Effect Of Thoracic Epidural Sympathetic Block On Ischemical Penumbral Apoptosis In Rats

PartⅠConstruct thoracic epidural sympathetic block model of SD ratsObjectives:Thoracic epidural anesthesia (TEA) is used increasingly in critical care, especially for cardiac and intestinal sympathetic block. In this study we constructed thoracic epidural sympathetic block(TESB)model in rats and evaluated cardiorespiratory function and sympathetic activity in it.Methods:30 rats received epidural catheterization in the intervertebral space T5-T6, infuse saline control (CON) or ropivacaine 0.25% (EPI25) or ropivacaine 0.5%(EPI50) epidural infusion at 0.2ml on day 1 and day 3. Mean arterial blood pressure, heart rate, respiration rate, and motor score were recorded at baseline and after 30, 60, 90, and 120 min. Skin temperature was measured at front paws, high-thoracic, mid-thoracic, and low-thoracic, hind paws, and the proximal and distal tail.Results:Changes in sympathetic activity were assessed by skin temperature changes from baseline (ΔT). In the EPI group, hemodynamics and respiration remained unchanged and only mild motor deficits occurred in EPI25 group.ΔT in thoracic segments was higher in the EPI than in the CON group (P<0.01 at all times at high-thoracic, mid-thoracic, and low thoracic segments). Skin temperature decreased in the distal tail in the EPI group.ΔT on day 3 was comparable to day 1.Conclusion: 0.25% ropivacaine TESB induced stable segmental sympathetic block without cardiorespiratory and motor side effects in rats. This new technique may be applied in prolonged models of critical illness.