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A slide–rule for assessment of venous admixture
Author(s) -
ZETTERSTRÖM H.
Publication year - 1989
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1989.tb02900.x
Subject(s) - medicine , arterial catheter , shunt (medical) , arterial blood , arterial oxygen tension , venous blood , oxygenation , anesthesia , pulmonary shunt , fraction of inspired oxygen , arterial blood gas analysis , catheter , cardiology , surgery , lung , hemodynamics , mechanical ventilation
Determination of venous admixture (physiological shunt, Qya/Qt) requires analysis of both arterial and mixed venous blood. When a pulmonary arterial catheter is not in use, the pulmonary oxygenating capacity may be assessed from arterial blood gas data, the fraction of inspired oxygen (Fio 2 ) and an assumed value of the arterial–mixed venous oxygen content difference. To facilitate this process, a slide–rule based on the “virtual shunt” concept is presented. It permits rapid assessment of Qya/Qt from known values of arterial oxygen tension (Pao 2 ) or saturation (Sao 2 ) and Fio 2 and may promote the choice of appropriate Fio 2 . The limitations of the slide–rule were studied theoretically and its validity was tested by comparing 100 determinations of virtual shunt with the corresponding Qya/Qt values. The slide–rule was found to estimate Qya/Qt more accurately than commonly used oxygenation indices such as the Pao 2 /Fio 2 ratio.