Key result
In postmortem human lungs, the compliance coefficient alpha for arterioles of branching orders 1-3 was 0.682, 0.472, and 0.354%/cmH2O, and for venules was 0.992, 0.612, and 0.424%/cmH2O, respectively.
This study provides baseline elasticity measurements for human pulmonary arterioles and venules, demonstrating specific compliance coefficients across different branching orders.
Supplies reference compliance values for human pulmonary arterioles and venules; leaves open applicability to living physiology and disease.
The elasticity and branching order of noncapillary microscopic blood vessels less than 100 microns diam were studied in human lungs obtained 7-30 h postmortem, using a silicone elastomer method that selectively filled pulmonary arterioles or venules. The lungs were inflated to 10 cmH2O pressure and a gradient of transmural vascular pressure of 0-17 cm H2O, from lobe base to apex, was established in the silicone-filled vascular system. Histological materials were obtained after airway fixation by formaldehyde solution and analyzed for vessel diameter in the branching order of 1, 2, and 3, with the smallest noncapillary vessel designated as order 1, in accord with the Strahler system. The change in vessel diameter within a branching order at different levels of transmural pressure is a derived measure of vascular elasticity expressed as compliance coefficient alpha, alpha Values are 0.128, 0.164, and 0.210 micron/cmH2O or 0.682, 0.472, and 0.354%/cmH2O, respectively, of orders 1-3 for arterioles and 0.187, 0.215, and 0.250 micron/cmH2O or 0.992, 0.612, and 0.424%/cmH2O, respectively, of orders 1-3 for venules. The percent is normalized with D0, which is the value of diameter (D) when the transmural pressure is zero. These data are compared with those for the cat where alpha = 0.274 for similar juxta-alveolar vessels.
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Yen et al. (1988) studied Postmortem human lungs. Transmural vascular pressure gradient vs. Zero transmural pressure was evaluated on Vascular elasticity expressed as compliance coefficient alpha for arterioles and venules of branching orders 1-3. In postmortem human lungs, the compliance coefficient alpha for arterioles of branching orders 1-3 was 0.682, 0.472, and 0.354%/cmH2O, and for venules was 0.992, 0.612, and 0.424%/cmH2O, respectively.
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