Ultrarapid, Convection-Enhanced Intravascular Hypothermia

Background and Purpose— Hypothermia has been shown to be neuroprotective in a variety of clinical settings. Unfortunately, poor delivery techniques and insufficient data in appropriate preclinical models have hampered its development in human stroke. To address these limitations, we have devised a 10F intravascular catheter capable of rapid systemic cooling of nonhuman primates. Methods— Placed in the inferior vena cava via a transfemoral approach, the catheter was used to induce mild systemic hypothermia 3 hours after the onset of hemispheric stroke in baboons. Results— Cooling was achieved at a rate of 6.3±0.8°C/h. Target brain temperatures (32.2±0.2°C) were reached at the same time (47.7±6.32 minutes) as target esophageal temperatures (32.0±0.0°C). Hypothermia was maintained for 6 hours in all animals. Animals did not experience the infections, coagulopathy, or cerebral edema commonly seen with surface cooling methods in human stroke. Conclusions— These data suggest that a brief episode of mild core hypothermia instituted at a clinically relevant time point can be achieved in primate stroke and that our intravascular cooling technique provides safe, rapid, and reproducible hypothermia.