Pulmonary blood flow measured by inspiratory inert gas concentration forcing oscillations

E.M. Williams, M.C. Sainsbury, L. Sutton, L. Xiong, A.M.S. Black, J.P. Whiteley, D.J. Gavaghan, C.E.W. Hahn

Research output: Contribution to journalArticlepeer-review


The aim of this study was to discover if the forced inspired inert gas sinewave technique could be used to measure pulmonary blood flow, using nitrous oxide as the indicator gas, following inotropic stimulation of the heart by dobutamine, in the presence of a constant alveolar ventilation. Cardiac output (range 1-4.5 L min-1) was measured in six dogs by thermodilution and by calculation from the sinusoidal expired partial pressures of argon and nitrous oxide using: (i) analytical equations and a conventional continuous ventilation three-compartment lung model, which did not include recirculation; and (ii) a digital simulation tidal ventilation lung model (Gavaghan and Hahn, 1996. Respir. Physiol. 106, 209-221) which was adapted to include nitrous oxide mixed-venous recirculation from a combined single viscera compartment. The continuous ventilation model calculations always underestimated thermodilution cardiac output, with the bias error increasing to almost -1 L min-1 at the longest forcing periods, 4-5 min. In contrast, the tidal ventilation model calculations were in close agreement to thermodilution cardiac output, with biases of -0.04 and -0.26 L min-1 at forcing periods of 2 and 3 min, respectively. Copyright (C) 1998 Elsevier Science B.V.
Original languageEnglish
Pages (from-to)47-56
Number of pages10
JournalRespiration Physiology
Issue number1
Publication statusPublished - 1 Jul 1998
Externally publishedYes


  • Cardiac output, measurement, N2O
  • Mammals, dog
  • Methods, forced inspired inert gas sinewave
  • Model, mathematical, cardiac output
  • Pulmonary blood flow, N2O
  • dobutamine
  • nitrous oxide
  • animal experiment
  • article
  • controlled study
  • dog
  • heart output
  • intravenous drug administration
  • lung blood flow
  • lung ventilation
  • model
  • nonhuman
  • oscillation
  • priority journal
  • thermodilution


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