Background. Continuous and minimally invasive near-infrared spectroscopy (NIRS)-derived gastric tissue oxygen saturation (GStO2) and muscle tissue oxygen saturation (MStO2) were evaluated in a clinically relevant porcine model of hemorrhagic shock and abdominal compartment syndrome (ACS). Methods. Phenobarbital-anesthetized swine underwent pulmonary artery catheter insertion for mixed venous oxygen saturation (SvO2) measurement and midline laparotomy to permit placement of a gastric NIRS probe, a jejunal (regional-carbon dioxide [PrCO2]) tonometer, superior mesenteric artery (SMA) flow probe, and a portal vein oxygen saturation (SpvO2) catheter. A muscle NIRS probe was placed on the front limb. After randomization, Group 1 underwent hemorrhage and resuscitation. Group 2 had no hemorrhage or resuscitation. ACS was induced by peritoneal fluid infusion in both groups. A significant decrease in SMA flow, SpvO2, GStO2, SvO2, and MStO2 was observed after hemorrhage in Group 1 and with abdominal hypertension in both groups. Results. GStO2 significantly correlated with SMA flow (Group 1: r2 = O.90; Group 2: r2 = 0.83) and- mesenteric oxygen delivery [mesenteric oxygen delivery, Group 1: r2 = O.73; Group 2: r2 = 0.89). MStO2 significantly correlated with SvO2 (Group 1: r2 = 0.99; Group 2: r2 = 0.65) and systemic oxygen delivery (SD02, Group 1: r2 = 0.60; Group 2: r2 = 0.88). Tonometer-derived PrCO2 values did not change at any time point in either group. Conclusions. NIRS measurement of GStO2 and MStO2 reflected changes in mesenteric and systemic perfusion respectively during hemorrhage and ACS.
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