Abstract
We explored the effects of balloon filling into the inferior vena cave as a relatively simple and atraumatic method to study the relationship between oxygen uptake (VO 2) and oxygen supply (DO 2) during an acute reduction in blood flow. Via a femoral vein, a Foley catheter was inserted with its balloon placed above the renal veins and filled with fluid for 40 minutes. A fluid challenge with saline was performed before and during the balloon filling. In nine control dogs, the critical DO 2 (D0 2crit) below which VO 2 started to decline was found at 18.5 mL/kg/min. In nine dogs receiving endotoxin as a bolus of 0.5 mg/kg followed by an infusion of 0.02 mg/kg/min, the D0 2crit was found at 18.4 mL/kg/min. In seven dogs, increasing doses of endotoxin did not influence D0 2crit. In two dogs, prolonged balloon filling demonstrated the stability and also the reversibility, of the model. As the DO 2crit is much higher on this model than in other studies using acute hemorrhage, six dogs were submitted first to balloon filling and second to hemorrhage. The DO 2crit was 14.6 mL/kg/min during balloon filling but only 9.0 mL/kg/min during hemorrhage ( P < .01). These differences in extraction capabilities are probably due to blood flow redistribution in the present model. Thus, balloon filling in the inferior vena cave represents a relatively atraumatic and reversible model to study the effects of an acute reduction in blood flow on the VO 2 DO 2 relationship. However, the DO 2crit is significantly higher in this balloon-filling model than in hemorrhaggc models. In the present study, effects of endotoxin on the tissues' extraction capabilities could not be demonstrated. In view of the probable effects of balloon filling on the distribution of blood flow, this model might not be suitable to study global changes in VO 2 DO 2 relationships.
Published Version
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