[Design of portable blood pressure depressor based on slow breathing training]

Abstract

Clinical studies had demonstrated that slow breathing could lower blood pressure significantly. Based on this knowledge, a portable blood pressure depressor was designed in this study. The device used a miniature variable distance capacitive sensor to collect respiratory signal, an STM32 as the main control chip, a WT588D voice chip to generate voice and music and guide slow breathing, and a 3.5-inch color screen to display breathing state and provide guidance. For patients with difficulty in adapting themselves to the slow breathing training, an intelligent guiding breathing algorithm based on feedback regulation mechanism was proposed to train patients to breathe slowly. Ten volunteers with hypertension were recruited and then trained to breathe slowly, accumulating up to 100 times using this device. The results showed that breath rate of the volunteers decreased from 15.16±0.92 times per minute to 9.40±0.29 times per minute, and meanwhile, time length of breath rate less than 8 times per minute in the proportion of total treatment time increased from 0.079±0.017 to 0.392±0.019 as the training times increased. In a conclusion, the proposed blood pressure depressor worked effectively in guiding slow breathing training.

Keywords: blood pressure depressor; hypertension; portable; slow breathing training.

图 1

Block diagram of the pressure normalizing apparatus ADC: analog to digital converter; FSMC: flexible static memory controller 降压仪结构框图 ADC：模数转换器；FSMC：可变静态存储控制器

图 2

Variable distance capacitance sensor circuit 变极距电容传感器电路

图 3

Block diagram of the voice module application 语音模块应用方框图

图 4

DAC output circuit DAC 输出电路

图 5

Relationship between sensor frequency and respi-ratory waveform 传感器频率变化与呼吸波形的关系

图 6

BPM detection algorithm BPM 检测算法

图 7

Algorithm of guide breathing based on feedback regulation 基于反馈调节的呼吸引导算法

图 8

Diagram of the music guidance control timing 音乐引导控制时序图

图 9

Slow breathing training for a hypertensive volunteer 高血压志愿者进行慢呼吸训练

图 10

Trends of BPM changes and normalized accounting with BPM less than 8.0 breath/min BPM 变化与 BPM<8.0 次/分的归一化占比变化趋势