Cryolipolysis for fat reduction using Cooltech® Define technology: A large‐sample retrospective clinical study

Cryolipolysis is a noninvasive technique for localized fat reduction, which induces selective apoptosis of the adipocytes using controlled exposure to intense cold. During the past 10 years, this technique has been shown to be safe and effective and its application has significantly increased. In this context, Cooltech® devices have been widely used around the world.

3][4] Compared to liposuction, cryolipolysis has few side effects.Common side effects include erythema, edema, and pain in the treatment area, which typically resolve within a few hours or days. 2Rare side effects include paradoxical adipose hyperplasia (PAH), the mechanism of which has not yet been clearly established. 2e first cryolipolysis device was approved by the Food and Drug Administration (FDA) for the treatment of localized fat on the flanks in 2010 and on the abdomen in 2012 (CoolSculpting device, Zeltiq, California). 5,6Since then, the use of cryolipolysis has become widespread in the United States.
Nowadays, several cryolipolysis devices are available worldwide, such as Cooltech® and Cooltech® Define, which are used extensively around the world for body contouring and localized fat reduction.
Cooltech® creates suction in the treated area through a vacuum applicator which surrounds the fatty tissue.During a 70-min session, the temperature in the area is reduced in a defined and controlled manner until it reaches −8°C, this temperature is then maintained until the treatment time is completed.In general, the full cryolipolysis process with Cooltech® includes the following steps: application of a cryoprotector on the treatment area, suction of the localized fat deposit into the applicator, cooling by means of parallel aluminum plates, and finally, a manual massage to promote blood flow to the area and facilitate lymphatic drainage. 7Cooltech® makes use of six different handpieces with varying shapes and cavities designed to fit different body areas and volumes of fat tissue.Clinical and in silico studies have been conducted, which have shown a high correlation between simulated and clinical data. 8,9Indeed, the simulation of the cooling dynamics of cryolipolysis applicators is of significant value to the development of new devices.Regarding the clinical studies conducted with Cooltech®, Fajardo-Urdiales et al. 10 and Vélez-González et al. 11 produced good results in terms of efficacy (fat tissue reduction of up to 19%), safety (no severe side effects), and tolerance by patients.Furthermore, a study by Naranjo et al. 12 showed that the application of Cooltech® combined with biological detergent improved localized adiposity reduction by approximately 25%, as verified through high-power focused ultrasound measurements.
Cooltech® Define is the second-generation cryolipolysis device from the Cooltech® brand.It provides 360° uniform cooling of the treated area.Furthermore, Cooltech® Define includes nine different handpieces to, more optimally, accommodate different areas of the body where localized fat is present.It also provides the option to use four different applicators simultaneously, thereby saving time for both the physician and the patient.Numerical stimulations and clinical evaluations were performed to assess the results of the new applicator design, 13,14 which showed that Cooltech® Define achieves superior results in terms of localized fat reduction (up to 50%) and patient comfort.
While cryolipolysis studies exist in literature, the majority are conducted in the United States or include small and retrospective case series.Therefore, the purposes of this large-sample retrospective clinical study are to improve the statistical value of the results with a cryolipolysis device, include different body areas, and show the results of the technique in Europe.

| MATERIAL S AND ME THODS
This retrospective single-center cohort study has analyzed data collected at Studio Vignoli (Bologna, Italy) between 2019 and 2023.
A total of 287 patients (208 female and 79 male), seeking sessions for localized fat reduction, underwent treatments with the Cooltech® Define system (Sinclair), resulting in a total of 1118 treatments.All patients completed the treatment and attended follow-up visits.All study procedures were conducted according to the Declaration of Helsinki, and all participants signed written consent forms.
The inclusion criteria comprised healthy adults of both sexes with localized subcutaneous fat tissue, while individuals with a BMI higher than 30 or less than 18.5, skin disorders in or near the treatment area, diabetes, Raynaud's disease, essential mixed cryoglobulinemia, visceral hernias, surgical scars in the treatment area, autoimmune pathologies, ongoing systemic diseases, unrealistic expectations, or pregnancy/lactation were excluded.
Prior to the session, patients received comprehensive information about the procedure and the realistic expectation for fat reduction.An expert physician visually and manually assessed the treatment area, selecting the appropriate handpiece.The cryolipolysis procedure was performed by an expert physician following the manufacturer's protocol.
Cryolipolysis sessions were conducted using the Cooltech® Define system, a medical device that employs four 360° contact-cooling applicators for facial and body areas with localized adiposity.The device applies suction to ensure proper skin contact with the cooling cavity and to provide uniform and controlled cooling.Several steps are performed on the treatment area during the cryolipolysis procedure: (1) a suction test without cooling to assess the suitability of the applicators for the target area and to ensure proper contact with the cooling cavity; (2) the application of a cryoprotectant pad (Cool Gel Pad; Sinclair); (3) suction; (4) cooling for 70 min; (5) the end of the treatment and the removal of the applicators and cryoprotectant pad; (6) a posttreatment mechanical massage lasting 2-5 min; and (7)   gradual elimination from the body of lysed adipocytes over a period of 1-3 months.The procedure is depicted in the scheme in Figure 1.
The procedure was applied to various facial and body areas: love handles, flanks, thighs, gluteal sulcus, knees, chest, arms, infrascapular, infrapectoral, abdomen, and ankles.The device features nine different applicators to accommodate each body area, of which Oval, Oval Curved, Curved, Double, Straight, and Tight were used.The device has four connectors to allow up to four simultaneous procedures to be performed on four different areas.
Following the session, subjects were instructed to resume their regular activities and a follow-up session was scheduled.Posttreatment care instructions were given to the patients to inform them about the common side effects such as erythema, edema, bruising, soreness, and temporary sensory changes in the treatment area, such as numbness or itching.The physician recommended analgesic treatment for moderate to intense posttreatment pain.
Skin fold (plicometry) measurements were taken prior to treatment and during follow-up visits.High-resolution baseline and follow-up photographs were captured.Tolerance assessment was performed through patient comments made during the session, immediately afterward, after 12-24 h, and during follow-up visits.
The results were expressed as mean ± standard deviation (SD), and a two-sided paired t-test was used to compare means between the groups.Statistical analysis was conducted using Excel, with a pvalue <0.05 indicating statistical significance.

| RE SULTS
A total number of 287 patients were involved in the study.Among the participants, 72.47% were female (n = 208) and 27.53% were male (n = 79).In total, 1118 treatments were conducted on various  Furthermore, these treatment areas were also analyzed according to the sex of the patient, as can be seen in Figure 4.  Additionally, the analysis of the frequency of use of each applicator per treatment area was conducted and depicted in Figure 6.
The Oval applicator was used primarily for the outer thighs (84.51% of the treatments performed on the outer thigh area), inner thighs (66.06%), flanks (56.68%), and love handles (48.44%).As an alternative, the Curved applicator was also employed on the same body sites and particularly on the gluteal sulcus (58.06%).The Oval

TOTAL TREATMENTS PER APPLICATOR
Curved applicator was principally used in the abdominal region (36.52%).In smaller areas, such as the arms, the Straight (44%), and Tight (56%), handpieces were typically employed.Finally, the Double applicator was used exclusively for the abdominal site (45.05%).
In terms of safety assessment, a small number of patients (n = 19 treatments, frequency of 1.70%) reported pain during or after the treatment.Additionally, there was one case of PAH (n = 1, frequency of 0.09%) observed.In approximately 4.47% of cases (n = 50 treatments), the administration of analgesics was suggested to manage discomfort.
To evaluate the effectiveness of the cryolipolysis procedures, the fold thickness (mm) was measured before the treatment and during follow-up visits, with an average time difference of 69 ± 74 days (Figure 7).

| DISCUSS ION
In recent years, the popularity of noninvasive techniques for localized fat reduction has soared as they offer a nonsurgical alternative to liposuction, which carries the risks commonly associated with surgical procedures.Among the various technologies employed for this purpose, cryolipolysis, radiofrequency, and highintensity focused ultrasound have emerged as prominent choices.
However, cryolipolysis stands out as the leading treatment option for noninvasive fat reduction, boasting remarkable efficacy and a high satisfaction rate. 1 In light of this, the current study sought to evaluate the effectiveness and safety of cryolipolysis treatment using the Cooltech® Define cooling system.To the best of our knowledge, this study represents one of the largest reviews of cryolipolysis patient data in European countries.The findings from this research provide valuable insights into the outcomes of cryolipolysis as a noninvasive fat reduction approach.
The study enrolled a total of 287 patients, comprising 208 females and 79 males.In total, there were 1118 treatments conducted on different body areas, with an average of two sessions per patient.
The Cooltech® Define cooling system was utilized across numerous areas, with the highest proportion of treatments applied to the flanks, accounting for 33.19% of the total, followed by the abdomen at 26.49%.The optimized design of Cooltech® Define, featuring 360° uniform cooling and a variety of handpiece shapes and cavities, was found to be a key factor in achieving such positive outcomes.This design allowed for a good fit of different body areas in the applicator, thereby enhancing the overall efficacy and comfort of the treatment process.Furthermore, the suction test conducted by the operator at the beginning of the procedure played an important role in ensuring the correct choice of handpiece.This step not only contributed to the good results of the treatment, but also helped the physician to perform the procedure correctly, leading to high levels of efficacy and safety.
Comparative analysis, both through mathematical simulations and clinical settings, was previously conducted between Cooltech® and Cooltech® Define devices.These investigations strongly suggested that the enhanced efficacy of Cooltech® Define could be attributed to factors such as its uniform cooling, ability to reach lower temperatures in the subcutaneous tissue during the process, and the optimally designed handpieces, which collectively contribute to superior results for fat reduction. 13,14en it comes to safety, cryolipolysis has a notable advantage over invasive procedures, exhibiting a strong safety profile. 15,16e most common and relatively mild side effects observed were erythema (skin redness), edema (swelling), transient pain, and temporary numbness in the treated area, typically resolving within a few hours or days after the procedure. 15However, it is essential to acknowledge that there have been reports of rare and severe side effects associated with cryolipolysis, one of which is PAH.This phenomenon involves the development of painless, firm, and visibly enlarged tissue in the treated area, occurring months after the cryolipolysis treatment. 16The exact mechanism behind PAH remains unclear, but several hypotheses have been proposed.
One theory suggests that inadequate cooling of adipocytes could lead to subapoptotic injury, triggering subsequent growth in the treated area. 15Another hypothesis revolves around the possibility of a high level of ischemia (restriction of blood flow) in the treated area due to the vacuum setting of the applicator, potentially resulting in hypoxic injury and subsequent adipocyte proliferation. 17rthermore, PAH incidence may be higher in individuals with metabolic disorders and those who maintain unhealthy eating habits after the treatment, such as consuming a hypercaloric diet rich in saturated fats.Additionally, leading a sedentary lifestyle could also contribute to an increased risk of developing PAH. 17[20][21] While PAH is considered a rare occurrence, its potential severity underscores the importance of carefully monitoring patients after cryolipolysis treatments and maintaining vigilance with regard to any unusual developments.
This study included 1118 treatments and revealed a PAH incidence rate of 0.09%, indicating a relatively low occurrence of this rare side effect.This favorable outcome can be attributed to several factors related to both the cryolipolysis procedure and the patient.carefully selecting suitable candidates and anatomical locations for treatment, 22 and matching them with the appropriate handpiece, positive outcomes can be maximized while minimizing adverse events.Moreover, to ensure the safety of surrounding tissue during the cryolipolysis process, a cryoprotectant membrane, the Cool Gel Pad, is employed.This membrane contains glycerol, which serves as a cryopreservative for skin cells, preventing the formation of ice crystals and minimizing the potential for cellular damage. 7e Cooltech® Define device incorporates safety measures to control both temperature and suction levels, minimizing any risk of skin lesions.Throughout the 70-min treatment, the device maintains temperature settings and utilizes vacuum controls to promptly halt the procedure if any potential harm to the patient is detected.Furthermore, the design of the Cooltech® Define handpieces contributes to the overall safety of the treatment.These handpieces are ergonomically configured to ensure proper suction and optimal contact of the skin with the cooling plates.As a result, the lower suction pressure used in the treatment avoids mechanical stress in the treated area, safeguarding blood circulation and enhancing patient comfort.By integrating these safety measures and precautions, this device is shown to provide a reliable and effective solution for cryolipolysis, with a low incidence of adverse events, ultimately contributing to a positive and satisfactory patient experience.
The combined results of this study underscore the favorable efficacy and safety of the noninvasive cryolipolysis procedure.However, it is essential to acknowledge certain limitations that may impact the generalizability of the findings.
One limitation stems from the retrospective and single-center nature of the investigation, which may introduce biases and limit the ability to draw broad conclusions about the treatment's performance across different settings and patient populations.A multicenter

| CON CLUS ION
In conclusion, this large-sample, single-center retrospective study provides compelling evidence supporting the effectiveness, safety, and tolerability of the cryolipolysis method using the Cooltech® Define cooling system for localized fat reduction.The treatment showed significant reductions in fold thickness in the targeted areas, indicating very positive outcomes for patients seeking fat reduction.
Moreover, the study reported a low rate of side effects, highlighting the safety profile of the procedure.Overall, these findings support cryolipolysis with Cooltech® Define as a valuable and reliable noninvasive option for individuals looking to reduce localized fat deposits while minimizing the risk of complications.
body areas, with a maximum of 10 separate cryolipolysis sessions performed on a single subject.The distribution of the number of sessions performed in the study is illustrated in Figure 2. The distribution of the number of sessions among the patients included in the study is as follows: 46.24% underwent only one session (n = 517 treatments), 27.10% had two separate sessions (n = 303 treatments), 11.99% received three sessions (n = 134 treatments), 5.99% underwent four sessions (n = 67 treatments), 3.40% had five sessions (n = 38 treatments), 2.06% received six sessions (n = 23 treatments), 1.25% had seven sessions (n = 14 treatments), 1.07% underwent eight sessions (n = 12 treatments), 0.72% had nine sessions (n = 8 treatments), and finally, 0.18% received 10 different cryolipolysis sessions (n = 2 treatments).Regarding the area of treatment, the flanks underwent the most procedures (n = 371 treatments, 33.18%).Additionally, a total of 296 treatments (26.49%) were conducted on the abdominal areas.The total treatments performed based on anatomic site are shown in

Figure 5 .
Figure5.The most frequently used applicator was the Oval, with

F I G U R E 3
Number of treatment cycles by anatomic site.

4
Treatment sites by patient sex, showing the number of treatments in each anatomic location for females (F) and males (M).

Figures 8 -
Figures 8-13 show examples of the reduction in fold thickness through a series of before-and-after images depicting various patients.These images serve as compelling clinical examples showcasing the efficacy of cryolipolysis.The visual evidence clearly illustrates the transformative effects of the treatment on the targeted areas.

F 7
Difference in fold thickness (mm) before and after cryolipolysis treatment.Data are reported as mean ± SD. 91% ± 12.55% To cater to the specific needs of various body regions, the physician used a range of applicators, taking advantage of their distinct shapes and depths.The Oval and Curved were the most frequently utilized, making up 41.68% and 20.48% of the total treatments, respectively.These findings underscore the versatility and adaptability of the Cooltech® Define device in effectively addressing localized fat reduction across different body areas.The results of the study clearly showed the clinical effectiveness of both the methodology and the Cooltech® Define cooling device.The success of the treatment was evidenced by a very large thickness reduction of 69.91% (−24.64 ± 7.14 mm) over an average follow-up period of 69 days.

First
and foremost, patient selection is critical in preventing potential complications.Experienced dermatologists and physicians play a crucial role in informing patients about the possible side effects of cryolipolysis, setting realistic expectations, and emphasizing the importance of follow-up visits and patient awareness.By F I G U R E 8 Before (left) and after (right) images of abdominal and flank treatments with a fold thickness change of −25 mm in both areas.

F I G U R E 9
Before (left) and after (right) images of abdominal and flank treatments with a fold thickness change of −25 mm and −20 mm, respectively.F I G U R E 1 0 Before (left) and after (right) images of abdominal and flank treatments with a fold thickness change of −8 mm and −30 mm, respectively.F I G U R E 11 Before (left) and after (right) images of flank treatments with a fold thickness change of −20 mm.F I G U R E 1 2 Before (left) and after (right) images of outer thigh treatments with a fold thickness change of −30 mm.F I G U R E 1 3 Before (left) and after (right) images of flank treatments with a fold thickness change of −20 mm (left flank) and −30 mm (right flank).
approach with a larger and more diverse sample would be beneficial for confirming and expanding upon the results obtained in this study.Another limitation lies in the absence of demographic information about the population being studied, including age, ethnicity, and weight.These factors could potentially influence treatment outcomes, and a deeper understanding of their correlation with efficacy and safety outcomes would provide valuable insights for tailoring cryolipolysis treatments to individual patients.Also, it would be advisable to use more than one technique to measure treatment effectiveness with greater precision and less error, such as ultrasound and 3D optical imaging systems.To address these limitations and strengthen the knowledge base surrounding cryolipolysis, future studies should focus on randomized multicenter clinical trials.These trials should be designed to explore the relationships between treatment efficacy, safety, and demographic data to shed light on the frequency and rate of positive results as well as adverse outcomes in relation to patient characteristics.By conducting comprehensive and well-controlled studies, the field can better understand how to optimize cryolipolysis treatments for various patient profiles, ultimately enhancing the overall effectiveness and safety of this noninvasive fat reduction procedure.