Nasogastric Tube, Nasogastric Tube Placement, Ultrasound
Conditions
Brief summary
A prospective observational diagnostic study will be conducted to assess the sensitivity and specificity of ultrasound in verifying the correct nasogastric tube placement, using X-ray as the reference standard.
Detailed description
This study is a prospective observational diagnostic investigation aimed at evaluating the accuracy of ultrasound in confirming nasogastric tube (NGT) placement. Participants aged 18 years or older requiring NGT insertion will be recruited via convenience sampling from community nursing centres across five clusters and medical and geriatric wards in four acute or convalescent hospitals. Nurses performing index tests will complete standardized POCUS training (8-hour theory and practical sessions, written exams, 3-month bedside practicum with ≥20 positive scans) prior to competency assessment. Direct visualisation of an NGT in both the oesophagus and stomach will be interpreted as correct stomach placement. When the acoustic shadow of an NGT was not seen in the stomach, 50cc of air was injected through the NGT, and it was considered well-placed if the ultrasonography showed dynamic fogging. Correct gastric placement is assumed if the acoustic shadow of an NGT is visible in the oesophagus and stomach, even if fogging is not detectable. The reference standard will be post-index test X-ray confirmation. Diagnostic performance metrics, including sensitivity, specificity, positive and negative predictive values, and likelihood ratios, will be calculated to assess the efficacy of ultrasound. Variability in diagnostic accuracy across participant characteristics will be analyzed. Additionally, the study will compare the time intervals between ultrasound and X-ray, delays in feeding initiation post-placement, and associated costs, including emergency department admissions, unplanned hospitalizations, and ambulance transportation. The findings will provide critical evidence on the diagnostic utility of ultrasound for NGT placement verification, informing potential revisions to clinical practice guidelines and supporting stakeholder decisions on integrating ultrasound as a reference test.
Interventions
DEVICEDiagnostic ultrasound
A portable wireless ultrasound system (Vscan Air, General Electric Healthcare) with dual probes-linear array (3-12 MHz) for neck scanning and curved array (2-5 MHz) for subxiphoid scanning-will be used. The linear probe is placed transversely on the anterior neck, slid left at the thyroid level to focus on the esophagus, then rotated for longitudinal views. The curved probe is applied subxiphoid, using the liver as a landmark, and tilted left to image the stomach. A positive result is confirmed by visualizing the NGT shadow in the esophagus and stomach, followed by dynamic upsurge fogging after injecting 50cc of air. Ultrasonography and X-ray results will be compared.
DEVICEDiagnostic X-ray
This study will employ chest radiography as the reference standard for verification of correct nasogastric tube placement. Radiographic imaging will be conducted following NGT insertion and interpreted by physicians to verify positional accuracy.
Sponsors
Pamela Youde Nethersole Eastern Hospital
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Aged 18 or older; * Living in the community or admitted to a medical and geriatric ward; * Requiring the use of an NGT during the recruitment period for assessment, monitoring, nutritional assistance, drainage, and/or medication administration; * Aspirated fluids with a pH value of more than 5.5 after insertion or with insufficient fluids for pH testing after insertion;
Exclusion criteria
* Uncooperative patients; * Had head and neck injury * Have had a gastrectomy or by-pass surgery; * History of abdominal trauma or receiving emergency life support intervention at time of recruitment.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Diagnostic Accuracy of Ultrasound in correct Nasogastric Tube placement confirmation | An average of 18 months | Sensitivity: True Positive / (True Positive + False Negative) x 100% Specificity: True Negative / (True Negative + False Positive) x 100% Positive Predictive Value: True Positive / (True Positive + False Positive) x 100% Negative Predictive Value: True Negative / (True Negative + False Negative) x 100% Positive Likelihood Ratio: sensitivity / 1 - specificity Negative Likelihood Ratio: 1 - sensitivity / specificity |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Time lag between USG & x-ray | An average of 18 months | The study will assess the time lag between ultrasound confirmation and subsequent X-ray imaging for nasogastric tube placement verification. |
| Delay between tube placement and feeding by x-ray | An average of 18 months | The study will evaluate the delay between nasogastric tube placement and the initiation of feeding, as confirmed by X-ray. |
| Cost of ED admission, unplanned admission, ambulance transportation | An average of 18 months | The study will analyze costs associated with Emergency Department admissions, unplanned hospital admissions, and ambulance transportation related to nasogastric tube placement confirmation. |
Countries
Hong Kong
Outcome results
None listed