Affiliations: Division of Neonatology, Wilford Hall Medical Center,
Lackland Air Force Base, TX, USA
Note: [] Corresponding author: Dr. Eric Rabenstein, Wilford Hall Medical
Center, 2200 Bergquist Drive, Suite 1, Lackland AFB, TX 78236-5300, USA. Tel.:
+1 210 292 6679; Fax: +1 210 292 7933; E-mail: Eric.rabenstein@med.navy.mil
Abstract: 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 (33.5°C) 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°C 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 33.5°C 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°C) 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.
Keywords: Hypothermia, neonatal, hypoxic ischemic encephalopathy, transport
