A Comparison of Complete Blood Replacement With Varying Hematocrit Levels on Neurological Recovery in a Porcine Model of Profound Hypothermic (<5°C) Circulatory Arrest

Publisher Website
Google Scholar
Abstract
Profound hypothermia (,5°C) may afford better neurologi- cal protection after circulatory arrest; however, there are the- oretical concerns related to microcirculatory sludging of blood components at these ultra-low temperatures. We hy- pothesized that at temperatures ,5°C, complete blood re- placement results in superior neurological outcome. Twelve Yorkshire pigs (30 kg) underwent thoracotomy, cardiopul- monary bypass (CPB), and were randomly assigned to one of three target hematocrits during circulatory arrest: 0%, 5%, 15%. Hextend® (6% hetastarch in a balanced electrolyte ve- hicle) was used for the CPB prime and as an exchange fluid. Animals were cooled to a temperature ,5°C, underwent 1-h circulatory arrest, and were warmed to 35°C with adminis- tration of blood to increase the hematocrit to .25% before separation from CPB. The primary outcome, peak postoper- ative neurobehavioral score, was compared between groups. The 0% group (mean 6 sd) had significantly (P , 0.02) better neurobehavioral scores than the 5% and 15% groups (6.0 6 2.9 vs 1.3 6 1.0 and 1.5 6 0.6) respectively. Other variables (e.g., intracranial pressure) were similar be- tween groups. In a porcine model of profound hypothermia (,5°C) and circulatory arrest, complete blood replacement resulted in superior neurological outcome. This finding sug- gests that at ultralow temperatures, the presence of some blood component (e.g., erythrocytes, leukocytes) may be deleterious.

This publication has 18 references indexed in Scilit: