A NEW SOLUTION FOR LIFE WITHOUT BLOOD - ASANGUINEOUS LOW-FLOW PERFUSION OF A WHOLE-BODY PERFUSATE DURING 3 HOURS OF CARDIAC-ARREST AND PROFOUND HYPOTHERMIA

Background The benefits of hypothermia for preventing ischemic injury are well known, but its application in surgery to protect the whole bo dy during procedures requiring circulatory arrest is currently limited to <1 hour at 15 degrees C using 50% hemodilution. In a significant d eparture from previous methods, we have developed a technique of asang uineous blood substitution with low-how perfusion and cardiac arrest a t <10 degrees C in a canine model. Our approach has been to design a h ypothermic blood substitute that would protect the brain and visceral organs during several hours of bloodless perfusion. Two different solu tions have been designed to fulfill separate requirements in the proce dure. Methods and Results With the use of extracorporeal cardiac bypas s, 14 adult dogs were exsanguinated during cooling; 11 dogs were blood substituted using in combination the ''purge'' and ''maintenance'' so lutions (group 1), and 3 dogs were perfused throughout with the ''purg e'' solution alone as controls (group 2). After cardiac arrest, the so lutions were continuously circulated for 3 1/2 hours by the extracorpo real pump (flow rate, 40 to 85 ml.kg(-1).min(-1); mean arterial blood pressure, 25 to 40 mm Hg). The temperature was maintained at <10 degre es C (nadir, 6.6+/-0.1 degrees C) for 3 hours, and the hematocrit was kept at <1% before controlled rewarming and autotransfusion. In the ex perimental group, the heart always started spontaneously in the temper ature range of 11 degrees C to 27 degrees C, and 8 animals have surviv ed long-term (current range, 14 to 110 weeks) without any detectable n eurological deficit. In contrast, two control animals survived after e xtensive and aggressive cardiac resuscitation efforts; after surgery t hey exhibited transient motor and sensory deficits for approximately 1 week. Evaluation of biochemical and hematological parameters showed o nly a transient and inconsequential elevation in enzymes leg, brain, l iver, cardiac) in group 1 compared with the markedly greater elevation s in group 2. For example, immediate postoperative values (mean+/-SEM) for lactate dehydrogenase were 114+/-10 for group 1 versus 490+/-210 for group 2 (P<.03); for SOOT, values were 93+/-18 for group 1 versus 734+/-540 for group 2 (P<.05). On day 1 for creatine kinase (CK), the group 1 value was 7841+/-2307 versus 71550+/-2658 for group 2 (P=.03), and for CK-BB, the group 1 value was 108+/-22 versus 617+/-154 for gr oup 2 (P=.03). Neurological evaluation using deficit scores (NDS) was based on a modification of the Glasgow Coma Scale score: 0, normal; 1, minimal abnormality; 2, weakness; 3, paralysis; 4, coma; and 5, death . At days 1 and 2 after surgery, NDS (mean+/-SEM) were 0+/-0 for the e xperimental group versus 1.5+/-0.5 for the control group. At days 3 an d 7 after surgery, NDS were 0+/-0 for group 1 Versus 1.0+/-1.0 for gro up 2. Conclusions The faster neurological recovery of dogs treated wit h the ''intracellular-type'' maintenance solution supports the biochem ical data showing the benefits of this type of blood substitute for ex tending the safe limits of hypothermic cardiac arrest procedures to >3 hours.