Robust Repeatable Respiratory Monitoring with EIT

重症监护室（ICU）中的机械通气通常是急性呼吸窘迫综合征（ARDS）和急性肺损伤（ALI）患者的救命措施。然而，近年来，已经清楚的是，机械通气可以加重肺损伤，甚至可能是肺损伤的主要因素，例如呼吸机诱导的肺损伤（VILI）和呼吸机相关性肺炎（VAP）。因此，肺保护性通气（LPV）策略已被开发，包括呼气末正压（PEEP）和高频振荡通气（HFOV）。尽管使用LPV，但ARDS和ALI的死亡率仍然很高，报告的死亡率在33%至55%之间，胸部电阻抗断层成像（EIT）已成为一种有前途的新的床边成像工具。它是一种非侵入性技术，基于皮肤上的电测量提供内部电导率分布。现有的研究和商业EIT系统通常将测量电极布置在围绕胸部的环中，并且基于过度简化的二维通用形状（例如，圆形或椭圆形横截面）来产生二维图像切片。不幸的是，这样的方法产生显著的图像伪影和差的可重复性水平。为了消除这个问题，EIT测量和图像重建必须被视为一个完全三维的问题，考虑到电极的位置和患者的身体形状。该项目的目的之一是提供可靠和强大的三维EIT图像重建的基础上，从其他方式，如磁共振成像（MRI）和X射线计算机断层扫描获得的三维知情的身体形状。改善对通气分布的了解将使临床医生能够设置更合适的通气参数，以减少VILI的潜在发生。特别是，床旁EIT监测的价值，以确定PEEP的效果相比，传统的间接方法，如动脉氧合或全球潮气量，仍然是未知的。此外，尽管肺力学和局部通气之间存在明确的联系，但呼吸机设置通常基于血气和压力-容积曲线，而不是肺力学的测量。该项目的一个重要目的是为临床医生提供强大的基于图像的肺力学模型，这将进一步帮助EIT在ICU中的验证。以前的临床EIT研究通常利用EIT仪器在相对较慢的帧速率下操作，不灵活的驱动和测量策略沿着，电极数量有限。在这个项目中，我们将开发一个最先进的快速3D EIT系统，使用先进的测量技术，尚未在临床环境中产生重大影响。事实上，从来没有一个实质性的调查EIT在ICU，它已经汇集了高品质的EIT测量，三维图像重建和肺力学建模的验证的独特组合。我们建议建立一个世界领先的能力，在测量和成像EIT在ICU。该项目建立在曼彻斯特大学（UoM）和英国伦敦国王学院和盖伊和圣托马斯NHS信托基金应用胸EIT的领先临床小组的大量专业知识的基础上。我们还将建立在世界领先的能力，在建模和动态MRI采集，包括氧增强和动态对比增强MRI。拟议的项目注册强烈的EPSRC研究主题的医疗技术。

Mechanical ventilation in the intensive care unit (ICU) is often a life-saving intervention for patients suffering from acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). However, in recent years, it has become clear that mechanical ventilation can exacerbate lung damage and may even be the primary factor in lung injury e.g. ventilator-induced lung injury (VILI) and ventilator associated pneumonia (VAP). Consequently, lung protective ventilation (LPV) strategies have been developed, including positive end expiratory pressure (PEEP) and high frequency oscillatory ventilation (HFOV). Despite the use of LPV, the mortality associated with ARDS and ALI is still great, with reported rates between 33 and 55%.Thoracic electrical impedance tomography (EIT) has emerged as a promising new imaging tool for bedside use. It is a non-invasive technique which provides the internal conductivity distribution based on electrical measurements on the skin. Existing research and commercial EIT systems have typically arranged measurement electrodes in rings around the thorax and produced two-dimensional image slices based on over-simplified two-dimensional generic shapes e.g. circular or elliptical cross-sections. Unfortunately, such an approach creates significant image artefacts and poor levels of repeatability. In order to eliminate this problem, EIT measurements and image reconstruction must be treated as a fully three-dimensional problem, taking into account the electrode positions and the body shape of the patient. One of the aims of this project is to provide reliable and robust three-dimensional EIT image reconstruction based on 3D informed body shape acquired from other modalities such as magnetic resonance imaging (MRI) and x-ray computed tomography.Currently, there exists no consensus amongst clinicians on how to optimize PEEP ventilator settings. Improved knowledge about the distribution of ventilation will enable clinicians to set more appropriate ventilation parameters in order to reduce the potential occurrence of VILI. In particular, the value of bedside EIT monitoring for determining the effect of PEEP in comparison with traditional indirect methods, such as arterial oxygenation or global tidal volumes, is still largely unknown. Additionally, despite the clear link between lung mechanics and regional ventilation, ventilator settings are normally based on blood gases and pressure-volume curves rather than measurements of lung mechanics. A significant aim of this project is to provide clinicians with robust image-based lung mechanics models which will further aid the validation of EIT in the ICU.Previous clinical EIT studies have generally utilized EIT instruments operating at relatively slow frame rates, inflexible drive and measurement strategies along with limited number of electrodes. In this project, we will develop a state-of-the-art fast 3D EIT system using advanced measurement techniques which have not yet had a significant impact in the clinical environment. In fact, there has never been a substantial investigation of EIT in the ICU which has drawn together the unique combination of high quality EIT measurements, three-dimensional image reconstruction and the validation of lung mechanics modelling.We propose to establish a world-leading capability in the measurement and imaging by EIT in the ICU. This project builds upon the substantial expertise in EIT at the University of Manchester (UoM) and the UK's leading clinical group in applied thoracic EIT at Kings College London and Guy's and St Thomas' NHS Trust. We will also build upon the world-leading capability at UoM in modelling and dynamic MRI acquisition including oxygen-enhanced and dynamic contrast-enhanced MRI. The proposed project registers strongly on the EPSRC research theme of healthcare technologies.