Continuous monitoring of blood pressure by analyzing the blood flow sound of arteriovenous fistula in hemodialysis patients.

BACKGROUND: Patients with end-stage renal disease undergoing hemodialysis (HD) have an elevated risk of cardiovascular disease-related morbidity and mortality. To prevent from such a life-threatening event, the continuous blood pressure (BP) monitoring system may contribute to detect BP decline in early stages and may help to do appropriate disposal. Our research team has introduced an electronic stethoscope (Asahi Kasei Co, Ltd., Tokyo, Japan), which translates sound intensity of Arteriovenous Fistula (AVF) to BP data using the technique of Fourier transformation that can predict continuous BP non-invasively. This study, we investigated whether electronic stethoscope-guided estimated BP (e-BP) would actually reflect systolic BP measured by sphygmomanometer (s-BP), and whether e-BP could predict fall of BP during HD.

METHODS: Twenty-six patients who underwent HD treatment in our hospital were evaluated prospectively. We obtained sound intensity data from the electronic stethoscope which was equipped with the return line of HD. Then, the data were translated into e-BP data to be compared with s-BP. Correlation of total of 315 data sets obtained from each method was examined. An accuracy of diagnosis of intra-dialytic hypotension (IDH) was evaluated.

RESULTS: Total of 315 data sets were obtained. A close correlation was observed between e-BP and s-BP (r = 0.887, p < 0.0001). Sensitivity and positive predictive value of predicted-BP for detection of IDH was 90 and 81.3%, respectively.

CONCLUSIONS: Electronic stethoscope-guided BP measurement would be helpful for real-time diagnosis of BP fall in HD patients. Further investigations are needed.