Epidural cooling for regional spinal cord hypothermia during most or all of descending thoracic or thoracoabdominal aneurysm repair

Purpose: Hypothermia has some protective effect against ischemia of the spinal cord in thoracoabdominal aneurysm repair. Its method is divided into systemic or regional cooling. Several experimental studies of the regional cooling of the spinal cord have been performed, however, clinical reports are few. The purpose of this study is to evaluate the effect and safety of perfusion cooling of the epidural space during thoracic or thoracoabdominal aortic replacement. Methods: Between January 1998 to June 2001 37 patients (True aneurysm: 18 patients, type B aortic dissection: 19 patients) underwent thoracic or thoracoabdominal aortic replacement with an aid of epidural perfusion cooling. The age ranged from 23 to 78 years old with a mean age of 61 years old. Separate perfusion of upper and lower body was used in all cases. Temperature was lowered to around a 31°C or 32°C. In cases where proximal cross-clamping was danger, deep hypothermic circulatory arrest was used.

Results: Ten patients underwent most or all of descending thoracic aneurysm repair with no spinal cord injury and hospital death. Number of patients of the Crawford type I, type II, and type III were 14, 8 and 5 patients, respectively. One Crawford type II patient was complicated with postoperative spinal cord injury (2.7%). There was one hospital death (2.7%) in Crawford type III. The mean epidural cooling time was 150 minutes, and mean infusion volume of cold saline was 981 cc. The mean lowest cerebrospinal fluid (CSF) temperature was 24.3°C, and mean temperature differences between nasopharynx and CSF was 6.3°C.

Conclusion: Perfusion cooling of the epidural space during most or all of the descending thoracic or thoracoabdominal aneurysm repair was effective in reducing postoperative spinal cord injury and a safe method in clinical situations.