gms | German Medical Science

Einleitung: Ischemia of the spinal cord and the subsequent reperfusion injury are central problems of vascular surgery procedures on the aorta e.g. aneurysm repair. In a pig animal model we showed in the past that erythropoietin (EPO) attenuates the morphological signs of spinal cord ischemia/reperfusion (I/R) injury and improves neurological function. As observation time was only 10 hours short it failed therefore to assess clinical neurological follow-up. This small animal model bases on an existing model performed before, now optimizing clamping time and evaluating the benefit of perioperative i.v. EPO adminstration. This should give answer to the question of the clinical outcome up to 4 days.

Material und Methoden: To evaluate the optimal clamping time 36 New Zealand White Rabbits were used. After i.v. ketamin narcosis the aorta was clamped to produce paraplegia of the lower limbs. The ischemic times ranged from 15 over 17 to 20, 22 and 25 min to define best fitting clamping time. Afterwards, in a randomized and blinded trial, rabbits received either vehicle (control, n=10) or EPO (n=10; 5000 IU/kg) over the last 30 min before clamping and during the first 30 minutes of reperfusion. Intraoperatively blood pressure (invasive), heart rate, oxygen saturation and temperature were recorded. Clinical neurological examinations were performed using a modified Tarlov score every twelve hours. After 96h the entire spinal cord was harvested for histological examination.

Ergebnisse: After 96 h postoperative observation period the animals of the 15 min clamping group showed a tarlov score of 3.65 ± 1.55; 17 min 4 ± 1.75; 20 min 1.5 ± 2.22; 22 min 0 ± 1.59; 25 min 0 ± 0. Histological and clinical findings were significantly correlated, p = 0.007. Therefore a clamping time of 22 minutes was defined for further experiments. The following study groups consisted of control animals (NaCl; n=10) and EPO treated animals (n=10) challenged with 22 minutes aortic clamping. While the control animals showed no neuronal function at all (median=0), the EPO group standed out with improved spinal cord function (median=4,25) after 36 hours of reperfusion. This benefit was lost again after 96 hours of reperfusion (median=0).

Schlussfolgerung: Since the procedure is saving time, manpower and costs when compared to the large animal model, it is an ideal setup for therapeutic studies on ischemia and reperfusion injury (I/R) after aortic crossclamping. EPO showed impressive benefits in ischemic neuronal tissue by improving spinal cord function.