Near-infrared spectroscopy reflects changes in mesenteric and systemic perfusion during abdominal compartment syndrome

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.