0502 Dynamic parameters of preload predict impairments of intestinal microcirculation in a porcine model of ischemia-reperfusion

INTRODUCTION.Dynamic preload parameters such as stroke volumevariation (SVV) and pulse pressure variation(PPV) have been widelyrecommended for evaluation of volume responsiveness. However,when guiding volume therapy, either hypovolaemia as well asvolume-overload have to be avoided. Over-infusion results in im-pairments of microcirculation, which are associated with decreasedoutcome[1]. Endothelial dysfunction - that can be caused by ische-mia/reperfusion - aggravates this problem and promotes interstitialswelling leading to further deterioration of microcirculation[2]. Todate no effort has been made to evaluate whether SVV and PPVpotentially can help to avoid decreases of microcirculation due tovolume overload.OBJECTIVES.The aim of this study was to evaluate, whether lowvalues of PPV and SVV do have the potential to predict animpairment of intestinal microcirculation caused by volume-overloadin experimental ischemia/reperfusion.METHODS.In 8 pigs ischemia/reperfusion was induced duringexperimental aortic bypass surgery. Mean microcirculatory bloodflow (mFlux) of the ileum was measured using direct laser-speckle-contrast-imaging. PPV and SVV were measured using aortic flow-probes and femoral microtip-catheters. 6 hours after ischemia/reper-fusion injury measurements were performed during 4 consecutivevolume-loading steps (VLS). We performed ROC Analysis to deter-mine ability and potential thresholds of SVV and PPV to predict amicrocirculatory decrease due to volume loading. A reduction of≥10% mFlux was considered a relevant decrease.RESULTS.I In total 28 VLS were analysed. Haemodynamic changesthroughout the protocol are shown in Table 137. In ROC-analysis SVVpresented with an AUC of 0,76 (CI 95% 0,57-0,96; p = 0,034) and PPVwith an AUC of 0,84 (CI 95% 0,68-0,99; p = 0,003). ROC curves arepresented in Fig. 182. Youden Index was calculated to determineideal cut-off values predicting microcirculatory decrease. The follow-ing cut-off values can be proposed: SVV < 12,69% (Youden Index0,57; sensitivity 77,78%, specificity 73,33%), PPV < 8,02 (Youden Index0.64; sensitivity 72,73%; specificity 87,50%). CONCLUSION.The results of our study show that low values of SVVand PPV do have the potential to predict decreases of intestinalmicrocirculatory blood flow caused by volume-overload in experi-mental ischemia/reperfusion. Therefore, dynamic preload parametersmay not only be used to detect volume responsiveness but mightalso help to prevent microcirculatory impairments.