Optical Detection of Exhaled Intravenous Anaesthetics

在这个建议中，我们回应了手术期间患者血液中麻醉浓度临床在线监测的真实和迫切需求。尽管临床常规使用静脉麻醉药，但没有可行的传感器用于在线监测其血浆浓度。该项目的重点是为异丙酚开发下一代传感技术。异丙酚在外科手术中被广泛用作麻醉药物，在重症监护病房中被用作危重病人的镇静剂。异丙酚对心血管系统有深远的影响，可以降低血压、心输出量和重要器官（如大脑和肾脏）的灌注。因此，不正确使用异丙酚的后果是严重的。目前，异丙酚诱导麻醉的有效性仅在症状上进行评估。一种可行的在线监测异丙酚呼出水平的能力将大大提高对其管理的控制水平。它既可以通过根据个人需要调整剂量来提高麻醉管理的质量，又可以减少临床恢复时间和患者的善后护理，并带来相关的成本效益。我们建议通过光学测量患者呼出气中异丙酚的浓度，研究临床在线监测患者血液中异丙酚的可行性。最近的医学研究表明，手术期间患者呼出的气体中含有十亿分之一的异丙酚混合比例。该应用程序是雄心勃勃的，高影响的，非常热门的推动领域的前沿。呼出异丙酚浓度的可行光学传感策略面临的挑战是普遍存在的低浓度；异丙酚的光谱表征较差；产生竞争信号的污染物种的存在；而且，重要的是，需要一个强大、快速和经济的系统，有机会在临床环境中部署。目前还没有能够满足所有这些需求的技术。在这个项目中，我们提出了两种有潜力满足要求的最先进的光学检测技术。我们建议对呼出异丙酚在线监测的可行性进行系统研究，首先，量化异丙酚的吸收截面，其次，确定使用选定的候选技术可达到的检测限，第三，研究呼出气体中存在的其他气体引起的光谱干扰的影响。该项目是一项开创性的活动，基于一个独特的多学科专业团体，专注于高影响力的研究挑战。高影响应用是在与医学麻醉专业人员，T. Absalom教授和D. Wheeler博士，剑桥大学临床医学院麻醉学部协商后建立的。只有这种合作才能提供临床样品收集和制备所需的专业知识和最新技术。研究人员在新型光学传感器开发方面的专业知识以极好的方式符合项目要求。如果成功，这项研究可能会导致麻醉师在手术室操作方式的范式转变。

In this proposal we respond to a real and acute need for clinical online monitoring of anaesthetic concentrations in patients' blood during surgery. Despite of the routine clinical use of intravenous anaesthetics no viable sensors for online monitoring of their blood plasma concentration exist. The project focuses on the development of next generation sensing technology for propofol, which is used widely as an anaesthetic drug during surgery and as a sedative in critically ill patients on intensive care units. Propofol exerts profound effects on the cardiovascular system, reducing blood pressure, cardiac output, and the perfusion of vital organs such as the brain and kidneys. The consequences of incorrect administering of propofol are therefore grave. Currently the effectiveness of propofol induced anaesthesia is only assessed symptomatically. A viable online capability to monitor exhaled levels of propofol would dramatically improve the level of control over its administration. It would both improve the quality of anaesthetic management by tailoring dosage to individuals' needs and reduce clinical recovery times and patient aftercare with associated cost benefits. We propose to study the feasibility of clinical online monitoring of propofol in patient's blood by optically measuring the concentration of propofol in the patient's exhaled breath. Recent medical studies have shown that mixing ratios of propofol at a level of parts per billion by volume exist in the patients' exhaled breath during surgery. The application is ambitious, high impact, and very topical pushing the frontiers of the field. Challenges for viable optical sensing strategies of exhaled propofol concentration are the low concentrations prevailing; the poor spectroscopic characterization of propofol; the presence of contaminant species that create competitive signals; and, importantly, the requirement for a robust, fast and economical system that stands a chance to be deployed in a clinical context. Currently there are no available technologies that meet all these demands. In this project we propose two state of the art optical detection techniques that have the potential to meet the requirements. We propose to conduct a systematic study on the feasibility of online monitoring of exhaled propofol by, first, quantifying the absorption cross sections of propofol, secondly, determining the attainable detection limits using the selected candidate technologies and, thirdly, studying the effects of spectral intereference caused by the other gases present in the exhaled breath. The project is a pioneering activity and is based on a unique multidisciplinary ensemble of professionals focusing on a high impact research challenge. The high impact application has been established in consultation with medical anaesthesia professionals, Prof. T. Absalom and Dr. D. Wheeler, Division of Anaesthesia, School of Clinical Medicine, University of Cambridge. Only this collaboration can provide the needed expertise and state of the art knowledge on the clinical sample collection and preparation. The Researcher's expertise in the development of novel optical sensors matches the project requirements in an excellent fashion. If successful, this research could lead to a paradigm shift in the way anesthetists are able to operate in the operating theatre.