Purpose: We investigated the feasibility of achieving regional hypothermia of the spinal cord with an infusion of iced (4 degrees C) saline solution administered into an epidural catheter while monitoring cerebral spinal fluid (CSF) temperature in eight patients undergoing thoracic or thoracoabdominal aneurysm resection.
Methods: As part of the anesthetic management, an epidural catheter was placed at T11-12, and a subarachnoid thermistor catheter was placed at L3-4. Approximately 30 minutes before aortic cross-clamping, iced (4 degrees C) saline solution was infused into the epidural catheter until CSF temperature decreased to approximately 25 degrees C. The infusion was then adjusted to maintain this temperature until the aorta was unclamped. The subarachnoid catheter was also used to measure CSF pressure and provide for CSF drainage. Surgery was performed in all patients with a clamp-and-sew technique with selective intercostal vessel reattachment.
Results: Infusion of a mean volume of 489 ml (range 80 to 1700 ml) of iced saline solution into the epidural space before aortic cross-clamping led to a decrease in mean CSF temperature to 26.9 degrees C (range 25 degrees to 28.8 degrees C) in 15 to 90 minutes. During cross-clamping and aortic replacement the mean CSF temperature was maintained between 25.2 degrees to 27.6 degrees C and, with discontinuation of the infusion, returned to within 1 degrees C of body core temperature by the end of the procedure. Body core temperature was not significantly affected by the epidural infusion. Mean CSF pressure increased during the epidural infusion but could be reduced by removing saline solution from the epidural space. No postoperative neurologic deficits were observed.
Conclusion: Epidural cooling appears to be a satisfactory method of achieving regional spinal cord hypothermia in patients requiring resection of thoracic or thoracoabdominal aortic aneurysms.