Creating a wearable artificial kidney: A difficult but necessary goal

ORLANDO, Fla. – “Dialysis is a promise unfulfilled,” said Jonathan Himmelfarb, MD, director, Kidney Research Institute.

What is the promise? For that answer Himmelfarb, during his session at the National Kidney Foundation Spring Clinical Meetings, referred to quotes from the pioneers of hemodialysis, Willem Kolf and Belding Scribner.

“If we are going to keep patients alive by artificial means, we then incur the responsibility to see that it is a good life and an enjoyable life,” Kolff said in 1968.

“If the treatment of chronic uremia cannot fully rehabilitate the patient, the treatment is inadequate,” Scribner said in 1963.

Dialysis keeps people alive, but it doesn’t restore health, Himmelfarb said. And it doesn’t fully rehabilitate.

Obstacles to creating a better treatment option for ESRD patients

To provide a better treatment option for end-stage renal disease patients, you first have to know what a patient wants from treatment, Himmelfarb said. Our current understanding of what patients want is incomplete.

He referred to data from the Standardized Outcomes in Nephrology–Hemodialysis (SONG-HD) Initiative for a glimpse of what is important to hemodialysis patients. According to a survey, the most important outcomes for patients were fatigue, ability to travel, free time away from dialysis, impact on family, and ability to work.

Simply put, ESRD patients want to live their lives as unrestricted as possible.

Being confined to a treatment schedule that hinders their ability to visit out-of-state family and take vacations, or being too washed out and tired to even take a trip, or perform daily tasks, severely diminishes their quality of life. According to the SONG data, and other studies, quality of life is more important to many patients than mortality.

There are also physiological obstacles to improving treatment. Our understanding of uremia is incomplete, Himmelfarb said. And our measure of dialysis adequacy is inadequate.

Developing a wearable artificial kidney

The logical progression of dialysis treatment improvements, according to Himmelfarb, would be portable (think a smaller, lighter version of the NxStage System One), wearable, and implantable.

And through the Kidney Research Institute and the University of Washington, Himmelfarb is working on the wearable.

The wearable artificial kidney. Photo from NKF slides

In 2015, they tested a device developed by Victor Gura, MD, FASN, from the David Geffen School of Medicine at UCLA, on seven hemodialysis patients.

Himmelfarb said they felt good about the trial. They learned a lot, the patients were excited about the freedom the device gave them, and outcomes were good.

The following study data is taken from Himmelfarb’s slides.

As expected, there were technical difficulties, and it was “far from perfect.” After all, they are trying to redesign a device meant to be stationary and only work for several hours at a time, into a device that is wearable and working 24 hours a day.

Technical complications included:

Numerous alarms related to kinked tubing with position changes

Production of CO2 bubbles exceeded ability of auto-venting degassing mechanism to remove

The main pump had variable flow

One patient stopped treatment after four hours due to clotting

One patient stopped after 11 hours due to discoloration of the dialysate.

The team is currently working on redesigning the device, and challenges remain, including:

Decreasing the size

The complexity of tubing

The many steps required to connect and disconnect the priming cartridges

Vascular access (it is currently exclusive to patients with catheters)

There is a need for an ultrafiltration leg bag

The need for clinician education, training and familiarity.

And one challenge that needs particular consideration is device failure, which Himmelfarb said will inevitably happen sometimes. The causes of device failure can include:

Biocompatibility

Clotting/bleeding

Biofilm

Infection

Foreign body reaction

Fibrosis

Sensor and software failure

Human factors ("If you give patients freedom, what will they do with it?")

Goals for a wearable dialysis device

Himmelfarb said he is excited by the study results, but he does not want to give patients a false sense of hope. There is still a tremendous amount of work to be done.

In a perfect world, he said, buying a wearable artificial kidney would be like choosing a car. There would be options based on what patients need and want from a device. That’s a long way from the treatments currently offered to ESRD patients, but it’s a goal worth working toward.

“It would be great if one day I can put myself out of business,” Himmelfarb said. -by Rebecca Zumoff