Journal of Applied Physiology, Vol 63, Issue 3 1114-1121, Copyright © 1987 by American Physiological Society

ARTICLES

Gravity-independent inequality in pulmonary blood flow in humans

T. S. Hakim, R. Lisbona and G. W. Dean
Department of Physiology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.

Single-photon emission computerized tomography of the lung with 99mTc-labeled human albumin macroaggregates (99mTc-MAA) was used in six healthy subjects to study the three-dimensional distribution of pulmonary blood flow. 99mTc-MAA was injected while the subjects were resting in the supine position and holding their lung volume at normal end expiration. Tomography was performed on each subject from 120 projections of radioactivity in the lungs acquired with a rotating gamma camera. To minimize lung motion artifacts, the subjects were asked to hold their breath at end expiration during the 10-s duration of data acquisition in each projectional angle. Perfusion images of lung slices (11 mm thick) were reconstructed, and the radioactivity within each slice was expressed per unit lung volume of 3.7 X 3.7 X 11 mm. Perfusion images of a midcoronal slice from each subject manifested a concentric pattern of radioactivity that decreased significantly from the center to the periphery, suggesting that blood flow rate per unit lung volume was up to 10 times larger near the central region. This gradient in activity between the center and the periphery of the coronary slices was gravity independent as the subjects were supine. Images of sagittal slices from the middle of the right lung also manifested a similar pattern of concentric gradient in activity, with the vertical distribution (gravity related) almost comparable with the horizontal distribution (gravity independent). These results indicate that pulmonary blood flow in resting supine humans is spatially stratified with a marked central-to-peripheral gradient in all directions. It appears that zone 4 (reduced blood flow) is not a phenomenon limited to the dependent region of the lung as commonly thought but rather is a manifestation of this spatial distribution whereby blood flow is lowest in all peripheral regions of the lung.

This article has been cited by other articles:

				M. Hughes and J. B. West Point:Counterpoint: Gravity is/is not the major factor determining the distribution of blood flow in the human lung J Appl Physiol, May 1, 2008; 104(5): 1531 - 1533. [Full Text] [PDF]

				G. K. Prisk, K. Yamada, A. C. Henderson, T. J. Arai, D. L. Levin, R. B. Buxton, and S. R. Hopkins Pulmonary perfusion in the prone and supine postures in the normal human lung J Appl Physiol, September 1, 2007; 103(3): 883 - 894. [Abstract] [Full Text] [PDF]

				J. Petersson, A. Sanchez-Crespo, S. A. Larsson, and M. Mure Physiological imaging of the lung: single-photon-emission computed tomography (SPECT) J Appl Physiol, January 1, 2007; 102(1): 468 - 476. [Abstract] [Full Text] [PDF]

				Z. A. Aziz, A. U. Wells, S. R. Desai, S. M. Ellis, A. E. Walker, S. MacDonald, and D. M. Hansell Functional Impairment in Emphysema: Contribution of Airway Abnormalities and Distribution of Parenchymal Disease Am. J. Roentgenol., December 1, 2005; 185(6): 1509 - 1515. [Abstract] [Full Text] [PDF]

				S. M. Walther, M. J. Johansson, T. Flatebo, A. Nicolaysen, and G. Nicolaysen Marked differences between prone and supine sheep in effect of PEEP on perfusion distribution in zone II lung J Appl Physiol, September 1, 2005; 99(3): 909 - 914. [Abstract] [Full Text] [PDF]

				G. Tusman, M. Areta, C. Climente, R. Plit, F. Suarez-Sipmann, M. J. Rodriguez-Nieto, G. Peces-Barba, E. Turchetto, and S. H. Bohm Effect of pulmonary perfusion on the slopes of single-breath test of CO2 J Appl Physiol, August 1, 2005; 99(2): 650 - 655. [Abstract] [Full Text] [PDF]

				S. Montmerle, P. Sundblad, and D. Linnarsson Residual heterogeneity of intra- and interregional pulmonary perfusion in short-term microgravity J Appl Physiol, June 1, 2005; 98(6): 2268 - 2277. [Abstract] [Full Text] [PDF]

				G. Musch, J. D. H. Layfield, R. S. Harris, M. F. V. Melo, T. Winkler, R. J. Callahan, A. J. Fischman, and J. G. Venegas Topographical distribution of pulmonary perfusion and ventilation, assessed by PET in supine and prone humans J Appl Physiol, November 1, 2002; 93(5): 1841 - 1851. [Abstract] [Full Text] [PDF]

				M. A. Chornuk, S. L. Bernard, J. W. Burns, R. W. Glenny, D. D. Sheriff, S. E. Sinclair, N. L. Polissar, and M. P. Hlastala Effects of inertial load and countermeasures on the distribution of pulmonary blood flow J Appl Physiol, August 1, 2000; 89(2): 445 - 457. [Abstract] [Full Text] [PDF]

				G. K. Prisk Physiology of a Microgravity Environment: Invited Review: Microgravity and the lung J Appl Physiol, July 1, 2000; 89(1): 385 - 396. [Abstract] [Full Text] [PDF]

				J. E. Souders, J. B. Doshier, N. L. Polissar, and M. P. Hlastala Spatial distribution of venous gas emboli in the lungs J Appl Physiol, November 1, 1999; 87(5): 1937 - 1947. [Abstract] [Full Text] [PDF]

				Y Nakano, H Sakai, S Muro, T Hirai, Y Oku, K Nishimura, and M Mishima Comparison of low attenuation areas on computed tomographic scans between inner and outer segments of the lung in patients with chronic obstructive pulmonary disease: incidence and contribution to lung function Thorax, May 1, 1999; 54(5): 384 - 389. [Abstract] [Full Text]

				S. Nyren, M. Mure, H. Jacobsson, S. A. Larsson, and S. G. E. Lindahl Pulmonary perfusion is more uniform in the prone than in the supine position: scintigraphy in healthy humans J Appl Physiol, April 1, 1999; 86(4): 1135 - 1141. [Abstract] [Full Text] [PDF]

				R. W. Glenny, S. Bernard, H. T. Robertson, and M. P. Hlastala Gravity is an important but secondary determinant of regional pulmonary blood flow in upright primates J Appl Physiol, February 1, 1999; 86(2): 623 - 632. [Abstract] [Full Text] [PDF]

				W. A. Altemeier, H. T. Robertson, and R. W. Glenny Pulmonary gas-exchange analysis by using simultaneous deposition of aerosolized and injected microspheres J Appl Physiol, December 1, 1998; 85(6): 2344 - 2351. [Abstract] [Full Text] [PDF]

				C. M. Mann, K. B. Domino, S. M. Walther, R. W. Glenny, N. L. Polissar, and M. P. Hlastala Redistribution of pulmonary blood flow during unilateral hypoxia in prone and supine dogs J Appl Physiol, June 1, 1998; 84(6): 2010 - 2019. [Abstract] [Full Text] [PDF]

				M. P. Hlastala, M. A. Chornuk, D. A. Self, H. J. Kallas, J. W. Burns, S. Bernard, N. L. Polissar, and R. W. Glenny Pulmonary blood flow redistribution by increased gravitational force J Appl Physiol, April 1, 1998; 84(4): 1278 - 1288. [Abstract] [Full Text] [PDF]

				J. C. Parker, C. B. Cave, J. L. Ardell, C. R. Hamm, and S. G. Williams Vascular tree structure affects lung blood flow heterogeneity simulated in three dimensions J Appl Physiol, October 1, 1997; 83(4): 1370 - 1382. [Abstract] [Full Text] [PDF]

				Y. Oyamada, M. Mori, I. Kuwahira, T. Aoki, Y. Suzuki, K. Suzuki, A. Miyata, K. Nishio, N. Sato, K. Naoki, et al. Effects of active vasoconstriction and total flow on perfusion distribution in the rabbit lung Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1997; 273(4): R1465 - R1473. [Abstract] [Full Text] [PDF]

				J. B. West, A. R. Elliott, H. J. B. Guy, and G. K. Prisk Pulmonary Function in Space JAMA, June 25, 1997; 277(24): 1957 - 1961. [Abstract] [PDF]

				S. M. Walther, K. B. Domino, R. W. Glenny, N. L. Polissar, and M. P. Hlastala Pulmonary blood flow distribution has a hilar-to-peripheral gradient in awake, prone sheep J Appl Physiol, February 1, 1997; 82(2): 678 - 685. [Abstract] [Full Text] [PDF]