Testing nasogastric tube positioning in the critically ill: exploring the evidence

Diagnostic accuracy of methods used to verify nasogastric tube position in mechanically ventilated adult patients: a systematic review

BACKGROUND

Nasogastric tubes are widely used in hospitals, e.g. for the administration of nutrients. However, nasogastric tubes can be inserted accidently into the airways leading to complications like pneumonia, pneumothorax and even death. Mechanically ventilated patients are at high risk of having a nasogastric tube misplaced, since they often have reduced consciousness and weak cough reflex. A variety of methods have been used for determination of nasogastric tube placement, but with varying success.

OBJECTIVES

The present systematic review was carried out to evaluate the diagnostic accuracy of methods used to determine nasogastric tube placement in mechanically ventilated adult patients.

INCLUSION CRITERIA

Studies including mechanically ventilated adult patients with a nasogastric tube were considered for inclusion, regardless of the type of nasogastric tube.All methods (index tests) used to verify nasogastric tubes placed in the airways and in the gastrointestinal tract were included. As a reference standard, X-ray was used to verify the accuracy of each index test.The studies that were included in the present systematic review were designed based on diagnostic test accuracy studies.The outcome was the accuracy (sensitivity and specificity) of the methods to discriminate between respiratory and gastrointestinal placement of the nasogastric tube.

SEARCH STRATEGY

The search strategy aimed to find both published and unpublished studies before September 2013. Eleven electronic databases were searched including CINAHL, PubMed, Scopus and Embase.

METHODOLOGICAL QUALITY

Methodological quality was assessed independently by two reviewers using QUADAS as a critical appraisal tool.

DATA EXTRACTION

Data were extracted by two reviewers independently using a modified Joanna Briggs Institute data extraction form including specific details such as: population, setting, index test, sensitivity and specificity.

DATA SYNTHESIS

Sensitivity and specificity were extracted from the studies and presented in tables. When these were not written in the studies, calculations were performed based on data presented in the studies.

RESULTS

Five relevant papers describing two different methods for determining nasogastric tube position were identified: colorimetric capnography (four studies) and capnography (one study).In all four studies examining colorimetric capnography the sensitivity was 100% when nasogastric tubes were inserted intentionally into the airways through an already existing tracheal tube, thereby imitating misplaced nasogastric tubes. When inserted through the nose, the sensitivity was 88-100% and specificity was 99-100%.Capnography obtained a specificity of 100% but sensitivity for when the nasogastric tube was inserted through the nose could not be calculated based on available data.

CONCLUSIONS

We found evidence (Level 2b) for colorimetric capnography to be a valid method for verifying nasogastric tube placement.Capnography also detected nasogastric tube position with very high accuracy. However, since these methods were tested in only a single study with a limited sample size, further research is required before clinical recommendations can be made.Despite the impressive results obtained by using colorimetric capnography, implication for practice is not straightforward. A concern is that the colorimetric capnograph is not produced by the manufacture to fit a NG tube and therefore has to be connected to the NG tube by an adaptor-system. Practical issues therefore have to be resolved if the method is supposed to become a standard procedure in a clinical setting.The execution of the procedure using colorimetric capnography differs between the studies. This systematic review therefore recommends that further research should be done to optimize the execution of the procedure.We also recommend that further research be done to reproduce the results obtained using capnography, since this method was tested only in a single study with a limited sample size.

A case of a ‘lost’ nasogastric tube

Objectives:

To present the case of a ‘lost’ nasogastric tube and to highlight the importance of imaging and/or chest X-ray after nasogastric tube insertion, especially in unreliable patients.

Case report:

A 50-year-old man, undergoing radiotherapy treatment for squamous cell carcinoma of the tongue base, was admitted for pain control and nasogastric tube feeding. This patient required multiple nasogastric tubes over a two-week period. The patient repeatedly denied pulling the nasogastric tube out and we were unable to establish the exact mode of nasogastric tube removal. On one such occasion another tube was inserted and a check X-ray showed two feeding tubes; the latest one was lying in the left main bronchus and the old nasogastric tube was observed in the oesophagus, with its upper end jutting above the hypopharynx. It was apparent that the patient had somehow cut the tube and swallowed it.

Conclusion:

This case not only illustrates the importance of flexible nasendoscopy and/or chest X-ray for checking the position of the nasogastric tube, but also highlights that some patients are not tolerant of nasogastric tubes. The use of nasogastric tubes should be avoided in these patients to prevent any self-inflicted injury.

Best evidence: nasogastric tube placement verification

Further research on cost-effective techniques to verify enteral tube placement is warranted using a variety of pediatric populations with differing conditions that may impact gastric pH. It is imperative that clinical facilities review current policies and procedures to ensure that evidence-based findings are guiding nursing practice. Many nurses continue to rely on auscultation to verify NGT placement. Education and competency validation can assist with current practices for NGT placement being consistently incorporated by all personnel in the health care setting. Continuing to search for evidence related to nursing care will guide the direct care RN in providing best practice.

Practical approach to paediatric enteral nutrition: a comment by the ESPGHAN committee on nutrition

Enteral nutrition support (ENS) involves both the delivery of nutrients via feeding tubes and the provision of specialised oral nutritional supplements. ENS is indicated in a patient with at least a partially functioning digestive tract when oral intake is inadequate or intake of normal food is inappropriate to meet the patients' needs. The aim of this comment by the Committee on Nutrition of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition is to provide a clinical practice guide to ENS, based on the available evidence and the clinical expertise of the authors. Statements and recommendations are presented, and future research needs highlighted, with a particular emphasis placed on a practical approach to ENS.Among the wide array of enteral formulations, standard polymeric feeds based on cow's-milk protein with fibre and age adapted for energy and nutrient content are suitable for most paediatric patients. Whenever possible, intragastric is preferred to postpyloric delivery of nutrients, and intermittent feeding is preferred to continuous feeding because it is more physiological. An anticipated duration of enteral nutrition (EN) exceeding 4 to 6 weeks is an indication for gastrostomy or enterostomy. Among the various gastrostomy techniques available, percutaneous endoscopic gastrostomy is currently the first option. In general, both patients and caregivers express satisfaction with this procedure, although it is associated with a number of well-recognised complications. We strongly recommend the development and application of procedural protocols that include scrupulous attention to hygiene, as well as regular monitoring by a multidisciplinary nutrition support team to minimise the risk of EN-associated complications.