Principles of Lasers and Biophotonic Effects

Effect of photobiomodulation in the balance between effector and regulatory T cells in an experimental model of COPD

Introduction

Currently, Chronic Obstructive Pulmonary Disease (COPD) has a high impact on morbidity and mortality worldwide. The increase of CD4+, CD8+ cells expressing NF-κB, STAT4, IFN-γ and perforin are related to smoking habit, smoking history, airflow rate, obstruction and pulmonary emphysema. Furthermore, a deficiency in CD4+CD25+Foxp3+ regulatory T cells (Tregs) may impair the normal function of the immune system and lead to respiratory immune disease. On the other hand, the anti-inflammatory cytokine IL-10, produced by Treg cells and macrophages, inhibits the synthesis of several pro-inflammatory cytokines that are expressed in COPD. Therefore, immunotherapeutic strategies, such as Photobiomodulation (PBM), aim to regulate the levels of cytokines, chemokines and transcription factors in COPD. Consequently, the objective of this study was to evaluate CD4+STAT4 and CD4+CD25+Foxp3+ cells as well as the production of CD4+IFN- γ and CD4+CD25+IL-10 in the lung after PBM therapy in a COPD mice model.

Methods

We induced COPD in C57BL/6 mice through an orotracheal application of cigarette smoke extract. PMB treatment was applied for the entire 7 weeks and Bronchoalveolar lavage (BAL) and lungs were collected to study production of IFN- γ and IL-10 in the lung. After the last administration with cigarette smoke extract (end of 7 weeks), 24 h later, the animals were euthanized. One-way ANOVA followed by NewmanKeuls test were used for statistical analysis with significance levels adjusted to 5% (p < 0.05).

Results

This result showed that PBM improves COPD symptomatology, reducing the number of inflammatory cells (macrophages, neutrophils and lymphocytes), the levels of IFN-γ among others, and increased IL-10. We also observed a decrease of collagen, mucus, bronchoconstriction index, alveolar enlargement, CD4+, CD8+, CD4+STAT4+, and CD4+IFN-γ+ cells. In addition, in the treated group, we found an increase in CD4+CD25+Foxp3+ and CD4+IL-10+ T cells.

Conclusion

This study suggests that PBM treatment could be applied as an immunotherapeutic strategy for COPD.

Near-Infrared II Photobiomodulation Preconditioning Ameliorates Stroke Injury via Phosphorylation of eNOS

BACKGROUND

The current management of patients with stroke with intravenous thrombolysis and endovascular thrombectomy is effective only when it is timely performed on an appropriately selected but minor fraction of patients. The development of novel adjunctive therapy is highly desired to reduce morbidity and mortality with stroke. Since endothelial dysfunction is implicated in the pathogenesis of stroke and is featured with suppressed endothelial nitric oxide synthase (eNOS) with concomitant nitric oxide deficiency, restoring endothelial nitric oxide represents a promising approach to treating stroke injury.

METHODS

This is a preclinical proof-of-concept study to determine the therapeutic effect of transcranial treatment with a low-power near-infrared laser in a mouse model of ischemic stroke. The laser treatment was performed before the middle cerebral artery occlusion with a filament. To determine the involvement of eNOS phosphorylation, unphosphorylatable eNOS S1176A knock-in mice were used. Each measurement was analyzed by a 2-way ANOVA to assess the effect of the treatment on cerebral blood flow with laser Doppler flowmetry, eNOS phosphorylation by immunoblot analysis, and stroke outcomes by infarct volumes and neurological deficits.

RESULTS

Pretreatment with a 1064-nm laser at an irradiance of 50 mW/cm2 improved cerebral blood flow, eNOS phosphorylation, and stroke outcomes.

CONCLUSIONS

Near-infrared II photobiomodulation could offer a noninvasive and low-risk adjunctive therapy for stroke injury. This new modality using a physical parameter merits further consideration to develop innovative therapies to prevent and treat a wide array of cardiovascular diseases.

[Local ablative procedures for treatment of thyroid nodules]

Thyroid nodules are very frequent in the iodine deficiency regions of central Europe and some of the affected patients are referred for definitive treatment, such as surgery and radioiodine treatment. In recent years nonsurgical and non-radioiodine techniques have been introduced to treat thyroid gland pathologies. These techniques include the probe-based techniques of radiofrequency, microwave and laser application. The only noninvasive technique is high-intensity focused ultrasound. All mentioned techniques have the goal to reduce the volume of the thyroid nodule by application of energy/heat. The knowledge of all techniques and their advantages and risks is necessary to help physicians and patients in making decisions for the appropriate method of treatment of thyroid nodules.

Optimized Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) Laser Parameters for the Removal of Dental Ceramic Restorations

OBJECTIVES

The use of lasers for debonding adhesively luted ceramic restorations is a rather recent oral laser application in dentistry. The removal of all-ceramic restorations in the mouth can often be a troublesome task. A novel method for the debonding of ceramic restorations without damaging the restorations is Er:YAG laser irradiation. The aim of this study was to evaluate the Er:YAG laser for debonding procedures of different dental ceramics and to identify appropriate laser settings.

MATERIAL AND METHODS

Lithium disilicate, zirconium-reinforced lithium silicate, feldspatic ceramic, and zirconium dioxide were investigated. Ten ceramic rectangular-shaped specimens with 1 and 2 mm thickness were produced from each material. All specimens were irradiated with four different power settings 1.5; 2.5; 3.5; 4.5 W, pulse duration 50 μs, laser repetition rate 10 Hz, time of irradiation 10 s. The transmitted energy was measured with a powermeter. Additionally the suitability of the Er:YAG laser to remove the adhesively bonded ceramic and the time until loss of retention was evaluated.

RESULTS

The transmission rate for 1 and 2 mm platelets was determined for zirconium-reinforced lithium silicate at 54.6%/35.6%, lithium disilicate at 53.2%/35.7%, zirconium dioxide at 40.6%/32.4%, and for the feldspathic ceramic at 19.4%/10.1%. For zirconium-reinforced lithium silicate and zirconium dioxide 2.5 W (250 mJ/10 Hz) was an appropriate energy level for effective debonding. Whereas for lithium disilicate and for feldspathic ceramic, 4.5 W (450 mJ/10 Hz) is required for efficient debonding.

CONCLUSIONS

There are differences regarding transmission rates between ceramic types for the Er:YAG laser light and additionally depending on the type of ceramic different energy settings should be used for adequate debonding. Based on our in-vitro experiments we recommend 2.5 W for zirconium-reinforced lithium silicate and zirconium dioxide and 4.5 W for lithium disilicate and feldspatic ceramic. Transmission rates of different ceramic types and varying influences of thicknesses and bonding materials should be considered to adjust the laser parameters during laser debonding of adhesively luted all-ceramic restorations.

A Case Series of 11 Horses Diagnosed with Bone Spavin Treated with High Intensity Laser Therapy (HILT)

The aim of this work was to characterize and describe the effect of High Intensity Laser Therapy (HILT) used in the treatment of chronic osteoarthritis in horses. Over a 2 year period, 11 horses with diagnosed bone spavin were treated with HILT as a monotherapy. The horses chosen for this report presented hind limb lameness, were positive in a spavin flexion test and showed improvement after intra-articular anesthesia of the tarsometatarsal joint. Additionally, all the horses presented radiological signs of tarsus osteoarthritis and had not been treated for bone spavin for a minimum of 6 months. Each horse received 10 HILT therapies over 14 days' treatment time with the same laser protocol. At post-treatment orthopedic examination, 4 horses (36%) had improved 2 lameness grades (in the 5 grade American Association of Equine practitioners lameness scale), 4 horses (36%) had improved 1 lameness grade and 3 horses (28%) did not improve. Additionally, 3 horses were totally sound after HILT. Post-treatment spavin test result improvement was observed in 5 horses (45%), and 6 horses (55%) showed the same spavin test grade as before treatment. There were no horses that were sound in the spavin test performed after HILT. Therefore, it seems probable that the application of HILT in horses suffering from bone spavin may decrease joint pain, which influences visual lameness reduction.

Low-Level Laser Therapy: Potential and Complications

Introduction: Laser therapy has attracted experts' attention in medical sciences. Many benefits of laser therapy are presented besides some complications. In the present study, it is tried to present a new perspective of laser therapy in the various fields of medicine. Methods: Laser therapy-related articles which are combined with regenerative medicine, cosmetic, dentistry, neurodegenerative diseases, kidney, bone fracture, and vaginal function in the English language were searched through the google scholar search engine in the range of 2000-2021. After title screening, the abstracts were evaluated to access the full texts. Results: Basic concepts and various kinds of lasers which are applied in medicine were explained. Applications of laser therapy in various fields of medicine such as pain reduction, wound healing, regenerative medicine, dentistry, and several other body organs were highlighted and some complications were pointed. Conclusion: High potential of laser therapy for application in medicine implies a reconsideration of the laser properties and also styles of laser applications to improve the treatment and prevention of its side effects.

Phonosurgery: A review of current methodologies

Cold-steel has served as the gold standard modality of phonosurgery for most of its history. Surgical laser technology has revolutionized this field with its wide use of applications. Additional modalities have also been introduced such as coagulative lasers, photodynamic therapy, and cryotherapy. This review will compare the surgical modalities of cold steel, surgical lasers, phototherapy and cryotherapy. The mechanism of action, tissue effects and typical uses will be addressed for each modality.

Utilisation of an 810 nm diode laser for surgical management of oral soft tissues related to orthodontic treatment: A case series

The present case series demonstrates the efficacy of an 810 nm diode laser for the surgical management of oral soft tissues related to orthodontic treatment. Three orthodontic patients aged 16-23 years underwent operculectomy, ablation of soft-tissue overgrowth over orthodontic appliance and gingivectomy along with gingival recontouring procedures, respectively, using the 810 nm diode laser. In each case, an initiated laser fibre tip was utilised to ablate the tissue at the treatment site by making a light contact with the tissue (average power output = 1-1.6 W, continuous wave emission mode, fibre diameter = 400 µm, spot size = 0.0013 cm², energy density = 124.9-199.9 J/cm², irradiance = 796-1273 W/cm², total energy dose = 300-480 J). The maximum total length of treatment was 300 s (5 min). None of the patients reported any instantaneous or delayed postoperative complications over six months. Utilisation of the 810 nm diode laser for surgical management of oral soft tissues related to orthodontic treatments can be considered safe, effective and justifiable over the conventional scalpel technique; however, it must be performed by trained and experienced clinicians only.

Increasing dental zirconia micro-retentive aspect through ultra-short pulsed laser microstructuring: study on flexural strength and crystal phase characterization

Objectives

Although ultra-short pulsed laser (USPL) microstructuring has previously improved zirconia bond-strength, it is yet unclear how different laser-machined surface microstructures and patterns may influence the material’s mechanical properties. Therefore, the aim of this study was to assess the flexural strength of zirconia after different USPL settings creating three different geometrical patterns with structures in micrometer scale.

Methods

One hundred sixty zirconia bars (3Y-TZP, 21 × 4 × 2.1 mm) were prepared and randomly divided into five groups (n = 32): no surface treatment (negative control-NC); sandblasting with Al₂O₃ (SB); and three laser groups irradiated with USPL (Nd:YVO₄/1064 nm/2-34 J/cm²/12 ps): crossed-lines (LC), random-hatching (LR), and parallel-waves (LW). Bars were subjected to a four-point flexural test (1 mm/min) and crystal phase content changes were identified by X-ray diffraction. Surface roughness and topography were analyzed through 3D-laser-profilometry and SEM. Data were analyzed with parametric tests for roughness and Weibull for flexural strength (α = 5%).

Results

LR (Mean[95%CI]: 852.0 MPa, [809.2–894.7]) was the only group that did not show a significantly different flexural strength than NC (819.8 MPa, [796.6–842.9]), (p > 0.05). All laser groups exhibited higher Weibull moduli than NC and SB, indicating higher reliability and homogeneity of the strength data. An increase of monoclinic phase peak was only observed for SB.

Conclusion

In conclusion, USPL created predictable, homogeneous, highly reproducible, and accurate surface microstructures on zirconia ceramic. The laser-settings of random-hatching (12 ps pulses) increased 3Y-TZP average surface roughness similarly to SB, while not causing deleterious crystal phase transformation or loss of flexural strength of the material. Furthermore, it has increased the Weibull modulus and consequently material’s reliability.

Clinical significance

Picosecond laser microstructuring (LR conditions) of 3Y-TZP ceramic does not decrease its flexural strength, while increasing materials realiability and creating highly reproducible and accurate microstructures. These features may be of interest both for improving clinical survival of zirconia restorations as well as enhancing longevity of zirconia implants.

Optical inactivation of a proprioceptor in an insect by non-genetic tools

BACKGROUND

The specific role of sensory organs in locomotor pattern generation is traditionally investigated by means of mechanical ablation in arthropods that currently do not allow genetic manipulation. Mechanical ablation is irreversible, and may lead to injury discharges and changes in the structural integrity of the cuticle.

NEW METHOD

Here, we present a new method to temporarily or permanently deprive parts of an insect nervous system of sensory feedback from leg proprioceptors by means of blue light application. We illuminated campaniform sensilla (CS) with a blue LED (420-480 nm) or a 473 nm laser at different light intensities to optically eliminate sensory and motor neuron responses to mechanical stimulation.

RESULTS

We were able to eliminate all stimulus-evoked responses of CS. Individual CS groups were precisely and selectively inactivated without affecting nearby proprioceptors, using an optical fiber (Ø 200 µm) to guide the light. Our results demonstrated that lower light intensities significantly increase the required exposure time, but also the chance for recovery, thus making the effect reversible.

COMPARISON WITH EXISTING METHODS

In contrast to mechanical ablation, optical inactivation of individual sensory organs is non-invasive and does not affect the behavioral state of the animal, nor does it induce escape behavior. This is especially relevant in non-model system experimental animals where optogenetic manipulation cannot be used, due to a lack of established methods of access.

CONCLUSION

Our results show that the proposed method is a reliable alternative to mechanical ablation and can be successfully applied to the CS, as it fulfills all requirements regarding selectivity, efficiency, and reproducibility.

Utilization of 810 nm Diode Laser Treatment in Periodontitis as an Alternative to Surgical Debridement Approach

The efficacy of surgical periodontal may be compromised by inadequate patients' self-performed plaque control or lack of supportive periodontal therapy. This clinical case report aimed to evaluate the effectiveness of 810 nm diode laser-assisted full-mouth sulcular debridement, as a potential treatment modality in the management of chronic periodontitis along with a 12-month follow-up evaluation. Each periodontal pocket was lased within 2 mm of deepest point, using a light contact of "hot tip" of the fiber with tissue [Average power-1W, emission mode-continuous wave, in "contact", beam diameter-400 µm, spot area at tissue-0.0013 cm² , fluence-124.9 J cm^-2 , power density-796 W cm^-2 , total energy-300 J, total treatment duration-300 s (5 min)]. The patient was followed up to 12 months and did not report any immediate or delayed complications such as any sign of photothermal damage, pain, tissue swelling and deformation, bleeding and infection. 810 nm diode laser-assisted sulcular debridement at low-power settings showed overall clinical and radiographic improvements and can be deemed as a potential alternative to surgical debridement approach, in persistent moderate periodontal pockets (4-6 mm).

The use of Thulium-Doped Fiber Laser (TDFL) 1940 nm as an energy device in liver parenchyma resection, a-pilot-study in Indonesia

Introduction

Several modalities are used to improve the outcome of liver resection surgery. Laser-based surgery may become promising option; therefore we aim to report our experience regarding the efficacy and safety of Thulium-Doped Fiber Laser (TDFL) 1940 nm in liver parenchyma resection.

Methods

A cross sectional study in which patients with pre-existing liver pathology during July 2019 and July 2020 were randomly assigned to receive liver resection using TDFL integrated with raman laser emitting at 1940 nm and 1470 nm wavelength. Data on estimated blood loss during liver transection, liver transection speed, morbidity rate, and postoperative variables including complications, length of hospital stay (days), and mortality were analyzed.

Results

A total of 17 consecutive liver resections were performed, among them are 7 major and 11 minor hepatectomies. The Multipulse TM+1470 were used on 8 procedures consisted of 1 major and 7 minor hepatectomies, the mean amount of blood loss during operation and liver transection was 628.13 ± 141.31 mL and 294.63 ± 94.81 ml, respectively. The mean liver transection speed was 1.52 ± 0.27 cm²/min. No biliary leak, post-hepatectomy-liver failure, and mortality were reported.

Conclusion

TDFL provided by Multipulse TM+1470 is an effective and safe tool for liver surgery, providing good hemostasis and allowing for safe and effective exposure of vascular. Further study with larger samples might be needed proved the efficacy and safety of TDFL in liver surgery.

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Despite promising laser device features, the usage in liver surgery is still rare.

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TDFL provides precision transection and good hemostasis.

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Low intraoperative blood loss is observed in TDFL liver surgery.

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No bile leak and post hepatectomy liver failure was observed after TDFL surgery.

Antimicrobial Capacity and Surface Alterations Using Photodynamic Therapy and Light Activated Disinfection on Polymer-Infiltrated Ceramic Material Contaminated with Periodontal Bacteria

This study determined the antimicrobial efficiency of light-activated disinfection (LAD) and photodynamic therapy (PDT) on polymer-infiltrated ceramic network (PICN) material contaminated with three periodontal bacteria and explored if PDT and LAD cause PICN surface alterations. Sixty PICN discs were contaminated with Tannerella forsythia, Porphyromonas gingivalis, and Treponema denticola and randomly divided into five groups (n = 12 samples/each) according to the treatment groups: Group PDT-PDT (630 ± 10 nm diode laser) with methylene blue; Group DL-808 nm diode laser in contact mode without photosensitizer; Group MB-methylene blue without light application; Group CHX-0.12% chlorhexidine digluconate solution and; Group NT-no treatment. Each disc was then placed in tubes containing phosphate buffered saline (PBS) and vortexed for 30 s to remove the remaining bacteria from the discs. A total of 10× serial dilutions were performed followed by plating of 30 μL of suspension on Brucella agar plates. The colony forming units (CFU) were calculated after 72 h. PICN discs with the attached biofilms were used for confocal microscopy investigation for live/dead bacterial viability. A random single sample from each group was selected to study the bacterial adherence and topographical alterations on PICN discs under scanning electron microscope (SEM). The PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group (p < 0.05). When compared with MB group, the two laser groups were significantly superior (p < 0.05). The MB group did not show significant differences for any bacteria when compared to NT. The bacteria with the CHX group and DL groups appeared dead with few areas of surviving green stained bacteria. The PDT group showed the highest dead cell count (p < 0.05). PDT and DL groups indicate no significant changes on the surface compared to the sterile PICN discs on visual assessment. Photodynamic therapy produced superior periodontal bacteria reduction over the surface of PICN surface. PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group. Both PDT and DL treatment strategies are effective without producing surface alterations on PICN.

Efficacy of high-intensity laser therapy on arthropathy of the hands in patients with systemic lupus erythematosus: a double-blinded, randomized controlled trial

OBJECTIVE

To determine the efficacy of high-intensity laser therapy (HILT) on arthropathy of the hands in patients with systemic lupus erythematosus.

DESIGN

A double-blinded randomized, controlled study.

SETTING

Outpatient setting.

PARTICIPANTS

Fifty patients, 30-50-years-old, suffering from arthropathy of the hands were randomly assigned either into the experimental group, received HILT plus the routine physical therapy program or the control group, received sham HILT plus the same routine physical therapy program.

INTERVENTION

All treatment interventions were applied at a frequency of three sessions per week for eight weeks.

OUTCOME MEASURES

Handgrip strength, joints swelling counts, joints tenderness counts, visual analog scale (VAS) were measured before and after eight-weeks of interventions.

RESULTS

There were statistically significant differences in handgrip strength, joint swelling count, joint tenderness count and VAS in favor of the study group (P < 0.05). After eight-weeks of intervention, the mean (SD) for handgrip strength, joint swelling counts, joint tenderness count, and pain score was 28.34 ± 8.3 kg, 4.4 ± 2.18, 5 ± 2.1, and 35.6 ± 13.87 mm in the study group, and 22.96 ± 8.76 kg, 7.36 ± 2.14, 9.08 ± 1.63, and 58.8 ± 10.54 mm in the control group, respectively. The MD (95%CI) for handgrip strength, joint swelling counts, joint tenderness count, and pain score was 5.38(0.53,10.23) kg, -2.96(-4.19, -1.73), -4.08(-5.15, -3.01), and -23.2(-30.2, -16.2) mm between groups, respectively.

CONCLUSIONS

Adding HILT to the routine physical therapy program might be more effective than routine physical therapy program alone in improving handgrip strength, decreasing joint swelling counts, joint tenderness counts, and pain in patients with arthropathy of the hands.

Current Concepts of Laser-Oral Tissue Interaction

Fundamental to the adjunctive use of laser photonic energy for delivering therapy and tissue management, is the ability of the incident energy to be absorbed by target tissues. The aim of this review is to examine the differential performance of the separate components of oral hard and soft tissues when exposed to laser photonic irradiance of variable wavelengths and power values. Through an examination of peer-reviewed published data and materials, the interaction of laser photonic energy and target tissues are explored in detail. Varying laser wavelength emissions relative to anatomical structures explores the ability to optimise laser–tissue interactions, and also identifies possible risk scenarios as they apply to adjacent non-target structures. The concepts and practical aspects of laser photonic energy interactions with target oral tissues are clearly demonstrated. Emphasis was placed on optimising the minimum level of laser power delivery in order to achieve a desired tissue effect, whilst minimising the risk or outcome of collateral tissue damage.

Acute exposure of 532 nm laser differentially regulates skin tissue transcription factors

High energy laser, particularly 532 nm, is widely used in defense and medical applications and there is need to address its occupational safety. Thermal and non-thermal effects of 532 nm high energy laser on skin are cause of concern. This study indicates impact of 532 nm laser on rat skin and first of its kind of attempt to understand transcriptional activation of genes as an early response following laser exposure. Skin of experimental rats were exposed to 532 nm radiance at 0.1, 0.25 and 0.50 W/cm2 for 10 sec. Thermographic changes of skin exposed to 532 nm laser exhibited increased Tmax temperature in radiance dependent manner. After thermal imaging, skin of experimental rats was collected 1 h post laser exposure for studying differential gene expression. The skin exposed to lower power density (0.1 W/cm2) did not show significant changes in expression of gene pathways studied. At moderate radiance (0.25 W/cm2), predominantly canonical wnt/B-catenin pathway genes notch1, axin2, ccdn1, wnt5a and redox homeostasis genes; txn1, nqo1 and txnrd1 were expressed. At higher radiance (0.5 W/cm2), significant repression of genes related to wound healing process particularly notch/wnt pathway viz. hes5, wnt1, wn3b with higher expression of dab2 was recorded. The data obtained from these studies would help in drawing safety limits for skin exposure to 532 nm laser. Further, genes expressed at moderate and high level of radiance exposure to skin were distinct and differential and provide new avenue to configure pathway to counteract laser induced delay in tissue injury and hair follicular damage.

Correlation between light absorbance and skin color using fabricated skin phantoms with different colors

The objective of this study is to investigate the need for detailed classification of skin colors through the quantification of skin color and light absorbance differences. Skin color is one of the most important factors in dermatological laser treatments. Dermatological laser treatments are currently performed based on the experience and judgment of the doctor with the Fitzpatrick scale. However, the Fitzpatrick scale and the doctor's experience were not quantified assessment methods for skin color classification and laser parameters selection. Improper selection of laser irradiating parameters can lead to undesirable tissue effects and treatment outcomes. We analyzed the correlations between absorbance and quantified colors using skin phantoms to identify that using the Fitzpatrick scale in dermatological treatments have limitations. Absorbance differences for different skin colors are measured at 532 nm with a custom-built system for radiant power measurements using skin phantoms fabricated with nine different colors. Some correlations between the color and absorbance agree with the Fitzpatrick scale. Generally, absorbance for the bright colored phantoms is lower than that for the darker colored phantoms. However, some phantoms fabricated with bright colors exceptionally have higher absorbance than those with darker colors. This means that for conventional standards, the Fitzpatrick scale may not always be accurate at 532-nm lights. Through these experiments, we demonstrate the need for a reliable classification standard for skin colors based on quantification of the skin colors and absorbance differences for each skin color as an alternative to the Fitzpatrick scale, which has limitations at certain wavelengths.

INFLUENCE OF “NOVUMEDICAL” EQUIPMENT ON NON-SPECIFIC RESISTANCE OF THE ORGANISM TAKING INTO ACCOUNT ADAPTATION REACTIONS

Studies have shown the effectiveness and perspective of using «NovuMedical» devices for the purpose of primary and secondary prevention of diseases, increasing the personal interest of patients in extending the period of active longevity due to regular recovery at home. The preventive effect of the equipment is not directed against the symptoms of the disease, but to increase the body's resistance. Before treatment, the normal type of adaptive response was detected in 75 % of patients, the workout reaction was noted in 45.4 %, the calm activation reaction – 23.2 %, the reaction of increased activation in 6.2 % of cases, and the stress response was recorded in 25.2 %. After the treatment, the workout reaction was detected in 44.1 % of cases, the calm activation reaction – 22.2 %, the increased activation zone – 33.3 %. The preformed factors used in the apparatuses are a bioregulator in the broad sense of modulating the physiological functions of the body, which makes it possible to “rejuvenate” the sick organism, at least to equalize the biological and passport age, to restore the original potential of sanogenetic reactions. Apparatus for home use can be the basis for the primary population prevention and secondary individual prevention of a wide range of diseases and premature aging.

Non-Ionizing Radiation in Swedish Health Care-Exposure and Safety Aspects

The main aim of the study was to identify and describe methods using non-ionizing radiation (NIR) such as electromagnetic fields (EMF) and optical radiation in Swedish health care. By examining anticipated exposure levels and by identifying possible health hazards we also aimed to recognize knowledge gaps in the field. NIR is mainly used in health care for diagnosis and therapy. Three applications were identified where acute effects cannot be ruled out: magnetic resonance imaging (MRI), transcranial magnetic stimulation (TMS) and electrosurgery. When using optical radiation, such as class 3 and 4 lasers for therapy or surgical procedures and ultra-violet light for therapy, acute effects such as unintentional burns, photo reactions, erythema and effects on the eyes need to be avoided. There is a need for more knowledge regarding long-term effects of MRI as well as on the combination of different NIR exposures. Based on literature and after consulting staff we conclude that the health care professionals' knowledge about the risks and safety measures should be improved and that there is a need for clear, evidence-based information from reliable sources, and it should be obvious to the user which source to address.

Changes in local skin temperature after the application of a pulsed Nd:YAG laser to healthy subjects: a prospective crossover controlled trial

Pulsed Nd:YAG laser (1064 nm) is a recent modality that is used for the rehabilitation of musculoskeletal disorders, but there is no evidence about its thermal effects. The aim of the study was to investigate the changes in local skin temperature (LST) after the application of a pulsed Nd:YAG laser to healthy subjects. The study participants were 30 male subjects with an average age of 21.96 (± 0.92) years. A rectangular area (15 × 10 cm²) was marked at the front of the dominant thigh and scanned with a laser beam at 3000 J with 20 J/cm² for 15 min. The other thigh was considered as a control side. The minimum, average, and maximum LSTs were measured using a thermographic camera. The measurements were performed before laser application, immediately after, and then every minute until the LST returned to the pre-treatment value. An independent t test and repeated measures ANOVA were used to analyze the changes in LST. The level of significance was set at p < 0.05. The pulsed Nd:YAG laser significantly increased the minimum, average, and maximum LSTs in comparison with the control. The increase was significant for up to 5 min after the application, and it took 10 min to reach the baseline values. The level of increase was 1.23-4.03 °C, and the average increase was 2.6 °C. The pulsed Nd:YAG laser significantly increased the minimum, average, and maximum LSTs of the thigh area in normal subjects, and the thermal effect lasted for 5 min after application.

Treatment of Lower Limbs Telangiectasias with Nd: Yag Laser-Prospective Study on 446 Patients

In the last two decades Nd: YAG laser has become a standard of treatment of telangiectasias of the lower limbs in C₁EAP stage of chronic venous insufficiency. This paper shows the results of a two years study period of telangiectasias of lower limbs with Nd: YAG laser conducted in a specialised centre in this type of procedures. The study group consisted of 446 patients (21 males and 425 females) with telangiectasias (C₁EAP) on the lower limbs between January 2016-December 2017. The patients had to complete a form in which they noted the initial state on a scale from 1 to 10 but also the result of the treatment and the intensity of the pain during the laser treatment. Moreover, the doctor also evaluated the results of the treatment for each and every patient taking also into account the initial phase of the disease. We observed a significant improvement of the clinical appearance (the reduction of telangiectasias) almost in the entire study group, regardless of the gender and the age, but the intensity of the pain was higher in men and in persons under the age of 30. Based on these data we can conclude that Nd: YAG laser represents a minimally invasive therapeutic option with minor side effects and major aesthetic results and furthermore it can be combined with several other methods (microsclerotherapy, radiofrequency, complex surgery) in order to improve peripheral chronic venous insufficiency.

Laser Catheter Modulation of the Sinus Node in the Treatment of Inappropriate Sinus Tachycardia: Experimental and Clinical Results

Inappropriate sinus tachycardia (IST) is a rare type of arrhythmia that is currently difficult to treat successfully. The effects of laser catheter applications aimed at the sinus nodal area were tested experimentally and the technique was used for the treatment of IST. Continuous-wave, mapping-guided 1,064 nm neodymium-doped yttrium aluminum garnet laser applications at 15 W (9.5 W/mm²) per 15 seconds (142.5 J/mm²) and an irrigation flow of 30 mL/min were aimed at the sinus nodal area in five dogs (three applications each) and one human patient (two applications) by use of an 8-French open-irrigated electrode-laser mapping and ablation (ELMA) catheter provided with three miniature pin electrodes (0.5 mm × 4.0 mm) with interelectrode distances of 2.0 mm arranged symmetrically and radially around the endhole of the catheter tip. Laser application was aimed at the largest and earliest atrial potentials recorded in the focused local electrograms 30 ms to 45 ms prior to the onset of the P-wave in the surface lead electrocardiogram. Lesions were evaluated morphometrically. Holter monitoring in the patient was performed prior to and after treatment. During laser application in the dogs, sinus nodal potential amplitudes dwindled gradually from a mean of 42 mm ± 24 mm to 5.0 mm ± 3.0 mm and sinus cycle lengths lengthened from 452 ms ± 35 ms to 634 ms ± 35 ms (p < 0.0001 for both). In the patient, electrical potential amplitudes in the local electrograms dwindled from 41.0 mm to 5.0 mm and, in the Holter monitor, heart rate decreased from 109 bpm ± 29 bpm to 79 bpm ± 26 bpm (p < 0.0001). IST ablation was painless and without complications. During a follow-up of 4.9 years, the patient was asymptomatic and her heart rate and chronotropic competence remained normal. In conclusion, ablation of IST was achieved by substrate mapping-guided laser application while using the open-irrigated EMLA catheter RytmoLas (LasCor GmbH – Laser Medical Devices, Taufkirchen, Germany). However, this is a proof-of-concept study and further research, preferably in the form of multicenter study trials, is needed for confirmation of the results.

Comparison of high-intensity laser therapy and combination of transcutaneous nerve stimulation and ultrasound treatment in patients with chronic lumbar radiculopathy: A randomized single-blind study

Objective:

To compare the effects of high-intensity laser therapy (HILT) and a combination of transcutaneous nerve stimulation (TENS) with ultrasound (US) therapy on pain and functionality in patients with chronic lumbar radiculopathy.

Methods:

This prospective randomized comparative study was conducted in Department of physical medicine and rehabilitation, Turgut Ozal Medicine Center, Malatya, Turkey from April 2016 to September 2016. A total of 54 patients with chronic lumbar radiculopathy were enrolled in this study. The patients were randomly divided into two groups: Group 1 (n:27) received 10 sessions of a combination of hot pack, TENS, US and exercise, and Group 2 (n:27) received hot pack, HILT and exercise. The outcomes measured were low back with unilateral leg pain level measured by visual analog scale (VAS) and functionality measured with the Oswestry Disability Index (ODI) at the end of the therapy and four weeks later. p-value less than 0.05 considered statistically significant.

Results:

In two groups, VAS (low back with unilateral leg pain) and ODI scores showed significant changes. At the end of the 2 weeks intervention, participants in Group-1 showed a significantly greater decrease in pain than participants in Group-2. Statistically significant differences in pain variation and functionality (VAS and ODI) were observed four weeks after treatment sessions for participants in the TENS+US therapy group compared with participants in the HILT group.

Conclusion:

HILT and TENS+US combined with exercise were effective treatment modalities in decreasing the VAS and ODI scores. TENS+US combined with exercises were more effective than HILT combined with exercise.

Safety and Efficacy of En Bloc Transurethral Resection With 1.9 µm Vela Laser for Treatment of Non-Muscle-invasive Bladder Cancer

OBJECTIVES

To evaluate the safety and efficacy of 1.9 µm Vela laser in treatment of primary non-muscle-invasive bladder cancer.

METHODS

The data of the patients with non-muscle-invasive bladder cancer treated by either en bloc transurethral resection with 1.9 µm Vela laser (n = 26) or conventional transurethral resection of bladder tumor (n = 44) were analyzed retrospectively. The preoperative characteristics and intraoperative complications were compared in the 2 groups.

RESULTS

Patients who were treated by 1.9 µm Vela laser obtained a higher rate of specimens meeting the requirements of pathologic assessment for tumor staging compared with the patients treated by conventional transurethral resection of bladder tumor. No obturator nerve reflex and bladder perforation occurred during surgery in the 1.9 µm Vela laser group. However, 7 patients in the conventional transurethral resection of bladder tumor group encountered obturator nerve reflex, and 3 of them encountered bladder perforation (P <.05). There were no significant differences between the 2 groups in operative duration and transfusion rate. Patients in the 1.9 µm Vela laser group had shorter postoperative continuous bladder irrigation time than that in the conventional transurethral resection of bladder tumor group. There was no significant difference in the overall recurrence rate between the 2 groups during the follow-up periods.

CONCLUSION

En bloc transurethral resection with 1.9 µm Vela laser in the treatment of non-muscle-invasive bladder cancer demonstrates an advantage over conventional transurethral resection of bladder tumor in reducing intraoperative complications, improving the quality of the specimens admitted for pathologic assessment, and shortening the duration of postoperative continuous bladder irrigation.

Laser application in neurosurgery

BACKGROUND

Technological innovations based on light amplification created by stimulated emission of radiation (LASER) have been used extensively in the field of neurosurgery.

METHODS

We reviewed the medical literature to identify current laser-based technological applications for surgical, diagnostic, and therapeutic uses in neurosurgery.

RESULTS

Surgical applications of laser technology reported in the literature include percutaneous laser ablation of brain tissue, the use of surgical lasers in open and endoscopic cranial surgeries, laser-assisted microanastomosis, and photodynamic therapy for brain tumors. Laser systems are also used for intervertebral disk degeneration treatment, therapeutic applications of laser energy for transcranial laser therapy and nerve regeneration, and novel diagnostic laser-based technologies (e.g., laser scanning endomicroscopy and Raman spectroscopy) that are used for interrogation of pathological tissue.

CONCLUSION

Despite controversy over the use of lasers for treatment, the surgical application of lasers for minimally invasive procedures shows promising results and merits further investigation. Laser-based microscopy imaging devices have been developed and miniaturized to be used intraoperatively for rapid pathological diagnosis. The multitude of ways that lasers are used in neurosurgery and in related neuroclinical situations is a testament to the technological advancements and practicality of laser science.

[Erbium laser application for oral surgery in patients with platelet hemostatic disorders]

Hemostatic disorders are typically associated with prolonged bleeding after or during surgical procedures. The aim of the study was to increase the efficiency of oral surgery in these patients using erbium laser. Selected 46 patients receiving oral surgery were randomly divided in 2 groups: 43 patients with thrombocytopenia, trombocytemia and other platelet disorders treated with erbium laser and a control group of 43 patients without concomitant pathology determined for conventional surgical treatment. No postoperative bleeding was seen in group 1. Conventional procedures were associated with significantly more postoperative pain and epithelization took 1-3 days longer. Erbium laser radiation is an up-to-date method which can be successfully used for oral surgery in patients with hemostatic disorders.

The In Vivo Effect of Ytterbium-Doped Fiber Laser on Rat Buccal Mucosa as a Simulation of Its Effect on the Urinary Tract: A Preclinical Histopathological Evaluation

Purpose

The aim of this study was to perform a histological analysis of the effect of a ytterbium-doped fiber (YDF) laser on oral buccal mucosa tissue in vivo to simulate its effect on the mucosa of the lower urinary tract.

Methods

A total of 90 8-week-old Sprague-Dawley rats were anesthetized with urethrane (1.2 g/kg intraperitoneally). A prespecified inner buccal mucosal site was irradiated with a YDF master-oscillator power amplifier (MOPA) system for 60 seconds, with output power settings of 0.5, 1, and 2 W, respectively, in 3 treatment groups. Specimens of irradiated tissue were harvested at 2 hours, 24 hours, 2 weeks, and 4 weeks after irradiation. The tissue specimens were stained with hematoxylin and eosin for histological analysis.

Results

In the group treated with 0.5 W, basal cell elongation and vacuolization were observed at 2 hours and 24 hours after treatment, respectively. No evident injury was observed after 2 or 4 weeks. The group treated with 1 W presented partial basal layer separation, and even complete epidermal ablation, within 2 hours. At 24 hours after laser treatment, new capillaries on an edematous background of fibroblasts and myofibroblasts, as well as profuse infiltration of the neutrophils to the basal layer, were observed. Collagen deposition and reepithelization were observed in specimens taken 2 weeks and 4 weeks after treatment. The group treated with 2 W presented bigger and deeper injuries at 2 hours after irradiation. Meanwhile, subepidermal bullae with full-thickness epidermal necrosis and underlying inflammatory infiltrate were observed 24 hours after treatment. The presence of fibrous connective tissue and collagen deposition were observed 2 weeks and 4 weeks after the treatment.

Conclusions

To our knowledge, this is the first report regarding the effect of a YDF laser on living tissue. Our study demonstrated that the typical histological findings of the tissue reaction to the YDF MOPA apparatus were very similar to those associated with thermal injuries. The extent and degree of tissue damage increased proportionally to the output power.

Optical Imaging of the Breast: Basic Principles and Clinical Applications

OBJECTIVE

The objective of this article is to summarize the physical principles, technology features, and first clinical applications of optical imaging techniques to the breast.

CONCLUSION

Light-breast tissue interaction is expressed as absorption and scattering coefficients, allowing image reconstruction based on endogenous or exogenous contrast. Diffuse optical spectroscopy and imaging, fluorescence molecular tomography, photoacoustic imaging, and multiparametric infrared imaging show potential for clinical application, especially for lesion characterization, estimation of cancer probability, and monitoring the effect of neoadjuvant therapy.

Laser applications in surgery

In modern medicine, lasers are increasingly utilized for treatment of a variety of pathologies as interest in less invasive treatment modalities intensifies. The physics behind lasers allows the same basic principles to be applied to a multitude of tissue types using slight modifications of the system. Multiple laser systems have been studied within each field of medicine. The term "laser" was combined with "surgery," "ablation," "lithotripsy," "cancer treatment," "tumor ablation," "dermatology," "skin rejuvenation," "lipolysis," "cardiology," "atrial fibrillation (AF)," and "epilepsy" during separate searches in the PubMed database. Original articles that studied the application of laser energy for these conditions were reviewed and included. A review of laser therapy is presented. Laser energy can be safely and effectively used for lithotripsy, for the treatment of various types of cancer, for a multitude of cosmetic and reconstructive procedures, and for the ablation of abnormal conductive pathways. For each of these conditions, management with lasers is comparable to, and potentially superior to, management with more traditional methods.

Temperature Distributions of the Lumbar Intervertebral Disc during Laser Annuloplasty : A Cadaveric Study

Objective

Low back pain, caused intervertebral disc degeneration has been treated by thermal annuloplasty procedure, which is a non-surgical treatement. The theoretical backgrounds of the annuloplasty are thermal destruct of nociceptor and denaturization of collagen fiber to induce contraction, to shrink annulus and thus enhancing stability. This study is about temperature and its distribution during thermal annuloplasty using 1414 nm Nd : YAG laser.

Methods

Thermal annuloplasty was performed on fresh human cadaveric lumbar spine with 20 intact intervertebral discs in a 37℃ circulating water bath using newly developed 1414 nm Nd : YAG laser. Five thermocouples were attached to different locations on the disc, and at the same time, temperature during annuloplasty was measured and analyzed.

Results

Thermal probe's temperature was higher in locations closer to laser fiber tip and on lateral locations, rather than the in depth locations. In accordance with the laser fiber tip and the depth, temperatures above 45.0℃ was measured in 3.0 mm depth which trigger nociceptive ablation in 16 levels (80%), in accordance with the laser fiber end tip and laterality, every measurement had above 45.0℃, and also was measured temperature over 60.0℃, which can trigger collagen denaturation at 16 levels (80%).

Conclusion

When thermal annuloplasty is needed in a selective lesion, annuloplasty using a 1414 nm Nd : YAG laser can be one of the treatment options.

Technology of Lasers and Their Applications in Oral Surgery: Literature Review

The word “Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation”. Recent advances in laser technology have brought a kind of revolution in dentistry. The purpose of this article is to provide an overview of clinical application of lasers in oral medicine and especially in oral surgery, including their advantages, disadvantages and safety.

Fiber-integrated concept to electrically tune pulsed fiber lasers based on step-chirped fiber Bragg grating arrays

We present a novel method to discretely tune the emission wavelength of pulsed fiber-integrated lasers. As spectral filter, a step-chirped fiber Bragg grating (FBG) array is employed combining a monolithic structure with an unrivaled design freedom enabling large tuning bandwidths as well as tailored spectral characteristics towards fingerprint tuning features. Together with an electrical control mechanism ensuring programmable operation, this tuning method promotes fiber-integrated lasers to access new fields of applications e.g. in biophotonics and distributed sensing. The potential of this tuning concept is investigated based on an Ytterbium-doped fiber laser. The system shows superb emission properties including excellent wavelength stability, high spectral signal contrast (up to 50dB) and narrow linewidth (15GHz) as well as adjustable pulse durations in the nanosecond range with peak powers up to 100W. Additionally, the unique spectral potential of this method is demonstrated by realizing filter designs enabling e.g. a record tuning range of 74nm for fiber-integrated lasers.

Performance analysis of the beam shaping method on optical auditory neural stimulation in vivo

Previous research has shown that infrared neural stimulation (INS) could be an alternative approach to evoke auditory neural activities. The laser beam property of the fiber output is a considerable aspect of INS, and the corresponding effects on auditory responses in vivo deserve further discussions. The paper presents a beam-shaped infrared laser stimulation method of auditory nerves. Pulsed 980-nm fiber-coupled laser systems were used as the radiant sources. The gradient reflective index (GRIN) lens was added at the port of the optical fiber as a beam shaping structure. The laser spot sizes and properties between the beam-shaped output and the bare fiber output were preliminarily analyzed by a laser beam profiler. And further experiments in vivo with four deafened adult guinea pigs were conducted. Optically evoked auditory brainstem responses (OABRs) of the animal samples were recorded and compared under the two output configurations. The results show a decrease of the beam divergence compared to a bare output fiber, and the INS with a beam shaping design evokes above 13 % increase on OABR amplitudes than the bare fiber output, especially when enlarging the distance between the optical fiber and the nerve tissue. The beam shaping design can enhance the effect of INS for evoking auditory nerves, and it could be an optimized design in the future implementation of optical cochlear implants.

Short-term effects of high-intensity laser therapy on frozen shoulder: A prospective randomized control study

BACKGROUND

Frozen shoulder, which is characterized by shoulder pain and limitation of the range of motion (ROM), is a common disorder. High-intensity laser therapy (HILT) was recently introduced in the musculoskeletal therapeutic field.

OBJECTIVE

The objective of this study is to evaluate the clinical efficacy of HILT in patients with frozen shoulder.

DESIGN

A prospective randomized controlled study.

METHOD

Patients with frozen shoulder were randomly divided into 2 groups: a HILT group (n = 33) and a placebo group (n = 33). The treatment was administered 3 times per week on alternate days for 3 weeks. For all patients, the visual analog scale (VAS) for pain, VAS for satisfaction, and passive ROM were measured at baseline and 3, 8, and 12 weeks after the treatment.

RESULTS

The HILT group had a lower pain VAS score at 3 weeks (3.2 ± 1.7 vs. 4.3 ± 2.2, p = 0.033) and 8 weeks (2.2 ± 2.0 vs. 3.4 ± 2.7, p = 0.042), however, no statistically significant difference in the pain VAS was observed between the two groups at the final follow-up (12 weeks). No statistical difference in the ROM and the satisfaction VAS was observed between the 2 groups at serial follow-ups.

CONCLUSIONS

In management of frozen shoulder, HILT provided significant pain relief at 3 and 8 weeks, but not at the final follow-up time point. HILT is a noninvasive adjuvant treatment that can reduce pain in frozen shoulders. Further study is needed in order to optimize the dose and duration of HILT.

Open-irrigated laser catheter ablation: influence of catheter-tissue contact force on lesion formation

PURPOSE

Catheter-tissue contact force (CF) is a major determinant for radiofrequency (RF) ablation lesion size and quality. We sought to test the influence of catheter CF on lesion formation by using an open-irrigated electrode-laser mapping and ablation (ELMA) catheter.

METHODS

With the ELMA catheter in a stable vertical position, continuous wave 1064 nm laser impacts at 15 W (9.5 W/mm(2)), 30 s (285 J/mm(2)), irrigation flow 30 mL/min, were aimed at the endocardial surface of bovine myocardium in heparinized stagnant blood (ACT >350 s) at room temperature (18 °C). Lesions were produced with CFs of 100 g, 10 g, in contact but without pressure, with the catheter tip 2.0 mm, and 5.0 mm away (n = 10, each). Lesions were evaluated morphometrically and were compared by the unpaired t tests.

RESULTS

There were no significant differences between volumes of lesions achieved with catheter-tissue CF of 100 g, 10 g, and in contact without pressure: 297 ± 56.0 vs. 300 ± 39 vs. 320 ± 24, respectively (p > 0.05). However, volumes of lesions produced at a distance of 2 mm (95 ± 14 mm(3)) were significantly smaller (p < 0.0001), whereas at a distance of 5.0 mm, no lesions were produced. No steam-pop with crater or thrombus formation occurred.

CONCLUSIONS

By using an open-irrigated ELMA catheter, catheter-tissue CF is not a determinant for laser ablation lesion size and quality. Maximum sizes of lesions can be achieved with the catheter in intimate endocardial contact without pressure. However, lesions can be produced also at a catheter-tissue distance of 2.0 mm. Noticeably, there is no thrombus formation during laser application with the free floating ELMA catheter in the stagnant blood.

Biophotonic effect of diode laser irradiance on tensile strength of diabetic rats

Low-energy laser irradiance at certain wavelengths is able to stimulate the tissue bio-reaction and enhance the healing process. Collagen deposition is one of the important aspects in healing process because it can increase the strength of the skin. This study was designed to examine the biophotonic effect of irradiance on collagen production of diabetic wound in rat model. The tensile strength of skin was employed as a parameter to describe the wound. Diabetic rat models were induced by streptozotocin via intravenous injection. Skin-breaking strength was measured using an Instron tensile test machine. The experimental animals were treated with 808-nm diode laser at two different powers-0.1 and 0.5 W/cm(2)-and 30, 60, and 120 s for each session. The tensile strength was optimized after treated with high-power diode laser. The photostimulation effect was revealed by accelerated healing process and enhanced tensile strength of wound. Laser photostimulation on tensile strength in diabetic wound suggests that such therapy facilitates collagen production in diabetic wound healing.

Mechanism study of laser cochleostomy-induced early hearing loss in a rat model

Hearing loss following laser-assisted ear surgery has been reported. However, the mechanism responsible for the hearing loss remains largely speculative. The aim of this study was to investigate the correlation between laser-induced hearing loss and changes in the number of hair cell ribbon synapses and ultrastructure in the cochlea. Laser cochleostomy was performed with a superpulsed carbon dioxide (CO2) laser at 2 and 5 W in Sprague-Dawley rats. Auditory brainstem responses (ABRs) were measured preoperatively and 2 days after surgery. The synapse numbers in apical and middle cochlear turns were quantified. Transmission electron microscopy was employed to further examine the subcellular changes in the cochlea. Click and tonal ABR threshold shifts in both 2 and 5-W groups displayed a frequency-dependent loss within the frequency range measured. Laser cochleostomy induced a significant decrease of synapse numbers in the middle turn in both groups (p < 0.05). Electron microscopy data indicated varying degrees of auditory nerve degeneration in both groups. Auditory nerve degeneration might contribute to laser-caused hearing loss even under low-energy laser cochleostomy. The high-energy laser-induced hearing loss was associated with more reduction of synapse number.

Influence of irrigation on incision and coagulation of 2.0-μm continuous-wave laser: an ex vivo study

BACKGROUND

Several lasers are suitable for laparoscopic surgery but with remarkable smoke formation, which compromises surgical visibility and safety. Slow irrigation eliminates laser smoke efficiently, but gives rise to the concern of reducing the laser incision and coagulation efficiency.

METHODS

Canine kidney specimens were manually cut with a 2-μm continuous-wave Thulium-YAG laser. Two laser powers (20 and 40 W) combined with 3 irrigation rates (0, 20, and 80 mL/min) were experimented. The depth of the cutting slot and the thickness of the coagulation layer were measured microscopically and compared statistically between different setting combinations using 2-way analysis of variance.

RESULTS

The incision depth was decreased significantly at high (80 mL/min) but not low rate (20 mL/min). The thickness of the coagulation layer changed insignificantly with the irrigation rate.

CONCLUSIONS

Slow irrigation had an acceptable influence on the incision and the coagulation ability of 2.0-μm continuous-wave laser and is suitable and efficient to address the smoke issue in laser laparoscopic surgery.

Análise da eficácia do laser de baixa potência no tratamento da dor tendínea em ratos imunossuprimidos

O comprometimento do sistema imune, que pode ser apresentado por indivíduos com doenças crônicas, leva à baixa resposta imunológica. Um dos tratamentos utilizados para lesões agudas em tendões é o laser de baixa potência, contudo há uma lacuna em relação ao seu uso em imunodepressão. O objetivo do presente estudo foi analisar se o laser de baixa potência é eficaz para o tratamento da dor em ratos imunodeprimidos submetidos a trauma tendíneo. Foram utilizados 23 ratos, machos, da linhagem Wistar, divididos aleatoriamente em três grupos: grupo controle, placebo e laser. Os animais foram imunodeprimidos (por administração de Ciclosporina A) e submetidos à lesão no tendão calcâneo direito, com impacto de cerca de 0,40 J. Para o tratamento, utilizou-se laser de baixa potência, 670 nm, 30 mW e dose de 2 J/cm², durante 3 dias. A avaliação da dor foi realizada pelo teste de incapacidade funcional e por filamento de Von Frey digital. Os resultados apresentaram valores significativos para o grupo laser, com diminuição de dor funcional e da dor à pressão na superfície plantar e no local lesionado (tendão calcâneo direito). Portanto, concluiu-se que o laser de baixa potência é eficaz para reduzir a dor em ratos imunodeprimidos submetidos a trauma tendíneo.

Percutaneous treatment of intervertebral disc herniation

Interventional radiology plays a major role in the management of symptomatic intervertebral disc herniations. In the absence of significant pain relief with conservative treatment including oral pain killers and anti-inflammatory drugs, selective image-guided periradicular infiltrations are generally indicated. The precise control of needle positioning allows optimal distribution of steroids along the painful nerve root. After 6 weeks of failure of conservative treatment including periradicular infiltration, treatment aiming to decompress or remove the herniation is considered. Conventional open surgery offers suboptimal results and is associated with significant morbidity. To achieve minimally invasive discal decompression, different percutaneous techniques have been developed. Their principle is to remove a small volume of nucleus, which results in an important reduction of intradiscal pressure and subsequently reduction of pressure inside the disc herniation. However, only contained disc herniations determined by computed tomography or magnetic resonance are indicated for these techniques. Thermal techniques such as radiofrequency or laser nucleotomy seem to be more effective than purely mechanical nucleotomy; indeed, they achieve discal decompression but also thermal destruction of intradiscal nociceptors, which may play a major role in the physiopathology of discal pain. The techniques of image-guided spinal periradicular infiltration and percutaneous nucleotomy with laser and radiofrequency are presented with emphasis on their best indications.