Development of a new method for monitoring blood purification: the blood flow analysis of the head and foot by laser Doppler blood flowmeter during hemodialysis

The management of blood pressure in hemodialysis patients greatly affects not only their quality of life, but also the duration of dialysis (dialysis life). Approximately 25% of dialysis patients suffer from continuous low blood pressure; however, the relationship between blood pressure and blood flow during dialysis has not been established. We hypothesized that with complete extracorporeal circulation, blood purification methods might affect blood flow, resulting in a change in blood pressure. The purpose of this study was to develop a noninvasive continuous monitoring method (NICOMM) as a microcirculation monitor by devising a laser-Doppler flowmeter (LDF) system with a wavelength of 780 nm. The aim was to use this system to simultaneously measure blood flow rate in both the head and the foot during dialysis and to determine the effectiveness of NICOMM by measuring blood flow and arterial distensibility. When exhibiting a significant decline in blood pressure at 240 min after the initiation of hemodialysis, a drop in blood flow in parallel with the blood pressure fall was recorded by the LDF. However, no changes were observed, in the readings by a continuous hematocrit monitor (Crit-Line monitor, CLM). Furthermore, a significant correlation was registered between mean arterial blood pressure and blood flow rate in the earlobe tissue from 180 min after the initiation of hemodialysis to the completion of hemodialysis (p < 0.001, r = 0.78). Comparisons were made by measuring vascular dehydration using the CLM. NICOMM showed more stable readings than the CLM in monitoring blood flow in response to changes in blood pressure.