Gas tonometry for evaluation of gastrointestinal mucosal perfusion: experimental models of trauma, shock and complex surgical maneuvers - Part 1

Abstract

Substantial clinical and animal evidences indicate that the mesenteric circulatory bed, particularly the gut mucosa, is highly vulnerable to reductions in oxygen supply and prone to early injury in the course of hemodynamic changes induced by trauma, shock, sepsis and several complex surgical maneuvers. Gut hypoxia or ischemia is one possible contributing factor to gastrointestinal tract barrier dysfunction that may be associated with the development of systemic inflammatory response and multiple organ dysfunction syndrome, a common cause of death after trauma, sepsis or major surgeries. Monitoring gut perfusion during experiments may provide valuable insights over new interventions and therapies highly needed to reduce trauma and sepsis-related morbidity and mortality. We present our experience with gas tonometry as a monitor of the adequacy of gastrointestinal mucosal perfusion in clinical and experimental models of trauma, shock and surgical maneuvers associated with abrupt hemodynamic changes, such as aortic occlusion and hepatic vascular exclusion. Next issue we will be presenting our experience with gas tonometry in experimental and clinical sepsis.

Abdominal pressure and gastrointestinal function: an inseparable couple?

“…At the same time, this arrangement makes the tip of the villus highly susceptible to damage from hypoxia and/or hypotension ( Fig. 1) [14,17]. The oxygen extraction rate can be increased remarkably from 20% at rest in order that temporary reductions in blood flow can be tolerated.…”

“…In healthy subjects, the presence of nutrients in the small intestine augments intestinal blood flow via stimulation of secretion of vasoactive gastrointestinal hormones [17]. The magnitude of this increase in intestinal blood flow is dependent on meal size and the rate of nutrient delivery into the small bowel and can increase up to two-fold (superior mesenteric artery flow) [17].…”

“…The magnitude of this increase in intestinal blood flow is dependent on meal size and the rate of nutrient delivery into the small bowel and can increase up to two-fold (superior mesenteric artery flow) [17]. Such meal-induced splanchnic blood pooling, diverting around 20% of total blood flow to the intestines, results in a temporary "relative systemic hypovolemia" [59].…”

Gas tonometry for evaluation of gastrointestinal mucosal perfusion: experimental and clinical sepsis¹. part 2

“…Substantial clinical and animal evidences indicate that the mesenteric circulatory bed, particularly the gut mucosa, is highly vulnerable to reductions in oxygen supply and prone to early injury in the course of hemodynamic changes. We have presented our experience with gas tonometry in experimental models of trauma, shock and complex surgical maneuvers 1 . We also analyzed the concepts of the tonometric method and how PCO 2 is a marker of blood flow and tissue hypoxia.…”

“…We also analyzed the concepts of the tonometric method and how PCO 2 is a marker of blood flow and tissue hypoxia. 1 In the present issue, we further analyze the role of gas tonometry in experimental and clinical sepsis and septic shock. lic needs are typically increased by the inflammatory response to infection, increasing CO 2 load.…”