Dialysis
Researchers invent an intelligent hemofiltration system
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"It's critical that we take the very best care of patients. We set out to build something that was not just good enough but was the best." John Bissler, MD | |
Four hours a day, three days a week. That's the amount of time 10-year-old Matthew Watson has spent at Cincinnati Children's Hospital Medical Center since he began dialysis treatment last December while waiting for a kidney transplant.
Matthew was born with a blocked urethra, which caused kidney damage while he was still in the womb. He was 18 months old when his left kidney was removed. His remaining kidney functioned at only 10 percent of normal.
Soon after his family moved to Cincinnati from Chicago four years ago, Matthew developed a limp. His mother, Marion Watson, took him to Cincinnati Children's, where he was diagnosed with renal rickets and end stage renal disease.
Healthy kidneys filter blood to remove toxins formed when the body digests food. These toxins are eliminated from the body through the urine. The kidneys also perform other important functions, including helping activate vitamin D to maintain healthy bones. An inability to perform this function results in a bone disease known as renal rickets. Matthew's limp was the first visible sign that his kidney function was declining.
By November 2003, his kidney failure had progressed to the point that Matthew needed a transplant. Until a donor could be found, he would need dialysis, relying on a machine to clean the toxins from his blood because his own kidney could no longer do the job.
Dialysis Treatment Three Days a Week
Dialysis treatment meant a huge change in Matthew's daily routine. While his fourth grade classmates spent their day at school, Matthew spent hours every Monday, Wednesday and Friday hooked to a machine in the Dialysis Unit at Cincinnati Children's. His mother quit her job so she could take Matthew to his appointments.
It's been a hard year for his family, but Matthew made the best of it. "Never once has he complained," his mother says. "He just keeps going. Sometimes when I get depressed, I look at him and take strength."
Matthew brought his positive attitude to the Dialysis Unit. He made friends with the children and the staff. The nurses came to know the games he liked to play best and his favorite foods on the hospital menu. After the dialysis session, he'd make up for lost time by playing as hard as he could.
Despite all the school he missed, Matthew kept up with his work. "His teacher took him under her wing," his mother says. "She came over in the evenings to help him with his schoolwork. He went to summer school, and he passed." Marion was delighted that Matthew would be able to go on to the fifth grade.
And there was more good news for Matthew. When, after months of testing, his mother was ruled out as a potential organ donor, his older brother, Hassan, asked to be tested and was a good match. In a transplant operation on October 5, Matthew got a new kidney from his brother.
Research to Find a Better Way
Dialysis kept Matthew healthy until his transplant, but imagine how much more normal life would have been for him and his family if he could have had his treatments at home, while relaxing after school or while sleeping.
Safe, convenient home therapy may soon be possible thanks to research at Cincinnati Children's. A research team led by nephrologist John Bissler, MD, has developed technology and computer software that is revolutionizing dialysis treatment.
Dialysis is performed in a hospital setting or a dialysis center because nurses must monitor the equipment and make adjustments as needed throughout the treatment session. The intelligent, computer-controlled system Dr. Bissler invented opens the door to safe dialysis at home, without a nurse being present.
A Stunningly Accurate System
Dr. Bissler's interest in new technology for dialysis began in 1988, soon after he came to Cincinnati Children's for a fellowship in nephrology. As he cared for patients in the intensive care unit, he became frustrated by the limitations of the monitoring equipment. He wanted:
- Better quality
- More accurate information
- Smarter equipment
He envisioned a monitor that would automatically adjust when it recognized a problem instead of simply beeping. Over the years, he tried various solutions and eventually found an approach that works.
Traditional dialysis equipment works by diffusion across a membrane. On one side is the patient's blood; on the other side is a fluid composed of sterile water and dialysite that supplies needed salts. Moving from an area of high concentration to an area of low concentration, toxins in the blood diffuse across the membrane and are washed out, while the fluids and salts diffuse into the blood.
The machine Dr. Bissler invented works by filtration. Taking advantage of new, stronger materials, his machine forces blood through a membrane that acts like a colander, straining toxins from the blood as the filters in the kidney do. The system then replaces fluids and salts and returns the blood to the body.
His hemofiltration technology uses highly accurate scales, pumps, filters and pressure transducers to remove a predetermined amount of fluid from the blood in a predetermined period of time. "Fluid balance is critical," Dr. Bissler explains. "Even a small error can be very dangerous. We were looking for stunningly accurate filtration. Tracking weight as the measure solved the problem. What we invented was a way to control the volumes so it is safe."
The whole system is computer-controlled, using sophisticated software developed by research colleague Nat Hemasilpin, a clinical engineer at Cincinnati Children's. "The machine thinks like I do," Dr. Bissler says. "It notices changes and wonders what's wrong. If the pump is going too fast or too slow, the computer automatically adjusts the rate of flow. If the filter is going bad, the computer gives a warning and tells you how much time you have to fix it. And it pays attention 100 percent of the time."
Bringing the Technology to the Marketplace
Having created an intelligent hemofiltration system that greatly improved the accuracy and safety of therapy, Dr. Bissler needed a commercial partner that could bring it to market to improve outcomes for patients with kidney disease. In the United States alone, more than 400,000 adults and children suffer from severe kidney disease.
Working through the Cincinnati Children's Office of Intellectual Property, he licensed the technology to British Technology Group (BTG), a world leader in the commercialization of new health care technologies. BTG is working with companies that produce dialysis machines to incorporate Dr. Bissler's technology into their equipment.
Today the technology is widely used in intensive care units to help the sickest patients. It is expected to be available for outpatient and home use within two to three years.
"It's critical that we take the very best care of patients," Dr. Bissler says. "We set out to build something that was not just good enough but was the best. I feel good that what we've developed is helping patients and improving their chances of surviving kidney disease." He looks forward to the day when many patients can have hemofiltration safely and conveniently in their own homes.
