Friday December 14 2007
A patient wearing the device (picture courtesy of The Lancet)
“A new portable kidney dialysis machine could allow patients to move freely, lead normal lives and even sleep through their treatment”, The Guardian reported today.
The newspaper also suggested that the wearable device “could increase survival chances” for patients who have end-stage kidney failure. The suggestion is based on doctors’ belief that haemodialysis might be more effective if given every day (currently limits on hospital costs and resources make this impractical). The new machine offers the possibility of more frequent dialysis while permitting the patient a normal life.
The newspaper reports are based on a small pilot study in eight people who had been receiving conventional dialysis for an average of almost 18 years. The volunteers wore the new dialysis device for four to eight hours and were intensely monitored for side effects. The main aim of the study was to see whether the device was safe, and to collect preliminary data on how well it removed waste products from the blood, so that larger and longer-term studies could be conducted.
Although this study had promising results and has paved the way for the larger studies, the authors of the research acknowledge that the device will need further improvements before these studies are conducted. It is premature to speculate that the machine will improve survival chances.
Where did the story come from?
Dr Andrew Davenport and colleagues from the Royal Free and University College Hospital Medical School, London; Cedars Sinai Medical Center, USA; Ospedale San Bortolo, Italy; Xcorporeal Inc. (the manufacturers of the device) and BioQuantetics Inc, carried out this research. The study was funded by Xcorporeal Inc. and the special trustees of the Royal Free Hospital.
One of the authors is the director of Xcorporeal Inc., while others are employees of this company or BioQuantetics Inc. The authors state that the funding sources had no role in design, conduct, analysis, or interpretation of the trial, or in the writing and revision of the paper.
The study was published in the peer-reviewed medical journal: The Lancet.
What kind of scientific study was this?
In this small, uncontrolled pilot trial, researchers looked at the safety and efficacy of a portable haemodialysis unit for people with end-stage kidney disease.
The researchers enrolled eight people who were receiving dialysis three times a week for end-stage kidney failure. The average age of these volunteers was 52, and they had been on dialysis for an average of about 18 years.
The volunteers were connected to the wearable haemodialysis device, which they wore for four to eight hours each day. Patients were advised to eat and drink normally. The device also delivered doses of anticoagulant (unfractionated heparin) as needed to stop clotting.
The researchers monitored the patients regularly for changes in their blood, to see whether the dialysis was removing urea and other waste products from the blood effectively, and to see if there were any adverse changes in the levels of the chemical components of the blood, or in blood pH. Patients were constantly monitored during the trial for heart problems, or changes in the oxygen levels in their blood.
At the end of the treatment, the patients were weighed (as one aim of dialysis is to remove excess fluid from the body, which results in a reduction in bodyweight).
Afterwards, the patients answered a questionnaire on whether they had experienced any adverse effects, and whether they were satisfied with the treatment.
What were the results of the study?
The researchers found that there were no adverse changes in any of the blood chemicals when people were undergoing dialysis with the portable unit. The volunteers’ blood pressure, heart rate, and heart cycle remained stable during the trial, and there were no serious adverse effects on the heart.
The portable dialysis unit cleared urea and other waste products from the blood effectively and the patients had less excess fluid after dialysis than before.
Bubbles of carbon dioxide gas occasionally formed in the dialysis device, which disrupted the flow of the dialysed fluid, but it was not necessary to stop the treatment in any patient. Two people had some blood clotting at the catheter site (where the dialysis machine’s needle entered the body), and one of these discontinued treatment. The needle became detached in one person, but the safety device at the attachment site prevented the patient loosing blood; their needle was reinserted and dialysis successfully restarted.
The patients reported that their treatment took little time to recover from (immediately to one minute). All reported that they were satisfied with their treatment, and would recommend it to others. Five of the patients who attempted to sleep managed to do so without difficulty.
What interpretations did the researchers draw from these results?
The researchers concluded that the wearable haemodialysis unit “showed promising safety and efficacy results”, but further studies were needed to confirm these results.
What does the NHS Knowledge Service make of this study?
This pilot study has shown the feasibility of using a wearable dialysis machine for people with kidney disease. It paves the way for larger, longer-term studies, and studies that compare this type of wearable dialysis machine with standard haemodialysis. The authors note that the device will also need some adaptations before it can be used in larger trials, including solving the problem of carbon dioxide bubbles formation, and possible changes to the anticoagulation system.
These studies and improvements to the portable dialysis unit are needed before confidence can be placed in the efficacy and safety of the device, and before it is at a stage to be made widely available.
Sir Muir Gray adds...
Innovative technology has a major part to play in improving health and healthcare - even in the age of the genome.