Use of an epidural cooling catheter with a closed countercurrent lumen to protect against ischemic spinal cord injury in pigs

Objective: We developed an epidural cooling catheter containing cold saline solution circulating in an isolated lumen. After placement by a minimally invasive approach, we evaluated protection effect against ischemic spinal cord injury in pigs. Methods: Fourteen pigs underwent thoracic aortic double clamping for 45 minutes under systemic mild hypothermia (36°C). Group A (n = 7) underwent local hypothermia with the cooling catheter. Group B (n = 7) underwent catheter placement only, without cooling. Spinal cord somatosensory evoked potentials were recorded to assess electrophysiologic status. Neurologic function was evaluated with a modified Tarlov score. Results: At aortic crossclamping, spinal temperature in group A (26.5°C ± 2.4°C) was significantly lower than that in group B (35.3°C ± 0.6°C, P = .0001). Mean time from aortic crossclamping to onset of potential loss was significantly longer in group A (28.4 ± 6.6 minutes) than in group B (18.3 ± 5.0 minutes, P = .007). Mean duration of total loss of potentials was significantly shorter in group A (19.0 ± 6.7 minutes) than that in group B (31.3 ± 5.9 minutes, P = .003). Group A showed significantly better neurologic function (mean Tarlov score 4.4 ± 0.8) than that of group B (0.1 ± 0.4, P = .0001). Mean total number of intact motor neurons was significantly greater in group A (24.5 ± 6.8) than that of group B (9.9 ± 6.8, P = .0001). Conclusion: By cooling the spinal cord selectively and continuously, the newly designed epidural cooling catheter prevented ischemic injury in a pig model of aortic crossclamping.