Iloprost protects the spinal cord during aortic cross-clamping in a caninemodel

Background. Surgical procedures on the thoracoabdominal part of the aorta m ake the spinal cord vulnerable to ischemia. Paraplegia is the most severe c omplication following thoracoabdominal operations. In this study, iloprost was used as an agent to decrease the severity of ischemia and reperfusion i njury to the spinal cord during aortic occlusion and declamping. Methods. Twelve adult mongrel dogs weighing 17 +/- 2 kg were used in this s tudy. The animals were randomly assigned to either group I, which received saline solution (6 dogs), or group II, which received prostacyclin. Group I was referred to as the control group and group II as the iloprost group. A fter baseline measurements were completed, the aorta was cross-clamped for sixty minutes distal to the left subclavian artery. No pharmacologic agents were used to control blood pressure in group I. Proximal and distal mean a rterial pressures (DMAP) were monitored continuously. DMAP were considered as diastolic pressure in preocclusion and reperfusion periods. Iloprost adm inistration was started at a rate of 5 ng/kg/minute five minutes before the aortic occlusion. This dosage was increased to 25 ng/kg/minute during aort ic occlusion. Results. Mean proximal arterial pressure was 147 +/- 12 mmHg in the control group and 116 +/- 13 mmHg in the iloprost group at occlusion (p<0.01). Mea n distal arterial pressure was 19 +/- 7 in the control group and 32 +/- 5 i n the iloprost group during clamping (p<0.05). Functional outcome was evalu ated according to Tarlov scores 24 hours after the study. Although none of the animals recovered completely from the control group, 4 animals from the iloprost group recovered (p<0.05). Following the neurologic assessment, an imals were sacrificed and specimens were taken for the electron microscopic study. Electron microscopic changes documented that severe mitochondrial d amage and vacuolisation occurred in the control group. However these change s were more subtle in the iloprost group. Conclusions. As a result of this study we concluded that iloprost infused b efore and during clamping of the thoracic aorta mitigates the spinal cord i njury due to ischemia and reperfusion following unclamping.