Value of peripheral tissue oxygen tension in animal experimental models of haemorrhagic and septic shock

Introduction

Current clinical parameters on efficiency of resuscitation are often insufficient, and unable to reliably assess tissue hypoxia. Considerable interest has been aimed to direct monitoring of tissue oxygen tension (ptO₂). However, no golden standard has yet been found. Animal experimental models have shown interesting results in hypovolemic and septic shock and have lead to some interesting clinical studies. The purpose of this review is to evaluate the current value of ptO₂ monitoring in animal experimental studies under various pathophysiological conditions.

Methods

An electronic literature search on Pubmed and Embase databases was conducted to find relevant articles on tissue oxygenation and hemorrhage, trauma and endotoxemia. An initial amount of 7,876 articles were retrieved. After applying inclusion and exclusion criteria and critical appraisal, 48 articles were ranked on their level of evidence.

Results

After screening of the 48 articles, 19 articles were found to be suitable to answer our goal. Ten articles discussed tissue oxygenation in a hemorrhagic model and nine articles in a model of endotoxemia. No relevant articles concerning ptO₂ and experimental trauma were found. Eight articles compared splanchnic ptO₂ measurements in relation to ptO₂ measured in several peripheral sites, like subcutaneous and skeletal muscle tissue. A positive correlation between these locations was found in seven articles. A decrease in both peripheral and central tissue oxygen pressure (ptO₂) was found during hemorrhage. Importantly, peripheral ptO₂ changed earlier during hemorrhage before any hemodynamic parameter did. In contrast, only one article found an earlier change in hemodynamic parameters than in peripheral ptO₂. Nine articles discussed ptO₂ in a model of septic shock. Only two studies compared peripheral ptO₂ measurements with splanchnic ptO₂ measurements. Both sites had decreased ptO₂ values in endotoxemia and both were found to change before any changes in hemodynamic parameters.

Conclusions

A significant relation between intestinal ptO₂ and peripheral ptO₂ was found in studies on experimental models of hemorrhagic and septic shock. This suggests that peripheral sites like the subcutaneous tissue or skeletal muscles tissue are reliable locations for measurements of ptO₂.