Submitted on December 8, 2004
Accepted on March 9, 2005
Arginine-Vasopressin Reduces Intestinal Oxygen Supply and Mucosal Tissue Oxygen Tension
Hans Knotzer1*, Werner Pajk1, Stephan Maier1, Ruth Ladurner2, Axel Kleinsasser1, Volker Wenzel1, Martin W Dunser1, Hanno Ulmer3, and Walter R Hasibeder4
1 Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Tirol, Austria
2 General Surgery, Innsbruck Medical University, Innsbruck, Tirol, Austria
3 Biostatistics and Documentation, Innsbruck Medical University, Innsbruck, Tirol, Austria
4 Anesthesiology and Critical Care Medicine, Krankenhaus der Barmherzigen Schwestern Ried, Ried, Upper Austria, Austria
* To whom correspondence should be addressed. E-mail: johann.knotzer{at}uibk.ac.at.
We investigated intestinal oxygen supply, and mucosal tissue oxygen tension during administration of increasing dosages of continuously infused Arginine-Vasopressin (AVP) in an autoperfused, innervated jejunal segment in anesthetized pigs. Mucosal tissue PO2 was measured employing two Clark-type surface oxygen electrodes. Oxygen saturation of jejunal microvascular hemoglobin was determined by tissue reflectance spectrophotometry. Microvascular blood flow was assessed by laser-Doppler velocimetry. Systemic hemodynamic variables, mesenteric-venous and systemic acid base and blood gas variables, and lactate measurements were recorded. Measurements were performed at baseline and at 20 minute intervals during incremental AVP infusion (n = 8; 0.007; 0.014; 0.029; 0.057; 0.114; and 0.229 IU.kg-1.h-1 , respectively), or infusion of saline (n = 8). AVP infusion lead to a significant (p<.05), dose-dependent decrease in cardiac index (from 121±31 to 77±27 mL.kg-1. min-1 at 0.229 IU.kg-1.h-1) and systemic oxygen delivery (from 14±3 to 9±3 mL/kg/min at 0.229 IU.kg-1.h-1) concomitant with an increase in systemic oxygen extraction ratio (from 31±4 to 48±10 %). AVP decreased microvascular blood flow (from 133±47 to 82±35 perfusion units (PU) at 0.114 IU.kg-1.h-1), mucosal tissue oxygen tension (from 26±7 to 7±2 mmHg at 0.229 IU.kg-1.h-1) and microvascular hemoglobin oxygen saturation (from 51±9 to 26±12 % at 0.229 IU.kg-1.h-1) without a significant increase in mesenteric venous lactate concentration (2.3±0.8 vs. 3.4±0.7 mmol.L-1). We conclude that continuously infused AVP decreases intestinal oxygen supply and mucosal tissue oxygen tension, due to a reduction in microvascular blood flow and due to the special vascular supply in the jejunal mucosa in a dose-dependent manner in pigs.
