Observational Study to Assess Oxygen Saturation Predictive Power Related to Intradialytic Acute Hypotension

During the last 40 years a lot has been achieved in dialysis regarding both monitors safety and membranes overall performances Anyway, intradialytic symptoms still remain a major concern for nephrologists: in particular, hypotension is the most frequent [1].

Intradialytic hemodynamic monitoring systems have been developed to have continuous surveillance of the main hemodynamic variables (heart rate, body temperature, blood pressure itself, cardiac output, ecc…).

In a second moment, the further evolution was towards the retroactive control systems, to force some of the variables involved in the genesis of the hemodynamic stability, along a pre-determined, ideal, trend. In this view, various bio-feedback mechanisms have been proposes along the years, for example, to tackle hypovolemia-related hypotension. Their scientific rationale is the control of either blood volume or directly natremia, in order to pilot plasma refilling towards the vascular compartment [2].

Despite the great achievements obtained, the forecasting of acute hypotension during hemodialysis still remains a complex problem, likely involving more than one variable.

SO2 can be considered an indirect expression of the hemodynamic stability. Moreover, in dialysis, it has always been regarded as a bio-compatibility marker for membranes [3]. Nowadays, SO2 changes during dialysis are easy to measure with a fully, non-invasive sensor assembled on the arterial line.

We planned this study to analyze on a large number of sessions the short-term variability of SO2 during hemodialysis in relationship with hemodynamic tolerance.

Inclusion criteria

• Dialysis vintage > 6 months
• Well functioning arterovenous fistula or central venous catheter
• thrice weekly HD treatment schedule
• Acute hypotensions in the last month before study start > 20% of sessions

Exclusion criteria

• Mental illness
• life expectancy < 6 months
• any profiling and/or biofeedback strategies routinely prescribed