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Abstract: SA-PO1021

Wearable Device for Continuous, Noninvasive Monitoring of Blood Hemoglobin Levels in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Kuraguntla, David John, GraftWorx, South San Francisco, California, United States
  • Gupta, Samit K., GraftWorx, South San Francisco, California, United States
  • Miller, Forrest, GraftWorx, South San Francisco, California, United States
Background

Maintenance of euvolemia is a major challenge for hemodialysis patients, who account for a combined 6.5M annual hospital days. Clinical outcomes could be improved, and healthcare costs lowered, by preventing fluid overload. This study presents a novel wearable device that enables remote monitoring of multiple key fluid status metrics in dialysis patients. This device, SmartPatch, incorporates multi-wavelength photoplethysmography (PPG) and acoustic, thermal and mechanical sensors to measure blood hemoglobin concentration (Hb), hematocrit (Hct), oxygen saturation and volumetric flow rate. The SmartPatch system also comprises an end-to-end data path that facilitates secure data transmission and analysis and generates actionable alerts. The aim of this study was to evaluate the system’s ability to accurately and precisely measure Hb and Hct, critical markers for anemia that dictate dialysis treatment.

Methods

29 hemodialysis patients with arteriovenous fistulas currently undergoing hemodialysis were recruited across three clinical sites. Each of these patients had a SmartPatch device placed on the skin over their fistula. A total of 257 sets of multi-channel PPG data were recorded and analyzed using the GraftWorx data hub and software backend. A subset of 76 reads was used to train an Hb quantitation algorithm, with reference values obtained from a HemoCue Hb 201+ device. This algorithm was then tested on the remaining 181 reads to determine the accuracy and precision of the SmartPatch when measuring Hb and Hct.

Results

The SmartPatch system measured Hb and Hct with respective root-mean-square error (RMSE) of 0.863 g/dL and 2.585 Hct compared to reference values obtained from the HemoCue device, whose accuracy has been reported to be between 0.3 and 1.6 g/dL (0.9 to 4.8 Hct). The standard deviations for each read on the same patient–with the same device–were computed and averaged, weighted by group size, as a measure of precision. These precision metrics were computed to be 0.283 g/dL and 0.85 Hct for Hgb and Hct, respectively.

Conclusion

The results of this study illustrate the ability of the wearable SmartPatch system to non-invasively measure blood Hb and Hct in hemodialysis patients with AV fistulas, to a degree of accuracy comparable to available methods. This study also demonstrated the efficacy of the end-to-end GraftWorx data path.