INTERMITTENT WHOLE-BODY PERFUSION WITH SOMATOPLEGIA VERSUS BLOOD PERFUSATE TO EXTEND DURATION OF CIRCULATORY ARREST

Background Continuous whole-body perfusion for >3 hours with a cold as anguineous blood substitute, hypothermosol (HTS) solution, has been re ported to preserve organ function. We used this solution in a survival animal model to evaluate its possible application in extending the sa fe duration of deep hypothermic circulatory arrest (DHCA). Methods and Results Fifteen piglets were placed on cardiopulmonary bypass (CPB), were cooled to a nasopharyngeal temperature of 15 degrees C, and under went 100 minutes of DHCA. Control animals (group C, n=5) had uninterru pted DHCA, group HTS animals were perfused with maintenance HTS for 5 minutes every 25 minutes during DHCA (n=5), and group B animals were i ntermittently perfused as for group HTS with the blood in the bypass c ircuit (n=5). Cerebral oxygenation was assessed with near-infrared spe ctroscopy throughout CPB and DHCA. Animals were allowed to recover aft er CPB and underwent daily neurobehavioral evaluation by the neurologi cal deficit score (NDS: 0, normal; 500, brain death) and overall perfo rmance categories (OPC: 1, normal; 5, brain death). Blood samples were drawn on postoperative day (POD) 1 for selected biochemistry analysis . On POD 4, the brain of each animal was perfusion-fixed for histologi cal evaluation, and a neurohistological score (NHS: 0, normal; 5+, nec rosis) was assigned for the degree of neuronal injury. All animals exc ept one from group HTS survived surgery. Mean perfusion pressures were significantly elevated in group B compared with group C and group HTS during the rewarming phase (P<.05). The HbO(2) signal increased in al l groups during the cooling phase of CPB and remained significantly ab ove baseline only in group B during DHCA (P<.05). SOOT, LDH, ALP, and CPK levels on POD 1 were elevated above baseline in all groups. The in crease in SCOT and ALP was significantly greater in group HTS than in the other groups (P<.02). The NDS was lower in group B on each postope rative evaluation, being significant relative to group C and group HTS on POD 1 (P<.05) and significantly lower than group C on POD 2 (P<.05 ). The OPC score was significantly lower in group B than in group C an d group HTS on POD 2 (P<.05) and significantly lower than in group C o n PODs 3 and 4 (P<.05). The NHS was lower in group B than in the other 2 groups, being significant relative to group C in the neocortex (P<. 007). Conclusions Intermittent whole-body asanguineous perfusion with hypothermosol solution does not extend cerebral protection in a porcin e survivor model of DHCA. Neurobehavioral and histological outcomes ar e improved in animals receiving intermittent blood perfusion during pr olonged DHCA.