title: Sclerosant foam structure and stability is strongly influenced by liquid air fraction.
abstract: OBJECTIVE
  To determine the effects of sclerosant foam preparation and composition on foam structure, the time course of liquid drainage, and foam coarsening.
  
  
  METHODS
  Sodium tetradecyl sulphate (STS) and polidocanol (POL) foams were investigated in a range of concentrations (0.5-3%) and liquid-plus-air fractions (LAF; 1 + 2 to 1 + 8). Foam was injected into a vein simulation model (polyvinyl chloride tubing, inner diameter 3 mm, constant pressure 5-7 mmHg) filled with saline or blood. Liquid drainage, bubble count, and diameter were measured and documented by serial photography.
  
  
  RESULTS
  Liquid drainage was faster in the vertical position than the horizontal one. In all variations, very small bubbles (diameter <30 μm) were generated initially that coarsened to form micro-foams (<250 μm). By 3 minutes mini-foams (>250 μm) and by 7.5 minutes macro-foams (>500 μm) were formed. Following injection, the upper regions of foam coarsened faster as liquid drained to the bottom of the vessel. Wet preparations produced significantly smaller bubbles. Low concentration POL foam produced significantly higher bubble counts and coarsened slower than STS.
  
  
  CONCLUSIONS
  Foam structure is strongly influenced by the LAF. Despite the initial formation of micro-bubbles in the syringe, mini- and macro-bubbles are formed in target vessels with time post-injection.
authors.affiliation: School of Aerospace, Mechanical & Mechatronic Engineering, University of Sydney, Sydney, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Cameron
authors.forename: T
authors.initials: T
authors.lastname: Chen
authors.forename: D E
authors.initials: DE
authors.lastname: Connor
authors.forename: M
authors.initials: M
authors.lastname: Behnia
authors.forename: K
authors.initials: K
authors.lastname: Parsi
mesh_terms: D000388:Air; D007275:Injections, Intravenous; D045423:Microbubbles; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D008968:Molecular Conformation; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry*; D011143:Polyvinyl Chloride; D012597:Sclerosing Solutions / Q000008:administration & dosage / Q000737:chemistry*; D012981:Sodium Tetradecyl Sulfate / Q000008:administration & dosage / Q000737:chemistry*; D013997:Time Factors
chemical_list: D012597:Sclerosing Solutions; D000077423:Polidocanol; D011092:Polyethylene Glycols; D011143:Polyvinyl Chloride; D012981:Sodium Tetradecyl Sulfate
keywords: Coarsening; Foam stability; Liquid drainage; Polidocanol; Sclerosants; Sodium tetradecyl sulphate