Low temperature offers better foam stability

BACKGROUND

The foam's structural longevity, linked to the effectiveness of sclerotherapy, depends on preparation conditions. The factors enhancing the treatment's effectiveness and efficacy are still under discussion.

METHODS

We conducted an in vitro preclinical research, which included 144 independent trials. A total of 8 combinations involving 18 trials were designed according to settings of +4°C and room temperature (20-22°C), liquid-to-air ratios of 1/1 and 1/4, and polidocanol concentrations of 0.5% and 1% using the modified Tessari method. Our study aimed to examine the effect of air ratio, agent temperature, and polidocanol concentration on stability by assessing the foam half-time (FHT) and defining the optimal preparation conditions.

RESULTS

The mean FHT was 117 ± 30.4 s. The longest FHT was in a 1:4 air-to-sclerosant ratio at +4°C, regardless of the sclerosant concentration (for %0.5 mean FHT: 146.2 ± 13.9 s, for % 1 mean FHT: 146.9 ± 18 s). There was a significant interaction among the three variables on FHT (p = 0.001). Temperature emerged as the primary factor (F(1, 136) = 124, p < 0.001, ηp2 = 0.477), with lower temperatures markedly enhancing the longevity (p < 0.001). Preparation at a temperature of 4°C resulted in an extended FHT of 32.5 s compared to 22°C (95% CI: 24.06-41.04 s).

CONCLUSION

The temperature, agent concentration, and gas ratio significantly influence the stability of the physician-compounded foam. The low temperature at +4°C may offer better FHT for sclerotherapy.

Telangiectasia diameter in response to thermal stimulus: experimental data and possible clinical applications

BACKGROUND

Telangiectasias are dilated blood vessels on the skin that develop progressively because of several diseases, including chronic venous disease. The skin blood flow has differences compared to the rest of the circulatory system. These vessels have a permanent vasoconstrictor tone that can respond to vasoconstriction/vasodilation stimulative substances and higher or lower temperatures. The aim of this study was to investigate any possible telangiectasias vasoconstriction or vasodilation in response to temperature changes.

METHODS

This study is a clinical trial with 26 outpatients of vascular surgery with telangiectasias in the lower limbs. We used direct skin digital microscopy to obtain telangiectasias images at room temperature and after the thermal stimulus with cold pads. These photographs were processed using AmScopeAmLite (United Scope LLC Euromex Optics Group b.v., Los Angeles, CA, USA) and the capillary diameter and area were measured in Adobe Illustrator (Adobe Inc., Mountain View, CA, USA). The data collected was analyzed in SPSS Statistics (SPSS Inc., Chicago, IL, USA) with a paired t-test for the telangiectasias area and a Wilcoxon matched-pairs signed-rank test for the telangiectasias diameter.

RESULTS

In comparison to telangiectasias measures at room temperature, we found a statistically significant decrease in the diameter (median of -0.04 mm; interquartile range: -0.10 mm to -0.01 mm; P<0.001) and area (mean of -26.54 mm²; 95% Confidence interval (-36.31, -16.76) mm²; P<0.001 in response to the cold stimulus.

CONCLUSIONS

Telangiectasias respond to cold patch application with a significantly statistical microscale quantifiable vasoconstriction. This intervention has the potential to improve the current state of telangiectasias sclerotherapy due to its mechanism helping to stabilize the applied foam. We speculate that topic cold used as a neoadjuvant treatment could improve the efficiency, stability, and other outcomes of sclerotherapy. Also, complementary use of topical cold stimulus application may be of interest in the therapeutic management of telangiectasias.

Ultrasound-guided foam sclerotherapy is safe and effective in the management of superficial venous insufficiency of the lower extremity

BACKGROUND

Superficial venous disease of the lower extremity has a significant impact on quality of life. Both truncal and tributary vein reflux contribute to this disease process. Endovenous foam sclerotherapy is a widely used technique throughout the world for the management of superficial venous reflux and ultrasound guidance improves its safety and efficacy.

METHODS

A PubMed search for ultrasound-guided foam sclerotherapy (UGFS) was conducted and all abstracts were reviewed to identify clinical trials and systematic reviews for a full-text analysis. Additional articles were also identified through searching the references of the selected studies.

RESULTS

The production of foam for sclerotherapy in a 1:3 or 1:4 ratio of air to sclerosant is optimal in a low silicone, low-volume syringe system. Physiologic gas may decrease any side effects, with the trade-off of decreased foam stability. Proper technique with appropriate sterility and cleansing protocols are paramount for safe and effective treatment. The technical success of UGFS for great saphenous vein disease is inferior to endothermal and surgical modalities and retreatment is more common. However, the clinical improvement in patient-reported quality of life is similar between these three modalities. When used for tributary veins in combination with endothermal approaches of the truncal veins, UGFS has high rates of success with excellent patient satisfaction. UGFS has demonstrated an excellent safety profile comparable with or superior to other modalities.

CONCLUSIONS

With proper technique, UGFS is safe and effective for the management of superficial venous disease.

An Optical Method for Immediate Evaluation of Microfoam Stability in Foam Sclerotherapy

OBJECTIVES

The objective of our study was to develop an optical method that instantly evaluates the stability of sclerosing foam, which would enable early predictions of the clinical performance of the foam and reduce the occurrence of clinical side effects.

METHODS

Based on the principle of light scattering, we developed a method to optically test foam stability and verified it experimentally using sodium morrhuate (2 mL; 0.05 g/mL) and carbon dioxide. A self-made foam preparation instrument was used to achieve a preparation speed of 275 mm/s. The liquid-gas ratios were considered as 1:3, 1:4, and 1:5. Curves of illuminance with respect to the drainage rate and decay time were obtained. By fitting the curve, the relationship between foam half-life time (FHT) and foam decay was obtained. Thus, foam stability was evaluated using the initial illuminance value; the foam transfer time was approximately 3 s.

RESULTS

The experimental FHT varies between 205 and 232 s. Illuminance is exponentially related to drainage rate and linearly related with time. FHT can be expressed by the initial illuminance and illuminance curve fitting coefficients. The half-life of the foam decreases as the initial illuminance value increases, for the same sclerosing drug. The suitability of foam stability is determined by the position of the initial value in the chart.

CONCLUSION

Optical methods are feasible for evaluating foam stability over a short period of time. Clinically predicting the stability of freshly prepared foam can reduce number of incidences of further complications. This will promote the development of foam sclerotherapy and provide a basic understanding of the internal mechanical properties of foam.

Comparison of the Safety and Efficacy of Foam Sclerotherapy With 1: 2 Polidocanol to Air Ratio Versus 1: 4 Ratio for the Treatment of Reticular Veins of the Lower Extremities

BACKGROUND

Foam sclerotherapy is a common treatment of lower extremity reticular veins. The effect of different liquid-gas ratios on foam stability and efficacy has been controversial.

OBJECTIVE

To evaluate the use of 2 different polidocanol (POL) to air ratios for the treatment of reticular veins of the lower extremities.

METHODS AND MATERIALS

Patients with lower extremity reticular veins were randomized to foam sclerotherapy with POL mixed with 4 mL of room air for one lower extremity or 2 mL for the other lower extremity. All telangiectasias were treated with glycerin immediately after treatment of the reticular veins. Adverse events (AEs) and efficacy were evaluated by both subject and blinded investigator.

RESULTS

Thirty subjects completed the study. No statistically significant difference was seen in AEs between the 2 different POL to air ratios by subject questionnaire and blinded investigator scores at all time points. Subjects and blinded investigator reported a mean improvement between 0% and 50% at Day 21 and 26% to 75% at Day 90, which was not significantly different between groups.

CONCLUSION

Two different POL to air ratios, 1:2 versus 1:4, were similarly safe and efficacious for the treatment reticular veins of the lower extremities.

Bleomycin Polidocanol Foam (BPF) Stability - In Vitro Evidence for the Effectiveness of a Novel Sclerosant for Venous Malformations

OBJECTIVE

This study investigated the in vitro stability of a novel sclerosant, bleomycin polidocanol foam (BPF), for venous malformation (VM) sclerotherapy.

METHODS

The study was designed with control groups treated with polidocanol (0.5%, 1%, and 3%) only. The experimental groups included 21 BPFs, which was made by dissolving bleomycin at seven different concentrations (0.1%-1.5%) in polidocanol (0.5%, 1%, and 3%). The Tessari method was used to prepare sclerosant foam with a liquid:gas ratio of 1:4 at room temperature in vitro. The foam stability was measured for each group. The decay process, one component of foam stability, was recorded with a camera. Foam decay process experiments were performed 10 times per group. The stability indices included drainage rate, drainage time, half life, and microscopic measurement of the foams (mean bubble diameter, minimum and maximum bubble diameters, wall thickness, and bubble diameter distribution).

RESULTS

Compared with the control groups, the half lives of BPFs mainly increased significantly with the addition of bleomycin (p < .001). BPF with 3% polidocanol and 0.1% bleomycin recorded the highest half life (246 ± 1.6 sec), and this group also achieved the smallest bubble diameter and wall thickness (69.9 μm and 5.80 μm) among the experimental groups. For the same polidocanol concentration, the bubble diameter and wall thickness increased when bleomycin was added.

CONCLUSION

Bleomycin concentrations account for different BPF stability. BPF stability mainly increased significantly with the addition of a small amount of bleomycin but this advantage was no longer apparent with increasing bleomycin dose.

Recent developments on foaming mechanical and electronic techniques for the management of varicose veins

Introduction: Varicose veins are a common disease, causing significant impairment of quality of life to afflicted individuals. Conventional surgery has represented the traditional treatment for years, with significant post-operative complications. By the end of the 20^th century, novel approaches had been developed to induce biochemical sclerosis into the treated vein in order to exclude it from blood circulation.Areas covered: Foaming techniques for treatment of varicose veins, both clinically-approved methods and those under experimental studies. A brief description of cavitation, which is the basis of microbubbles formation, and an overview of foam properties have been also provided, including a discussion on clinical efficacy and safety profile.Expert commentary: Foam sclerotherapy has rapidly gained popularity since it represents the most minimally invasive and cost-effective procedure in the short term. Several different methods of foam preparation have been described in literature. In general, the foam generation method may affect characteristics such as stability and bubble size distribution, which in turn affect the therapeutic action of foam itself. Therefore, the selection of a suitable foaming technique is of importance for treatment success. Future developments on foaming techniques are expected to make sclerotherapy, already an effective treatment, even safer and more versatile therapeutic procedure.

Modified Method to Increase the Volume and Stability of Bleomycin Foam: An Experimental Study

BACKGROUND

Bleomycin foam is an effective sclerotherapy method for venous malformations. The preparation method is rather complicated, and the volume and stability of the foam are limited.

OBJECTIVE

To modify the currently used method for preparing bleomycin foam, to simplify the preparation procedure, and to produce foam with greater volume and increased stability.

MATERIALS AND METHODS

Experiment 1: 6.0 IU of bleomycin powder was dissolved in different human serum albumin (HSA):saline solution (SS) ratios of 0.5:1.5, 0.75:1.25, 1:1, 1.25:0.75, 1.5:0.5, 1.75:0.25, and 2:0 in volume; then, an air:liquid ratio of 2:1 was used to create foam using the Tessari method. Experiment 2: 6.0 IU of bleomycin was dissolved directly in 2.0 mL of HSA; then, air:liquid ratios of 1:1, 2:1, 3:1, and 4:1 were used to create foam using the Tessari method. The optimum proportions of HSA:SS and air:liquid were screened by comparing the foam half-life (FHL).

RESULTS

Experiment 1: the optimum proportion of HSA:SS was 2:0, and the FHL was 7.5 minutes. Experiment 2: the optimum proportion of air:liquid was 3:1, and the FHL was 9.0 minutes.

CONCLUSION

The modified method is simpler and could produce more stable bleomycin foam with greater volume.

Physical Vein Models to Quantify the Flow Performance of Sclerosing Foams

Foam sclerotherapy is clinically employed to treat varicose veins. It involves intravenous injection of foamed surfactant agents causing endothelial wall damage and vessel shrinkage, leading to subsequent neovascularization. Foam production methods used clinically include manual techniques, such as the Double Syringe System (DSS) and Tessari (TSS) methods. Pre-clinical in-vitro studies are conducted to characterize the performance of sclerosing agents; however, the experimental models used often do not replicate physiologically relevant physical and biological conditions. In this study, physical vein models (PVMs) were developed and employed for the first time to characterize the flow behavior of sclerosing foams. PVMs were fabricated in polydimethylsiloxane (PDMS) by replica molding, and were designed to mimic qualitative geometrical characteristics of veins. Foam behavior was investigated as a function of different physical variables, namely (i) geometry of the vein model (i.e., physiological vs. varicose vein), (ii) foam production technique, and (iii) flow rate of a blood surrogate. The experimental set-up consisted of a PVM positioned on an inclined platform, a syringe pump to control the flow rate of a blood substitute, and a pressure transducer. The static pressure of the blood surrogate at the PVM inlet was measured upon foam administration. The recorded pressure-time curves were analyzed to quantify metrics of foam behavior, with a particular focus on foam expansion and degradation dynamics. Results showed that DSS and TSS foams had similar expansion rate in the physiological PVM, whilst DSS foam had lower expansion rate in the varicose PVM compared to TSS foam. The degradation rate of DSS foam was lower than TSS foam, in both model architectures. Moreover, the background flow rate had a significant effect on foam behavior, enhancing foam displacement rate in both types of PVM.

Effect of Multiple Factors on Foam Stability in Foam Sclerotherapy

Foam sclerotherapy is a widely used treatment for varicose veins. However, complications caused by poor foam stability still remain. Most studies ignore multiple influencing factors and only study a single factor. Furthermore, a stable foam preparation using different preparation conditions has not been developed. This study aimed to explore the changing laws of foam stability under multifactorial conditions, and to determine the influence of various factors and optimal preparation conditions on the half-life of foam. A two-level orthogonal test was conducted using four factors (syringe size, surfactant, preparation temperature, and pump speed). Classifications were established as follows: syringe sizes, 2.5 mL and 5 mL; surfactant concentrations, 6% and 0%; preparation temperatures, 20 °C and 10 °C; and pump speeds, 250 mm/s and 125 mm/s, respectively. Eight experimental group (EG) multi-factor combinations were tested. Half-life and drainage time were recorded for analysis. The initial drainage time was within 200 s, but the difference between the groups was also about 200 s. The drainage rate curves of all EGs gradually increased over time. Conversely, the foam half-life extended by about 10 times for the four factors. In addition, the analyses revealed that the order of influence was surfactant >temperature >pump speed >syringe size. The most stable foam preparation was determined. Syringe size, surfactant, temperature, and pump speed had markedly observable influences on foam half-life. A combination of multiple factors can be used to prepare a more stable foam in clinical scenarios and to suitably superimpose favorable conditions to avoid unfavorable conditions.