Measurement of cardiac output by open-circuit acetylene uptake: a computer model to quantify error caused by ventilation-perfusion inequality

Harm J Bogaard, Peter D Wagner

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2 Citations (Scopus)


The ability to assess cardiac output (Q(T)) noninvasively has been the focus of interest for many researchers. While the open-circuit acetylene (C2H2) method seems promising, it is prone to error due to ventilation-perfusion (V/Q) inequality. Measurements during exercise, at high altitude or in patients with chronic obstructive pulmonary disease (COPD) could be unreliable and further validation studies under these circumstances may be needed. We used a computer model based on formulae derived from the multiple inert gas elimination technique to quantify error in Q(T) measurements resulting from V/Q inequality at rest, during exercise or at high altitude. Moreover, potential errors encountered in patients with COPD were quantified. In healthy subjects, V/Q inequality related measurement error seems negligible, under both normoxic and hypoxic conditions and especially during exercise. In COPD, errors up to 20% at rest and up to 15% during exercise are expected. It is therefore concluded from our model that the open-circuit C2H2 uptake method is expected to be accurate in normal subjects. Its validity in COPD needs further study.

Original languageEnglish
Pages (from-to)1023-32
Number of pages10
JournalPhysiological measurement
Issue number10
Publication statusPublished - Oct 2006


  • Acetylene
  • Cardiac Output/physiology
  • Computer Simulation
  • Exercise/physiology
  • Humans
  • Hypoxia/physiopathology
  • Models, Biological
  • Pulmonary Disease, Chronic Obstructive/physiopathology
  • Ventilation-Perfusion Ratio/physiology

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