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Contributed by Mark Callanen, PT, DPT, OCS
In 2016, 11.5 million Americans misused opioid medications which contributed to the death of 17,087 prescription drug users1. These staggering statistics have heightened the demand in the US healthcare market for therapies that address both acute and chronic pain conditions without the use of pharmaceutical therapies. Therapeutic laser, via the process of photobiomodulation (PBM), is a non-invasive modality that addresses pain in a number of ways.
Clinically effective PBM takes place when a light source provides an adequate dose of photonic energy to injured tissue. Laser and LED devices are the two most common light sources used for this purpose. The general mechanism for PBM involves biochemical stimulation of the electron transport chain in eukaryotic cells, which triggers several positive biochemical changes in injured tissue. These changes to musculoskeletal tissue and nerve tissue can decrease pain2,3,4, reduce inflammation5,6,7, and accelerate tissue healing.8,9,10
A 2015 study from the Annals of Cardiac Anesthesia demonstrated the effectiveness of laser therapy at reduced post-surgical pain after open-heart surgery. The painful sternal incision associated with this surgery usually requires oral opioids and rescue analgesia (injectable opioids), administered via a patient-operated button to self-control discomfort after surgery.
The study looked at 100 patients that had laser treatment administered 30-minutes after surgery to the sternal area. Statistically significant pain reduction was noted at 1 hour and 24 hours after treatment. Only 40 patients had pain of 5/10 or greater 24 hours after treatment, which necessitated a second laser treatment. Pain was recorded at 0/10 for all patients by the third day (hour 54). No patients required a 3rd dose of laser, and of note, no rescue opioid analgesia was required for the laser therapy group11.
This is significant because it demonstrates laser’s pain-relieving efficacy, and ability to reduce medication usage as part of the patient group’s multimodal (MMA) analgesia protocol. This is extremely important because even a few days of opioid use can lead to chronic dependence.
A 2017 study that analyzed 1.3 million non-cancer patients showed that 6% of patients that used opioids for only 1 day were still taking the medicine one year later! The number doubled to 12% for patients that used opioids for 6 days, and for patients that were on a 12-day supply of opioids, 24% of those patients, almost one in four, were still taking the drugs one-year later12.
Given that pain management is a multifaceted process, knowing what approaches are supported by evidence-based practice is key. In 2017 the American College of Physicians released its practice guidelines for Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain13. In it, there was a strong recommendation for patients with chronic low back pain to initially select nonpharmacologic treatment. Several activities were recommended including exercise, multidisciplinary rehabilitation, acupuncture, mindfulness-based stress reduction, and tai-chi to name a few. The only stand-alone modality that they supported for chronic back pain was low level laser therapy.
The Journal of Sport Physical Therapy (JOSPT) followed suit in 2017 by endorsing laser therapy among other treatments for use in treating both chronic neck pain with mobility deficits as well as acute neck pain with radiating symptoms14.
These evidence-based guidelines for both neck and lower back conditions will hopefully encourage clinicians that are quick to dismiss modalities in their clinical practice to reexamine laser therapy. In doing so, they will find that there is growing support for it as part of a comprehensive plan of care when addressing pain and other musculoskeletal injuries.
While drawing conclusions on the best way to address pain is still open for debate, a few things are starting to become clear. It is evident that the risks involved with opioids are causing them to fall out of favor for short and long-term pain relief. Additionally, the receptiveness by the medical community to prescribe non-pharmacological pain management treatment methods has never been higher.
Knowing what active strategies, as well as how to incorporate modalities like laser therapy into a comprehensive, evidence-based plan of care, will be key factors in promoting change in the US pain market as the evidence on this topic continues to emerge.
References1. Hedegaard H, Warner M, Miniño AM. Drug overdose deaths in the United States, 1999–2016. NCHS Data Brief, no 294. Hyattsville, MD: National Center for Health Statistics. 2017/ CDC. Wide-ranging online data for epidemiologic research (WONDER). Atlanta, GA: CDC, National Center for Health Statistics; 2016. Available at http://wonder.cdc.gov 2. Chow et al. Inhibitory Effects of Laser Irradiation on Peripheral Mammalian Nerves and Relevance to Analgesic Effects: A Systematic Review. Photomedicine and Laser Surgery Volume X, Number X, 2011ª Mary Ann Liebert, Inc. Pp. 1–17. 3. Holanda, V.M. et al. (2017) The Mechanistic Basis for Photobiomodulation Therapy of Neuropathic Pain by Near Infrared Laser Light. Lasers Surg Med. 2017 Jul;49(5):516-524. 4. Jimbo, K. et al. (1998) Suppressive effects of low-power laser irradiation on bradykinin evoked action potentials in cultured murine dorsal root ganglion cells. Neurosci Lett. 240(2):93-96. 5. Mizutani, K. et al. (2004) A clinical study on serum prostaglandin E2 with low-level PBMT. Photomed Laser Surg. 22(6)537-539. 6. Lopes-Martins, R.A. et al. (2005) Spontaneious effects of low-level PBMT (650 nm) in acute inflammatory mouse pleurisy induced by carrageenan. Photomed Laser Surg. 23(4):377-381. 7. Prianti, A.C.G. et al. (2014) Low-level PBMT (LLLT) reduces the COX-2 mRNA expression in both subplantar and total brain tissues in the model of peripheral inflammation induced by administration of carrageenan. Lasers Med Sci. 29(4):1397-1403. 8. Karu, T 1991, ‘Low-Intensity Laser Light Action Upon Fibroblasts and Lymphocytes’, in Calderhead, RG & Ohshiro, T, Progress in Laser Therapy, J. Wiley and Sons, Chichester, New York, Brisbane, Toronto, Singapore, pp.175-180. 9. Benayahu, D, Maltz, L, Oron, U, Stein, A 2005, ‘Low-Level Laser Irradiation Promotes Proliferation and Differentiation of Human Osteoblasts in Vitro’, Photomedicine and Laser Surgery, vol. 23, no. 2, pp. 161-166. 10. Abrahamse, H, Mathope, T, Moore, T, Mvula, B 2008, ‘The effect of low level laser therapy on adult human adipose derived stem cells’, Lasers in Medical Science, vol. 23, no. 3, pp. 277–252. 11. Karlekar A, Bharati S, Saxena R, Mehta K. Assessment of feasibility and efficacy of Class IV laser therapy for postoperative pain relief in off-pump coronary artery bypass surgery patients: A pilot study. Ann Card Anaesth. 2015; 18: 317-22. 12. Shah A, Hayes CJ, Martin BC. Characteristics of Initial Prescription Episodes and Likelihood of Long-Term Opioid Use — United States, 2006–2015. MMWR Morb Mortal Wkly Rep 2017;66:265–269. 13. American College of Physicians. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline. Ann Intern Med. 2017 Apr 4;166(7):514-530. 14. JOSPT. Neck Pain: Revision 2017 Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability and Health From the Orthopaedic Section of the American Physical Therapy Association. J Orthop Sports Phys Ther. 2017;47(7): A1-A83.
Contributed by Mark Callanen, PT, DPT, OCS
In Part 1 of this laser forum, we discussed the basic terms related to the physics of laser therapy. Here we will cover the significant role irradiance (power density) and dosage (energy density) plays in 3 concepts pertinent to photobiomodulation (PBM) therapy.
1. Higher irradiance allows more photons to be applied at depth for a given wavelength. Please refer to the image below for a visual representation of this concept.
This is important with regard to PBM as it is a threshold-phenomena. If sufficient light does not reach the injured target tissue, there will be no notable therapeutic change1. Higher powered lasers can help with this problem by providing higher photonic density at the skin which helps transfer proportionate levels of light to deeper tissues. This concept can be referred to as “therapeutic depth”. It is worth noting that this is a complicated topic that goes well beyond the scope of this article and that there are several variables that impact optimal tissue dosing.
2. When treating with a laser, it can be difficult to maintain therapeutic dosing levels when treating over large surface areas. This is because as the treatment area grows, so does the denominator of the energy density equation (J/cm2) which can dilute the dose of energy being applied if higher joule levels are not applied proportionately. Having more laser power to utilize makes this adjustment easier for the clinician. Note: (J = W x s).
The graphic below helps clarify how adding power impacts treatment time for a given energy density and a given area.
In summary, adding power to the energy equation can significantly reduce the time needed to apply a therapeutic PBM dose of light.
3. The final important clinical factor that higher irradiance impacts is with regard to pain relief. More specifically, analgesia that can be created at peripheral sensory nerves when higher irradiances are applied to C and A-delta sensory nerves. It has been shown that when > 270 mW/cm2 is applied to these nerves, neuroplastic changes take place within 2-3 minutes at the peripheral nerve that slows the conduction rate of the pain signal3. This physical change to the nerve quickly reduces pain4.
Additionally, it has been shown that an inhibition of nociceptive action potentials takes place when higher power densities are applied to nerve tissue. Specifically, a 30% neural blockade has been shown to start 10-20 min after treatment, which further reduces pain perception4.
There are other longer lasting benefits that PBM provides with regard to reducing inflammation around damaged tissue, but this is a mechanism of healing that is not unique to treatment with higher irradiances1,2,4.
One final note with regard to safety, treating with higher power density does increase the risk of thermal effects on surface tissue as more heat is produced. Using ideal wavelengths that minimize photonic absorption at the skin and utilizing appropriate treatment heads that help manage surface heat is an important component to consider when treating with Class 4 lasers.
LightForce Therapy Lasers influence® Technology helps to easily manage these factors through a combination of patented software and hardware features. The patented large massage ball and large cone applicators play an integral role in delivering high powered treatments that are safe and comfortable to the patient.
If after reading this you still have questions about the effectiveness of higher powered lasers, please watch this informative animation, or contact us directly at firstname.lastname@example.org.References
1. Huang, Y. Biphasic Dose Response in Low Level Light Therapy. Dose Response. 2009; 7(4): 358–383.
2. Bjordal JM, Couppe C, Chow RT, Tuner J, Ljunggren EA. A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders. Aust J Physiother. 2003;49:107–16.
3. Holanda, V.M. et al. (2017) The Mechanistic Basis for Photobiomodulation Therapy of Neuropathic Pain by Near Infrared Laser Light. Lasers Surg Med. 2017 Jul;49(5):516-524
4. Cotler, H et al. The Use of Low Level Laser Therapy (LLLT) For Musculoskeletal Pain. MOJ Orthop Rheumatol. 2015 ; 2(5).
Contributed by Mark Callanen, PT, DPT, OCS
There is often confusion in the medical field when clinicians research the topic of laser. At the center of the confusion is power and its relationship to lasers’ effect on tissue, which is referred to as photobiomodulation (PBM)1.
To understand the role of power, there needs to be an understanding of its relationship to laser dosing, penetration, and how higher power lasers impact tissue(s). This two-part blog is intended to clarify some of the key terms related to the physics of laser therapy and expound on the clinical implications of treating with higher power density. But first, let’s look at a few key terms:
Photons: When any form of light is introduced to tissue, small “packets” of light called photons are emitted from the light source. At any specific wavelength of light, every photon contains exactly the same amount of energy. Think of a photon as the building block of light.
Energy: The total energy applied during treatment is the addition of all the individual photons that are emitted over a predefined period. The International System of Radiometric Units uses the joule (J) as the unit of energy to measure this property. Joules are the product of power and time.
Power is measured in watts or milliwatts and plays a key role in the total energy that is applied to tissue. Total energy (joules) by definition is the product of power (watts) and time (seconds). (J = W x s).
Therefore, increasing the power of a light source will deliver more joules of energy per unit time to a target. This plays a significant role in delivering photons to deeper tissues. A simple way to envision its importance is to think about how much light a 10 W bulb produces in a dark room vs a 100 W bulb. The more wattage the bulb emits, the more light will be present in the room. This analogy is similar to the wattage of a laser that is applied to the skin – the higher the wattage, the more “light” that is delivered into the tissue (at a given wavelength).
Now that you have more clarity on power and energy, the last important characteristic to understand is the concept of density with regard to these two terms. Density brings into account the area that is treated, and will be noted in cm2.
Power Density (W/cm2): This term describes the intensity of the light, or its “brilliance” and is referred to as irradiance in the literature. Irradiance impacts the number of photons that will be applied at depth for a given wavelength and is directly related to the heat that will be produced at the surface when a light source is applied.
Energy Density (J/cm2): Commonly referred to as fluence, it is synonymous with dosage when defining PBM treatment parameters. It defines the total amount of energy that is applied per unit area and can be influenced by increasing the time of the treatment and/or the power that is being applied from the light source. (J= W x s).
To summarize, these terms all play a role in understanding the basic physical properties of light and how it impacts PBM. With this knowledge in place, Part 2 will discuss the benefits of higher power laser therapy as it relates to 3 key treatment attributes. Stay tuned!
References: 1. Anders JJ, Lanzafame RJ, Arany PR. Low-level light/laser therapy versus photobiomodulation therapy. Photomed Laser Surg 2015;33:183–184