The purpose of the proposed pilot project is to examine the effectiveness of a newly developed ring device (developed by Co-I Kayvan Najarian) for assessing cardiovascular reactivity to stress. The ring device permits continuous and noninvasive monitoring of vascular tone. According to the general adaptation syndrome (GAS) model, vasoconstriction happens in the first stage of stress during the antishock phase, which along with tachycardia leads to an increase in the blood pressure. Measures of hemodynamic processes (e.g., systemic vascular resistance) have typically been invasive (e.g., using forearm blood flow) and or have only been used in the lab (e.g., impedance cardiography). To date there have been no truly portable and low-powered devices or systems that can be used for the non-invasive continuous monitoring of vascular tone. The ring is made of a polyvinylidene fluoride (PVDF) sensor that can measure the mechanical movements of the arterial wall as blood passes through the digital arteries. The mechanical movements are transformed into a voltage that is measured by an acquisition device in the form of a wristband. The reflection waves are known to change as a result of several different physiological conditions such as vasoconstriction, vasodilation, hypotension and hypertension[4]. These reflection waves can easily be detected and measured in the PVDF signal as opposed to other non-invasive signals such as the photoplethysmography signal that is collected using a pulse oximeter. Moreover, the features of the PVDF signal, including the amplitude and morphology based features, are shown to be effective in detecting vasoconstriction caused by other physiological events such as intradialytic hypotension and hemorrhage [5, 6]. We have investigated the effectives of the PVDF signal in detecting stress with four participants in the laboratory. Preliminary results indicate that the ring is responsive to laboratory stress induction. We are now poised to extend our pilot and further assess the feasibility of the ring device in the laboratory as well as in daily life.
Funding:
University of California - San Francisco
Funding Period:
09/12/2016 to 09/30/2017