Protection Of Spinal Cord Ischemia After Clamping Of Descending Aorta- The Experimental And Clinical Trial Of Distal Aortic Perfusion, Cerebrospinal Fluid Drainage And Retrograde Venous Perfusion Under The Monitoring Of Cerebrospinal Fluid Biochemical Mar

Due to the anatomic characteristic of blood supply for spinal cord. The main complication for TAAA/DTAA surgery was spinal cord ischemia injury. Many efforts were made to prevent this complication. This study design to clinically and experimentally examine differences in spinal complication after extended cross-clamping thoracoabdominal aorta comparing simple cross-clamp technique and the use of surgical adjuncts i.e. distal aortic perfusion, cerebrospinal fluid drainage and retrograde venous perfusion. The study also design to evaluate and describe neurospecific protein to serve as marker of spinal cord injury in cerebrospinal fluid during and after thoracoabdominal aortic aneurysm surgery. This study consist three parts as following:Part one The effect of spinal cord protection during aortic cross clamping ---- Comparing of distal aortic perfusion, cerebrospinal fluid drainage, and retrograde venous perfusionObjective To investigate spinal cord protection during aortic cross clamping in canine model under three different adjuncts, cerebrospinal fluid drainage (CSFD), distal aortic perfusion (DAP) and retrograde venous perfusion (RVP). Method Twenty dogs were randomized to four treatment groups. 1. received only aortic cross-clamp; 2. DAP and CSFD; 3. DAP +CSFD+RVP; 4. CSFD + RVP. All animals underwent 60 min of complete aortic cross-clamp. The neurological outcome of spinal cord were evaluated by muscle motility score of animals'hind legs. CSF level of glial fibrillary acidic protein(GFAP) and Light subunit of neurofilament (NFL) were determined during operation and post-operation. All the outcome were compared between four groups.Results Compared to group 2 and 3, the muscle motility score were significantly decreased in group 1 and 4 without different between group 1 and 4 or group 2 and 3. GFAP and NFL level in CSF during operation did not change significantly among 4 groups. After 3 hours post-operation, GAFP and NFL level were significantly increased compared to group 2 and 3. The difference of GFAP and NFL between group 1 and 4 or group 2 and 3 were not significant.Conclusion DAP plus CSFD was effective adjunct to spinal cord ischemia of aortic clamping whereas RVP was not. RVP maybe a promising route for cooling and drug administration of spinal cord. GFAP and NFL in CSF showed as good indexes as GFAP showed more pronounced increase.Part two The significance of biochemical markers of cerebrospinal ischemia during and after repair of aneurysm of descending and thoracoabdominal aortaObjective To investigate the relation between the release of biochemical markers in cerebrospinal fluid (CSF) and spinal cord ischemia during thoracoabdominal aortic or descending thoracic aortic aneurysm (TAAA/DTAA) repair operation and its postoperative period.Methods From Jan 2005 to Sep 2006, 43 patients undergoing elective TAAA/DTAA repair using sequential cross-clamping, distal aortic perfusion and CSF drainage were studied. CSF concentration of the markers glial fibrillary acidic protein(GFAP), the light subunit of neurofilament(NFL), and S100B were detected at ten different timepoints from before surgery until 3 days postoperatively. The concentration of biochemical marker were compared between spinal cord ischemia and asymptomatic patients.Results Four patients with spinal cord symptoms had significant increase of CSF biomarkers during the postoperative period although did not increase during operative period. Compared to asymptomatic patients, in symptomatic patients, the mean peak value of GFAP, NFL and S100B are139–fold, 4.5-fold and 7.7–fold respectively. The concentration curve of GFAP at the period after 3 hour of postoperation was totally separated from that of asymptomatic patients. In two delayed paraplegia cases, biomarkers increased 6 and 19 hours before onset of symptom. By intensive treatment, both cases had significantly been improved in neurological outcome.Conclusions Biochemical markers in CSF increase too late for intraoperative monitoring of spinal cord ischemia, but GFAP is promising marker for identifying patients for postoperative delayed paraplegia. Part three Observation of spinal cord cooling effect for retrograde hypothermic perfusion during thoracoabdominal aortic aneurysm repairObjective To evaluate spinal cord cooling effect of retrograde venous hypothermic perfusion during thoracoabdominal aneurysm repair.Methods 17 cases thoracoabdominal aneurysm repair were performed under multiple spinal cord protection strategies include sequential cross-clamping, cerebrospinal fluid drainage and distal aortic perfusion using BioMedicus pump artriofemoral bypass. Besides these, the hemizygous vein were cannulated and perfused by cold blood from side arm of BioMedicus visceral and renal perfusion system. Through the intrathecal catheter at L4-5 intervertebral level, spinal temperature was measured by micro-thermometer during perfusion period. By comparing the temperature between spinal cord and nasopharyngeal, the cooling effect of perfusion was evaluated.Results Spinal cord temperature went down immediately after 5 minutes'cold perfusion. At 25th minutes of perfusion, spinal cord temperature reached the lowest point, which was 3.1℃gap to nasopharygeal temperature (p<0.01). Conclusion Retrograde homozygous venous perfusion with hypothermic blood revealed its cooling effect to spinal cord. It provides another feasible adjunct way for spinal cord protection during thoracoabdominal aneurysm repair.