Whole body hypothermia using a portable cooling unit in a neonatal pig model: Implications for transport

摘要

Background: Recent studies demonstrate a neuroprotective effect of therapeutic hypothermia following newborn hypoxic-ischemic encephalopathy; however, initiation of cooling must begin within 6 hours of birth. Evidence from animal models suggests that the earlier treatment is begun, the more efficacious hypothermia is in preventing brain injury. Unfortunately, timely initiation of therapy is often practically difficult to achieve for outborn neonates. Currently, there is no standardized methodology to safely initiate and regulate hypothermia during neonatal transport. Methods: This study evaluated the effectiveness of the Electri-Cool II Cold Therapy Unit (Cincinnati Sub-Zero) to induce and regulate mild whole body hypothermia (33.5degC) in a neonatal porcine model. Seven healthy neonatal piglets (2-3.5 kg) were initially allowed to passively cool from baseline in an open air isolette over 1 hour. Following this, animals were rewarmed to baseline (if necessary) and then actively cooled to 33.5癈 using the Electri-Cool II. Once the target temperature was achieved, temperature was closely monitored using rectal and skin temperature probes over the next 1 hour. Results: None of the study animals significantly lowered their temperature from baseline during the passive cooling period. By comparison, piglets actively cooled with the Electri-Cool II reached 33.5degC in a mean of 38 +- 19.7 minutes. Once at target temperature, hypothermia was maintained in the piglets with minimal average variation (0.3 +- 0.1癈) for the duration of the active study cooling period. Conclusion: The Electri-Cool II is superior to passive cooling for inducing and maintaining mild whole body hypothermia in a neonatal piglet model. Further evaluation of this device to include its potential utility during transport of newborn infants is warranted.