title: Effects of norepinephrine on tissue perfusion in a sheep model of intra-abdominal hypertension.
abstract: BACKGROUND
  The aim of the study was to describe the effects of intra-abdominal hypertension (IAH) on regional and microcirculatory intestinal blood flow, renal blood flow, and urine output, as well as their response to increases in blood pressure induced by norepinephrine.
  
  
  METHODS
  This was a pilot, controlled study, performed in an animal research laboratory. Twenty-four anesthetized and mechanically ventilated sheep were studied. We measured systemic hemodynamics, superior mesenteric and renal blood flow, villi microcirculation, intramucosal-arterial PCO2, urine output, and intra-abdominal pressure. IAH (20 mm Hg) was generated by intraperitoneal instillation of warmed saline. After 1 h of IAH, sheep were randomized to IAH control (n = 8) or IAH norepinephrine (n = 8) groups, for 1 h. In this last group, mean arterial pressure was increased about 20 mm Hg with norepinephrine. A sham group (n = 8) was also studied. Fluids were administered to prevent decreases in cardiac output. Differences between groups were analyzed with two-way repeated measures of analysis of variance (ANOVA).
  
  
  RESULTS
  After 2 h of IAH, abdominal perfusion pressure decreased in IAH control group compared to IAH norepinephrine and sham groups (49 ± 11, 73 ± 11, and 86 ± 15 mm Hg, P < 0.0001). There were no differences in superior mesenteric artery blood flow, intramucosal-arterial PCO2, and villi microcirculation among groups. Renal blood flow (49 ± 30, 32 ± 24, and 102 ± 45 mL.min(-1).kg(-1), P < 0.0001) and urinary output (0.3 ± 0.1, 0.2 ± 0.2, and 1.0 ± 0.6 mL.h(-1).kg(-1), P < 0.0001) were decreased in IAH control and IAH norepinephrine groups, compared to the sham group.
  
  
  CONCLUSIONS
  In this experimental model of IAH, the gut and the kidney had contrasting responses: While intestinal blood flow and villi microcirculation remained unchanged, renal perfusion and urine output were severely compromised.
authors.affiliation: Academic Medical Center, Department of Translational Physiology, University of Amsterdam, Meibergdreef 9, 1105, Amsterdam, AZ, The Netherlands, gonzaloferrara@gmail.com.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Ferrara
authors.forename: Vanina S
authors.initials: VS
authors.lastname: Kanoore Edul
authors.forename: Juan F
authors.initials: JF
authors.lastname: Caminos Eguillor
authors.forename: Enrique
authors.initials: E
authors.lastname: Martins
authors.forename: Carlos
authors.initials: C
authors.lastname: Canullán
authors.forename: Héctor S
authors.initials: HS
authors.lastname: Canales
authors.forename: Can
authors.initials: C
authors.lastname: Ince
authors.forename: Elisa
authors.initials: E
authors.lastname: Estenssoro
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Dubin