title: Influence of tissue pressure on central venous pressure/peripheral venous pressure correlation: An experimental report.
abstract: BACKGROUND
  Peripheral venous pressure (PVP) has been shown to correlate with central venous pressure (CVP) in a number of reports. Few studies, however, have explored the relationship between tissue pressure (TP) and PVP/CVP correlation.
  
  
  METHODS
  PVP and CVP were simultaneously recorded in a bench-top model of the venous circulation of the upper limb and in a single human volunteer after undergoing graded manipulation of tissue pressure surrounding the intervening venous conduit. Measures of correlation were determined below and above a point wherein absolute CVP exceeded TP.
  
  
  RESULTS
  Greater correlation was observed between PVP and CVP when CVP exceeded TP in both models. Linear regression slope was 0.975 (95% CI: 0.959-0.990); r (2) 0.998 above tissue pressure 10 cmH2O vs. 0.393 (95% CI: 0.360-0.426); and r (2) 0.972 below 10 cmH2O at a flow rate of 2000 mL/h in the in vitro model. Linear regression slope was 0.839 (95% CI: 0.754-0.925); r (2) 0.933 above tissue pressure 10 mmHg vs. slope 0.238 (95% CI: -0.052-0.528); and r (2) 0.276 in the en vivo model.
  
  
  CONCLUSIONS
  PVP more accurately reflects CVP when absolute CVP values exceed tissue pressure.
authors.affiliation: Department of Emergency Medicine, Waikato Hospital, Hamilton, New Zealand, USA.
authors.forename: Martyn G
authors.initials: MG
authors.lastname: Harvey
authors.affiliation: Department of Emergency Medicine, Waikato Hospital, Hamilton, New Zealand, USA.
authors.forename: Grant
authors.initials: G
authors.lastname: Cave
keywords: Central venous pressure; Peripheral venous pressure; Tissue pressure