Updated: Jan 21
If you're in laser therapy practice, you know that a lot of patients do well and some just seem to not respond. Why is that? What's happening in those tissues? And more importantly, how do we work around that? How do we get that patient better?
The full title of the paper I'm referring to is titled Microcirculatory Response to Photobiomodulation: Why Some Respond and Others Do Not: a Randomized Controlled Study. This came out in Lasers in Surgery and Medicine in February 2020. What I'll do today is talk to you about how they designed this study and the findings from the study, then I'll talk about the things that they weren't really able to get into with these results. There is so much contained in this study, but there's some basic principles here that are really critical. If you're a laser therapy practitioner, you need to know these things. So here we go. This study took 20 patients and they used red or infrared LED light on the patient's left wrist for five minutes and they looked at left and right hand skin perfusion, skin blood volume changes, and skin temperature, as well as the patient's respiration rate, heart rate and blood pressure. So they measured all of this the entire time. And remember, they're only applying either red or infrared light to just the left side so the right side serves as a control for this. For the red LED light, they're using 633 nanometer light at a total energy procession of 21 joules per centimeter squared, which is fairly high. And then for the infrared, they were using 830 nanometer infrared diodes, with 16.5 joules per centimeter squared. So they were able to use the LED cluster to irradiate the entire anterior wrist getting light to the ulnar and radial arteries. They left it on for five minutes and they blocked the light so that none of the light could reach the right hand. They applied the light for five minutes. They measured while the light was on as well as 20 minutes after the light was switched off.
Photobiomodulation and Microcirculation
The idea here was that patients would see an increase in circulation in the hand distal to where the light was being applied. On that left side only, and the right side would stay constant. And that is exactly what they saw. They said that photo biomodulation increased all micro circulatory variables measured during the five minute irradiation. And then it was either maintained or increased further until it reached saturation during the 20 minute followup period. They said that it induced arteriolar vasodilation that results in both immediate and long lasting increased capillary flow and tissue perfusion in healthy individuals.
Red vs Infrared Light
The comparison they made between red and infrared LEDs was that the infrared produced that increase in skin blood flow, arterial, and blood volume pulsation during the radiation and the follow-up. The red LEDs did not. So that's one of the factors right there; the color of light you use, the wavelength, matters. There is a difference between red and infrared. They act differently on the tissues and in this particular study, what the author saw is that to get good improvements in blood flow down in the hand, you needed to be in the infrared range, not the red light range.
Stop and think with me for just a minute here on what type of conditions that you see in clinical practice could benefit from increased circulation downstream. Well, one would be carpal tunnel syndrome. Right? Improved blood flow into the hand sounds pretty darn good for carpal tunnel patients. What about Raynaud's Syndrome? Raynaud's is a blood flow disorder that patients experience a white, blue, red progression of blood flow reduction, hypoxia, and painful reperfusion. It's worsened by cold weather. I mean, go ahead and think about anything else that can benefit from increased distal blood flow. And this is just setting an LED cluster on the patient's wrist for five minutes and seeing improvements in that downstream blood flow in healthy patients.
Laser Therapy and Nitric Oxide
So what did these researchers find about healthy versus unhealthy patients? We know from other studies that adding a nitric oxide inhibitor will actually eliminate the benefits of vasodilation from photobiomodulation. So if you have any medication or chemistry factors that could inhibit nitric oxide, then you're not going to get this microvasculature response because the mechanism just isn't working. Laser therapy is not magic. You can't just throw light onto somebody with no examination with, with no real sense of how that patient's health is and just expect miracles. If there's something going on that isn't healthy in the body, it could impact the mechanisms that make laser therapy work. Nitric oxide inhibition will absolutely interfere with the process of stimulating more blood flow through light therapy.
Laser Therapy and Health Conditions
The next thing they saw is it patients with very cold hands at the beginning of the study, before the light was applied or patients with very hot hands before the light was applied, did not see the same type of response. Patients with normal hand temperature they saw good improvements in warmth and blood flow, but patients with cold hands only saw improvements in blood flow, not warmth. Patients with the overly warm hands also did not see improvement in blood flow. Now patients with overly warm hands are already in a state of vasodilation. That's what the study says. So can you really "improve" that anymore? Evidently not. They're already maxed out.
Patients with very cold hands incidentally remarked that the light source felt very hot despite not seeing a downstream increase in warmth in the hand. Now, I think that's interesting. What's going on there? Well, first, why do patients have this hot hand or cold hand status? What happens in the body that makes people's hands unusually cold or unusually hot? Start thinking about some of the metabolic disorders, thyroid problems, diabetes. There are multiple conditions that can cause a cold or hot handed patient, and those are usually things that are bad. There are other things going on in the body that mean that when it comes to blood flow, the patient's not normal. So again, laser therapy is just not this magic bullet that always works no matter what. You have to make sure that the patient's metabolic conditions are managed correctly and addressed. Otherwise your chances of seeing good improvements from light therapies are reduced.
What else can affect the mechanisms of how patients respond? How about anemia? If the blood is not carrying enough oxygen to a damaged site, you will not have good improvements, at least not very quickly. What about other factors are there?
B vitamins, trace minerals, calcium, potassium, sodium- all these need to be balanced to have good blood flow fluid exchange and ATP production. Because again, you have to enable the body's mechanisms to work if you're going to try and improve those mechanisms by utilizing light or laser therapy.
Troubleshooting Problem Patients
Those are some of the factors that we train our doctors to get into and to recognize when there is a patient who's not responding. There are factors that can affect the patient's progress other than just the laser settings you're using or the device you're using. But the wavelength is very important. The patient's metabolic status is important, their blood chemistry and their nutrition is important. A matter of fact, their macro nutrition is also important. And then another one is exertion. We've all probably seen patients who do this; you get them feeling a little bit better, and then they go out and they go for a 10 mile hike or they hit the gym really hard because they're feeling so good. Then they say "Well, doc, it's just not working. I'm feeling just as bad as I was." And then you dig into that a little bit and you find out they felt so good after the last treatment that they went and cleaned their entire house. No wonder they're hurting again!
Laser Therapy Training
We train our doctors how to spot when a patient's macro nutrition is not sufficient and those micro nutrition problems like trace minerals. How do you know when somebody is low on these nutrition factors without having to run blood work every single time you see the patient? Many, many times it is not the laser's fault. There are other things going on with the patient and you have to get into that. If you're going to see good success rates, if you want to learn more, if you want to know more about how to evaluate your patients, how to look for these warning signs that you may have a metabolic or a nutrition issue that could inhibit your patient's progress, then get ahold of us- firstname.lastname@example.org.