Increased cardiac output increases shunt: Role of pulmonary edema and perfusion

P. H. Breen, P. T. Schumacker, J. Sandoval, I. Mayers, L. Oppenheimer, L. D. Wood

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


In low-pressure pulmonary edema increased cardiac output [Q̇(T)] increases shunt [Q̇s/Q̇(T)]; we tested whether the mechanism is an increase in extravascular lung water in turn mediated by the accompanying increase in microvascular pressure. In six pentobarbital sodium-anesthetized dogs ventilated with O2 we administered oleic acid into the right atrium. From base line to 2 h post-oleic acid we measured concurrent significant increases in Q̇s/Q̇(T) (6-29%, O2 technique) and extravascular thermal volume (ETV, 2.6-7.1 ml/g dry intravascular blood-free lung wt, thermal-green dye indicator technique) that were stable by 90 min. Then, bilateral femoral arteriovenous fistulas were opened and closed in 30-min periods to cause reversible increases in Q̇(T) and associated Q̇s/Q̇(T). When fistulas were open the time-averaged Q̇(T) increased from 5.1 to 6.9 min (P < 0.05), the simultaneous Q̇s/Q̇(T) rose from 30.7 to 38.4% (P < 0.05), but ETV did not increase. We conclude that increasing lung edema does not account for our rise in Q̇s/Q̇(T) when Q̇(T) increased.

Original languageEnglish (US)
Pages (from-to)1313-1321
Number of pages9
JournalJournal of applied physiology
Issue number4
StatePublished - 1985

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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