Investigating the inaccuracies of indirect method of blood pressure measurement associated to the cuff constructing fabrics
Numerous cuffs have been manufactured using different materials in which textile fabric is the main constituent. There are no specific guidelines for the selection of the cuff fabric and its design. In this investigation, five different types of cuffs (made of woven and non-woven fabrics) were selected, and their pressure distribution was noted while mimicking the process of blood pressure measurement. It was achieved by measuring pressure at the interface of the selected cuffs and a bare metal cylinder. I-scan, an interface pressure measurement system was employed to record the interface pressure profiles under the cuffs against 140 mmHg to 40 mmHg pressure inside the cuffs. The data obtained from the pressure sensing system was processed in MATLAB to examine pressure distribution at 96 points in detail. The results show that the cuffs registered non-uniform pressure distribution at the interface which is also non-identical among the selected cuffs. The pressure at the interface is found to be lower than the pressure inside the cuff, which shows that pressure attenuates as transfers to the surface of the object underneath it. The range of the pressure difference varies from 10 mmHg to 15 mmHg. This study indicates that the pressure distribution under a cuff depends on the constructing fabric and its properties. It is concluded that there is a need to select appropriate fabric with optimized properties for desired pressure distribution which may lead to accurate estimation of blood pressure.