Effects of low-level laser therapy on the healing of foot ulcers in people with diabetes mellitus

1.Universidade da Integração Internacional da Lusofonia Afro-Brasileira – Departamento de Enfermagem – Redenção (CE), Brazil. 2.Universidade Federal do Ceará – Departamento de Enfermagem – Fortaleza (CE), Brazil. 3.Hospital Sírio-Libanês – Serviço de Estomaterapia – São Paulo (SP), Brazil. *Correspondence author: thiagomoura@unilab.edu.br Received: Jan. 18, 2020 | Accepted: Mar. 09, 2020 ABSTRACT Objective: Identify the effects of low-level laser therapy on the healing of diabetic foot. Method: Systematic review of the PubMed, LILACS, SciELO, CINAHL, Cochrane, Web of Science and Scopus databases, in which 92 articles were identified and six were included in the final sample after the eligibility criteria. Results: The articles pointed out as effects of laser therapy the effectiveness in the progression of the tissue repair process of the diabetic foot, pain relief, anti-inflammatory action, increased tissue perfusion of the lesion and improvement of the vascular response and the nervous system. Conclusion: Laser is an adjuvant therapy that can accelerate the wound healing process, relieve pain, improve neovascularization, and thus minimize the risk of complications, such as lower limb amputation and improvement of quality of life for people with diabetes and impaired skin integrity.


INTRODUCTION
Diabetic foot is caused mainly by peripheral neuropathy and arterial disease, which lead to foot ulceration. This ulceration can progress with infection and/or soft tissue destruction, which results in walking deficits and considerable impact on the quality of life, in addition to resources spent on prolonged hospitalization, rehabilitation, home care and direct and indirect costs to the patient, their families and society, due to loss of productivity 3,4 .
Approximately 15% of people with DM will suffer from foot ulcers in their lifetime, where conventional treatments such as daily cleansing and dressing with 0.9% saline solution, essential fatty acids, hydrogel and betadine solution have shown little success in progressing tissue repair, with a higher rate of complications [5][6][7] .
A cohort of 1055 people with DM in 19 specialized centers in Brazil showed that 24.2% had previous foot ulcer and 13.7% prior amputation, and out of these, 5.3% had more than one amputation 8 .
Thus, in recent years, adjuvant therapies have been tested to stimulate the wound healing process in people with DM 5 .
Among the new therapies, low-level laser therapy (LLLT) is considered a noninvasive, painless, low-cost and effective method of wound treatment, as it acts on the physiological and biochemical events of the healing process [9][10][11] . Studies available on the application of laser therapy for the treatment of foot ulcers in people with DM are still scarce. Although there are favorable reports for its use, further research should be carried out to obtain the effects of laser in the treatment of such lesions, as well as to identify the number of applications, dose and wavelength required for tissue repair, which reinforces the relevance of the study.
The high occurrence of DM justifies the research in the population in recent years and the increase in cases of nontraumatic amputations in the lower limbs, which highlights the need for not only treatment of the underlying disease, but also prevention of injuries and monitoring of diabetic foot with other adjuvant therapies that can promote healing progress.
This study aims to identify the effects of low-level laser therapy on diabetic foot healing.

METHODS
It is a systematic review of the literature, which aimed to identify, select and analyze the scientific production on the effects of laser therapy on the healing of diabetic foot. Systematic reviews use systematic and explicit methods to choose and critically evaluate relevant research 12 .
The bibliographic survey was conducted between January and June 2019. To collect the data, the PICO strategy was used, whose acronym means: P -Population, points to the population in focus, I -Intervention, determines the type of intervention, C -Comparison, identifies which control minimizar o risco de complicações, como amputação do membro inferior e melhora da qualidade de vida de pessoas com diabetes e integridade da pele prejudicada. DESCRITORES: Terapia a laser; Cicatrização de feridas; Pé diabético; Estomaterapia.
Effects of low-level laser therapy on the healing of foot ulcers in people with diabetes mellitus group will be tested with the response, and, O -Outcome, the outcomes that will be evaluated. This strategy helps to formulate the research question and enables the identification of keywords that assist in locating relevant primary studies in databases 13 .
Given the above, the guiding question of this study, based on the PICO strategy, illustrated in Table 1 To certify the methodological quality of the articles included, the PRISMA recommendation was used, which consists of a checklist with 27 items of systematic analysis and metanalysis 14 . All scientific productions used were duly cited and referenced concerning research copyrights.

Profile of publications
The six articles included in this review are presented in Table 2, which aimed to analyze the effects of laser therapy on the healing process of diabetic foot.
Regarding The selected studies were conducted in the following countries: Brazil (n = 3), India (n = 1), Italy (n = 1) and Iran (n = 1). Regarding the category of the main author of the publications, two belong to physiotherapy, two to medicine, one to nursery and one to biomedicine.

Treatment protocol
The In other studies, there was a statistically significant reduction of post-laser pain, through the evaluation of pain through the visual analog scale, which scores the levels of pain from 0 to 10, in which there was a reduction from an average of 9 on the scale to 5 after using the laser 15,16 .
It is therefore perceived that, in addition to contributing to the decrease in treatment time, the laser is a supporting therapy that can provide relief in the Algic state and local discomfort. The reduction in pain can impact the quality of life and enable the patient to be more active in their daily life activities.
The application of laser also promoted increased neovascularization and proliferation of fibroblasts, with a decrease in the amount of inflammatory infiltrate in the lesions, which contributes to the modulation of tissue repair with faster and more organized healing 15,18 .
Through this process, the laser can recruit cytokines and essential growth factors to stimulate wound healing 19 .
There was no unanimity in the studies regarding the Effects of low-level laser therapy on the healing of foot ulcers in people with diabetes mellitus The limitation in the number of published researches on diabetic foot and LLLT is stressed. It is, therefore, essential to conduct new studies that present increasingly promising results on the use of laser in wound treatment and that clarify the stages of healing, the scientific determination of the influential dosage parameters and wavelength, with strict study criteria to validate the efficacy and safety data demonstrated in this review.