation. Venous pressure, fixed by the distal liquid overflow, was maintained at+10 cm H2O while alveolar pressure was +5 cm H2O. Thus, for most of the parenchyma conditions were consistent with Zone III as described by Westet al. The arterio-venous pressure difference was varied between 3 and 50 cm H2O. For comparison, pressure-flow relations were obtained concurrently with a capillary viscometer capable of attaining wall shear rates of less than 1 sec−1. In 12 alterations of hematocrit (concentrations and dilutions) with 9 lobes it was found without exception that (1) increasing the hematocrit causes a shift of the pressure-flow curve in the direction of decreased flow and (2) decreasing the hematocrit caused a shift of the curve in the direction of increased flow. Analysis showed these changes to be statistically significant. Some evidence was also found that pressure-flow curves become more non-linear as hematocrit is increased.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00592291
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