Noncontact Video-Based Vital Signs Continuous Monitor for Unconstrained Conscious Rodents

Animal experiments should minimize pain and discomfort and maximize animal welfare to satisfy the experimental animal 3R principle. The quality of vital signs monitor results collected from conscious and stress-free rodents is superior, ensuring experimental data's reliability, accuracy, and scientificity. This work proposes a non-contact video-based vital signs continuous monitoring method for uncontrained conscious rodents. Firstly, rodents are tracked using keypoint detection, and Regions of Interest (ROI) on the rodents are selected based on signal-to-noise ratio (SNR) distribution of vital signs. Secondly, corner motion within the ROI region is tracked to synthesize skin pulsations, from which respiratory signals are extracted. Finally, a method is proposed to eliminate the influence of respiratory harmonics, thereby removing respiratory interference and extracting the heart rate. Four rats and four mice were used to measure the performance of the proposed method. This work is the first to use a camera to continuously monitor the heart rate of unrestrained and conscious rodents. Compared with the ground truth (semi-implantable electrocardiogram), the relative heart rate (HR) error was 1.86 ± 0.82% and 1.20 ± 0.33% for rats and mice, respectively. This method is used for uncontrained conscious rodents and has high applicability, allowing it to be used in various experimental environments and conditions. At the same time, this work contributes to the development of new methods for continuously and objectively evaluating animal welfare, thereby promoting the development of modern biomedical and ethical research.