The impact of maternal vasodilatation as pregnancy progress on peripheral arterial tonometry in assessment of endothelial function

Objective: The aim of our study was to explore the impact of maternal vasodilatationon on peripheral arterial tonometry used for assessing the endothelial function as physiological adaptation to pregnancy progress. Methods: Thirty-one healthy pregnant women of gestational weeks from 13 to 34 were tested using sphygmomanometer, peripheral arterial tonometry and photoplethysmographic assessment. Blood pressure, heart rate, reactive hyperemia index, augmentation index and reflection index were obtained in resting conditions. Data was analyzed in two groups divided as 2nd and 3rd trimester and further divided into three groups of early 2nd trimester, late 2nd trimester and 3rd trimester. Results: A rise of reactive hyperemia index of peripheral arterial tonometry from early 2nd to late 2nd trimester and then a fall to 3rd trimester had been found in association with continuous decrease of augmentation index derived either from peripheral arterial tonometry or photoplethysmography as well as reflection index from photoplethysmography and continuous increase of heart rate, during which blood pressure remained almost unchanged. A moderate level of correlation was observed between augmentation index derived from peripheral arterial tonometry and photoplethysmography. Conclusions: The reactive hyperemia index of peripheral arterial tonometry method is vasodilation dependent and likely to be less reliable in testing of endothelial function when more vasodilated.