Abstract 146: Relation Between Noninvasive Vascular Function Assessment Methods in Healthy and Obese Adults

Abstract

Peripheral arterial tonometry (PAT) is a novel method of non-invasive endothelial function assessment. However the physiology underlying PAT and its relationship to established methods of assessment not clear. Therefore we evaluated the relationship between PAT in the digital microcirculation with an established method of ultrasound assessment of flow-mediated dilatation (FMD) in the brachial artery in a sample of healthy and obese subjects. We also compared the augmentation index (AIx) derived from PAT and compared this with AIx derived by radial applanation tonometry (SphygmoCor). Using a cross-sectional design 16 healthy individuals (age 36±16years; BMI 25±5kg/m 2 ) and 14 overweight and obese patients (age 57±7years; BMI 31±6kg/m 2 ) were examined. Vascular function was assessed using FMD and PAT techniques simultaneously after an overnight fast. 14 overweight subjects had augmentation index (AIx) assessed using radial applanation tonometry immediately prior to PAT and FMD procedures. Bivariate correlation analysis was used to assess the relationship between variables. No significant correlations between fasting FMD and PAT were observed in the healthy (r=0.249 p=0.372) or overweight and obese group (r=-0.345 p=0.227). There was no correlation between the endothelium-independent responses to nitroglycerin measured by PAT and brachial ultrasound (r=0.357 p=0.210). AIx derived from EndoPAT was significantly correlated with AIx values obtained with Sphygmocor (r=0.770 p=0.001). In conclusion AIx derived from SphygmoCor and EndoPAT were significantly correlated however PAT and FMD were not related in healthy or obese adults. This may be due to differing vascular biology of the PAT response to hyperaemia in the digital circulation compared with the FMD response measured in conduit vessels. PAT as a method of endothelial function assessment requires further validation in population sub groups.