• B Schwarz, H Hofstötter, N Salak, W Pajk, H Knotzer, A Mayr, B Labeck, R Kafka, H Ulmer, and W Hasibeder.
• Department of Anesthesia and Critical Care Medicine, Division of General and Surgical Intensive Care Medicine, Leopold Franzens University, Anichstrasse 35, 6020 Innsbruck, Austria.
• Intensive Care Med. 2001 Mar 1;27(3):593-601.

ObjectivesTo investigate effects of intravenous norepinephrine (NE) and phenylephrine (PE) on intestinal oxygen supply in an autoperfused, innervated jejunal segment.Design And SettingProspective, randomized animal study in an animal research laboratory.Materials And MethodsIn 24 anesthetized and normoventilated pigs a segment of the jejunal mucosa was exposed by midline laparotomy and antimesenteric incision. Mucosal oxygen tension (PO2muc; Clark-type surface oxygen electrodes), microvascular hemoglobin oxygen saturation (HbO2, tissue reflectance spectrophotometry), and microvascular blood flow (perfusion units, PU; laser Doppler velocimetry), systemic hemodynamics, mesenteric-venous acid base and blood gas variables, and systemic acid base and blood gas variables were recorded after a resting period and at 20-min intervals during infusion of NE (0.01, 0.05, 0.1, 0.5, 1, 2 micrograms x kg-1 x min-1; n = 8) or PE (0.1, 0.5, 1, 2, 5, 10 micrograms x kg-1 x min-1; n = 8) and in controls (n = 8) without treatment.ResultsNE infusion led to significant tachycardia, an increase in cardiac output, and systemic oxygen delivery and consumption while PE progressively increased mean arterial pressure with only small effects on systemic blood flow. NE or PE infusion did not affect mesenteric venous oxygen tension (baseline: PE 53 +/- 5, NE, 52 +/- 4.2 mmHg), mesenteric oxygen extraction ratio (baseline: PE 0.29 +/- 0.08, NE 0.3 +/- 0.06), jejunal microvascular blood flow (baseline: PE 254 +/- 127, NE 282 +/- 72 PU), PO2muc (baseline: PE 31 +/- 9.1, NE 33 +/- 11 mmHg), and HbO2 (baseline: PE 52 +/- 9.6%, NE 58 +/- 11.6%).ConclusionDespite major differences in systemic hemodynamics jejunal tissue oxygen supply is not affected by progressively increasing intravenous infusion of norepinephrine and phenylephrine.

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