To test the hypothesis that systemic hypothermia (SH) to 30°C in combination with partial left heart bypass (PLHB) at either a high or low distal arterial perfusion pressure (DAPP) following 45 minutes of crossclamp (XC) occlusion of the thoracic aorta will protect against clinical and histological spinal cord ischemia in the dog.
A blinded, prospective, randomized, and controlled experimental trial.
Tertiary care center animal laboratory.
Seventeen adult mongrel dogs.
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). Main Outcome Measures: Clinical and histological neurological injury evaluation by separate blinded observers.
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
Systemic hypothermia to 30°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.Arch Surg. 1997;132:633-640