Correlation between cerebral near-infrared spectroscopy and macro-hemodynamic changes post-fluid resuscitation in the Sus scrofa model of hemorrhagic shock

s Objectives: Current resuscitation approaches fo-cus on macrohemodynamic circulation, whereas adequate tissue perfusion and target organ oxygen delivery should be the primary goals. This study aimed to compare the macrohemodynamic markers with microcirculation markers (cere-bral oxygenation) in response to shock and fluid resuscitation. Design: This is an experimental study using an intact in vivo model of hemorrhagic shock. Setting: This study was conducted at a certified animal experimental laboratory. Patients and participants: Male domestic piglets (Sus scrofa) 6-10 weeks old were used as the model for this study. Interventions: Measurement of microcirculation in animal model of hemorrhagic shock. Measurement and results: Under anesthesia, the pressure-targeted shock was induced via venous blood drawing to reduce mean arterial pressure (MAP) by 20%, followed by normovolemic resuscitation using NaCl 0.9% of equal volume to the blood drawn. After 30 minutes, hypervolemic resuscitation using 40 ml/kg NaCl 0.9% was given. Pulse contour cardiac output (PiCCO) was used to monitor cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index (SVRI), and oxygen delivery (DO2), while near-infrared spectroscopy (NIRS) measured cerebral saturation (SctO2). All parameters were recorded at baseline, shock, immediately following normovolemic resuscitation, hypervo-lemic resuscitation (hypervolemic-1), and the next 30 minutes (hypervolemic-2), and 60 minutes (hypervolemic-3). There were strong correlations between delta SctO2, delta CI, delta SVI, and delta DO2 during the hemorrhagic shock and normovolemic phase (p<0.05). No macrohemodynamic parameters represent the cerebral oxygenation during hypervolemic-1 up to hypervolemic-3. Conclusions: Macrohemodynamic parameters were not correlated to SctO2 as a surrogate for microcirculation in every phase. We recommend routinely monitoring microcirculation as a target goal of resuscitation in critically ill patients.