Intitute of Sound and Vibration Research, University of Southampton, Southampton, United Kingdom.
Med Eng Phys. 2010 Mar;32(2):168-73. doi: 10.1016/j.medengphy.2009.11.006. Epub 2009 Dec 16.
The auditory evoked potential termed the middle latency response (MLR) has been suggested as an indicator of adequacy of anaesthesia during surgery. However, the response is small and must be extracted from high levels of background noise. A key consideration in using the MLR for clinical monitoring is whether data quality is sufficient to detect small changes. The aim of this study was to investigate the quality of the MLR recorded during anaesthesia, as a rigorous analysis of data quality is lacking in many studies. MLR recordings from patients sedated in intensive care after cardiac surgery were compared to recordings from a reference group of young volunteers with normal hearing. Data quality was measured with the F(sp) parameter. A bootstrap analysis was used to measure statistical response presence and to detect within-subject changes during clinical anaesthesia. Noise levels were high in the normative group probably due to myogenic and EEG activity. With 5 Hz click stimulation, MLR presence in the normative group was below 30%. Response presence improved using stimulation paradigms with chirps or maximum length sequences and reached 100% with a combination of maximum length sequences and chirps. F(sp) values generally improved during anaesthesia as noise levels reduced and MLR presence was 100% for MLS click stimulation. Changes in the MLR amplitude with propofol infusion rate were small. Some within-subject changes in MLR amplitude were detected using the bootstrap analysis, but 100% detection was not possible.
Obtaining good quality MLR data in awake subjects is challenging. Data quality improves during clinical anaesthesia and with advanced stimulation methods, but reliable detection of changes in the MLR for clinical monitoring remains a challenge.
被称为中潜伏期反应（MLR）的听觉诱发电位已被提议作为手术期间麻醉充分性的指标。然而，该反应较小，必须从高水平的背景噪声中提取出来。在使用 MLR 进行临床监测时，关键考虑因素是数据质量是否足以检测到微小的变化。本研究旨在调查麻醉期间 MLR 记录的质量，因为许多研究缺乏对数据质量的严格分析。与具有正常听力的年轻志愿者的参考组相比，对接受心脏手术后在重症监护病房镇静的患者进行 MLR 记录。使用 F(sp)参数来测量数据质量。使用自举分析来测量统计响应存在，并在临床麻醉期间检测个体内变化。参考组中的噪声水平很高，可能是由于肌源性和 EEG 活动。使用 5Hz 点击刺激时，参考组中的 MLR 存在率低于 30%。使用啁啾或最大长度序列的刺激范式以及最大长度序列和啁啾的组合，响应存在性得到改善，达到 100%。随着噪声水平降低，F(sp)值通常在麻醉期间得到改善，并且 MLS 点击刺激的 MLR 存在率为 100%。丙泊酚输注率对 MLR 幅度的变化很小。使用自举分析检测到一些 MLR 幅度的个体内变化，但无法实现 100%的检测。
在清醒的受试者中获得高质量的 MLR 数据具有挑战性。数据质量在临床麻醉期间以及使用先进的刺激方法时会提高，但可靠地检测临床监测中 MLR 的变化仍然是一个挑战。
