Effect of Goggle Slippage on the Video Head Impulse Test Outcome and Its Mechanisms
Effect of Goggle Slippage on the Video Head Impulse Test Outcome and Its Mechanisms
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DOI：
10.1097/mao.0000000000001233
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发表时间：
2017-01-01
影响因子：
2.1
通讯作者：
Kwon, Seong Keun
中科院分区：
文献类型：
--
作者：
Suh, Myung-Whan;Park, Jae Hong;Kwon, Seong Keun
目的：本研究的目的是定量测量视频头部脉冲测试（vHIT）期间护目镜带的松紧度，并根据松紧度识别滑动引起的伪影。我们的目的是阐明由护目镜滑动引起的错误增益的机制，并解释与之相关的典型伪影。受试者和方法：将气管内导管套囊压力计与EyeSeeCam vHIT系统（Interacoustics，阿森斯，丹麦）耦合，以监测带紧度。比较了8名健康受试者在以下绑带紧度条件下的瞬时增益（40、60和80 ms）和回归增益：松（25 cm H2O）、紧（35 cm H2O）和非常紧（45 cm H2O）。为了阐明由护目镜滑动引起的错误增益的机制，将具有前庭眼反射（VOR）增益为0的假固定瞳孔附接到受试者的眼睑。错误的增益记录模式进行了分析，作为松紧带decreased.Results：最常见的滑动引起的伪影是：1）最初向后的眼睛运动的头部运动，2）加速颠簸，3）高增益，和4）减速颠簸。在40 ms时，与45 cm H2O条件（0.90 +/- 0.26 cm H2O）相比，25 cm H2O条件（0.68 +/- 0.32 cm H2O）下的增益显著较低。在80 ms时，与45 cm H2O条件（1.16 +/- 0.30 cm H2O）相比，25 cm H2O条件（1.24 +/- 0.27 cm H2O）的增益更高。随着绑带的松紧度以剂量依赖性方式降低，这些发现逐渐变得更加明显。当记录假瞳孔时，尽管假瞳孔绝对没有运动，但记录了朝向头部运动的初始向后眼睛运动（负VOR增益）和模仿小VOR（正VOR增益）的眼睛跟踪。这些伪影记录被认为是有关的故障低（40毫秒）和高（80毫秒）gain calculation.Conclusions：滑倒引起的伪影被认为是因为弹弓般的运动的护目镜头部运动过程中在三个不同的阶段（滞后，过冲，弹跳的护目镜）。监测带紧度的压力可以是用于最小化这种滑动的解决方案。为了进行可靠的vHIT记录和增益计算，需要至少45 cm H2O的绑带松紧度。
Objectives: The aim of this study was to quantitatively measure the tightness of the goggle strap during the video head impulse test (vHIT) and to identify slippage-induced artifacts according to tightness. We aimed to elucidate the mechanism of faulty gain caused by goggle slippage and explain the typical artifacts associated with it.Subjects and Methods: An endotracheal tube cuff manometer was coupled to the EyeSeeCam vHIT system (Interacoustics, Assens, Denmark) to monitor strap tightness. The instantaneous gain (40, 60, and 80 ms) and regression gain were compared in eight healthy subjects under the following strap tightness conditions: loose (25 cm H2O), tight (35 cm H2O), and very tight (45 cm H2O). To elucidate the mechanism of faulty gain caused by goggle slippage, a fake fixed pupil with a vestibule ocular reflex (VOR) gain of 0 was attached to the subject's eyelid. The faulty gain recording pattern was analyzed as the tightness of the strap was decreased.Results: The most common slippage-induced artifacts were: 1) initial backward eye movement toward the head movement, 2) acceleration bumps, 3) high gain, and 4) deceleration bumps. At 40 ms, the gain was significantly lower in the 25 cm H2O condition (0.68 +/- 0.32 cm H2O) compared with the 45 cm H2O condition (0.90 +/- 0.26 cm H2O). At 80 ms, the gain was higher for the 25 cm H2O condition (1.24 +/- 0.27 cm H2O) compared with the 45 cm H2O condition (1.16 +/- 0.30 cm H2O). These findings were progressively more obvious as the tightness of the strap decreased in a dose-dependent manner. When the fake pupil was recorded, initial backward eye movement toward the head movement (negative VOR gain) and eye tracing mimicking a small VOR (positive VOR gain) were recorded, despite the fake pupil having absolutely no movement. These artifact recordings are presumed to be related to the faulty low (40 ms) and high (80 ms) gain calculation.Conclusions: Slippage-induced artifacts are presumed to be because of the slingshot-like movement of the goggles during head movement in three different phases (lagging, overshooting, and bouncing of the goggles). Monitoring the pressure of the strap tightness may be a solution for minimizing this slippage. A strap tightness of at least 45 cm H2O is required for reliable vHIT recording and gain calculations.