Modeling of an Innovative Nitrogen-Free Cryotherapy Device

Partial body cryotherapy cabins most often use liquid nitrogen as their cryogenic fluid, which raises safety concerns during operation. In this study, an innovative cryotherapy cabin design is presented, featuring an electric cooling system suitable for producing cold air at −30 °C. The geometry of the designed cryotherapy cabin is evaluated by a thermodynamic modeling which aims at optimizing the circulation of cold air flows inside the cabin. The numerical study is carried out in two successive phases, the first one being necessary to model the pre-cooling phase and to estimate the time required to reach an average temperature close to the set temperature of −30 °C. The second one aims at modeling a 3-min cryotherapy session by taking into account the thermal transfers between the human body and its environment. Results demonstrate the potential benefits of the cold air injection device which has been designed to optimize the thermal transfers and homogenize the temperatures within the therapeutic enclosure. The main innovation of this study is the ability to customize cryotherapy protocols by injecting cold air at different levels through targeting of specific body areas. Further calculations would be required to determine the precise impact of zone-targeted injection on skin cooling.

Pre-calculated relevant Nd: YAG laser parameters for optimized varicose veins treatment

Full clearance of enlarged veins, without side effects, had always been the ultimate dream of patients. Varicose veins’ treatment protocols were not very decisive and mostly associated with some side effects. The aim of this work is to demystify the exact dose of laser parameters; namely fluence and pulse duration, to successfully treat enlarged blood vessels in face, legs and arms without side effects. This necessitated the calculation of exact temperature rise of the targeted tissue before laser irradiation. The pre-calculated laser parameters required, for successful treatment, without side effects were tested to achieve optimum clinical results; using 1064nm pulsed Nd: YAG lasers for all skin photo types. For this work, two values of spot size (5mm and 3mm), variable pulse duration (15-30 ms), variable fluences (110-190 J/cm2) and variable skin cooling temperature (3-18 °C) were used. Pre and post-cooling were found necessary to ensure positive results and minimal discomfort.

The Efficacy of Skin Cooling for Pain Relief during Intralesional Steroid Injection for Keloid Treatment: A Randomized Cross-Over Study

Objective: To evaluate if pre-treatment skin cooling can reduce the pain during steroid injection. Materials and Methods: A randomized cross-over study was conducted between September 2015 and October 2016. This study received ethical approval ID035904 No. MURA2016/152. Forty-four subjects with keloid that needed intralesional steroid injection were divided into three pretreatment groups, no treatment, skin cooling with ice pack, and skin applying with a mixture of lidocaine 2.5% and prilocaine 2.5% (EMLA®), in random order. Pain intensity was measured by using 100-mm visual analogue scale (VAS). The satisfaction levels were assessed with orderly interval rating scale from 1 to 5. Repeated-measure analysis of variance (ANOVA) and Bonferroni pairwise comparison were used for data analyses. Results: The mean VAS score at the time of needle puncturing into the skin and during steroid infiltration was statistically significant lower in skin cooling compared to no treatment group (p<0.001) and EMLA group (p<0.05). The satisfaction level was also statistically significant higher in skin cooling compared to no treatment group (p<0.001) and EMLA group (p<0.001). Thirty-seven patients (84%) selected skin cooling method as the most favorable pre-anesthetic method for intralesional steroid injection. Conclusion: Skin cooling with ice before intralesional steroid injection of keloid effectively reduces pain and patients are also satisfied. Keyword: Keloid, Corticosteroid, Pre-treatment, pain, skin cooling

Perception of Thermal Comfort during Skin Cooling and Heating

Due to the static and dynamic activity of the skin temperature sensors, the cutaneous thermal afferent information is dependent on the rate and direction of the temperature change, which would suggest different perceptions of temperature and of thermal comfort during skin heating and cooling. This hypothesis was tested in the present study. Subjects (N = 12; 6 females and 6 males) donned a water-perfused suit (WPS) in which the temperature was varied in a saw-tooth manner in the range from 27 to 42 °C. The rate of change of temperature of the water perfusing the suit (TWPS) was 1.2 °C min−1 during both the heating and cooling phases. The trial was repeated thrice, with subjects reporting their perception of the temperature and thermal comfort at each 3 °C change in TWPS. In addition, subjects were instructed to report when they perceived TWPS uncomfortably cool and warm during cooling and heating, respectively. Subjects reproducibly identified the boundaries of their Thermal Comfort Zone (TCZ), defined as the lower (Tlow) and upper (Thigh) temperatures at which subjects reported slight thermal discomfort. During the heating phase, Tlow and Thigh were 30.0 ± 1.5 °C and 35.1 ± 2.9 °C, respectively. During the cooling phase, the boundary temperatures of Tlow and Thigh were 35.4 ± 1.9 °C and 38.7 ± 2.3 °C, respectively. The direction of the change in the cutaneous temperature stimulus affects the boundaries of the TCZ, such that they are higher during cooling and lower during heating. These findings are explained on the basis of the neurophysiology of thermal perception. From an applied perspective, the most important observation of the present study was the strong correlation between the perception of thermal comfort and the behavioral regulation of thermal comfort. Although it is not surprising that the action of regulating thermal comfort is aligned with its perception, this link has not been proven for humans in previous studies. The results therefore provide a sound basis to consider ratings of thermal comfort as reflecting behavioral actions to achieve the sensation of thermal neutrality.

Predictive Ability of Body Fat Percentage and Thigh Anthropometrics on Tissue Cooling during Cold Water Immersion

Context: Cold water immersion (CWI) is a common aid in exercise recovery. CWI effectiveness depends on the magnitude of muscle and core cooling. Individual cooling responses to CWI are variable and likely influenced by CWI dose and individual physiological characteristics. Objective: Evaluate body fat percentage and thigh anthropometrics as predictors of intramuscular and skin cooling responses to CWI. Design: Interrupted time-series. Setting: Sports medicine research center. Participants: Sixteen young adults (8 male, 8 female, age=24.3±1.84 years, height=176.4±12.7 cm, mass=86.6±29.4 kg). Intervention: Body fat percentage was measured using a three site skinfold. Thigh length, thigh circumference, anterior thigh adipose thickness, anterior thigh muscle thickness, and thigh volume were estimated using manual and ultrasound methods. Using sterile techniques, thermocouple probes were approximated in the belly of the rectus femoris (2 cm deep to sub-adipose tissue) and on the anterior mid-thigh surface. Participants cycled on an ergometer for 30 minutes at a target heart rate between 130 and 150 beats per minute. Post-exercise, participants were placed in CWI (immersion depth: iliac crest; 10°C) until intramuscular temperature was 7°C below pre-exercise baseline temperature, with a maximum immersion duration of 30 minutes. Main Outcome Measure(s): Intramuscular rectus femoris and thigh skin temperatures measured post exercise, after 10 and 15 minutes of CWI, and post-CWI. Results: Body fat percentage significantly predicted rectus femoris cooling magnitude and rate after 10 minutes of CWI, 15 minutes of CWI, and post-CWI (p &lt;0.001; R2 = 0.58–0.64). Thigh anthropometrics significantly predicted thigh skin cooling rate post-CWI (p = 0.049; R2 = 0.46). Conclusions: A simple three site skinfold assessment may improve the efficacious prescription of CWI through estimation of the dose required for minimal muscle tissue cooling.

Open Source Skin Cooling System for Focused Ultrasound Applications

The adverse event of skin burns and the restrictions caused by multi-hour treatment times continue to limit the clinical efficacy and cost effectiveness of MRgFUS thermal therapies. This proposal directly addresses these unmet needs with two primary aims. Aim 1 includes design and fabrication of a prototype cooling device, testing of clinically identified design specifications, and initial experimental validation ex vivo tissue experiments. This conformable skin-cooling device will reduce the potential for skin burns in desmoid tumor and other MRgFUS treatments. Aim 2 will assess the skin cooling device on a pre-clinical MRgFUS system with rabbit and pig studies and will integrate the device with the clinical ExAblate 2100 system. The ultimate goal of the device design is to be MRgFUS system independent. This may require a modular design that allows for both clinical and veterinarian applications. The completion of this proposal will deliver the engineering schematic, parts list and use manual of the completed device, validation data and install a single device at the Focused Ultrasound Center of Excellence at Stanford University.Presented here are the open-source parts list and assembly files to reproduce the skin cooling device, along with the device user manual. An open-access publication on the design methods and preclinical results will be published soon.