Using dialysis machine technology to reduce intradialytic hypotension

Intradialytic hypotension remains the most frequent complication associated with routine outpatient hemodialysis. Although increasing dialysis frequency and also lengthening dialysis session duration can reduce the risk of intradialytic hypotension, in practice, these options are limited to a small minority of dialysis patients. To help reduce intradialytic hypotension, a number of technological developments have been incorporated into the hemodialysis machine, based around relative blood volume monitoring, an indirect assessment of plasma volume. Further developments based on so called "fuzzy" logic feedback systems designed to adjust either or both the ultrafiltration rate and dialyzate sodium concentration according to relative changes in plasma volume. In addition, cooling and dissipation of the heat generated during dialysis also reduces the risk of intradialytic hypotension, and this can be regulated by cooling of the dialyzate using thermal control systems. In addition, convective therapies, such as online hemodialfiltration, have also been reported to reduce the frequency of intradialytic hypotension; whether this effect is simply due to increased cooling remains to be determined. Although all these developments have been reported to reduce the frequency of serious intradialytic hypotensive episodes, they have not been able to totally abolish hypotension, as they can not alone compensate for excessive weight gains and consequent excessive ultrafiltration requirements. Thus, in addition to the advances in hemodialysis machine technology designed to reduce intradialytic hypotension, attention also needs to be focused on reducing interdialytic weight gains, so reducing ultrafiltration requirement.