Studie av subkutant interstitielt trykk under sepsis (PISEP)

The pathophysiology of sepsis is characterized by the sudden onset of vasodilation and vascular permeability with capillary leakage. This leakage contributes to the development of generalized edema which is not clinically detectable below 4 litres but which becomes visible after a few days. The edema accumulates mainly at the subcutaneous level due to the high compliance of this tissue. Edema, and therefore hydrosodium overload, testifies to the severity of the inflammation. However, it could also be harmful in itself (affecting microcirculation and increasing mortality) as suggested by numerous clinical and experimental studies.

The transfer of fluids between vascular and interstitial compartments during sepsis therefore has a central role in the pathophysiology of the disease and associated mortality. These transfers are mainly controlled at the microvascular level (with constant permeability) by the difference between capillary (CP) and interstitial (IP) pressures. In healthy subjects, subcutaneous IP is discreetly negative (-1 mmHg) and varies very little. On the other hand, a sometimes drastic decrease in IP has been described in various localized and systemic inflammatory situations. These pressure variations may be explained by the collagen structure of the interstitial tissue and a change in the three-dimensional conformation of these macromolecules induced by inflammation mediators. In an animal model of sepsis, a study showed significantly lower pressure in a group of animals in endotoxic shock. IP has never been measured in humans during sepsis. The objective of this study is to analyze subcutaneous IP (SCIP) in patients with septic shock compared with controls in order to evaluate the direct role of interstitial tissue in the onset of edema during sepsis.