title: Accuracy of water displacement hand volumetry using an ethanol and water mixture.
abstract: BACKGROUND
  The traditional water displacement method for measuring limb volume is improved by adding ethanol to water.
  
  
  METHODS
  Four solutions were tested (pure water, 0.5% ethanol, 3% ethanol, and 6% ethanol) to determine the most accurate method when measuring the volume of a known object.
  
  
  RESULTS
  The 3% and 6% ethanol solutions significantly reduced (P < 0.001) the mean standard deviation of 10 measurements of a known sphere (390.1 +/- 0.25 mi) from 2.27 ml with pure water to 0.9 ml using the 3% alcohol solution and to 0.6 using 6% ethanol solution (the mean coefficients of variation were reduced from 0.59% for water to 0.22% for 3% ethanol and 0.16% for 6% ethanol). The spheres' volume measured with pure water, 0.5% ethanol solution, 3% ethanol solution, and 6% ethanol solution was 383.2 +/- 2.27 ml, 384.4 +/- 1.9 ml, 389.4 +/- 0.9 ml, and 390.2 +/- 0.6 ml, respectively. Using the 3% and 6% ethanol solutions to measure hand volume blindly in 10 volunteers significantly reduced the mean coefficient of variation for hand volumetry from 0.91% for water to 0.52% for the 3% ethanol solution (P < 0.05) and to 0.46% for the 6% ethanol solution (P < 0.05). The mean standard deviation from all 10 subjects decreased from 4.2 ml for water to 2.3 ml for 3% ethanol solution and 2.1 ml for the 6% solution.
  
  
  CONCLUSIONS
  These findings document that the accuracy and reproducibility of hand volume measurements are improved by small additions of ethanol, most likely by reducing surface tension of water.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA 92103-8894, USA. ahargens@ucsd.edu
authors.forename: Alan R
authors.initials: AR
authors.lastname: Hargens
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA 92103-8894, USA.
authors.forename: Jong-Moon
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA 92103-8894, USA.
authors.forename: Peihong
authors.initials: P
authors.lastname: Cao
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods*; D000431:Ethanol; D006225:Hand / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D009929:Organ Size; D015203:Reproducibility of Results; D012996:Solutions; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; D000431:Ethanol