Efficacy of Selective Brain Cooling Using a Nasopharyngeal Method in Piglets
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.
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. The duration of treatment was 60 min, with additional 30 min of observation.
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.
Nasopharyngeal cooling via cooled insufflated air can lower the brain temperature, with higher flows and lower temperatures of insufflated air being more effective.
KeywordsTemperature Hypothermia Newborn piglet Nasopharyngeal cooling
The authors would also like to thank Laura Morrison and Jennifer Hadway for their help in conducting the animal experiments. All work was performed in Lawson Health Research Institute.
Compliance with Ethical Standards
Conflicts of Interest
Lawson Health Research Institute.
- 6.Bullock MR, Povlishock JT. Guidelines for the management of severe traumatic brain injury. J Neurotrauma. 2007;24(Suppl 1):S1–106.Google Scholar
- 23.Mariak Z, White MD, Lewko J, Lyson T, Piekarski P. Direct cooling of the human brain by heat loss from the upper respiratory tract. J Appl Physiol. 1985;1999(87):1609–13.Google Scholar
- 25.Enviroment Canada (http://www.Ec.Gc.Ca/toxiques-toxics/default.Asp?Lang=en&n=98e80cc6-1&xml=aa329670-c3c7-4ad5-a7ab-5fd8a05439f1) [accessed 29 August, 2012].
- 26.Azzopardi D, Strohm B, Edwards AD, Halliday H, Juszczak E, Levene M, Thoresen M, Whitelaw A, Brocklehurst P, Steering G, Participants TCR. Treatment of asphyxiated newborns with moderate hypothermia in routine clinical practice: How cooling is managed in the UK outside a clinical trial. Arch Dis Child Fetal Neonatal Ed. 2009;94:F260–4.CrossRefPubMedGoogle Scholar
- 29.Bakhsheshi MF, Stewart EE, Morrison L, Lee TY. Comparison of selective brain cooling in juvenile and newborn piglets using a nasopharyngeal method. The 8th International Conference on Brain Monitoring and Neuroprotection in the newborn. 2014.Google Scholar
- 30.Bratton SL, Chestnut RM, Ghajar J, McConnell Hammond FF, Harris OA, Hartl R, Manley GT, Nemecek A, Newell DW, Rosenthal G, Schouten J, Shutter L, Timmons SD, Ullman JS, Videtta W, Wilberger JE, Wright DW. Guidelines for the management of severe traumatic brain injury. X. Brain oxygen monitoring and thresholds. J Neurotrauma. 2007;24(Suppl 1):S65–70.PubMedGoogle Scholar
- 31.Bratton SL, Chestnut RM, Ghajar J, McConnell Hammond FF, Harris OA, Hartl R, Manley GT, Nemecek A, Newell DW, Rosenthal G, Schouten J, Shutter L, Timmons SD, Ullman JS, Videtta W, Wilberger JE, Wright DW. Guidelines for the management of severe traumatic brain injury. Ix. Cerebral perfusion thresholds. J Neurotrauma. 2007;24(Suppl 1):S59–64.PubMedGoogle Scholar