title: The effects of environmental and compositional manipulations on the longevity of Tessari-made foam for sclerotherapy.
abstract: BACKGROUND
  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 nonsilicone 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.
  
  
  METHODS
  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 (23.9°C) and refrigerator (3°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.
  
  
  RESULTS
  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 (3°C) 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Whiteley Clinic, Guildford, Surrey, United Kingdom.
authors.forename: Salil B
authors.initials: SB
authors.lastname: Patel
authors.affiliation: Whiteley Clinic, Guildford, Surrey, United Kingdom.
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Ostler
authors.affiliation: Whiteley Clinic, Guildford, Surrey, United Kingdom; Faculty of Health and Biomedical Sciences, University of Surrey, Guildford, Surrey, United Kingdom.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Dos Santos
authors.affiliation: Whiteley Clinic, Guildford, Surrey, United Kingdom.
authors.forename: Tom M
authors.initials: TM
authors.lastname: Piriea
authors.affiliation: Whiteley Clinic, Guildford, Surrey, United Kingdom; Faculty of Health and Biomedical Sciences, University of Surrey, Guildford, Surrey, United Kingdom. Electronic address: mark@thewhiteleyclinic.co.uk.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Whiteley
mesh_terms: D002245:Carbon Dioxide; D004355:Drug Stability; D006207:Half-Life; D011092:Polyethylene Glycols; D012597:Sclerosing Solutions; D015911:Sclerotherapy; D012828:Silicones; D013594:Syringes; D013696:Temperature; D013997:Time Factors
chemical_list: D012597:Sclerosing Solutions; D012828:Silicones; D002245:Carbon Dioxide; D011092:Polyethylene Glycols