From the The Whiteley Clinica; and the Faculty of Health and Biomedical Sciences,University of Surrey.b
Author conflict of interest: none.
Presented as an oral presentation at the Twenty-sixth Annual Meeting of the American Venous Forum, New Orleans,LA, February 19-21, 2014; and presented and winner of first prize at the Annual Spring Meeting of the Royal Society of Medicine Venous Forum, London, United Kingdom, April 23-24, 2014.
Mark S. Whiteley, MS, FRCS (Gen)The Whiteley Clinic Stirling House, Stirling Road Guildford Surrey GU2 7RF, UK Email: firstname.lastname@example.org
The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest.
Copyright© 2014 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvsv.2014.07.010
Tessari-made foam sclerotherapy is performed around the world in a variety of clinics differing in methods, equipment, temperatures, and altitudes. We investigated how the following factors affected the foam’s longevity: silicone vs non- silicone syringes, volume of foam made, ratio of gas to sclerosant, use of air vs 50:50 mixture of carbon dioxide and oxygen, temperature, altitude, and 10 consecutive reuses of the syringes.
Sclerosant foam was made by the Tessari double-syringe technique. To calculate the longevity, the time was taken for half of the original volume of sclerosant to settle. Half-lives were compared with use of silicone and silicone-free syringes to make the foam. We investigated how the volume (5 mL vs 2 mL) and different ratios affected the foam by observing the half-life of 4:1, 3.5:1, and 3:1 ratios of gas to sclerosant. Air and a 50:50 mixture of carbon dioxide and oxygen were both used as the gas in changing the ratio and volume to see which produced better foam.
These experiments were conducted at room (23.9º C) and refrigerator (3º C) temperatures with a constant pressure. The different ratio, volume, and silicone vs nonsilicone syringe experiments were all repeated at 9314, 7460, 4575, and 2326 feet above sea level in addition to the baseline experiment, which took place at 236 feet above sea level.
To test how consecutive uses of syringes affected the foam, we made consecutive batches of foam reusing each pair of syringes 10 times; this was repeated five times with silicone syringes and twice with nonsilicone syringes.
Switching to nonsilicone syringes can increase longevity by 70%. A larger volume of foam and a 3:1 ratio produced longer half-lives at all temperatures and altitudes. The lower (3ºC) temperature increased the longevity of foam in all instances, as did the use of air. A high altitude (low pressure) had a detrimental effect on the foam’s longevity. Ten consecutive syringe uses had no significant impact on the foam’s half-life (silicone syringe mean between first five and last five uses, P [ .95).
The optimum conditions for making foam are nonsilicone syringes, larger volumes, a 3:1 air to sclerosant ratio, and low temperatures. Silicone syringes can be reused until friction becomes a burden. Temperature has a bigger effect than altitude on longevity of the foam. Making foam in larger volumes would allow the foam to last longer. To compensate for high altitudes (low pressures), decreasing the temperature will increase the foam’s longevity. (J Vasc Surg: Venous and Lym Dis 2014;-:1-7.)
Foam sclerotherapy is performed widely around the world in different environments, at different temperatures, at different altitudes, and with different ratios of sclerosant to gas, using different gases (air or carbon dioxidee oxygen mixtures) and different syringes. The most commonly used technique is the Tessari method of making foam. Foam sclerotherapy relies on the foam displacing the blood from the target vein, and so longer lasting foam will keep the blood out of the target vein longer, which is likely to have better results, although that needs to be shown. This study explores the variables to see how they affect the longevity of foam.
Our research demonstrates that we stop at nothing to ensure we offer our patients the highest quality ultrasound guided foam schlerotherapy yet devised. By using O2/CO2 it is also safer as we have reduced the risk associated with air embolism.
Salil B. Patel (The Whiteley Clinic Summer Research Fellow 2013 & Medical Student)
Alexandra E. Ostler (The Whiteley Clinic Summer Research Fellow 2013 & Medical Student)
Scott J. Dos Santos (The Whiteley Clinic Summer Research Fellow 2013 & BioMed Student)
Tom M. Piriea (The Whiteley Clinic Summer Research Fellow 2013 Post A Levels)
Mark S. Whiteley
1st Prize, Venous Forum of The Royal Society of Medicine, April 2014
Journal of Vascular Surgery; Venous and Lymphatic Disorders (In Print)
American Venous Forum, 26th Annual Meeting, New Orleans. Feb 2014
1st prize, Venous Forum Annual Spring Meeting, Royal Society of Medicine April 2014
Charing Cross International Symposium, London, April 2014
Foam Sclerotherapy is used widely with variable results. Few doctors have questioned their own technique and just treat patients on the basis that “it should work”.
We have studied the effects of:
Despite it being known that using air in foam sclerotherapy can cause:
Most doctors still use air to make foam for sclerotherapy as this makes good long lasting foam. This study showed that we can use the much safer Oxygen:Carbon Dioxide mixture making better foam if we use:
Clearly we can’t change the altitude, but it does explain worse results in clinics from hot and high altitude areas.
Mark Whiteley and his team had to perform many of these experiments in a walk in freezer at the University of Surrey and at several stations on Mount Titlis in Switzerland.