• B A Harris, P J D Andrews, I Marshall, T M Robinson, and G D Murray.
• School of Clinical Sciences and Community Health, University of Edinburgh, Edinburgh, UK. b.harris@ed.ac.uk
• Br J Anaesth. 2008 Mar 1;100(3):365-72.

BackgroundThis pilot study in five healthy adult humans forms the pre-clinical assessment of the effect of a forced convective head cooling device on intracranial temperature, measured non-invasively by magnetic resonance spectroscopy (MRS).MethodsAfter a 10 min baseline with no cooling, subjects received 30 min of head cooling followed by 30 min of head and neck cooling via a hood and neck collar delivering 14.5 degrees C air at 42.5 litre s(-1). Over baseline and at the end of both cooling periods, MRS was performed, using chemical shift imaging, to measure brain temperature simultaneously across a single slice of brain at the level of the basal ganglia. Oesophageal temperature was measured continuously using a fluoroptic thermometer.ResultsMRS brain temperature was calculated for baseline and the last 10 min of each cooling period. The net brain temperature reduction with head cooling was 0.45 degrees C (SD 0.23 degrees C, P=0.01, 95% CI 0.17-0.74 degrees C) and with head and neck cooling was 0.37 degrees C (SD 0.30 degrees C, P=0.049, 95% CI 0.00-0.74 degrees C). The equivalent net reductions in oesophageal temperature were 0.16 degrees C (SD 0.04 degrees C) and 0.36 degrees C (SD 0.12 degrees C). Baseline-corrected brain temperature gradients from outer through intermediate to core voxels were not significant for either head cooling (P=0.43) or head and neck cooling (P=0.07), indicating that there was not a significant reduction in cooling with progressive depth into the brain.ConclusionsConvective head cooling reduced MRS brain temperature and core brain was cooled.

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