Prevention of Hypovolemia-Induced Hypotension during Hemodialysis by Means of an Optical Reflection Method

Abstract

In this study protocol we evaluate the clinical value of the continuous monitoring of blood volume (BV) during hemodialysis (HD) by means of an optical reflection method. In the course of a dialysis session the ratio between the ultrafiltration (UF) rate and the patient's refill capacity determines the extent of decrease of BV. A steep fall of BV and, moreover, a remaining absolute BV too low, cause the greater part of hemodialysis-induced complaints. During 23 standard HD sessions BV was monitored by means of the optical method. Nine of the sessions were complicated by hypotension (group H). Comparison of the mean BV graphs of group H with the graphs of non-complicated sessions (non-H) produces several differences. Most important is the fact that BV is better preserved in group non-H, a difference which is already significant during the first ninety minutes of dialysis. By making use of the shape of the monitored BV graph an HD patient, in that way, might be recognized as hypotension-prone during the first third of a dialysis session. To prevent the occurrence of hypovolemia-induced hypotension two strategies can be followed. First, the decrease of BV of a patient prone to hypotension can be triggered to the mean BV decrease according to the BV graph of the non-H group. This can be achieved by interventional methods, e.g. temporary lowering of the UF rate. However, for this intervention the development of a closed-loop circuit is required. Another possibility is to measure a patient's maximal refill capacity each hour of hemodialysis by taking advantage of the displayed BV graph. When the UF rate during ensuing sessions is kept in rate with the measured maximum values the occurrence of hypovolemia-induced hypotension will be minimized.