Microcirculatory blood flow in the gastrointestinal tract during early septic shock

The autoregulation of microcirculatory blood flow (MBF) in the gut is impaired during sepsis. However, there is little data available on the distribution of blood flow in the different parts of the gastrointestinal tract and on the relationship between mucosal perfusion and supramesenteric artery flow (QSMA) during sepsis. The aim of this study was to elucidate the relationship between regional blood flow (QSMA) and the local flow in different tissues and parts of the gut and in the pancreas during early septic shock.

Materials and methods

Nine pigs (20–24 kg) were anesthetised endo-tracheally intubated and ventilated. Cardiac index (CI) was measured with thermodilution technique and mesenteric artery blood flow (QSMA) with an ultrasound flowprobe. Microcirculatory blood flow (MBF) was continuously monitored in multiple organs (pancreas, gastric-, jejunal-, colonic mucosa and muscularis of the jejenum) with a multichannel laser Doppler system. After baseline measurements a generalised faecal peritonitis was induced by instillation of 20 g of faeces in the abdominal cavity. After 240 min, i.v. fluids were administered which altered the hypodynamic shock to hyperdynamic septic shock.

Results and discussion

During the first 240 min (hypodynamic shock) CI and QSMA decreased by 50% (P < 0.01; Figs 1 and 2). Microcirculatory blood flow in the mucosa of the stomach and colon decreased similarly (Figs 3 and 4) while the mucosa of the jejunum was maintained close to baseline (Fig. 5). On the other hand, MBF in the pancreas and the jejunal muscularis decreased significantly more than the QSMA (Figs 6 and 7). Administration of i.v. fluids at 240 min was followed by a significant increase in CI and QSMA (Figs 1 and 2). Although this was followed by some increase in MBF in the mucosa of the stomach and colon as well as in the pancreas and jejunal muscularis, the relative amount of flow in these organs significantly decreased as compared with QSMA (Figs 3,4,5). MBF in the mucosa of the jejunum increased essentially parallel with the QSMA (Fig. 6).

Conclusion

• a) In septic shock jejenunal mucosal blood flow is maintained despite decreased mesenteric flow (QSMA), probably through redistribution of flow from muscularis to the mucosa (Fig. 8).

• b) Microcirculatory flow in the mucosa of the stomach and colon decreases parallell with QSMA during hypodynamic septic shock, while during hyperdynamic sepsis it decreases significantly compared with QSMA (Figs 3 and 4).

• c) Microcirculatory flow in the pancreas decreases significantly more than QSMA both during hypodynamic and hyperdynamic septic shock (Fig. 6).

Figure 1-8

Onset of Peritonitis at 0 min and Pentastrach administration at 240 min. Data presented as mean ± SEM. Paired ANOVA for repeated measurements was used for comparison. P < 0.05 was considered statistically siginficant