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

Lead Research Organisation: Bradford Teaching Hosp NHS Found Trust
Department Name: Bradford Institute for Health Research

Abstract

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.

Technical Summary

Naso-gastric tubes (NG-tubes) are used worldwide each year in hospital and community settings (UK-1million; US-1.2 million; EU-10million) to give enteral feeds and medicines to patients unable to swallow/tolerate oral feeds (e.g. from critical illness, deteriorating consciousness level, neurological condition (stroke) or post gastro-intestinal surgery). Accidental misplacement during blind insertion into the respiratory tract or pleura occurs in 1-3% cases, and into the oesophagus in 19%, with later tube migration in up to 50%. If fluids are given down a misplaced tube, serious patient harm or death can result, an NHS Never Event.

The recommended first-line NG-tube placement test is to obtain aspirate up the tube and check its acidity with pH paper. A pH of 1 to 5.5 is a 'safe range' to exclude respiratory tract misplacement and to use the tube. Obtaining aspirate is difficult (50-85% chance of success), and pH readings may be unclear. The second-line test is then an X-ray which can be misinterpreted (seen in 57% of never events), is costly, exposes patients to radiation, causes delays in feeding and increases movement/travel of seriously ill hospitalised patients or community patients needing longer-term feeding. A different approach is needed.

Our 3-year project aims to produce and test a new portable, sensor-based, NG-tube placement device (NG-Sure). It will measure gases and volatile chemicals at the NG-tube tip, to create 'VOC (volatile organic compound) fingerprints' and a pH reading (without needing aspirate). Fingerpints will differ according to tube location (stomach, lungs or oesophagus). We have proved clinical feasibility of our idea on 33 paired gastric and breath samples, and aim to develop, produce and test a prototype device in patients with a chosen set of sensors. Our experienced team will involve patients, carers, and NHS staff throughout, and examine financial benefits and potential markets.

Planned Impact

This applied, translational research project has a number of potential benefits to patients in hospital and community (home and residential care) settings, the NHS, to other healthcare providers (care homes, private healthcare providers), medical, nursing, dietetic and scientific communities, the UK and EU economy and wider society.

The device, NG-Sure, has the potential to produce outcomes with the following benefits:

Patients (within three years):
- NG-Sure will help reduce the risk of misplaced NG-tubes into a patent's lung or oesophagus and the associated patient harm, as a consequence of misplaced NG-tubes (e.g. aspiration pneumonia, malnutrition), and deaths.
- Reduced delay to the onset of feeding or medicines administration owing to waiting for X-ray verification (reported waits on average of four hours for these check X-rays), and interpretation of NG-tube position
- Less patient exposure to radiation from X-rays
- Improved patient and carer experience of NG-tube care using a new non-invasive device.
Inserting an NG-tube is necessary as part of the treatment for these patients, our sampling procedures will not be more invasive than this, and should not increase the discomfort for patients. In our earlier research there was no evidence of greater discomfort for patients during sampling processes. Use of the device may avoid the need for a patient to have an X-ray for NG-tube verification in the absence of aspirate or borderline/high pH.
- Increased confidence for patients, carers and clinicians (NG-tube users) as two measurements for NG-tube position will be provided to identify NG-tube location.

NHS (within three years):
- A safe, simple, convenient, and timely method of verifying NG-tube position in adults at the point of care in a cost-effective manner that could reduce the number of never events and serious incidents.
- Preliminary evidence on the safety (accuracy) and clinical utility (functionality) of NG-Sure, as well as an estimate of the reimbursement potential of NG-Sure to allow the NHS to make an informed decision regarding procurement
- Income generation for the NHS through a robust commercialisation plan and exploitation of arising IP
- Publication outputs in International peer-reviewed, professional and academic journals, with potential data sharing, as described and agreed in the project's Data Management Plan. Thus, raising the global profile of the host institution (Bradford Teaching Hospitals NHS Foundation Trust), its affiliated academic institution (Bradford Institute for Health Research), host Patient Safety Translational Research Centre, and NHS research.

NHS (within five to eight years):
- Potential savings to EU health providers of more than £400 million, assuming 10 million NG-tubes are used, and a 25% reduction in X-rays.
- Functionality to wirelessly upload data to hospital or primary care Electronic Patient Record (EPR) systems, or centralised reporting systems, to act as an alert for relevant staff
- Potential to translate VOC technology into other healthcare contexts, e.g. field of diagnostics - cancer diagnosis, detection of infections, screening for medication adherence, and positional checks for other invasive catheters/tubes.

The anticipated outputs of the research project include:
- Peer-reviewed evidence on the accuracy of VOC fingerprints coupled with pH detection as a position indicator for safe placement of NG-tubes in the stomach
- Evidence of safety testing for the NG-Sure device
- An effective method of sample collection and production of micro-sensors
- A prototype device for confirming NG-tube position.

Publications

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Title NG-Sure WP1 - fluid and air samples 
Description Dataset of results from Volatile Organic Compounds (VOCs) analysis from patient samples (gastric fluid, gastric air, oesophageal air, breath). 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? No  
Impact Use of dataset/analysis has been used to select sensors to create a new sensor array that will be used as part of a new medical device. Dataset used for creating a new statistical model used to discriminate between air samples from unknown origin (lung, oesophagus, or stomach). 
 
Title NG-Sure WP2 - air samples & feasibility of air sample collection method 
Description Generation of a new dataset comprising results of VOC analysis of samples of air collected from patients with an NG-tube in situ. Dataset about feasibility of air sample collection method. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? No  
Impact The data is being used to assess the feasibility of collecting air samples from a patient's NG-tube for analysis. The data helps guide the development of a new device designed to enhance the safety of NG-tubes by providing a new means of checking NG-tube position, without the need to collect gastric aspirate from patients and therefore avoiding additional testing e.g. x-rays. 
 
Description Bradford Teaching Hospitals NHS Foundation Trust 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact NG-Sure had a stand at the Bradford Teaching Hospitals NHS Foundation Trust Open Day Event held at Bradford Royal Infirmary. The event was to showcase the work done across the Trust to the local community, including research. NG-Sure had a stand to inform people about some of the work the study has been doing to enhance the safety of naso-gastric (NG) tubes. This involved having a medical mannequin available for people to try and insert a nasogastric tube and demonstrate the ways that this can go wrong. We also showed a short film that had been made for the CLAHRC. Members of the NG-Sure team were available to answer questions about the study throughout the day. People we spoke to said that they weren't previously aware of the problems associated with NG-tube insertion and that the device we are developing sounds useful.
Year(s) Of Engagement Activity 2019
URL https://www.bradfordhospitals.nhs.uk/2019/06/25/hospital-set-to-throw-open-its-doors-for-community-f...
 
Description NG-Sure Workshop at National Patient Safety Conference 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact The NG-Sure project team delivered a workshop about developing innovations for patient safety within the NHS. NG-Sure was used as a case study to demonstarte some of the key ideas and principles being discussed. People reported finding the workshop interesting and useful. We were approached by some clinicians who were interested in taking part in the research project and/or being kept up to date about the research project as it progressed.
Year(s) Of Engagement Activity 2019
 
Description Podcast - interview about conference workshop delivered on 15/10/19 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact The NG-Sure team delivered a workshop about the development process for patient safety innovations. Natasha Hardicre (Project Senior Research Fellow) was interviewed about the workshop. This is hosted on SoundCloud and shared via Twitter and provides a breif overview of the workshop key points for people who could not attend.
Year(s) Of Engagement Activity 2019
URL https://soundcloud.com/national-elf-service/natasha-hardicre
 
Description Press release about the NG-Sure project being awarded funding from the Medical Research Council 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A local newspaper wrote a press release to inform people in the local area about the awarding of funding to the project. This press release was done prior to the study commencing but has still contributed to dissemination of information about the study.
Year(s) Of Engagement Activity 2018
URL https://www.thetelegraphandargus.co.uk/news/16308439.grant-of-1m-awarded-to-bradford-and-leeds-resea...
 
Description Short film - 'Evidence Based Transformation within the NHS' 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The Chief Investigator for the NG-Sure Project, Angela Grange, talked about the ways in funding from the CLAHRC has facilitated work to demonstrate proof of concept regarding the development of a new device to detect the correct positioning of NG-tubes without the need for gastric aspirate or pH testing. This was part of a video that was highlighting the ways in which CLAHRC funding has been used for evidence-based transformation within the NHS, especially around achieving behaviour change about the safe placement of NG-tubes. The video provides a brief overview of the aim of the new device and why it would be a beneficial innovation.
Year(s) Of Engagement Activity 2019
URL http://clahrc-yh.nihr.ac.uk/clahrc-film
 
Description Stand at the opening of Wolfson Centre for Applied Health Research (CAHR) Open Day Event 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact NG-Sure had a stand at the Wolfson Centre for Applied Health Research (CAHR) Open Day Event. The evnt brought together academics from across the region to mark the opening of the new building and the collaboration between between various institutions. NG-Sure had a stand to showcase some of the work the study has been doing to enhance the safety of naso-gastric (NG) tubes. This involved having a medical mannequin available for people to try and insert a nasogastric tube and demonstrate the ways that this can go wrong. We also showed a short film that had been made for the CLAHRC. Members of the NG-Sure team were available to answer questions about the study throughout the day. People we spoke to said that they weren't previously aware of the problems associated with NG-tube insertion and that the device we are developing sounds useful.
Year(s) Of Engagement Activity 2019
 
Description Yorkshire & Humber Regional Meeting - Gastroenterology Clinicians 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact The Chief investigator for NG-Sure, Angela Grange, provided an overview of the project aims to Gastroenterology Consultants in the Yorkshire and Humber regional meeting. People reported finding the work interesting and suggested that the device, once developed, would be useful. A couple of clinicians proposed ideas for consideration in the device development.
Year(s) Of Engagement Activity 2019