A non-contact continuous blood pressure measurement method based on video stream / 生物医学工程学杂志

Hypertension is the primary disease that endangers human health. A convenient and accurate blood pressure measurement method can help to prevent the hypertension. This paper proposed a continuous blood pressure measurement method based on facial video signal. Firstly, color distortion filtering and independent component analysis were used to extract the video pulse wave of the region of interest in the facial video signal, and the multi-dimensional feature extraction of the pulse wave was preformed based on the time-frequency domain and physiological principles; Secondly, an integrated feature selection method was designed to extract the universal optimal feature subset; After that, we compared the single person blood pressure measurement models established by Elman neural network based on particle swarm optimization, support vector machine (SVM) and deep belief network; Finally, we used SVM algorithm to build a general blood pressure prediction model, which was compared and evaluated with the real blood pressure value. The experimental results showed that the blood pressure measurement results based on facial video were in good agreement with the standard blood pressure values. Comparing the estimated blood pressure from the video with standard blood pressure value, the mean absolute error (MAE) of systolic blood pressure was 4.9 mm Hg with a standard deviation (STD) of 5.9 mm Hg, and the MAE of diastolic blood pressure was 4.6 mm Hg with a STD of 5.0 mm Hg, which met the AAMI standards. The non-contact blood pressure measurement method based on video stream proposed in this paper can be used for blood pressure measurement.

Low Frequency Ultrasound Triggering Drug Release from Improved PLGA Microcapsules in Vitro / 中国康复理论与实践

@# Objective To study the effect of low frequency on drug release from improved PLGA microcapsules, and investigate the possibility of utilizing PLGA microcapsules as the carrier of ultrasound targeted drug delivery system to deliver drug into brain. Methods Doxorubicin loaded poly (D,L lactic-co-glycolic acid) (PLGA) microcapsules were prepared via double emulsion solvent evaporate method and coated with either chitosan or gelatin. In vitro drug release profile and the drug release rate under the exposure of low frequency pulsed ultrasound (25 kHz) and continuous wave ultrasound (35.1 kHz) were assayed. Results The coating with chitosan or gelatin can depress the burst of drug release. The drug release rate from uncoated and chitosan-coated microcapsules did not changed with the exposure of ultrasound, and the rate of gelatin-coated microcapsules did increased. The effect of pulsed ultrasound was stronger than that of continuous ultrasound. Conclusion The drug release from gelatin-coated PLGA microcapsules can be controlled and triggered by 25 kHz pulsed ultrasound, which may be a potent carrier of targeting drugs into brain.