Rapid hypothermic aortic flush can achieve survival without brain damage after 30 minutes cardiac arrest in dogs

Background Neither exsanguination to pulselessness nor cardiac arrest of 30 min duration can be reversed with complete neurologic recovery using conve ntional resuscitation methods. Techniques that might buy time for transport , surgical hemostasis, and initiation of cardiopulmonary bypass or other re suscitation methods would be valuable. We hypothesized that an aortic flush with high-volume cold normal saline solution at the start of exsanguinatio n cardiac arrest could rapidly preserve cerebral viability during 30 min of complete global ischemia and achieve good outcome. Methods: Sixteen dogs weighing 20-25 kg were exsanguinated to pulselessness over 5 min, and circulatory arrest was maintained for another 30 min. They were then resuscitated using closed-chest cardiopulmonary bypass and had a ssisted circulation for 2 h, mild hypothermia (34 degreesC) for 12 h, contr olled ventilation for 20 h, and intensive care to outcome evaluation at 72 h. Two minutes after the onset of circulatory arrest, the dogs received a f lush of normal saline solution at 4 degreesC into the aorta (cephalad) via a balloon catheter, Group I (n = 6) received a flush of 25 ml/kg saline wit h the balloon in the thoracic aorta; group n (n = 7) received a flush of 10 0 ml/kg saline with the balloon in the abdominal aorta. Results: The aortic flush decreased mean tympanic membrane temperature (Tty ) in group I from 37.6 +/- 0.1 to 33.3 +/- 1.6 degreesC and in group II fro m 37.5 +/- 0.1 to 28.3 +/- 2.4 degreesC(P = 0.001). In group I, four dogs a chieved overall performance category (OPC) 4 (coma), and 2 dogs achieved OP C 5 (brain death). In group II, 4 dogs achieved OPC 1 (normal), and 3 dogs achieved OPC 2 (moderate disability). Median (interquartile range [IQR]) ne urologic deficit scores (NDS 0-10% = normal; NDS 100% = brain death) were 6 9% (56-99%) in group I versus 4% (0-15%) in group II (P = 0.003). Median to tal brain histologic damage scores (HDS 0 = no damage; > 100 = extensive da mage; 1,064 = maximal damage) were 144 (74-168) in group I versus 18 (3-36) in group II (P = 0.004); in three dogs from group II, the brain was histol ogically normal (HDS 0-5). Conclusions A single high-volume flush of cold saline (4 degreesC) into the abdominal aorta given 2 min after the onset of cardiac arrest rapidly indu ces moderate-to-deep cerebral hypothermia and can result in survival withou t functional or histologic brain damage, even after 30 min of no blood flow .