Efficacy of Selective Brain Cooling Using a Nasopharyngeal Method in Piglets
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TRANSLATIONAL RESEARCH
Efficacy of Selective Brain Cooling Using a Nasopharyngeal Method in Piglets Mohammad Fazel Bakhsheshi1,2 • Errol E. Stewart1,2 • Joo Ho Tai4 Laura Morrison1 • Lynn Keenliside1 • Ting-Yim Lee1,2,3
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Ó Springer Science+Business Media New York 2015
Abstract Background Mild hypothermia is an effective neuroprotective strategy for a variety of acute brain injuries. Cooling the nasopharynx may offer the capability to cool the brain selectively due to anatomic proximity of the internal carotid artery to the cavernous sinus. This study investigated the feasibility and efficiency of nasopharyngeal brain cooling by continuously blowing room temperature or cold air at different flow rates into the nostrils of normal newborn piglets. Methods Experiments were conducted on thirty piglets (n = 30, weight = 2.7 ± 1.5 kg). Piglets were anesthetized with 1–2 % isoflurane and were randomized to receive one of four different nasopharyngeal cooling treatments: I. Room temperature at a flow rate of 3–4 L min-1 (n = 6); II. -1 ± 2 °C at a flow rate of 3–4 L min-1 (n = 6); III. Room temperature at a flow rate of 14–15 L min-1 (n = 6); IV. -8 ± 2 °C at a flow rate of 14–15 L min-1 (n = 6). To control for the normal thermal regulatory response of piglets without nasopharyngeal cooling, a control group of piglets (n = 6) had their brain temperature monitored without nasopharyngeal cooling.
& Mohammad Fazel Bakhsheshi [email protected] 1
Imaging Program, Lawson Health Research Institute, London, ON, Canada
2
Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada
3
Departments of Medical Imaging and Biophysics, The University of Western Ontario, London, ON, Canada
4
Center for Medical-IT Convergence Research, Seoul National University, Suwon, Republic of Korea
The duration of treatment was 60 min, with additional 30 min of observation. Results In group I, median cooling rate was 1.7 ± 0.9 °C/h by setting the flow rate of room temperature air to 3–4 L min-1. Results of comparing different temperatures and flow rates in the nasopharyngeal cooling approach reveal that the brain temperature could be reduced rapidly at a rate of 5.5 ± 1.1 °C/h by blowing -8 ± 2 °C air at a flow rate of 14–15 L min-1. Conclusions Nasopharyngeal cooling via cooled insufflated air can lower the brain temperature, with higher flows and lower temperatures of insufflated air being more effective. Keywords Temperature Hypothermia Newborn piglet Nasopharyngeal cooling
Introduction Clinical investigators have reported that mild and moderate hypothermia can be neuroprotective to reduce brain injury and decrease death and disability for a variety of acute brain injuries following cardiac arrest, and neonatal asphyxia [1–3]. The neuroprotective benefits of hypothermia have been linked to the time to initiate cooling after injury, depth of cooling and rewarming rate [4, 5]. Clinical studies indicate that the temperature range associated with better outcomes appears to be
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