Protective effect of hypothermia and left heart bypass on spinal ischemia in the dog.
OBJECTIVE
To test the hypothesis that systemic hypothermia (SH) to 30 degrees C in combination with partial left heart bypass (PLHB) at either a high or low distal arterial perfusion pressure (DAPP) following 45 minutes of cross-clamp (XC) occlusion of the thoracic aorta will protect against clinical and histological spinal cord ischemia in the dog.


METHODS
A blinded, prospective, randomized, and controlled experimental trial.


METHODS
Tertiary care center animal laboratory.


METHODS
Seventeen adult mongrel dogs.


METHODS
The animals were randomized into 5 groups: control group 1: XC plus no protection (n = 3); control group 2; XC plus systemic normothermia plus PLHB, with a DAPP less than 20 mm Hg (n = 3); treatment group 1: XC plus systemic normothermia plus PLHB, with a DAPP greater than 20 mm Hg (n = 3); treatment group 2: XC plus SH plus PLHB, with a DAPP greater than 20 mm Hg (n = 3); treatment group 3: XC plus SH plus PLHB, with a DAPP less than 20 mm Hg (n = 5).


METHODS
Clinical and histological neurological injury evaluation by separate blinded observers.


RESULTS
Control animals were neurologically and histologically ischemic. Treatment animals were neurologically and histologically normal. Partial left heart bypass with a DAPP greater than 20 mm Hg prevented paraplegia, with either systemic normothermia or SH. Systemic hypothermia plus PLHB, even with a DAPP less than 20 mm Hg, protected against spinal cord ischemia during thoracic aortic occlusion.


CONCLUSIONS
Systemic hypothermia to 30 degrees C combined with PLHB at either a high or low DAPP prevented spinal cord ischemia following thoracic aortic XC occlusion in our canine model and merits clinical trial in patients.
Rose
W W
WW
Division of Vascular Surgery, Henry Ford Hospital, Detroit, Mich, USA.
Reddy
D J
DJ
Ernst
C B
CB
Reickert
C A
CA
Patterson
J S
JS
D000818:Animals; D004285:Dogs; D018611:Heart Bypass, Left; D007036:Hypothermia, Induced; D007511:Ischemia / Q000473:pathology / Q000517:prevention & control*; D011897:Random Allocation; D013116:Spinal Cord / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology