As I’ve said, November is a big month for learning about new ideas in kidney transplant, replacement, and dialysis therapy.   Today, we’ll discuss one of the newer innovations-  a wearable artificial kidney, with its current design of 10 pounds and power supplied by 9 volt batteries.

Drs. V. Gura, M. Rivara, R. Munshi, S. Bieber, M. Beisai, C. Ezon, L. Kessler, and J. Himmelfarb (UCLA and Blood Purification Technologies, Inc.)  presented their results on the wearable artificial kidney (WAK) at the recent ASN (American Society for Nephrology) meeting.  Their device is based upon sorbent technology (to absorb the toxins removed during dialysis, reducing the dialysate volume and allowing for miniaturization and transportability)- and these were the first FDA approved human trials for the device.

Since this is a wearable device, no external blood pump was employed (so, instead of the 100 to 250 ml/min blood flows that pertains in dialysis, the blood flowed around 43 ml/min through the device).  To also keep power demands low, the dialysate flow was reduced from the normal 500 ml/min to 45 ml/min.

The first patient to try the new device was a 73 year old Washington (state) resident, who has both ESRD (kidney failure) and diabetes.  Instead of his normal therapy regime of four hours thrice weekly, he was hooked up to the device for 24 hours.   To ensure his safety during the trials, he was not permitted to leave the hospital- but was freely able to walk around- and, as opposed to when he is on dialysis- was able to eat what he wanted.  (Dialysis patients are limited in their phosphorus and potassium dietary intake, because these substances accumulate in the body, when one is on dialysis.)

All told, some seven patients participated in this trial.  One patient was removed from the device after 10 hours, due to discoloration found in the dialysate.  (This would normally imply that there was a membrane leak in the dialyzer.)  Another had clotting problems after four hours.   And, the seventh patient encountered device malfunctions and was removed from the treatment protocol early.

The researchers are now modifying the device design to repair these issues discerned in the limited trials   These modifications will be completed before the next phase of testing; this new phase will involve a series of patients wearing the device for a full week.  Chemicals will need to be added daily to ensure the sorbents and dialysate quality are maintained.  (The dialyzer will need to be replaced after a week’s usage- which is what sets the maximum limit of use without removal.)  The designers also hope to be able to cut the weight to five pounds, which would be a more manageable concept for patients.

Nevertheless, the test results were pretty encouraging.   As such, the FDA (Food and Drug Administration) has “fast-tracked” the device- the agency will examine test results carefully and will approve it for use as soon as possible- if the results so merit.

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