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Ventilation‐Perfusion Relationships During Halothane Anaesthesia and Mechanical Ventilation. Effects of Varying Inspired Oxygen Concentration
Author(s) -
Lundh R.,
Hedenstierna G.
Publication year - 1984
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.1399-6576.1984.tb02039.x
Subject(s) - halothane , medicine , anesthesia , hypoxic pulmonary vasoconstriction , perfusion , shunt (medical) , mechanical ventilation , oxygen , ventilation (architecture) , population , controlled ventilation , vasoconstriction , cardiology , mechanical engineering , chemistry , environmental health , organic chemistry , engineering
Ventilation‐perfusion relationships (VA/Q.), assessed by a multiple inert‐gas elimination technique, were studied during halothane anaesthesia and mechanical ventilation at different inspiratory oxygen fractions (F102). All nine patients (mean age 65 years, five smokers) displayed unaltered VA/Q. distributions with increasing F102 from a mean of 29% to 53%. A further increase in F102 to a mean of 85% caused an increase in true shunt (VA/Q=0) from 7 to 10% of cardiac output ( P <0.01), but no increase in “low” VA/Q (VA/ Q<0.1). On the return to F102 of 29%, true shunt was reduced to the initial level. The findings may fit in with release of hypoxic vasoconstriction when F102 is increased to 85%, or the opening up of a certain population of shunt vessels.