Cardiorespiratory interactions: Noncontact assessment using laser Doppler vibrometry

Abstract

The application of a noncontact physiological recording technique, based on the method of laser Doppler vibrometry (LDV), is described. The effectiveness of the LDV method as a physiological recording modality lies in the ability to detect very small movements of the skin, associated with internal mechanophysiological activities. The method is validated for a range of cardiovascular variables, extracted from the contour of the carotid pulse waveform as a function of phase of the respiration cycle. Data were obtained from 32 young healthy participants, while resting and breathing spontaneously. Individual beats were assigned to four segments, corresponding with inspiration and expiration peaks and transitional periods. Measures relating to cardiac and vascular dynamics are shown to agree with the pattern of effects seen in the substantial body of literature based on human and animal experiments, and with selected signals recorded simultaneously with conventional sensors. These effects include changes in heart rate, systolic time intervals, and stroke volume. There was also some evidence for vascular adjustments over the respiration cycle. The effectiveness of custom algorithmic approaches for extracting the key signal features was confirmed. The advantages of the LDV method are discussed in terms of the metrological properties and utility in psychophysiological research. Although used here within a suite of conventional sensors and electrodes, the LDV method can be used on a stand-alone, noncontact basis, with no requirement for skin preparation, and can be used in harsh environments including the MR scanner.

Heartbeat Detection by Laser Doppler Vibrometry and Machine Learning

“…Originally, LDV was mainly used for testing mechanical vibration in structures (e.g., wind turbine [ 14 ], washing machine [ 15 ], structural analysis [ 16 ], propeller [ 17 ]) or detecting defects in construction while avoiding direct contact with surfaces [ 18 ]. More recently, LDV has found application when a non-contact approach is required for evaluating cardiovascular function [ 19 , 20 ]. The interest in the use of LDV lies in the fact that, being a non-contact measurement, it does not interfere with vascular dynamics.…”

Development of a High-Resolution All-Fiber Homodyne Laser Doppler Vibrometer

“…The principle of the LDV relies on the coherent detection concerning the Doppler frequency shift of the reflected or scattered laser beam from a moving target [ 1 , 2 ]. Hitherto, its development has received great attention, and it is also widely applied to various fields ranging from the acousto-optic detection for the underwater sound [ 3 ], the remote voice acquirement [ 4 ], the health monitoring for the composite materials [ 5 , 6 , 7 , 8 ], the biomedical assessments [ 9 , 10 , 11 , 12 ], the trace explosive detection [ 13 , 14 ], and the vibration analysis of the component motions and the civil structures [ 15 , 16 ]. Compared with the contact sensors, such as the piezoelectric accelerometer, the LDV is good at performing the noncontact vibration measurement of the rotating structures.…”

Remote Monitoring of Vital Signs in Diverse Non-Clinical and Clinical Scenarios Using Computer Vision Systems: A Review

“…In this method, vital signs are extracted using a Doppler radar [19,20], or laser sensors [21] as well as digital signal processing (DSP) techniques [22] where the phase shift between the transmitted waves and the reflected received waves from a region of interest (ROI) are calculated. There are three types of Doppler-based methods-Doppler with electromagnetics [23,24], lasers [25,26], and ultrasonics [27][28][29].…”