Monitoring micro-rheological and multi-organ microcirculatory changes in abdominal sepsis in rats - a new approach to...

The hemorheological and microcirculatory aspects of the pathophysiology of sepsis are partially understood and are often controversial in terms of the dynamics, extent, and correlation of parameters. We aimed to simultaneously investigate hemorheological and multi-organ microcirculatory changes in abdominal sepsis in the rat. Sixteen male Wistar rats (body weight: 389.1 ± 44.9 g) were included in our studies. Animals were randomly assigned to sham-operated control (n=8) or sepsis group (n=8). In the sepsis group, sepsis induction was performed by coecum ligation and puncture after median laparotomy. In the sham-operated group, only laparotomy and abdominal wall closure were performed. Body and rectal temperature, respiratory rate, abdominal aortic blood flow (T206 Transonic System) were measured before and after 24 h after surgery, and microcirculatory recordings were captured using a Cytocam-IDF camera in several localizations (skin, coecum, kidney). A scoring system has been developed for the evaluation of the recordings. These video images were evaluated semi-quantitatively based on the deviations (oedema, presence of red blood cell aggregates, flow heterogeneity and vasculature regularity, scored with 0-4 points per category). After blood sampling, we determined hematological, hemorheological, acid-base, and metabolic parameters.

Body and rectal temperatures were significantly elevated in the sepsis group compared to the control group (p=0.005; p=0.016). Major increases in lactate and creatinine concentrations indicated progression of sepsis (p<0.001 vs. baseline). Increased deterioration of microcirculation was observed: the percentage and density of perfused vessels were significantly decreased in sepsis (coecum: p<0.001 vs. baseline). We saw similar results during scoring the videos, with heterogeneous blood flow and elevated number of aggregates. Erythrocyte aggregation parameters were increased in the sepsis and control group (p<0.001 vs. baseline) and erythrocyte deformability showed a significant decrease (EI_max: p=0.012 vs. baseline).

The micro-rheological parameters of erythrocytes and microcirculatory changes can majorly impact tissue perfusion during sepsis. The analysis of microcirculatory recordings and the new scoring system can provide useful information on the impact of sepsis on tissue microcirculation.