title: The effect of augmenting portal venous inflow on intrahepatic pressure and resistance in the isolated perfused porcine liver.
abstract: OBJECTIVE
  The literature regarding the relationship between portal venous flow and pressure is controversial. The aim of this study was to examine the effects of doubling portal venous inflow on hepatic hemodynamics.
  
  
  METHODS
  Portal venous pressure, intrahepatic portal venous resistance, hepatic arterial pressure and intrahepatic arterial resistance were assessed during basal portal venous inflow (756 +/- 142 mL/min; mean +/- SD) and enhanced portal venous inflow (1512 +/- 284 mL/min) in an isolated perfused normal porcine liver model (n = 6). Hepatic arterial flow was maintained constant throughout the experiments.
  
  
  RESULTS
  During the period of enhanced portal venous flow there was an increase in: portal venous pressure (from 9 +/- 2 to 22 +/- 7 mm Hg, P = 0.0076); the difference between portal venous and hepatic venous pressures (from 2 +/- 2 to 10 +/- 5 mm Hg; P = 0.0289); hepatic arterial pressure (from 84 +/- 9 to 151 +/- 33 mm Hg, P = 0.0019); and intrahepatic arterial resistance (from 0.3488 +/- 0.0637 to 0.6387 +/- 0.2020, P = 0.0046).
  
  
  CONCLUSIONS
  The increases in hepatic artery pressure and intrahepatic arterial resistance are a result of the hepatic arterial 'buffer response', a phenomenon not previously demonstrated in vitro. The magnitude of the observed changes in portal venous and hepatic venous pressure leads to the conclusion that, in the porcine liver, the intrahepatic venous resistance sites react by constricting to increases in portal venous inflow.
authors.affiliation: Department of Gastrointestinal Surgery, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
authors.forename: L R
authors.initials: LR
authors.lastname: Jiao
authors.forename: F S
authors.initials: FS
authors.lastname: Inglott
authors.forename: R T
authors.initials: RT
authors.lastname: Mathie
authors.forename: N A
authors.initials: NA
authors.lastname: Habib
mesh_terms: D000818:Animals; D006439:Hemodynamics; D008099:Liver / Q000473:pathology / Q000503:physiopathology*; D010477:Perfusion; D011169:Portal Vein / Q000502:physiology*; D013552:Swine; D014655:Vascular Resistance