title: Hypotension during fluid-restricted abdominal surgery: effects of norepinephrine treatment on regional and microcirculatory blood flow in the intestinal tract.
abstract: BACKGROUND
  Vasopressors, such as norepinephrine, are frequently used to treat perioperative hypotension. Increasing perfusion pressure with norepinephrine may increase blood flow in regions at risk. However, the resulting vasoconstriction could deteriorate microcirculatory blood flow in the intestinal tract and kidneys. This animal study was designed to investigate the effects of treating perioperative hypotension with norepinephrine during laparotomy with low fluid volume replacement.
  
  
  METHODS
  Twenty anesthetized and ventilated pigs were randomly assigned to a control or treatment (norepinephrine) group. Both groups received 3 ml · kg⁻¹ · h⁻¹ Ringer's lactate solution. In addition, the norepinephrine group received norepinephrine to stepwise increase blood pressure to 65 and 75 mmHg. Regional blood flow was measured in the splanchnic arteries. In the small bowel and colon, microcirculatory blood flow was measured using laser Doppler flowmetry. Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes.
  
  
  RESULTS
  Hepatosplanchnic and kidney blood flow remained unchanged after reversal of arterial hypotension to a mean arterial pressure of 75 mmHg with norepinephrine. For the norepinephrine group versus the control group, the mean ± SD microcirculatory blood flow in the jejunum (96 ± 41% vs. 93 ± 18%) and colon (98 ± 19% vs. 97 ± 28%) and intestinal tissue oxygen tension (jejunum, 45 ± 13 vs. 43 ± 5 mmHg; colon, 50 ± 10 vs. 45 ± 8 mmHg) were comparable.
  
  
  CONCLUSIONS
  In this model of abdominal surgery in which clinical conditions were imitated as close as possible, treatment of perioperative hypotension with norepinephrine had no adverse effects on microcirculatory blood flow or tissue oxygen tension in the intestinal tract.
authors.affiliation: Department of Anesthesiology and Pain Therapy, Regional Hospital Emmental and University of Bern, Bern, Switzerland. hiltebrand.l@bluemail.ch
authors.forename: Luzius B
authors.initials: LB
authors.lastname: Hiltebrand
authors.forename: Eliana
authors.initials: E
authors.lastname: Koepfli
authors.forename: Oliver
authors.initials: O
authors.lastname: Kimberger
authors.forename: Gisli H
authors.initials: GH
authors.lastname: Sigurdsson
authors.forename: Sebastian
authors.initials: S
authors.lastname: Brandt
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000818:Animals; D002302:Cardiac Output / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D007022:Hypotension / Q000188:drug therapy* / Q000209:etiology*; D007422:Intestines / Q000098:blood supply* / Q000187:drug effects; D007431:Intraoperative Complications / Q000188:drug therapy* / Q000209:etiology*; D007813:Laparotomy; D017078:Laser-Doppler Flowmetry; D008833:Microcirculation / Q000187:drug effects; D009638:Norepinephrine / Q000008:administration & dosage / Q000627:therapeutic use*; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology; D013152:Splanchnic Circulation / Q000187:drug effects; D013552:Swine; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D006454:Hemoglobins; D014662:Vasoconstrictor Agents; D009638:Norepinephrine