Heart, minds and other bits: The dark side of dialysis keeps getting darker by Dr. Chris McIntyre
Ruaa Al-Qazazi, MB ChB, MSc Candidate, Translational Medicine Graduate Program
Chronic kidney disease occurs when the kidneys lose their ability to filter and remove waste and extra fluid from the body. In hemodialysis, a man-made membrane (dialyzer) is used to purify the blood from fluids and waste products and to correct electrolyte imbalances.
Hemodialysis treatments are typically performed three times per week and last between three to five hours. Despite the importance of this intervention in patients with end-stage kidney disease, hemodialysis decreases patients’ quality of life and increases morbidity and mortality, leading to low treatment tolerability. This has been attributed to the industrializion of this process that has resulted from attempts to deliver hemodialysis to a larger number of patients at minimal cost.
In this week’s grand rounds presentation, Dr. Christopher McIntyre focused on the pathophysiology of hemodialysis-associated organ dysfunction and the potential harm of continuous hemodialysis exposure. Dr. McIntyre is Robert Lindsay Chair of Dialysis Research and Innovation at Western University. He serves as Director of the Lilibeth Caberto Kidney Clinical Research Unit at London Health Sciences Centre, where he is also a practicing clinical nephrologist. He emphasized that the synergistic nature of his clinical and research work makes it difficult to neatly differentiate between these two spheres.
This is exemplified by Dr. McIntyre’s statement that his observation of patients on chronic kidney dialysis led him to his current research path. “They arrived pink, talkative, and happy, and would leave pale, grey and silent,” Dr. McIntyre said. His research studies focus mainly on understanding the adverse effects of dialysis on the body organs and on reducing preventable harm to improve medical outcomes.
In his presentation, Dr. McIntyre stated that hemodialysis is capable of enforcing recurrent circulatory stress. This contributes to the development of cardiovascular diseases and induces perfusion-dependent injury in other organs such as the brain, gut, and kidney.
Hydrostatic ultrafiltration and dialysis-induced hypotension are two key players in the initiation of circulatory stress sufficient to cause reversible myocardial hypoperfusion identified as myocardial stunning. In chronic kidney dialysis, this injury becomes cumulative, resulting in contractile dysfunction and consequent heart failure both in children and adults. It has the same effect on the brain, leading to ischemic injuries and cognitive impairment. Dr. McIntyre also explained the role of disrupted gut mucosal structure and function in the distribution of endotoxins to the heart and brain, leading to the proinflammatory immune system activation in both organs.
During the medical grand rounds, new research suggesting that cooling the temperature of the dialysis fluid can decrease both heart and brain injuries was discussed. Preliminary data from a pilot study conducted by Dr. McIntyre and his team showed that reducing the dialysis fluid temperature by 0.5 ºC below body temperature could help protect the heart and the brain from injury. Currently, a multicenter trial is being conducted across Ontario to examine the efficacy of this intervention in reducing hospitalization and mortality rates in patients with kidney failure on dialysis.
Dr. McIntyre emphasized the importance of reducing the time of the dialysis sessions. Spreading the treatment over more days during the week may reduce intradialytic-induced hypotension. He encouraged the use of home hemodialysis devices to achieve this goal. Notably, this will require educating and empowering patients about the proper use of these devices. However, given that in patients with chronic kidney failure, hemodialysis-induced circulatory stress is a factor contributing to pathophysiology within multiple organ systems, the use of home hemodialysis devices may be exactly what is needed to promote patients’ health.