Arginine vasopressin reduces intestinal oxygen supply and mucosal tissue oxygen tension

We investigated intestinal oxygen supply and mucosal tissue Po 2 during administration of increasing dosages of continuously infused arginine vasopressin (AVP) in an autoperfused, innervated jejunal segments in anesthetized pigs. Mucosal tissue Po 2 was measured by 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-min 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 led 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 −1 ·min −1 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 at 0.114 IU·kg −1 ·h −1 ), mucosal tissue Po 2 (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). We conclude that continuously infused AVP decreases intestinal oxygen supply and mucosal tissue Po 2 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.