Improving dialysis through imaging
Lloyd Weiss was a 10-year-old-boy in Edmonton, Alberta when he had his left kidney removed.
“They told me it wasn’t functioning and so they took it out,” says Lloyd, now 62. “After that, everything seemed fine.”
He went to school, started working as an aircraft maintenance engineer and got married. Then, seven years ago he caught the Norwalk virus, destroying what was left of his remaining kidney.
Lloyd now undergoes dialysis three times a week at the Kidney Care Centre at London Health Sciences Centre (LHSC). He is one of over four million Canadians living with chronic kidney disease and one of 30,000 currently on dialysis.
Lloyd Weiss undergoes dialysis three times a week and participates in numerous research studies at Lawson.
The kidneys are crucial to human health as they filter waste from the body. When a person loses too much kidney function, they start on dialysis – a process that artificially filters waste from the blood.
Unfortunately, dialysis can cause a number of serious side effects.
Dr. Chris McIntyre, Lawson Scientist, and his team are the first in the world to use medical imaging to scan patients while undergoing dialysis.
“A large portion of our work focuses not on creating new treatments but on recognizing the harms in current ones, and then deliberately engineering those harms out,” says Dr. McIntyre.
Protecting the brain
There are two main forms of dialysis, of which hemodialysis is the most common. In hemodialysis, blood is removed from the body, filtered through a machine called a dialyzer and then pumped back in. This sudden removal of bodily fluids can cause low blood pressure and decreased blood flow to multiple organs.
Each round of dialysis is like another recurrent brain injury.
“Our studies show that a patient’s brain becomes starved of blood during dialysis,” explains Dr. McIntyre, also an LHSC Nephrologist. “Each round of dialysis is like another recurrent brain injury.”
Ischemia, a term used to describe restricted blood supply to tissues or organs, leads to less oxygen in the brain which can cause symptoms like abnormal cognitive function and eventually lead to tissue death or stroke.
Dr. Chris McIntyre’s research has shown that a dialysis patient’s brain becomes starved of blood during dialysis. The MRI scans on the left show a patient’s brain before dialysis while the scans on the right show a patient’s brain during dialysis. The red and yellow represent high blood flow while blue represents low blood flow.
Dr. McIntyre’s research team is using PET/MRI to determine whether a simple intervention can protect hemodialysis patients from brain injury. Deliberately making one part of the body ischemic may protect other parts of the body from ischemia, in this case to preserve function to a vital organ. Dr. McIntyre is using a technique called ischemic preconditioning, which consists of inflating a blood pressure cuff on the patient’s leg for one to two minutes before dialysis.
“We’ve already shown that ischemic preconditioning can protect the heart from dialysis. The question now is whether it works the same for the brain. It’s an intervention that’s completely free and safe, and could be implemented almost immediately.”
Preserving kidney function
Ischemia as a result of dialysis affects multiple organs, including the kidneys.
“Kidney function is important even for those whose kidneys are failing,” explains Dr. McIntyre. “We need to keep the kidneys as healthy as possible.”
Dr. Chris McIntyre is working to improve dialysis and patient outcomes through imaging research.
His team recently studied the effects of hemodialysis on blood supply to the kidneys, called renal perfusion. Research patients were scanned using CT perfusion imaging while undergoing dialysis under standard conditions, which resulted in an 18.4 per cent drop in blood supply.
Next, half of the participants were scanned again. This time the dialysate, a fluid used during the dialysis process, was cooled from 36.5 to 35 degrees Celsius.
Results show that dialysate cooling improved renal perfusion in two thirds of the patients. Previous studies showed that dialysate cooling can improve overall patient outcomes by limiting cardiovascular stress.
Results show that dialysate cooling improved renal perfusion in two thirds of patients.
“Dialysis may be destroying what’s left of remaining kidney function by limiting blood supply,” says Dr. McIntyre. “While further study is needed, it appears that dialysate cooling has potential to be used as a therapeutic approach to slow this decline.”
Revealing the harmful effects of salt
The research team was the first in the world to image sodium in the bodies of dialysis patients using PET/MRI. Dialysis cannot fully remove sodium from a patient’s body which means salt and its harmful effects remain.
“With a resident physicist on our team, we were able to write the code and produce the imaging coils needed to image salt in the human body,” notes Dr. McIntyre.
Using PET/MRI to measure sodium levels in 26 research participants, they found that dialysis patients have significantly higher sodium levels in the skin, muscle and bone of their legs when compared to healthy individuals. The high sodium levels correlated with health issues like anemia, malnutrition and inflammation. Imaging coils are now being built to look at sodium in a patient’s heart and kidneys.
“We need to better understand the harms that sodium is causing and start looking towards solutions to this problem.”
Lloyd Weiss (right) is participating in research with Dr. Chris McIntyre (left) to study harms caused by dialysis and possible improvements to treatment.
A hope for the future
For Lloyd Weiss, this research has been illuminating.
“I didn’t realize sodium was so bad for people on dialysis. I’ve also noticed how dialysis seems to affect my short-term memory,” he says. “This has been an eye-opener for everything.”
Lloyd has participated in multiple studies with Dr. McIntyre’s team.
“We’re so lucky to live in London with the people and tools to conduct this research. If my participation helps improve dialysis for patients in the future, I’m happy to do my part.”
Detecting cardiovascular stress with a smartphone camera
Through a commercial partnership with Intelomed, Dr. Chris McIntyre is testing a novel mobile app called mCVI™ that can detect changes in a person’s physiology with only a cell phone camera.
The app uses a smartphone camera to lock onto a person’s face and choose a part of the forehead. The picture is made up of three colours. The device measures microscopic changes in the relative intensity of the three colours and interprets those changes as a wave of blood flowing in and out of a person’s skin. This wave is used to measure pulse, respiratory rate and oxygen saturation. It can also predict blood flow in the heart, providing insight into cardiovascular health.
Dr. McIntyre’s team is validating the app for FDA approval. They are using it to monitor patient response to dialysis and hope it can one day provide early detection of cardiovascular stress.
Dr. Chris McIntyre is a Scientist at Lawson, Nephrologist at London Health Sciences Centre and Professor at Schulich School of Medicine & Dentistry, Western University.