Ileal microcirculation and mucosal acidosis during hyperdynamic porcine endotoxemia

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Introduction

The tonometric determination of the arterial-mucosal PCO₂-gap (Δa-rPCO₂) is used to monitor adequacy of gastrointestinal perfusion. As PrCO₂ also integrates other phenomena [1], we analyzed the influence of the intestinal villus microcirculation on increased Δa-rPCO₂during long-term hyperdynamic porcine endotoxemia.

Material and methods

Anesthetized and ventilated pigs received continuous i.v. endotoxin (ETX, n=12) for 24 h or placebo (Sham, n=6). Hydroxyethylstarch was infused to maintain MAP >65 mmHg together with a sustained increase in cardiac output [2]. Before the start of ETX (0 h), as well as 12 and 24 h afterwards, portal venous blood flow (Qpv, ultrasound flow probes) and lactate/pyruvate-ratios (L/P pv), ileal mucosal Δa-rPCO₂ (fiberoptic sensor)and bowel wall capillary Hb-O₂-saturation (Hb-O₂cap,remission spectrophotometry) were assessed together with intravital video records of the ileal mucosal microcirculation (number of perfused/not-perfused villi) by orthogonal polarization-spectrometry (Cytoscan^™) [3] obtained via an ileostomy.

Results

See Table. Median(25/75%); #P<0.05 vs 0 h (Friedman-Anova); ^§P<0.05 ETX vs Sham (Mann-Whitney).

Conclusion

Taking into account the unchanged portal venous blood flow, the progressive increase in Δa-rPCO₂ is mainly due to the heterogeneity of capillary villus perfusion. We can only speculate about the putative additional influence of a disturbed intracellular O₂-utilisation.

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