Laser speckle contrast imaging for assessing microcirculatory changes in multiple splanchnic organs and the gracilis muscle during hemorrhagic shock and fluid resuscitation

Objective: Hemorrhagic shock induces both macrocirculatory and microcirculatory impairment. Persistent microcirculatory dysfunction is associated with the dysfunction of multiple organs, especially in the splanchnic organs. However, few studies have simultaneously investigated microcirculation in multiple organs. In the present study, we used laser speckle contrast imaging to simultaneously investigate microcirculatory changes secondary to hemorrhagic shock and after fluid resuscitation among multiple splanchnic organs and the gracilis muscle. Materials and methods: 72 male Wistar rats were subjected to sham operation, hemorrhagic shock (total blood loss of 30 mL/kg) and saline resuscitation. Macrocirculatory parameters, including the mean arterial pressure (MAP) and heart rate, and microcirculatory parameters, including microcirculatory blood flow intensity and tissue oxygen saturation in the liver, kidney, intestine (mucosa, serosal muscular layer, and Peyer's patch), and gracilis muscle were compared in a period of 3 h. Results: Hemorrhagic shock induced a significant reduction of microcirculatory blood flow intensity in the kidney and intestine (especially the mucosa). Tissue oxygen saturation reduction secondary to hemorrhagic shock was comparable among the various splanchnic organs but lower than the gracilis muscle. Fluid resuscitation restored the MAP but not the microcirculatory blood flow in the intestine and the tissue oxygen saturation in each splanchnic organ. Conclusion: Hemorrhagic shock induced the largest reduction in microcirculatory blood flow intensity in the intestinal mucosa. By comparison, the reduction of tissue oxygen saturation was not significantly different among the various splanchnic organs. Although fluid resuscitation restored the MAP, the intestinal microcirculation remained damaged.