Oxygen consumption (V̇O2) is often assumed to be fixed by metabolic demand, but some investigations have found V̇O2 linearly dependent on O2 delivery (Q̇·CaO2) during positive end-expiratory pressure (PEEP) trials for the adult respiratory distress syndrome. However, in those studies V̇O2 was calculated using the same cardiac output (Q̇T) and O2 content measurements used to calculate the O2 delivery to which it was being compared. We therefore obtained independent measurements of V̇O2, Q̇T, and oxygen contents under 3 conditions in 21 dogs: 14 normal dogs, each receiving varying degrees of PEEP or central venous obstruction, and 7 dogs receiving PEEP after developing pulmonary edema from intravenously infused oleic acid. In all groups, V̇O2 measured from expired gas analysis remained unchanged until Q̇T·CaO2 was reduced to below 13 ml/kg/min. The V̇O2 was then linearly dependent on Q̇T·CaO2. We conclude that this reduction in V̇O2 is due to severe Q̇T·CaO2 reduction and not to any special effect of PEEP or lung injury.
|Original language||English (US)|
|Number of pages||5|
|Journal||American Review of Respiratory Disease|
|State||Published - 1985|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine