An epidural cooling catheter protects the spinal cord against ischemic injury in pigs.
BACKGROUND
Using swine, we investigated whether epidural placement of a cooling catheter rather than infusing iced saline solution could protect the spinal cord from ischemia during aortic surgery.


METHODS
We divided 14 domestic pigs into two groups of 7 each. Each underwent epidural catheter placement preceding 30 minutes of aortic cross-clamping distal to the origin of the left subclavian artery. In group 1, cold water was circulated continuously through the lumen of the catheter connected to an external unit. In group 2, animals received catheter placement without cooling. Spinal cord somatosensory evoked potentials were recorded. Neurologic status involving hind limbs was graded sequentially after surgery.


RESULTS
At aortic cross-clamping, spinal temperature in group 1 (31.7 degrees +/- 0.6 degrees C) was significantly lower than in group 2 (37.8 degrees +/- 0.4 degrees C; p < 0.0001). No significant elevation of intrathecal pressure accompanied cooling with the catheter (group 1, 8.1 +/- 1.7 mm Hg; group 2, 8.0 +/- 1.5 mm Hg). Mean duration of total loss of potentials was significantly shorter in group 1 (7.4 +/- 3.8 minutes) than group 2 (19.7 +/- 7.3 minutes; p = 0.0002). Pigs in group 1 exhibited better hind limb function recovery (mean Tarlov score, 4.7 +/- 0.5) than group 2 (0.6 +/- 0.8; p = 0.0017). Group 1 showed normal histologic characteristics, whereas group 2 showed loss of motor neurons in the ventral horns.


CONCLUSIONS
Epidural cooling catheter without iced saline infusion can cool the spinal cord without elevating intrathecal pressure, protecting the cord against ischemia.
Mori
Atsuo
A
Department of Cardiovascular Surgery, Saitama Cardiovascular and Respiratory Center, Saitama, Japan. mori_atsuo@hotmail.com
Ueda
Toshihiko
T
Hachiya
Takashi
T
Kabei
Nobuyuki
N
Okano
Hideyuki
H
Yozu
Ryohei
R
Sasaki
Tatsuumi
T
D000818:Animals; D001011:Aorta / Q000601:surgery; D005073:Evoked Potentials, Somatosensory; D007036:Hypothermia, Induced / Q000379:methods*; D020760:Spinal Cord Ischemia / Q000517:prevention & control*; D013552:Swine