Pulse wave analysis with diffusing-wave spectroscopy

Abstract

Hypertension is a major risk factor for cardiovascular disease and thus at the origin of many deaths by e.g. heart attack or stroke. Hypertension is caused by many factors including an increase in arterial stiffness which leads to changes in pulse wave velocity and wave reflections. Those often result in an increased left ventricular load which may result in heart failure as well as an increased pulsatile pressure in the microcirculation leading to damage to blood vessels. In order to specifically treat the different causes of hypertension it is desirable to perform a pulse wave analysis as a complement to measurements of systolic and diastolic pressure by brachial cuff sphygmomanometry. Here we show that Diffusing Wave Spectroscopy, a novel non-invasive portable tool, is able to monitor blood flow changes with a high temporal resolution. The measured pulse travel times give detailed information of the pulse wave blood flow profile.

Influence of probe pressure on the pulsatile diffuse correlation spectroscopy blood flow signal on the forearm and forehead regions

“…18,19,42 Recently, DCS measurement of blood flow pulsatility in the microvasculature has emerged as a potential complementary and alternative approach to Doppler ultrasound. [7][8][9][10][11] The DCS measurement is robust to the particular placement and orientation of its sensors, which can be held on the head with clinical tape or an elastic strap. 11,19 Accordingly, DCS is well-suited for continuous prolonged monitoring.…”

“…[7][8][9][10][11] The DCS measurement is robust to the particular placement and orientation of its sensors, which can be held on the head with clinical tape or an elastic strap. 11,19 Accordingly, DCS is well-suited for continuous prolonged monitoring. [20][21][22]45 Herein, we investigated the effects of pressure on the DCS blood flow pulsatility signal These data were obtained on the right foreheads of 11 healthy adult volunteers at multiple probe pressures for each subject (i.e., N ¼ 60 probe pressures total; 1-min of DCS data acquired for each pressure, 2.1-cm source-detector separation).…”

“…Recently, improvements in DCS measurement speed have been exploited to resolve the pulsatile heartbeat fluctuations of arterial blood flow. [7][8][9][10][11] DCS measurement of blood flow pulsatility has generated considerable interest in new clinical applications for the optical technology, which include assessment of intracranial pressure (ICP) 10,12,13 and arterial stiffness. 10,11 To date, Doppler ultrasound techniques have been dominantly used for noninvasive assessment of flow pulsatility in the clinic.…”

Highly parallel, interferometric diffusing wave spectroscopy for monitoring cerebral blood flow dynamics

“…Taking advantage of the parallel multispeckle detection of our iDWS system, we monitored high-speed pulsatile blood flow dynamics in the human brain in vivo [18,19,34,35]. A healthy adult human subject sat on a chair with her head placed on a chin rest.…”

“…In homodyne interferometry, multiple modes on a single detector reduce the speckle contrast (coherence factor), which hinders measurements of intensity dynamics [17]. Thus, in the DWS/DCS literature, bundles of SMF or FMF collector(s) with dedicated single photon-counting detector(s) are typically employed to achieve high-throughput, multispeckle detection needed for high-speed, deep-tissue sensing [18,19]. However, avalanche photodiode arrays and associated electronics are expensive, limiting the number of possible channels.…”