Modulation of inflammation during acute normovolemic anemia with different fluid replacement

Acute normovolaemic anemia (ANA) frequently occurs during cardiopulmonary bypass (CPB) and major surgeries. We investigated whether fluids (with different compositions) used to replace blood elicit any degree of systemic or lung inflammatory response.

We evaluated systemic and pulmonary inflammatory responses in a swine model of acute normovolemic anemia induced by 6% hydroxyethyl starch 130/0.4 (HES, N.=7), 0.9% saline solution (SS, N.=7), and gelatine (GEL, N.=7). Cytokine levels and neutrophil oxidative burst were analysed in the blood at baseline, 0, 60, and 120 min after hemodilution (TBL, TA, T60A, and T120A, respectively) as well as 60 (T60BI) and 120 min (T120BI) after autologous blood reinfusion. Lung histology and expression of cyclooxygenase-2 (COX-2) and E-selectin were analysed at T120BI.

TNF-α, IL-6, and IL-10 levels at T60A were significantly higher in the GEL (P<0.05) and SS (P<0.05) groups than in the Control group. IL-1β was increased significantly in the GEL group (P<0.05) at T60H. Stimulated neutrophil oxidative burst in the blood was increased significantly only in the GEL group at TA (P<0.05). The GEL group presented higher COX-2 and E-selectin expression, followed by the saline and starch groups. The presence of inflammatory cell infiltration, oedema, congestion, and alveoli collapse was increased in the SS and GEL groups.

In this animal model of acute normovolemic hemodilution, fluid solutions of hydroxyethyl starch, normal saline, and modified fluid gelatine were shown to be effective in replacing blood during ANA. However, compared to HES, GEL and NS elicited a more intense systemic and lung inflammatory response.