Protecting the central nervous system during ischemia: A difficult task

Abstract

This issue contains a remarkable study by Kawata and colleagues.1Kawata M, Takamoto S, Kitahoi K, Tsukihara H, Morota T, Ono M, et al. Erythropoietin protects the central nervous system during prolonged hypothermic circulatory arrest: An experimental study in a canine model.Google Scholar The prevention of central nervous system (CNS) damage during prolonged hypothermic circulatory arrest has significant ramifications. In this study the authors demonstrated that erythropoietin (EPO) crosses the blood brain barrier and protects the brain and spinal cord from prolonged ischemic injury during hypothermic circulatory arrest. The fact that the animals in this study were kept under hypothermic circulatory arrest for 120 minutes is simply astounding. The use of EPO for CNS protection during cold ischemia is a novel concept. However, the exact mechanism needs to be elucidated. Because EPO is already used in humans, and safety and efficacy data are already known, a clinical trial could be easily established.See related article on page 1331. See related article on page 1331. This study has limitations. Only 5 animals were used in each of the EPO and control groups. In addition, the animals were never fully allowed to recover and were always kept intubated and anesthetized during the recovery and neurologic assessment period. Even with the modification of the neurologic scoring system to allow for this, I have grave reservations about how accurately the animals’ neurologic status could be evaluated. One cannot argue with the results of the histologic analyses and the evaluation of the brain, spinal cord, and cerebrospinal fluid, and it seems as though EPO does have direct protective effects on the CNS. Whether these beneficial effects are long-lasting needs to be elucidated through chronic studies. Also, although many drugs have proven beneficial in protecting the brain and spinal cord during ischemia in experimental animal models, none have proven particularly beneficial in humans. Although the results of this study are remarkable and give us reason to be excited, we must temper our enthusiasm with the reality that this is but one study in a very small group of animals that were evaluated (while anesthetized and intubated) for only 12 hours postoperatively. Clearly, more work needs to be done. Erythropoietin protects the central nervous system during prolonged hypothermic circulatory arrest: An experimental study in a canine modelThe Journal of Thoracic and Cardiovascular SurgeryVol. 131Issue 6PreviewCurrent data suggest that erythropoietin protects the brain and the spinal cord from ischemic and traumatic injury. In this study, we determined whether erythropoietin protects the central nervous system during prolonged hypothermic circulatory arrest in an experimental canine model. Full-Text PDF