title: Repeatability, reproducibility, and effect of head position on central venous pressure measurement in standing adult horses.
abstract: BACKGROUND
  Central venous pressure (CVP) is a used as an estimation of intravascular volume status in various species. Techniques for measuring CVP in horses have been described, but the repeatability of these readings at a single time point or over time has not been established.
  
  
  OBJECTIVE
  That CVP measurements in healthy adult horses would be repeatable at each time point, that these readings would be reproducible over time, and that alteration in head position relative to the heart would alter CVP.
  
  
  METHODS
  Ten healthy adult research horses.
  
  
  METHODS
  In an experimental study, horses were instrumented with a central venous catheter. Readings were taken in triplicate q6h for 2 days by water manometry, and twice daily with the head in neutral, elevated, and lowered positions by electronic manometry.
  
  
  RESULTS
  Variation in the "neutral" measurements obtained at each time point was <0.1 ± 1.0 cmH(2)O (P = .718). There was a significant decrease in CVP over time (P = .015), which was eliminated when results were controlled for acute decrease in body weight of -1.35% (presumed hypohydration because of lack of acclimatization and decreased water intake). Head height had a significant and directional effect on CVP in that the elevated head position decreased CVP -2.0 ± 6.5 cmH(2)O (P < .001) while the lowered head position increased CVP by 3.7 ± 5.5 cmH(2)O (P < .001).
  
  
  CONCLUSIONS
  CVP values obtained by water manometry were repeatable in adult horses, but were reproducible only when controlled for changes in hydration. Care should be taken to maintain consistency in head position to prevent erroneous readings.
authors: Department of Clinical Studies, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348, USA.
authors: J L
authors: JL
authors: Norton
authors: R D
authors: RD
authors: Nolen-Walston
authors: C
authors: C
authors: Underwood
authors: R
authors: R
authors: Boston
authors: J
authors: J
authors: Slack
authors: B L
authors: BL
authors: Dallap
mesh_terms: D000818:Animals; D001795:Blood Pressure Determination / Q000662:veterinary; D002496:Central Venous Pressure / Q000502:physiology*; D006257:Head; D006736:Horses / Q000502:physiology*; D011187:Posture / Q000502:physiology; D015203:Reproducibility of Results