The purpose of this study is to use the photo-plethysmographic [PPG] waveform signal to guide the dialysis and ultrafiltration [UF] of chronic maintenance hemodialysis patients, and to further the investigators understanding of homeostasis in hemodialysis.

The investigators hypothesize that the signals generated from the PPG device along with traditional monitoring and nursing judgment, will allow experienced, oriented staff to anticipate hemodynamic instability, intervene to prevent or mitigate the intradialytic hypotention [IDH], forestalling the onset of non-facilitating compensatory reflexes that preclude the patient from achieving an appropriate post-dialysis weight consistent with euvolemia. Furthermore, it is hypothesized that the nephrologist and staff will be able to wean patients from anti-hypertensive medications and craft patient specific dialysis orders and UF profiles that achieve consistent, comfortable treatment to appropriate end points.

The study aims include:

Aim 1: To confirm the temporal sequence of PPG signals and changes in BP in routine hemodialysis.

Aim 2: To refine further the predictive algorithms of PPG, augmented with continuous cardiac event monitoring (pre-intra-post hemodialysis) Aim 3: To develop targeted interventions to reverse the cardiovascular stress indicated by the PPG and to maintain perfusion.

Aim 4: To develop care paths approved by the medical staff and primary care nephrologist allowing RNs to respond to signals from the PPG.

Inclusion Criteria:

1. Age >18 years

2. On dialysis > 6 months with a stable dialysis program

3. Consistent achievement of a spKt/V ≥ 1.2

4. HGB ≥ 10 gm% ± ESA support

5. Consistent failure to achieve a post weight ≤ dry weight + 0.5Kg

6. Able to give informed consent directly

7. Frequent hypotensive reactions (≥ 1 / treatment in 4 of last 8 treatments)

   • Symptoms of hypotension
   • Intervention administered because of IDH (saline, "turn downs, early termination, trendelenberg position)
   • Drop in BP irrespective of symptoms. SBP < 90 mmHG intra or post HD if pre SBP was > 110 mmHG; SBP < 85 mmHG or 15 mmHG drop from start if starting BP ≤ 110 mmHG.
   • Or judged by the nursing staff to be difficult to achieve dry weight.

Exclusion Criteria:

1. Dialysis Catheter Access that may interfere with continuous data collection, per PI determination. (Catheter access is a relative exclusion based on the history of catheter performance.)
2. Cognitive Impairment precluding cooperation, and consent
3. Restless or unlikely to wear the monitor head-band
4. Too unstable in the judgment of their nephrologist to be included in a study of this nature.