Journal of North Khorasan

Abstract Background & Objectives: In most cases, reduced blood flow due to obstruction is considered as a primary factor in pressure ulcer formation and occurrence of bedsore. The aim of this study was to design and manufacture a care system for tissues under pressure based on variation in blood flow at different depths of the tissue. Materials & Methods: In manufacture of system, two infrared light transmitter were located 5 and 10 mm away from receivers to measure the blood flow at two different depths of the heel tissue under pressure. Also, blood flow was measured in unload condition and after loading with 30 and 60 mmHg. The study was performed on 15 participants, the mean age was 54 years, 60% were men and 40% were women. Results: The primary results showed differences in blood flow in different depths of the tissue under pressure. Also, there was significant changes in signal amplitude during loading both pressures 30 and 60 mmHg compared to unloading condition. . Conclusion: Development of this system would be possible with increased flexibility in terms of probes and using potent optical receiver and transmitter to access more depth.

Abstract Background & Objectives: It is well known that measuring and monitoring blood pressure continuously is one of the most important problems especially in operating rooms and monitoring devices. Pulse transition time (PTT) is a parameter related to cardiovascular system and is extracted based on ECG and pulse oximetry signals and it can be used to measure continuous blood pressure changes. The aim of this study was to design a method to measure and monitor blood pressure continuously using PTT. Materials & Methods: Continuous recordings of pulse wave and ECG signal were done for 35 participants in 20 different positions using a setup which could record two signals. Finger pulse wave was recorded using photo pulse sensor on the left index finger and ECG in lead I by Ag-AgCl electrode on the chest. PTT was measured as the time interval from the ECG R wave to the peak of the pulse signal in the same cardiac circle. Parameters relating the PTT with blood pressure were estimated using collected data. Results: Results showed that the PTT parameter was correlated with systolic and diastolic blood pressure with correlation coefficients of 0.95 and 0.93, respectively. Therefore, blood pressure was monitored with appropriate accuracy. Conclusion: Hereby, a new noninvasive method was introduced for measuring blood pressure continuously in operating room and during the anesthesia.