Multimodality brain monitoring includes intracranial temperature (ICT) measurements. Different
ICT readings have been reported from Licox® and Hemedex® systems used in the same patient with the Hummingbird®
“SynergyDuo Ventricular” introducer.
To investigate the differences we report an analysis of causes for different ICT readings. In keeping with the
radial brain ICT gradient model model we calculated ICTs according to the sensors' penetration depths and compared the
results to clinical data from six patients.
The ICT accuracy is ±0.2°C for Licox® and ±0.3° for Hemedex® so any ICT difference ≤±0.5° between the
systems is not significant. The Hemedex®-ICT sensor is placed 15.5mm deeper than the Licox®-ICT sensor with the
Hummingbird®. The calculated ΔICT from the model range from -0.7° to -1.0° for a 37.5° arterial temperature, and a
22° ambient temperature. The ΔICT (ICTLicox
® – ICTHemedex
®) in six patients were -0.6°, SD = 0.7°, median = -0.6°,
max = 0.4°, min = -5.7°, range 6.1°. 41.1% of recorded data lie within the accuracy range of ±0.5°. 53.8% lie
within a range between -0.5° and -1.5°, and represent the differences which can be explained by different sensor
insertion depths and the model. Only 5% were outliers with ΔICT > -1.5°.
This study shows that the discrepancy in ICT measurements using different sensors can be explained by (a)
the ICT measurement accuracies/specifications, and (b) different insertion depths. Other causes may include (c)
environmental conditions and (d) unknown factors secondary to body – and/or brain physiology.