Splanchnic blood flows in a rat model of antibiotic-controlled intra-abdominal abscess during normoxia and hyperoxia.

We have characterized splanchnic blood flows in a rat model of antibiotic-controlled, intra-abdominal abscess (ACIA) in normoxic and hyperoxic environments. Abscesses (1.5 ml average volume) were established by implanting a fecal-agar pellet containing known numbers and strains of live Escherichia coli and Bacteroides fragilis into the peritoneal cavity of rats via a midline incision. Sham-operated rats (SR) served as controls. Cannulas (PE-50) were placed into the left ventricle of both SR and ACIA rats for injection of tracer microspheres (MS) and into the tail artery for a reference withdrawal site. Blood flow measurements were made in conscious unrestrained rats before, during, and after hyperoxic exposure by using MS labelled with either 51Cr or 85Sr or 141Ce. No change in cardiac output (CO), heart rate (HR), or mean arterial pressure (MAP) was seen between ACIA and SR groups. The administration of hyperoxia diminished the fractional distribution of CO to the liver (portal), stomach, cecum, colon, and pancreas in both groups. The percent CO to the liver (arterial), small intestine, and spleen did not change in either group. The blood flow to all splanchnic organs, except liver (arterial), was diminished during hyperoxia in both groups and recovered after hyperoxia. In conclusion, central hemodynamics and splanchnic blood flows are not altered by the presence of a large intra-abdominal abscess controlled by antibiotics. Splanchnic blood flows are diminished by hyperoxia.