Feasibility of volatile detection for NG tube placement (Phase III)
Research type
Research Study
Full title
Feasibility of Volatile Biomarker Positioning of Naso-Gastric (NG) Tubes to Enhance Patient Safety (Phase III)
IRAS ID
252022
Contact name
Angela Grange
Contact email
Sponsor organisation
Bradford Teaching Hospitals NHS Foundation Trust
Duration of Study in the UK
0 years, 6 months, 9 days
Research summary
Summary of Research
Naso-gastric (NG) tubes (a tube passed through a patient's nostril into their food pipe and then stomach, secured to the patient's cheek with tape) are widely used in the NHS for adult and child patients to provide enteral feeds or
medicines for patients who cannot swallow or tolerate feeds by mouth, or patients requiring intensive care/surgery.There are patient safety concerns if a NG-tube becomes misplaced into the patient's lung during insertion or moves out of the patient's stomach at a later stage, which can result in serious consequences for the patient or even death if
feeding occurs through a misplaced NG-tube. The current procedure for testing correct placement of an NG-tube relies upon getting gastric aspirate up an NG-tube for testing with pH paper, but only 65% success rates are reported for
getting aspirate. Then X-rays are used to verify NG-tube position; X-rays
are costly and inconvenient for patients, and also subject to misinterpretation. Something better is needed. The research proposed aims to build upon our earlier feasibility studies to test our proof of concept using volatile organic compounds (VOCs) as biomarkers for NG-tube position and measuring a pH response.The study will obtain biological samples from 15 patients undergoing a routine hospital gastroscopy procedure. These samples will be used to further develop sensors to analyse VOCs, including hydrochloric acid (HCl) as a gaseous marker for pH, from gastric aspirate, gastric air, oesophageal air and breath samples. The more selective array of chemical sensors will inform and support the development of a new portable bedside device that healthcare staff and carers could use to test correct placement of an NG-tube.
Summary of Results
A nasogastric tube (NG-tube) is a narrow, flexible tube which is passed into a patient’s stomach via their nose. Naso-gastric tubes are used to give feeds and medicines to patients who are unable to swallow or tolerate these feeds by mouth, and for some patients requiring intensive care or surgery.There is a risk that an NG-tube can become misplaced into the lungs when it is being inserted, or move out of the stomach at a later stage into the food-pipe (oesophagus) or the lung.
There are procedures for checking that the NG-tube is in the correct place (patient’s stomach) by drawing fluid up the NG-tube using a syringe and measuring the acidity of the fluid. Sometimes it can be difficult to get a sample of fluid up the NG-tube and an X-ray is then needed to check the NG-tube position. The X-ray will only show where the NG-tube is at the time of the X-ray and repeat X-rays may be required. Occasionally these X-rays can be misinterpreted - the location of the NG-tube is not correctly identified - and if the NG-tube is then used it may lead to patient harm.
Our study described here is the first of five pieces of work which overall aims to develop and test a new device to improve the correct detection of NG-tubes in adult patients. In this study we aimed to collect four samples from patients during their routine gastroscopy procedure:
1) fluid from the stomach;
2) air from the stomach;
3) air from the oesophagus (food-pipe)
4) air from a patient’s exhaled breath.
We wanted to analyse these samples and see if there were differences in their chemical composition according to the type of sample. In particular, we were testing for volatile organic compounds (VOCs) . If we could detect VOCs, and there were differences in these VOCs according to the different sample types, we could develop sensors to detect these VOCs. We could then build these sensors into a new technology that might improve the safety of NG-tube testing in the future.We aimed to recruit at least 15 patients to our study and collect four sample types from each patient. We recruited 43 patients but 7 patients were withdrawn as we were unable to get all four sample types. We successfully analysed all samples with a VOC analyser and identified VOCs. We found differences in the VOCs according to the sample type - stomach, oesophagus, and breath. We used further statistical analyses on our data to select three sensors to develop and build into a new prototype device. We aim to test this prototype in a future study. We will share our results when all of the studies in this programme of research have been completed.
REC name
West of Scotland REC 4
REC reference
18/WS/0221
Date of REC Opinion
21 Dec 2018
REC opinion
Further Information Favourable Opinion