The effects of chronic bacteremia on the metabolic response to exercise in the conscious rat.

Cardiac function was indirectly assessed in a rat model of chronic sepsis by measuring maximal oxygen uptake (VO2max) during exercise. A subcutaneous abscess cavity was created in rats by implanting a gauze sponge in the hindquarter area. Animals with sterile abscesses were compared with rats that had the abscess cavity infected with Escherichia coli and Bacteroides fragilis (gram-negative group) or these two organisms plus Staphylococcus aureus (gram-positive/negative group). VO2max was measured during exercise before and after the abscess cavity was infected. After a carotid artery cannula was placed, heart rate, mean arterial pressure, arterial blood gases, and acid-base status were measured in three groups of rats (sterile abscess, gram-negative, gram-positive/negative) during submaximal and maximal exercise. Results demonstrated that the infected rats were febrile and had elevated white blood cell counts and intermittent bacteremia, while rats with sterile abscesses did not. VO2max was similar in all groups of rats both before and after the abscess cavity was infected. The metabolic and hemodynamic variables measured during submaximal and maximal exercise in the different groups of rats were similar. These results do not support the contention that gram-positive and/or-negative bacteremia produce cardiac dysfunction during early sepsis.