Brain Injury Research Group, School of Translational Medicine, University of Manchester, Clinical Sciences Building, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.
Crit Care. 2009;13(4):R106. doi: 10.1186/cc7943. Epub 2009 Jul 2.
The influence of brain temperature on clinical outcome after severe brain trauma is currently poorly understood. When brain temperature is measured directly, different values between the inside and outside of the head can occur. It is not yet clear if these differences are 'real' or due to measurement error.
The aim of this study was to assess the performance and measurement uncertainty of body and brain temperature sensors currently in use in neurocritical care. Two organic fixed-point, ultra stable temperature sources were used as the temperature references. Two different types of brain sensor (brain type 1 and brain type 2) and one body type sensor were tested under rigorous laboratory conditions and at the bedside. Measurement uncertainty was calculated using internationally recognised methods.
Average differences between the 26 degrees C reference temperature source and the clinical temperature sensors were +0.11 degrees C (brain type 1), +0.24 degrees C (brain type 2) and -0.15 degrees C (body type), respectively. For the 36 degrees C temperature reference source, average differences between the reference source and clinical thermometers were -0.02 degrees C, +0.09 degrees C and -0.03 degrees C for brain type 1, brain type 2 and body type sensor, respectively. Repeat calibrations the following day confirmed that these results were within the calculated uncertainties. The results of the immersion tests revealed that the reading of the body type sensor was sensitive to position, with differences in temperature of -0.5 degrees C to -1.4 degrees C observed on withdrawing the thermometer from the base of the isothermal environment by 4 cm and 8 cm, respectively. Taking into account all the factors tested during the calibration experiments, the measurement uncertainty of the clinical sensors against the (nominal) 26 degrees C and 36 degrees C temperature reference sources for the brain type 1, brain type 2 and body type sensors were +/- 0.18 degrees C, +/- 0.10 degrees C and +/- 0.12 degrees C respectively.
The results show that brain temperature sensors are fundamentally accurate and the measurements are precise to within 0.1 to 0.2 degrees C. Subtle dissociation between brain and body temperature in excess of 0.1 to 0.2 degrees C is likely to be real. Body temperature sensors need to be secured in position to ensure that measurements are reliable.
目前，人们对严重颅脑外伤后大脑温度对临床结果的影响知之甚少。当直接测量大脑温度时，头部内外可能会出现不同的数值。目前尚不清楚这些差异是“真实的”还是由于测量误差。
本研究旨在评估目前在神经重症监护中使用的身体和大脑温度传感器的性能和测量不确定度。使用两个有机固定点、超稳定温度源作为温度参考。在严格的实验室条件下和床边测试了两种不同类型的脑传感器（脑型 1 和脑型 2）和一种体式传感器。使用国际公认的方法计算测量不确定度。
26°C 参考温度源与临床温度传感器的平均差值分别为+0.11°C（脑型 1）、+0.24°C（脑型 2）和-0.15°C（体式）。对于 36°C 温度参考源，参考源与临床温度计之间的平均差值分别为-0.02°C、+0.09°C 和-0.03°C，分别用于脑型 1、脑型 2 和体式传感器。第二天的重复校准证实，这些结果在计算的不确定度范围内。浸入式测试的结果表明，体式传感器的读数对位置敏感，当从等温环境的底部拔出温度计时，温度分别相差-0.5°C 至-1.4°C，相差 4cm 和 8cm。考虑到校准实验中测试的所有因素，与（名义）26°C 和 36°C 温度参考源相比，脑型 1、脑型 2 和体式传感器的临床传感器的测量不确定度分别为+/-0.18°C、+/-0.10°C 和+/-0.12°C。
结果表明，脑温度传感器在根本上是准确的，测量精度在 0.1 到 0.2°C 之间。大脑和体温之间超过 0.1 到 0.2°C 的细微分离很可能是真实的。为了确保测量可靠，体式传感器需要固定在适当的位置。
