Early Effects of Catecholamine Therapy on Mucosal Integrity, Intestinal Blood Flow, and Oxygen Metabolism in Porcine Endotoxin Shock

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Abstract
To determine the early effects of therapy of endotoxin (ET) shock with epinephrine, norepinephrine, or dopexamine on splanchnic circulation, oxygen metabolism, sigmoid mucosal pHi, bacterial translocation, and morphologic integrity of the ileal, colonic, and sigmoid mucosa. Conflicting concepts exist concerning the catecholamine therapy of septic shock, but little is known about the effects of catecholamine treatment on splanchnic circulation and mucosal integrity. ET shock was induced in pigs by ET infusion over 30 minutes, and animals were studied for 4 hours. All animals were resuscitated with fluid. To mimic the treatment of septic shock in humans, mean arterial pressure was maintained in two groups at >70 mm Hg with the administration of epinephrine or norepinephrine. A third group of animals received dopexamine at 7 μg/kg per minute. Systemic and splanchnic blood flow and oxygen metabolism were studied, sigmoid colon mucosal pHi was obtained tonometrically, and bacterial translocation was determined by culture of portal venous blood, mesenteric lymph nodes, liver, spleen, and lung specimens. Histologic sections of ileal, colonic, and sigmoid mucosa were morphometrically examined for therapy effects. All investigated catecholamines increased cardiac output and systemic oxygen delivery, whereas intestinal blood flow and oxygen delivery remained unchanged. Sigmoid mucosal pHi decreased in all study animals, but the decrease was most pronounced in the epinephrine group. Pigs receiving epinephrine also showed >40% damage of the mucosa of the ileum and colon, whereas animals receiving ET alone, norepinephrine, or dopexamine showed only moderate lesions with signs of restitution. No animal showed bacterial translocation. Systemic hemodynamics and oxygen metabolism data do not reflect intestinal perfusion. Norepinephrine or dopexamine administration in ET shock causes no additional impairment of intestinal integrity. Epinephrine therapy, in contrast, is associated with a significant reduction of mucosal pHi and considerable early mucosal damage. Its application in septic shock is hazardous.