Local cerebral blood flow is preserved in sepsis

Sepsis is often complicated by encephalopathy, neuroendocrine dysfunction and cardiovascular autonomic failure. The cause of septic brain dysfunction is not fully understood. The aim of the present study is to explore whether septic brain dysfunction in a common septic model in the rat correlates with abnormalities either of local cerebral blood flow (LCBF) of defined brain areas or of whole brain blood flow (CBF). 45 male Wistar rats (320+/-13 g) were randomly assigned to a sepsis group (31 rats, cecal ligature and puncture, CLP) or a control group (14 rats, sham operation). Of these 45 rats, 16 rats were used for blood analysis; the remaining 29 rats were used for CBF/LCBF measurements. LCBF measurements were performed 24h after initial surgery using quantitative autoradiography with 4-iodo[N-methyl-(14)C]antipyrine, which allows to analyze CBF on a regional/local and global basis. In 42 different brain regions bilateral optical density measurements were performed. Septic rats (vs. control) presented tachycardia (507+/-37 vs. 452+/-44 min(-1), P<0.05), leukocytopenia (2.96+/-2.37 vs. 8.83+/-2.9710(9) x L(-1), P<0.05), hypocapnia (29.3+/-4.6 vs. 36.4+/-3.9 mmHg, P<0.05), and higher serum lactate concentrations (5.7+/-3.9 vs. 2.2+/-2.0 mmol x L(-1), P<0.05). LCBF of all 42 areas, as well as, CBF (116+/-59 vs. 115+/-52 m x 100 g(-1)min(-1), n.s.) did not differ. The results showed that severe sepsis (mortality rate of 43 %) did not induce alterations in mean CBF and LCBF. It is concluded that brain dysfunction is not reflected in changes of CBF during severe sepsis.