Simple estimate of the true right to left shunt (Qs/Qt) at maintenance F1O2 by Sulphur Hexafluoride retention

A. Pesenti, R. Latini, A. Riboni, L. Gattinoni

Research output: Contribution to journalArticlepeer-review


Differentiating Qs/Qt over Qva/Q (as measured by the standard O2 content formula) appears to be of great interest in applying and evaluating different therapeutic approaches. The estimation of Qs/Qt by 100% O2 breathing may alter "per se" the lung condition and is unsatisfactory. We used Sulphur Hexafluoride (SF6; λ=6.10-3 ml ml-1 760 mmHg-1) to identify the true shunt (VA/Q1O2. A simple and rapid determination of SF6 retention is performed by ECD gas chromatography from contemporaneous arterial and mixed venous blood samples, taken during i.v. infusion of an SF6 containing solution. Qs/Qt estimate is then given by the ratio: PaSF6/P {Mathematical expression}SF6. It is not necessary to know the absolute gas partial pressures or concentration, hence absolute gas calibrations are not required. This method is suggested as feasible and satisfactory for clinical use, allowing the determination of Qs/Qt at the maintenance F1O2.

Original languageEnglish
Pages (from-to)283-286
Number of pages4
JournalIntensive Care Medicine
Issue number6
Publication statusPublished - 1982


  • Inert gas retention
  • Lung arteriovenous shunt
  • Lung ventilation perfusion ratio
  • Sulphur hexafluoride

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


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