BJA Advance Access published online on February 5, 2008
British Journal of Anaesthesia, doi:10.1093/bja/aem405
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Forced convective head cooling device reduces human cross-sectional brain temperature measured by magnetic resonance: a non-randomized healthy volunteer pilot study
1 School of Clinical Sciences and Community Health
2 Department of Anaesthesia, Critical Care and Pain Medicine
3 Department of Medical and Radiological Sciences, University of Edinburgh, Edinburgh, UK
4 Critical Care Unit
5 Scottish Funding Council Brain Imaging Research Centre, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
6 KCI Research and Development Facility, 11 Nimrod Way, Ferndown Industrial Estate, Wimbourne, Dorset BH21 7SH, UK
7 Public Health Sciences, University of Edinburgh Medical School, Teviot Place, Edinburgh EH8 9AG, UK
* Corresponding author: Critical Care Unit, Western General Hospital, Crewe Road, Edinburgh, UK. E-mail: b.harris{at}ed.ac.uk
Background: This 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).
Methods: After 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°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.
Results: MRS 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°C (SD 0.23°C, P=0.01, 95% CI 0.17–0.74°C) and with head and neck cooling was 0.37°C (SD 0.30°C, P=0.049, 95% CI 0.00–0.74°C). The equivalent net reductions in oesophageal temperature were 0.16°C (SD 0.04°C) and 0.36°C (SD 0.12°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.
Conclusions: Convective head cooling reduced MRS brain temperature and core brain was cooled.
Keywords: brain, cooling; healthy volunteers; measurement techniques, nuclear magnetic resonance; temperature, brain
Declaration of interest. KCI Research and Development Facility, Ferndown, UK was approached by B.A.H. and P.J.D.A. and agreed to assist with the study. KCI developed and provided the cooling device, paid for the MRS scans, fluoroptic thermometry, and volunteers’ expenses, and gave an unrestricted grant to cover part-time salary for B.A.H. They were not involved in the analysis and interpretation of data or the decision to submit the manuscript for publication.
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