Effect of Multiple Factors on Foam Stability in Foam Sclerotherapy

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.

The Effect of Pushing Rate on Foam Stability in the Tessari Method

BACKGROUND

The Tessari method is commonly used in sclerotherapy for producing foam, involving 2 syringes pushed back and forth 20 times with the use of a 3-way connector. Many factors affect the foam stability which is crucial for clinical efficacy.

OBJECTIVE

This study aimed to identify the optimal pushing rate which may impact the foam stability.

MATERIALS AND METHODS

Polidocanol (POL) solution (1% and 3%) was used to make sclerosant foam via the Tessari method, with a total of 20 pushes performed at different time durations: 10, 15, 20, 25, 30, 35, and 40 seconds. The foam stability was recorded using foam half-life time (FHT), and the pushing pressure to the syringe was recorded using a self-made electric device. Both FHT and the pressure among different groups were compared respectively.

RESULTS

The FHT was decreased as pushing duration exceeding 20 seconds in POL 1% and 15 seconds in POL 3%. Both the highest FHT and pressure point were located in the 10-second group.

CONCLUSION

It is recommended to complete 20 back-and-forth passages within 10 seconds to create stable foam.

Foam-in-Vein: Characterisation of Blood Displacement Efficacy of Liquid Sclerosing Foams

Sclerotherapy is among the least invasive and most commonly utilised treatment options for varicose veins. Nonetheless, it does not cure varicosities permanently and recurrence rates are of up to 64%. Although sclerosing foams have been extensively characterised with respect to their bench-top properties, such as bubble size distribution and half-life, little is known about their flow behaviour within the venous environment during treatment. Additionally, current methods of foam characterisation do not recapitulate the end-point administration conditions, hindering optimisation of therapeutic efficacy. Here, a therapeutically relevant apparatus has been used to obtain a clinically relevant rheological model of sclerosing foams. This model was then correlated with a therapeutically applicable parameter-i.e., the capability of foams to displace blood within a vein. A pipe viscometry apparatus was employed to obtain a rheological model of 1% polidocanol foams across shear rates of 6 s^-1 to 400 s^-1. Two different foam formulation techniques (double syringe system and Tessari) and three liquid-to-gas ratios (1:3, 1:4 and 1:5) were investigated. A power-law model was employed on the rheological data to obtain the apparent viscosity of foams. In a separate experiment, a finite volume of foam was injected into a PTFE tube to displace a blood surrogate solution (0.2% w/v carboxymethyl cellulose). The displaced blood surrogate was collected, weighed, and correlated with foam's apparent viscosity. Results showed a decreasing displacement efficacy with foam dryness and injection flowrate. Furthermore, an asymptotic model was formulated that may be used to predict the extent of blood displacement for a given foam formulation and volume. The developed model could guide clinicians in their selection of a foam formulation that exhibits the greatest blood displacement efficacy.

Sclerotherapy in Aesthetic Medicine: Myths and Realities

BACKGROUND

Sclerotherapy is commonly performed for elimination of reticular and telangiectatic leg veins. There are several variations in practice, from the preparation to post-therapy directives.

OBJECTIVE

To critically examine the misconceptions of sclerotherapy for aesthetic indications.

MATERIALS AND METHODS

This review assesses evidence for and against each of the most common myths regarding sclerotherapy for aesthetic indications.

RESULTS

Sclerotherapy can be safely used to treat veins in areas other than the lower extremities, with the exception of the face. Laser therapy is not superior to sclerotherapy for the treatment of small telangiectatic veins on the lower extremities. The type of syringe used to produce foam sclerotherapy is an important procedural consideration. After sclerotherapy, graduated compression stocking usage is a vital part of the procedure. Detergent sclerotherapy agents are similar, but not equivalent. Touch-up treatments after sclerotherapy should not be performed for 2 months post-treatment. Foam sclerotherapy does not have a high risk for air emboli. It is not advisable to treat the leg veins in "sections." Finally, one cannot reliably treat the telangiectatic veins without treating the feeding reticular veins for a satisfactory result.

CONCLUSION

Many aspects of sclerotherapy have existing evidence to dictate best clinical practice.

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.

Characterisation and optimisation of foams for varicose vein sclerotherapy

BACKGROUND

Foam sclerotherapy is the process of using an aqueous foam to deliver surfactant to a varicose vein to damage vein wall endothelial cells, causing the vein to spasm, collapse and ultimately be re-absorbed into the body. Aqueous foams are complex fluids that can exhibit a significant yield stress and high effective viscosity which depend on their composition, particularly the bubble size and liquid fraction.

OBJECTIVE

To characterise the properties of foams used for varicose vein sclerotherapy and determine their effectiveness in the displacement of blood during sclerotherapy.

METHODS

Foams are modelled as yield stress fluids and their flow profiles in a model vein are predicted. Values of the yield stress are determined from experimental data for three different foams using the Sauter mean of the bubble size distribution. Along with the measured liquid fraction of the foams, this information is collected into a Bingham number which entirely characterises the process of sclerotherapy.

RESULTS

Polydispersity in bubble size has a strong effect on the yield stress of a foam and the Sauter mean of the size distribution better captures the effects of a few large bubbles. Reducing the polydispersity increases the yield stress, and a higher yield stress results in a larger plug region moving along the vein, which is more effective in displacing blood. The width of the plug region is proportional to the Bingham number, which also has a quadratic dependence on the liquid fraction of the foam. Assuming typical values for the rate of injection of a foam, we predict that for a vein of diameter 5 mm, the most effective foams have low liquid fraction, a narrow size distribution, and a Bingham number B ≈ 4.5.

CONCLUSIONS

The Sauter mean radius provides the most appropriate measure of the bubble size for sclerotherapy and the Bingham number then provides a simple measure of the efficacy of foam sclerotherapy in a vein of a given size, and explains the ability of different foams to remove varicose veins. Foams containing small bubbles, with a narrow size distribution, and a low liquid fraction are beneficial for sclerotherapy.

Development of Glycerol-Rose Bengal-Polidocanol (GRP) foam for enhanced sclerosis of a cyst for cystic diseases

Polycystic kidney disease (PKD) is a common genetic disorder that results in a proliferating and enlarging cyst and ultimately leads to loss of kidney function. Because an enlarged cyst is a primary factor for limited kidney function, the large cyst is surgically removed by laparoscopic deroofing or sclerosant. This a relatively nascent treatment method entails complications and sometimes fail due to the cyst fluid refilling and infection. This study proposes using a more stable and effective polidocanol foam with glycerol and Rose Bengal (GRP form) to prevent cyst regeneration and irritation, which is caused by the required body movement during the treatment. Specifically, the foam retention time and viscosity were increased by adding glycerol up to 10% (w/v). The GRP form inhibited cellular proliferation and disrupted cellular junctions, e-cadherin, and cyst formation, demonstrated by the LDH, Live and Dead, and re-plating culture assays. The GRP foam was shown to be a safe and effective treatment as a commercial grade polidocanol foam form by an in vivo study in which subcutaneously injected mice injected with commercial 3% polidocanol, and the GRP foam showed no difference in inflammation. Thus, this study provides an advanced polidocanol form by adding glycerol and Rose-Bengal to help existing sclerotherapy.

Effect of Hyaluronic Acid and Pluronic-F68 on the Surface Properties of Foam as a Delivery System for Polidocanol in Sclerotherapy

The use of foams to deliver bioactive agents and drugs is increasing in pharmaceutics. One example is the use of foam as a delivery system for polidocanol (POL) in sclerotherapy, with the addition of bioactive compounds to improve the delivery system being a current subject of study. This work shows the influence of two bioactive additives on the structure and stability of POL foam: hyaluronic acid (HA) and Pluronic-F68 (F68). HA is a natural non-surface-active biopolymer present in the extracellular matrix while F68 is a surface-active poloxamer that is biocompatible with plasma-derived fluids. Both additives increase the bulk viscosity of the sample, improving foam stability. However, HA doubled and F68 quadruplicated the foam half lifetime of POL. HA reduced the size and polydispersity of the bubble size distribution and increased the surface elasticity with respect to POL. Both facts have a positive impact in terms of foam stability. F68 also altered bubble structure and increased surface elasticity, again contributing to the enhancement of foam stability. The surface characterization of these systems is important, as in foam sclerotherapy it is crucial to assure the presence of POL at the surface of the bubbles in order to deliver the sclerosant agent in the target vein.

Bubble-Induced Rupture of Droplets on Hydrophobic and Lubricant-Impregnated Surfaces

Bursting of bubbles is ubiquitous with numerous applications ranging from spraying of pesticides, drug delivery, and inkjet printing to forming emulsions. Understanding the parameters that influence the dynamics of bubble rupture is crucial to design systems with improved performance. Here, we experimentally investigate the behavior of air-bubble-induced rupture of a sessile droplet placed on hydrophobic and lubricant-impregnated surfaces (LIS). We demonstrate that the bubble dynamics inside a sessile droplet and subsequent rupture of the thinning film is dependent on the nature of the underlying substrate and the thermodynamic state of the droplet on the substrate. The growth of the bubble is shown to be dependent on the contact angle hysteresis of water and air on the substrate and the presence of a cloaking oil film around the water droplet. On a plain and textured surface with a high contact angle hysteresis, bubble-induced rupture initiates at the apex of the droplet. In the case of LIS that offers negligible pinning forces, the bubble-induced rupture of liquid shell initiates near the triple contact line. The dynamics of rupture of droplets placed on LIS is shown to be dependent on the viscosity of the impregnating and cloaking lubricant.

Foam-in-vein: A review of rheological properties and characterization methods for optimization of sclerosing foams

Varicose veins are chronic venous defects that affect >20% of the population in developed countries. Among potential treatments, sclerotherapy is one of the most commonly used. It involves endovenous injection of a surfactant solution (or foam) in varicose veins, inducing damage to the endothelial layer and subsequent vessel sclerosis. Treatments have proven to be effective in the short-term, however recurrence is reported at rates of up to 64% 5-year post-treatment. Thus, once diagnosed with varicosities there is a high probability of a permanently reduced quality of life. Recently, foam sclerotherapy has become increasingly popular over its liquid counterpart, since foams can treat larger and longer varicosities more effectively, they can be imaged using ultrasound, and require lower amounts of sclerosing agent. In order to minimize recurrence rates however, an investigation of current treatment methods should lead to more effective and long-lasting effects. The literature is populated with studies aimed at characterizing the fundamental physics of aqueous foams; nevertheless, there is a significant need for appropriate product development platforms. Despite successfully capturing the microstructural evolution of aqueous foams, the complexity of current models renders them inadequate for pharmaceutical development. This review article will focus on the physics of foams and the attempts at optimizing them for sclerotherapy. This takes the form of a discussion of the most recent numerical and experimental models, as well as an overview of clinically relevant parameters. This holistic approach could contribute to better foam characterization methods that patients may eventually derive long term benefit from.

Foam sclerotherapy compared with liquid sclerotherapy for the treatment of lower extremity varicose veins: A protocol for systematic review and meta analysis

BACKGROUND

There is a continued discussion on which is the best sclerosant to treat lower extremity varicose veins. Therefore, we did this meta-analysis to determine that foam sclerotherapy versus liquid sclerotherapy, which could perform better in the treatment of lower extremity varicose veins.

MATERIALS AND METHODS

We independently searched 5 databases from inception to February 1, 2019, for randomized controlled trials and prospective controlled trials for comparing foam sclerotherapy and liquid sclerotherapy for the treatment of lower extremity varicose veins. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of studies. The primary outcome and secondary outcomes were analyzed using stata 15.0. This meta-analysis was performed according to Cochrane Handbook.

RESULTS

There were significant differences in effective rate (P < .001, odd ratios = 5.64, 95% confidence interval = 3.93-8.10) and incidence rate of pain (P = .030, odd ratios = 1.52, 95% confidence interval = 1.04-2.21) between foam sclerotherapy and liquid sclerotherapy. And there were no significant differences among local inflammation (P = .896, rate difference = 0.00, 95% confidence interval = -0.03 to 0.03), thrombophlebitis (P = .90, rate difference = 0.00, 95% confidence interval = -0.02 to 0.02) and hyperpigmentation (P = .336, rate difference = 0.05, 95% confidence interval = -0.05 to 0.14).

CONCLUSIONS

Although foam sclerotherapy has a higher incidence rate of complications, it could achieve a more stable clinical efficacy in the treatment of lower extremity varicose veins than liquid sclerotherapy.

Sirolimus and propranolol inhibit endothelial proliferation while detergent sclerosants induce endothelial activation, microparticle release and apoptosis in vitro

OBJECTIVES

To investigate the effects of detergent sclerosants, sodium tetradecyl sulphate and polidocanol, on endothelial cell activation and microparticle release and the effects of detergent sclerosants, sirolimus and propranolol, on apoptosis in vitro.

METHODS

Cultured human umbilical vein endothelial cells and murine haemangioendothelioma (EOMA) cell lines were incubated with different concentrations of sodium tetradecyl sulphate and polidocanol, as well as sirolimus and propranolol. Endothelial activation was assessed using flow cytometry for CD62e (E-Selectin), CD54 (ICAM-1), CD105 (endoglin), CD144 (VE-Cadherin), CD146 (MCAM) and the release of endothelial microparticles. Cell proliferation was assessed using [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] and carboxyfluorescein succinimidyl ester assays. Apoptosis was assessed using flow cytometry for lactadherin/propidium iodide staining and for Caspase-3 expression.

RESULTS

Sublytic concentrations of sodium tetradecyl sulphate and polidocanol (0.075%-0.3%) increased the expression of the activation markers CD62e and CD54. The expression of CD105 decreased in sclerosant treated cultured human umbilical vein endothelial cells. Both sodium tetradecyl sulphate and polidocanol induced the release of endothelial microparticles. All agents inhibited cell proliferation. Sodium tetradecyl sulphate and polidocanol-induced apoptosis as evidenced by increased phosphatidylserine exposure and caspase-3 expression, whereas sirolimus and propranolol increased caspase-3 expression only.

CONCLUSION

Sublytic concentrations of detergent sclerosants induce endothelial activation and the release of endothelial microparticles. All agents were anti-proliferative in EOMA cell lines, with sodium tetradecyl sulphate and polidocanol inducing cellular apoptosis.

Identifying the Most Stable State of a Foam Sclerosant for Foam Sclerotherapy

BACKGROUND

Foam sclerotherapy is an effective treatment strategy for vascular malformations, and its sclerosing power depends on foam stability. Twenty quick passages have been widely used as an indicator of the most stable state of sclerosants, but the universality of their effectiveness has not been proven yet.

OBJECTIVE

We aimed to identify simple and objective indicators of the most stable state of commonly used sclerosants and provide practitioners with suggestions to judge when foam producing is completed in sclerotherapy.

MATERIALS AND METHODS

The universality of the effectiveness of 20 passages was tested by producing bleomycin foam with different passages. Further study was performed by testing modified bleomycin, polidocanol, and sodium tetradecylsulfate foam.

RESULTS

The bleomycin foam became denser as passages were added, and the sound of each passage became almost silent after 40 passages. The almost silent sound can be an indicator of foam stability for most sclerosants. It has a different application range compared with 20 quick passages.

CONCLUSION

We suggest that practitioners choose a different indicator depending on the foam used.

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.

Global guidelines trends and controversies in lower limb venous and lymphatic disease: Narrative literature revision and experts' opinions following the vWINter international meeting in Phlebology, Lymphology & Aesthetics, 23-25 January 2019

Guidelines are fundamental in addressing everyday clinical indications and in reporting the current evidence-based data of related scientific investigations. At the same time, a spatial and temporal issue can limit their value. Indeed, variability in the recommendations can be found both among the same nation different scientific societies and among different nations/continents. On the other side, Garcia already published in 2014 data showing how, after three years in average, one out of five recommendations gets outdated (Martinez Garcia LM, Sanabria AJ, Garcia Alvarez E, et al. The validity of recommendations from clinical guidelines: a survival analysis. CMAJ 2014;186(16):1211–1219). The present document reports a narrative literature revision on the major international recommendations in lower limb venous and lymphatic disease management, focusing on the different countries’ guidelines, trends and controversies from all the continents, while identifying new evidence-based data potentially influencing future guidelines. World renowned experts’ opinions are also provided. The document has been written following the recorded round tables scientific discussions held at the vWINter international meeting (22–26 January 2019; Cortina d’Ampezzo, Italy) and the pre- and post-meeting literature search performed by the leading experts.