Effect and optimum dosage of lidocaine infused through aorta to reduce ischemic spinal cord injury in rabbits

Objective This study was designed to investigate the effect and optimum dosage of lidocaine when infused through aorta to pretect the spinal cord against ischemia reperfusion injury(IRI) in rabbits. Methods Forty New Zealand white rabbits were divided randomly into 5 groups(n=8): one control group of normal saline(NS group) and 4 lidocaine groups at different doses of 10,20,40 and 80 mg/kg respectively(L10,L20,L40 and L80 groups).Spinal cord ischemia was induced by clamping the abodomial aorta just bellow the left renal artery combined with simultaneously clamping bilateral common iliac arteries for 30 minutes.A catheter was inserted into abdominal aorta close to the site of occlusion via femoral artery.Right after the cross-clamping,the rabbits received regional infusion of normal saline and different doses of lidocaine solution via the catheter into the clamped aorta.Half an hour later,the abdominal aorta and the bilateral common iliac arteries were unclampted for reperfusion.The hemodynamic changes were monitored and neurological status was assessed according to the modified Tarlov scale system at the moment of emergence and 6,24 and 48 hours after the reperfusion.Lumbar segments of the spinal cord(L4-L6) were removed at 48 hours after reperfusion for pathological examination,and the total number of normal motor neurons in the anterior horn were counted. Results Compared with control group,regional lidocaince infusion significantly improved the Tarlov scores and numbers of normal motor neurons,and lidocaine 40 mg/kg functioned the most effetive(P0.05).The heart rates of two rabbits decreased significantly in L80 group.Compared with other lidocaine groups,mean arterial pressure decreased in L80 group during the reperfusion(P0.05). Conclusions Regional infusion of lidocaine during clamping process can provide significant protection to the spinal cord against IRI in rabbits,and the most optimum dosage is 40 mg/kg in the research.