The History of Sclerosing Foams

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Dermatol Surg 30:5:May 2004 WOLLMANN: THE HISTORY OF SCLEROSING FOAMS 699 1969—Walter Gillesberger: 22 Low-Pressure Technique Gillesberger’s technique was based on the generation of a negative pressure in a (glass) syringe, so that air could enter through the capillary gap between the syringe piston and the plunger and thus generate bubbles (see Figure 7). Gillesberger’s syringe was not closed hermetically like the Monfreux syringe tip later on, but the negative pressure was strong enough to create a foam and was not compensated by the inflow of the sclerosant from the vial. The technique by Gillesberger or its refinement by Monfreux, who generated foam with an ‘‘absolute’’ negative pressure, is very simple. What is problematic is that there is no standardized ratio between air and sclerosant. Therefore, the foams produced in that manner are different, depending on the syringe type, needle, generated suction, and the resulting gas content; they may be more fluid one time and more viscous another time. This leads to different behavior in the vessel (degree and duration of the displacement of blood) and thus probably to an unpredictable efficacy in vivo. (The ability of foam to displace blood depends on its quality or characteristics: foams obtained with low sclerosant concentrations, with small amounts of air, and/or with rather large bubbles have a more or less fluid behavior; i.e., they are more easily washed away by liquids (blood) and have no or just a small and short-term displacing effect. Viscous foams (higher concentration, higher gas content, and small bubbles), in contrast, basically have a displacing effect in larger vessels. 41 If sclerosing foam is to be used for small diameter veins, precaution is recommended owing to the enhancement of the efficacy. A viscous foam would probably have too a strong effect in small veins; moreover, the foam breaks down as a result of the passage through the required fine needles. 42 Figure 7. The low-pressure technique: Pulling down the piston allowed air to enter the syringe through the tiny gap between the syringe piston and the plunger. 1984—Gerald Hauer: 23 Twin-Syringe Technique Hauer patented a twin-syringe set for foam preparation: Two parallel syringes, one filled with air, the other one filled with sclerosing solution, are simultaneously emptied into a ‘‘mixing chamber’’ by pressure, which leads to the formation of bubbles. The ratio of 1 plus 1 (sclerosing agent and air) suggests a dispersion that should have the effect of a foam block. 1986—Michael Grigg: 24 Double Syringes and Connecting Tubes In 1986, Grigg demonstrated a new foam production procedure: the principle was the generation of a turbulent flow between two syringes, connected via a plastic infusion tube, so that fluid and air could be pumped forward and backward. Belcaro later improved this technique by the addition of a further strongly foaming detergent solution in small amounts (0.1–0.2 mL). (‘‘Improved’’ in this context means prolongation of half-life. Owing to the commonly relevant amount of silicone in disposables (syringes and infusion tubes, etc.), the half-life of the foam was evidently limited because silicone, which destroys the surfactant arrangement of the foam lamellae, is a very strong foam breaker. Therefore, anything that contributes to the maintenance of foam bubbles supports the foam stability: this is, in addition to an increase of the surfactant concentration, in particular the minimization of the amount of silicone.) According to him, the foam half-life was approximately 4 min. This socalled ‘‘Irvine technique’’ (named after the laboratory in which the technique was demonstrated) can be considered to be a precursor of Tessari’s technique and the double-syringe system (DSS). Belcaro and coworkers 24 first performed investigations on the safety of the foam generated according to that technique: 5 to 10 mL of the foam produced with that technique did not cause any change of the pulmonary ventilation scintigraphy or perfusion scintigraphy in 12 patients. 1995—Juan Cabrera Garrido: 2 Rotating Brush Technique In 1995, Cabrera Garrido published data from the clinical use of ‘‘microfoam.’’ He had treated venous malformations and saphenous veins including collaterals with high volumes of foam. His objective was to fill the complete venous lumen by injecting high doses of foam at one time. A new aspect of the production was the use of a high-speed rotating brush (a modified dental bur), so that foam was agitated—like cream with a food mixer—and the facultative addition of CO2 as a carrier gas. In experiments, CO2—if
700 WOLLMANN: THE HISTORY OF SCLEROSING FOAMS Dermatol Surg 30:5:May 2004 Figure 8. Foam prepared with 3% polidocanol solution according to the double-syringe system (DSS). Sterile air or CO2 was used as gas. The degradation of foam is faster if CO2 is used instead of air and even more pronounced if the ratio is changed from 1:5 to 1:10. employed as the only gas—led to foams with quickly degrading bubbles (see Figure 8). Regarding the highdose treatment, more recent publications by Cabrera Garridos mentioned that the foam could flow from the greater saphenous vein into the deep venous system via the saphenofemoral junction or other connections, where it may provoke thromboses. 25 The number of deep venous thromboses in a first study on this foam (6% thromboses when administering 20 mL of Varisolve foam and more) 26 does not lend support to the high-dose foam therapy and requires special safety measures. 1997—Alain Monfreux: 27 Low-Pressure Technique and ‘‘Méthode MUS’’ Monfreux’s technique, published in 1997 under the name of ‘‘Méthode MUS,’’ was picked up primarily by French phlebologists. The principle was based on Gillesberger’s technique: generation of a negative pressure in the glass syringe filled with sclerosing solution, thus inlet of air through the fine gap between syringe barrel and plunger with corresponding pearling of the solution and transformation into a foam. Unlike Gillesberger, Monfreux generated an ‘‘absolute’’ negative pressure by placing a cap on the syringe. Although all concentrations of sclerosants can be used with this method, the efficacy cannot be predicted in each individual case: a defined ratio of gas and sclerosant or a defined bubble size cannot be determined, because many variables (e.g., the width of the capillary gap between the syringe barrel and plunger, force, and duration of traction at the plunger and thus the order of magnitude of the effective shearing force which is responsible for the pearling of the solution) depend on the brand and on the user. 1998—Symon Sadoun/Jean-Patric Benigni: 5,28 Advanced Low-Pressure Technique Both authors improved Monfreux’s technique by making it usable for plastic syringes: The principle— generation of a negative pressure in a syringe closed by a Luer stopper—remained similar: pulling down the piston to generate subatmospheric pressure was followed by quickly releasing the piston several times. As with Monfreux and his predecessors, a defined gas:sclerosant ratio could not be stated. 1998—Miguel Santos Gaston: 29 Advanced Low-Pressure Technique Gaston basically adopted the Monfreux technique, but added some more steps to the preparation procedure: once the foam was prepared according to Monfreux, he emptied the foam into a glass container and then aspirated the foam again. This was repeated several times, making—on the one hand—the foam more fine, but—on the other hand—more dry. 1999—Javier Garcia Mingo: 30,31 High-Pressure Technique and ‘‘Foam Medical System’’ Mingo was the first to describe a sterilizable, reusable device for the preparation of foam, which generates foam by the introduction of various gases from a pressure-gas cylinder and subsequent passage of the mixture through a fine nozzle, the ‘‘foam medical system.’’ The handling and cleaning of the device, which appears a little complicated, has prevented its wide use so far, although Mingo’s clinical results are considered very promising. 2000—Lorenzo Tessari: 32,33 Double Syringes, Three-Way Tap, and the ‘‘Tourbillon Technique’’ Tessari’s Tourbillon technique is at present, together with the similar DSS technique, the most commonly used technique. It corresponds basically to Irvine’s technique 24 but has clear advantages over the latter. Tessari uses two syringes as well (various sizes being described), but Tessari’s technique does not require ‘‘foaming aids’’: The two syringes are connected by a three-way stopcock, and the sclerosing solution and air are drawn back and forth by pump movements. Owing to the absence of a connecting tube, a lot of disturbing silicone is no longer present. A more detailed description of the pumping procedure (at least 10 times) to improve the standardization of the foam was given in 2001. 34 The three-way stopcock has an additional ‘‘technical finesse’’: it is possible to vary the size of the passage
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The History of Sclerosing Foams

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