Pulmonary blood flow distribution in anesthetized ponies

K. A. Jarvis, Eugene Steffey, W. S. Tyler, N. Willits, M. Woliner

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Results of recent investigations in humans and dogs indicate that gravity- independent factors may be important in determining the distribution of pulmonary blood flow. To further evaluate the role of gravity-independent factors, pulmonary blood flow distribution was examined using 15-μm radionuclide-labeled microspheres in five prone ponies over 5 h of pentobarbital sodium anesthesia. The ponies were killed, and the lungs were excised and dried by air inflation (pressure 45 cmH2O). The dry lungs were cut into transverse slices 1-2 cm thick along the dorsal-ventral axis, parallel to gravity. Radioactivity of pieces cut from alternate slices was measured with a gamma well counter. The main finding was a preferential distribution of pulmonary blood flow to dorsal-caudal regions and higher flow in the center of each lung slice when compared with the slice periphery. Flow was lowest in cranial and ventral areas. Differences of ±2 SD were observed between core and peripheral blood flow. No medial-lateral differences were found. Pulmonary blood flow distribution did not change over 5 h of anesthesia, and the basic flow pattern was not different in the left vs. right lung. These results suggest that in the intact prone mechanically ventilated pony (inspired O2 fraction ≥0.95) factors other than gravity are primary determinants of pulmonary blood flow.

Original languageEnglish (US)
Pages (from-to)1173-1178
Number of pages6
JournalJournal of Applied Physiology
Issue number3
StatePublished - Jan 1 1992


  • gravity
  • lung
  • microspheres
  • pulmonary circulation
  • regional blood flow

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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