By Miriam Lippel Blum
As with any information you find on the internet do not do this experiment unless you have shown the research to your physician, discussed it thoroughly, and have his or her permission.
Hemodialysis (HD) is usually performed in bright, clinic rooms using transparent tubing to move blood from person to machine and back again. This means during every dialysis session the dialyzor’s blood is exposed to harsh fluorescent lighting. This adds up to more than 450 hours a year (156 treatments x 3-5 hours). Uniquely during HD blood is exposed to light while it is in use, normally circulating blood is never exposed to light. This, I think, raises a question: does light have an impact on circulating blood?
Research done in Japan, and published in 2005 in the journal Clinical Chemistry, showed that light does have an impact. In Light-Shielded Hemodialysis Prevents Hypotension and Lipid Peroxidation by Inhibiting Nitric Oxide Production, Japanese researchers chronicle an experiment to measure the impact of light on circulating blood. The researchers simply covered the dialysis tubing and measured changes in nitric oxide (NO) and lipid peroxidation.
Why are these two blood measures important? Together, both are involved in stimulating inflammation which can contribute to a host of problems, e.g. atherosclerosis, decreased epo response, amyloidosis. Individually, too much nitric oxide in the bloodstream can cause hypotension, while lipid peroxidation is a prime suspect for causing vascular damage.
In their experiment, the authors decreased the circulating blood's light exposure by covering the tubing with aluminum foil for the duration of the run. The authors found that the levels of NO were decreased and blood pressures stabilized. And they found the decreased NO inhibited plasma lipid peroxide generation. The implication of this research is that light is not good for blood that is in use. This routine light exposure during HD is likely contributing to dialyzor cardiovascular problems.
This research has had a big impact on me. When I was on in-center HD, I had terrible intradialytic hypotension that was not related to fluid issues. No matter how much saline or hypertonic was pumped into me, my blood pressures still would fall dramatically. Often my treatments had to be suspended because my BP was too low to continue. I also developed severe cardiovascular disease within 9 months of starting in-center HD. (I was on PD before that.)
My husband, always on the lookout for things that will help my health, happened to come across the Clinical Chemistry article. I talked with my nephrologist and he agreed, why not see what would happen if we covered my tubing during treatment. We had some hassles with the clinic but since my doctor wrote an order allowing it, the clinic eventually gave in, after making me address some safety issues (I had to make sure my coverings could be removed quickly in case the machine had an air alarm sound, and the pump needed to be visible). So I made coverings with fabric and velcro so they could come off quickly and fashioned a little window for the blood pump with polarized plastic (like sunglasses) that would block light but still allow visibility.
The result was remarkable. My blood pressures stabilized allowing me to have treatment runs uninterrupted by drastic blood pressure drops. It worked so well that my nephrologist wanted to do some more research, unfortunately there was no funding.
Since that first effort I've fashioned reusable covers out double layers of heavyweight dark fabric. I use these covers along with strategically placed aluminum foil every run. I make sure to fully cover the tubing and dialyzer so that each time I hook up to NxStage I only briefly expose my blood to light. The only time my circulating blood is exposed is during the start and finish of treatments.
I recently talked to Dr. John Agar, about my light avoidance techniques and shared the Clinical Chemistry paper that led my husband and I down this road. Agar had never seen the research and found it very interesting. He said that some current Australian research showed a heretofore unexplained lower level of NO in patients on nocturnal dialysis. Perhaps this is because doing dialysis at night, in the dark, reduces the blood's light exposure. Light exposure that would be routine during conventional HD. This may also be another reason why nocturnal HD seems to be so much better and less damaging to dialyzors.
There is much more research that needs to be done in this area and many questions to be answered. For example: is there a particular wavelength of the light spectrum that causes the damage? Or is all light equally damaging? Does the source of the light matter i.e. fluorescent vs. incandescent vs sunshine? Does it have to be direct light? Would indirect lighting solve the problem?
Research on blood light exposure could have implications for the provision of dialysis. That the cardiovascular damage seen in dialyzors could be mitigated by something as easy and noninvasive as preventing light exposure is something that should be seriously considered. Research may show that the blood tubing needs to provide shielding or the research may show that redesigning the unit's lighting would solve the problem.
Whatever the solution the dialysis industry needs to address this remarkably uncommented on issue. As for me I have seen (and felt) enough to continue my habit of covering the blood lines and dialyzer.