Pulmonary blood flow redistribution by increased gravitational force

• Published in: Journal of applied physiology (1985) Vol. 84; no. 4; pp. 1278 - 1288
• Main Authors: Hlastala, Michael P, Chornuk, Myron A, Self, David A, Kallas, Harry J, Burns, John W, Bernard, Susan, Polissar, Nayak L, Glenny, Robb W
• Format: Journal Article
• Language: English
• Published: Legacy CDMS Am Physiological Soc 01.04.1998; American Physiological Society
• Subjects: Acceleration; Air breathing; Animals; Biological and medical sciences; Female; Fluorescence; Fundamental and applied biological sciences. Psychology; Gravitation; Hemodynamics - physiology; Life Sciences (General); Microspheres; Pulmonary Circulation - physiology; Pulmonary Gas Exchange - physiology; Regression Analysis; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Space life sciences; Swine; Swine, Miniature; Vertebrates: respiratory system; Non-Nasa Center; Nasa Discipline Cardiopulmonary; Gravitational force; Regional blood flow; Lung; Environmental factor; Respiratory system; Vertebrata; Mammalia; Centrifugal force; Artiodactyla; Hemodynamics; Minipig; Acceleration; Ungulata; Gravity; NASA Discipline Cardiopulmonary; Non-NASA Center
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.84.4.1278

Departments of 1  Physiology and Biophysics, 2  Medicine, and 3  Anesthesiology, University of Washington, Seattle 98195; 4  The Mountain-Whisper-Light Statistical Consulting, Seattle, Washington 98122; and 5  Crew Technology Division, Armstrong Laboratory, Air Force Medical Center, Brooks Air Force Base, Texas 78235 This study was undertaken to assess the influence of gravity on the distribution of pulmonary blood flow (PBF) using increased inertial force as a perturbation. PBF was studied in unanesthetized swine exposed to G x (dorsal-to-ventral direction, prone position), where G is the magnitude of the force of gravity at the surface of the Earth, on the Armstrong Laboratory Centrifuge at Brooks Air Force Base. PBF was measured using 15-µm fluorescent microspheres, a method with markedly enhanced spatial resolution. Each animal was exposed randomly to 1, 2, and 3 G x . Pulmonary vascular pressures, cardiac output, heart rate, arterial blood gases, and PBF distribution were measured at each G level. Heterogeneity of PBF distribution as measured by the coefficient of variation of PBF distribution increased from 0.38 ± 0.05 to 0.55 ± 0.11 to 0.72 ± 0.16 at 1, 2, and 3 G x , respectively. At 1 G x , PBF was greatest in the ventral and cranial and lowest in the dorsal and caudal regions of the lung. With increased G x , this gradient was augmented in both directions. Extrapolation of these values to 0 G predicts a slight dorsal (nondependent) region dominance of PBF and a coefficient of variation of 0.22 in microgravity. Analysis of variance revealed that a fixed component (vascular structure) accounted for 81% and nonstructure components (including gravity) accounted for the remaining 19% of the PBF variance across the entire experiment (all 3 gravitational levels). The results are inconsistent with the predictions of the zone model. fluorescent microspheres; cardiac output; pulmonary gas exchange; centrifuge; acceleration; gravity