What would you do if your swimming pool was dirty? Clean it of course. But how? Would you take out a few pails of water, treat the water in the buckets, then toss the water back into the pool and declare the pool clean? And if it were the bathroom that needed cleaning, would you clean it by treating a few bucket fulls of water from the pool? Seems an odd approach to me, but, metaphorically speaking, it is the approach used by ultraviolet (UV) and laser treatment of blood.
A weird bit medical therapy, I get the occasional ‘Hey Dr. Smartypants, what do you think of this treatment?’ email. UV blood irradiation is an odd treatment, with an peculiar history.
UV light does have many effects on tissues, as a trip to Hawaii can rapidly demonstrate to a pasty Oregonian. In my world UV is used to sterilize the environment and UV kills off everything from MRSA to C. difficile to tuberculosis. We vent potentially microbially contaminated air to the outside in part to dilute any infection but more importantly we know that most pathogens will die when exposed to solar UV light. Do not use UV light on people as a rule, since it causes tissue damage and we fret about injury to eyes and skin.
Back in the 1930’s a physician named Knott had two patients, one with a brain abscess and one with sepsis, who he evidently cured by irradiating the patients’ blood and returning it to them.* His rationale was since cutaneous TB can be cured by UV light (the discovery resulted in the 1903 Nobel Prize in medicine and physiology), perhaps other infections would be amenable to the therapy as well (1). (more…)