Correlation of blood pressure changes following postural change from sitting to standing with near infrared spectroscopy (NIRS)

Abstract

Sudden changes in the body position, e.g., sitting to standing, usually cause brain blood pressure to drop. This may disturb one’s balance especially in the elderly people. Also, maintaining balance after standing up is a vital issue for elderly and anyone suffering from nervous system disorders. As the body command center it is important to study and monitor brain hemodynamics after ones changes his/her position from sitting to standing. There are different modalities to study brain function in such scenarios among them functional near infrared spectroscopy (fNIRS) is chosen in this research due to the system simplicity, safety and less impact of motion artifacts. In this research, we aim to find the relationship of NIRS signal with the changes in blood pressure caused by changing the position from sitting to standing. For this purpose, fNIRS signals were recorded in 20 healthy young people during sit to stand position using a two-channel fNIRS system. In the same time an automatic sphygmomanometer is used to measure their blood pressure while sitting at rest, before standing up, immediately after standing up, and in rest standing. As a result, correlation values of 0.68 and 0.69 were obtained between the systolic blood pressure and the HbO2 signal recorded from the short channel and the THb signal recorded from long channel respectively.