Effects of Thoracic Epidural Anesthesia on Hemodynamics and Global Oxygen Transport in Ovine Endotoxemia

Abstract

Besides providing effective analgesia, thoracic epidural anesthesia (TEA) has been shown to decrease perioperative morbidity and mortality. Because of its vasodilatory properties in association with the sympathetic blockade, however, TEA may potentially aggravate cardiovascular dysfunctions resulting from sepsis and systemic inflammatory response syndrome. The objective of the present study was to assess the effects of TEA on hemodynamics, global oxygen transport, and renal function in ovine endotoxemia. After a baseline measurement in healthy sheep (n = 18), Salmonella typhosa endotoxin was centrally infused at incremental doses to induce and maintain a hypotensive-hypodynamic circulation using an established protocol. The animals were then randomly assigned to one of two groups. In the treatment group, continuous TEA was initiated with 0.1 mL.kg of 0.125% bupivacaine at the onset of endotoxemia and maintained with 0.1 mL.kg.h. In the control group, the same amount of isotonic sodium chloride solution was injected through the epidural catheter. In the animals surviving the entire experiment (n = 7 per group), cardiac index and mean arterial pressure decreased in a dose-dependent manner during endotoxin infusion. In the TEA group, neither systemic hemodynamics nor global oxygen transport were impaired beyond the changes caused by endotoxemia itself. Urinary output was increased in the TEA group as compared with the control group (P < 0.05). In this model of endotoxic shock, TEA improved renal perfusion without affecting cardiopulmonary hemodynamics and global oxygen transport.

Effects of thoracic epidural anesthesia on survival and microcirculation in severe acute pancreatitis: a randomized experimental trial

“…Additionally, there are several studies in animals suffering from systemic inflammation demonstrating the benefits of using TEA. Models using cecal ligation to induce severe systemic inflammation demonstrated an improvement of sepsis-induced alterations of hepatic blood flow as well as improved mucosal microcirculation in rats [24,26]. In a model of systemic inflammation during endotoxemia in an ovine model as well as in the rat, superior renal perfusion as well as an attenuation of impairment of gastrointestinal organ perfusion and improved microvascular mucosa perfusion could be demonstrated [22,24,25].…”

“…In perioperative and experimentally induced hemorrhage positive effects due to epidural anesthesia on gastrointestinal microcirculation could be demonstrated [22,23]. TEA is further reported to improve renal and gastrointestinal perfusion during endotoxemia [22,24,25]. This is also true for microvascular blood flow in the liver or ileal mucosa in other models of systemic inflammation [24,26].…”

“…TEA is further reported to improve renal and gastrointestinal perfusion during endotoxemia [22,24,25]. This is also true for microvascular blood flow in the liver or ileal mucosa in other models of systemic inflammation [24,26]. Some first attempts also showed promising results for the use of TEA in pancreatitis demonstrating reduced liver injury, improved ileal mucosal capillary perfusion and survival as well as pancreatic microcirculation in the rat [26-28].…”

Hemodynamic Effects of Thoracic Epidural Analgesia in Ovine Hyperdynamic Endotoxemia

“…9 In brief, a pulmonary artery catheter was percutaneously inserted through an introducer sheath in the right jugular vein. In addition, an arterial line was placed in the left femoral artery.…”

“…8 In a model involving the acute loading with high endotoxin doses and thus producing an acute hypodynamic circulation with decreased cardiac output, TEA has been shown to provide relative circulatory stability compared with a control group. 9 In contrast, the hyperdynamic state of sepsis is characterized by a high cardiac output in adaptation to peripheral vasodilation. However, the effects of TEA under the conditions of vasodilatory endotoxic shock are still unclear.…”