The Effect Of Propofol Ischemia Post-conditioning On Spinal Cord: Intra-aorta Verus Intravenous

Objective: To investigate the effect of propofol intra-aorta infusion and intravenous infusion on IL-6 and the concentration of propofol for an ischemia-reperfusion spinal cord injury in rabbits.Methods: Eighty-two healthy adult New Zealand white rabbits were randomly divided into 4 groups: control group (group C, n=4), Saline intra-aorta infusion group (group N, n=26), Propofol intra-aorta infusion group(group A, n=26) and Propofol intravenous infusion group(group V, n=26). Under general anesthesia, an epidural catheter was carmulated to the infrarenal abdominal aorta in N, A and V groups. Then the infrarenal abdominal aorta was occluded for 30rnin, during which Propofol 50mg/kg were infused continuously through the epidural catheter in group A or intravenous in group V respectively with a pump. In group N, the same volume of normal saline were infused with the same way and rate as group A. The mean blood pressure, doses of anesthetics and fluids administration during the whole procedure were recorded. At Oh after reperfusion , the lumbosacral 4-6 and thoracic 6-8 segments of spinal cords were harvested and the propofol concentration were examined in group A and V. At Oh(T₀) or 2h (T₂) after reperfusion in group N,A and V, and the time after anesthesia in group C, the lumbosacral 4-6 segments of spinal cords were also harvested and the IL-6 were examined. After the neurologic outcomes were scored on a 0-4 grading scale (Tarlov scale system) in which 0-1 were presented as paraplegia at 48h after reperfusion, the lumbosacral 4-6 segments of spinal cords were fixed , HE stained and the numbers of normal neurons in the anterior spinal cord were counted in each group. The difference of propofol and IL-6 concentrations were analyzed by using ANOVA. The numbers of normal neurons and the paraplegia incidence were analyzed by using Kruskal-Wallis tests. P＜0.05 was considered statistically significant.Results: The paraplegia incidence was lower(30%) and the median of normal neurons was higher (8.4) in group A than those in group N(80%, 2.2) and group V(100%,1.9) (P＜0.05). The IL-6 levels increased at T₂ than T₀ in group N,A and V(P＜0.05). The levels were decreased in group C than those at T₀,T₂ in group N and T₂ in group V (P＜0.05). In group N the IL-6 levels were higher than those in group A and V at the same time after reperfusion (P＜0.05). The IL-6 levels were increased in group V than those in group A at the same time after reperfusion. The propofol concentration in lumbosacral 4-6 of group A were higher than those in thoracic 6-8 of group A and both thoracic 6-8 and lumbosacral 4-6 of group V(P＜0.05). The mean blood pressures were decreased in group V than those in group A and N(P＜0.05), in which the doses of anesthetics and fluids administration were less than group V(P＜0.05).Conclusions: The expression of IL-6 in the ischemia-reperfusion injury spinal cord.would be inhibited by propofol. Intra-aorta infusion shows a better neurologic outcomes than intravenous infusion which would be contribute to the higher concentration of propofol in the ischemia spinal cord and the stronger inhibition of pro-inflammatory cytokines. And with less inhibition on circulation, propofol intra-aorta infusion would be considered as a better way in spinal cord protection.