Volatile Biomarker Positioning of Naso-gastric Tubes to Enhance Patient Safety (Acronym: NG-Sure)

鼻胃管（称为NG管）穿过鼻腔，从喉咙后部向下，通过食道（食物管）到达胃，用于向患者提供药物，液体或液体饲料。每年有100万根NG管在医院、社区（护理之家和家庭环境）的NHS中使用，如果病人不能吞咽或饮水，或者需要手术或重症监护，则将液体、饲料和药物送入病人的胃中。 有一个小的机会，NG管可以意外地放入肺（1至3次，100）或从胃移动到食物管（19次，100）。如果液体被错误放置的管子灌入，可能会导致严重的伤害或死亡，这在NHS中被称为“永不事件”。自2011年以来，报告了132起此类“从未发生过的事件”，尽管2011年、2012年和2016年发布了国家患者安全警报，警告NG管错位的危险，但报告的事件数量并未减少，仅2016/17年就发生了26起严重伤害和死亡病例。 到目前为止，检查NG管是否放置在胃中的推荐方法是将一些液体从称为抽吸物的管中取出，并使用pH试纸测试其酸性。低于5.5的阅读表明抽吸物是酸性的，并且管在胃中。然而，获取胃液是困难的，有50-85%的成功机会，所以通常使用X射线。X射线可能会被错误地解释（在57%的从未发生过的事件中）。此外，X射线的成本更高，给患者和工作人员带来延误和不便，并使患者暴露在辐射中。需要采取不同的办法。 我们的项目旨在开发和测试一种新的便携式，基于传感器的设备（称为NG-Sure），以准确检查NG管位置。NG-Sure使用传感器技术，测量气体或化学物质，称为挥发性有机化合物或VOC，在NG管的末端，除了pH值阅读外，还可以创建“气味指纹”。这些指纹是不同的，这取决于管的位置（胃，食物管或肺）。 我们已经进行了一项研究，以测试是否有可能准确地区分来自患者肺部的胃吸出物和呼吸的气味指纹。我们的结果是100%准确的，所有呼吸样本被正确识别为呼吸，所有胃样本被识别为胃穿刺液。我们已经在医院和社区环境中与不同的临床小组讨论了我们的想法，他们告诉我们需要解决NG管放置问题。在这里提出的工作，我们现在要开发，生产和测试的原型NG-Sure模型。为此，我们将：- 生成额外的气味指纹和呼吸pH读数，患者的食物管道和胃样本，以添加到我们现有的气味指纹数据库中-制定一种方法，在患者的NG管就位时，将测量气味指纹和pH读数所需的气体和化学样本送入患者的NG管-在整个项目中与医护人员和患者及其护理人员密切合作，以了解他们的需求和要求，因为我们设计和构建了我们的原型设备-在临床研究中使用200名患者测试我们的原型设备的安全性和功能，方法是将我们的设备与需要NG位置的患者的X射线进行比较-在使用前确认-研究我们的新设备与当前实践相比的经济效益，并确定大规模生产我们设备的方法。

Naso-gastric tubes (called NG-tubes) are passed through the nasal cavity down the back of the throat and through the oesophagus (food pipe) to the stomach and are used to give medication, fluids or liquid feeds to patients. Each year one million NG-tubes are used in the NHS in hospital, community (care home and home settings), to give fluids, feeds and medicines into a patient's stomach, if they cannot swallow or drink, or need surgery or intensive care. There is a small chance that NG-tubes can accidentally be put into the lungs (1 to 3 times out of 100) or move from the stomach into the food pipe (19 times out of 100). If liquid is then given down the misplaced tube, serious harm or death can result, this is known in the NHS as a Never Event. Since 2011 there have been 132 such 'never events' reported and, despite the publication of national patient safety alerts in 2011, 2012 and 2016 warning of the dangers of misplaced NG-tubes, the number of reported events has not decreased, with 26 cases of serious harm and death occurring in 2016/17 alone. Until now, the recommended way to check that an NG-tube is placed in the stomach is to get some fluid up the tube known as aspirate, and test how acidic it is using pH paper. A reading below 5.5 indicates the aspirate is acidic and that the tube is in the stomach. However, getting stomach fluid is difficult with a 50-85% chance of success of getting some, so X-rays are often used instead. X-rays can be interpreted incorrectly (as seen in 57% of never events). Moreover, X-rays cost more, cause delays and inconvenience for patients and staff, as well as exposure of radiation to patients. A different approach is needed. Our project aims to develop and test a new portable, sensor-based device (called NG-Sure) to give an accurate check of NG-tube position. NG-Sure works using sensor technology, measuring gases or chemicals, known as volatile organic compounds or VOCs, at the end of the NG-tube to create 'smell fingerprints' in addition to a pH reading. These fingerprints are different depending upon where the tube is situated (stomach, food pipe or lungs). We have carried out a study to test whether it is possible to accurately distinguish smell fingerpints for stomach aspirate and breath from a patient's lungs. Our results were 100% accurate, all breath samples were correctly identified as breath and all gastric samples were identified as stomach aspirate. We have discussed our idea with different clinical groups, in hospital and community settings, and they have told us that a solution to the problem of NG-tube placement is required. In the work proposed here we now want to develop, produce and test a prototype NG-Sure model. To do this we will:- Generate additional smell fingerprints and pH readings for breath, food pipe and stomach samples from patients to add to our existing database of smell fingerprints- Work out a way of getting the gas and chemical samples needed to measure the smell fingerprints and pH readings up the patient's NG-tube when it is in place- Work closely with healthcare staff and patients and their carers throughout the project to understand their needs and requirements as we design and build our prototype device- Test the safety and function of our prototype device once built in a clinical study with 200 patients by comparing our device against X-rays taken in patients who need the position of their NG-tube confirming before it is used- Study the financial benefits of our new device compared to current practice and identify ways to manufacture our device on a large scale.