Effects of norepinephrine and phenylephrine on intestinal oxygen supply and mucosal tissue oxygen tension.
OBJECTIVE
To investigate effects of intravenous norepinephrine (NE) and phenylephrine (PE) on intestinal oxygen supply in an autoperfused, innervated jejunal segment.


METHODS
Prospective, randomized animal study in an animal research laboratory.


METHODS
In 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.


RESULTS
NE 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%).


CONCLUSIONS
Despite major differences in systemic hemodynamics jejunal tissue oxygen supply is not affected by progressively increasing intravenous infusion of norepinephrine and phenylephrine.
Schwarz
B
B
Department of Anesthesia and Critical Care Medicine, Division of General and Surgical Intensive Care Medicine, Leopold Franzens University, Anichstrasse 35, 6020 Innsbruck, Austria.
Hofstötter
H
H
Salak
N
N
Pajk
W
W
Knotzer
H
H
Mayr
A
A
Labeck
B
B
Kafka
R
R
Ulmer
H
H
Hasibeder
W
W
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D006439:Hemodynamics / Q000187:drug effects*; D007022:Hypotension / Q000175:diagnosis / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism*; D007583:Jejunum / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism*; D017078:Laser-Doppler Flowmetry; D008833:Microcirculation / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology / Q000627:therapeutic use*; D010101:Oxygen Consumption / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D011897:Random Allocation; D013053:Spectrophotometry; D013552:Swine; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology / Q000627:therapeutic use*
D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009638:Norepinephrine