RETROGRADE CEREBRAL PERFUSION DURING PROFOUND HYPOTHERMIA AND CIRCULATORY ARREST IN PIGS

The purpose of this study was to evaluate the use of retrograde cerebr al perfusion via the superior vena cava during profound hypothermia an d circulatory arrest (CA) in pigs. In three groups of 5 pigs each, gro up A (control) underwent cardiopulmonary bypass and normothermic CA fo r 1 hour, group B underwent cardiopulmonary bypass, profound hypotherm ia, and CA (15 degrees C nasopharyngeal) for 1 hour, and group C under went the same procedure as group B plus retrograde cerebral perfusion. In group A none awoke. In group B, 2 of 5 did not awake and 3 of 5 aw oke unable to stand, 2 with perceptive hind limb movement and 1 moving all extremities. In group C all awoke, 4 of 5 able to stand and 1 of 5 unable to stand but moving all limbs. In neurologic evaluation group B had significantly lower Tarlov scores than group C (p = 0.0090). Gr oup B mean wake-up time, plus or minus standard error of the mean, was 124.6 +/- 4.6 minutes versus 29.2 +/- 5.1 in group C (p = 0.0090). In group B late phase CA cerebral blood now dropped 30.9% +/- 4.8%, but in group C it rose 24.7% +/- 9.3% (p = 0.0007, pooled variance t test, two-tailed). In group B late phase CA brain oxygenation decreased 46. 0% +/- 13.9% but it increased 26.1% +/- 5.4% in group C (p = 0.0013). This difference was reduced somewhat during rewarming (B, -21.2% +/- 1 4.9%; C, 16.4% +/- 4.7%; p = 0.043). Group B rewarming jugular venous O-2 saturation was 30.8% +/- 2.5% versus 56.0% +/- 4.4% in group C (p = 0.0011). We conclude that in pigs retrograde cerebral perfusion comb ined with profound hypothermia during CA significantly reduces neurolo gic dysfunction, providing superior brain protection.