Diagnostic Accuracy of Capnography in Nasogastric Tube Placement

Study Overview
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Brief Summary
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A prospective observational diagnostic study will be conducted to assess the sensitivity and specificity of using capnography in detecting the correct placement of nasogastric tubes using the reference standards of radiography and measurement of aspirates for pH value.

Detailed Description
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A prospective observational diagnostic study will be conducted. Patients ≥ 18-year-old and requiring the insertion of an nasogastric tube will be recruited using a convenience sampling method from general medical and geriatric wards, intensive care units (ICUs), accident and emergency departments (AEDs), and subacute/rehabilitation/infirmary wards in 21 acute or subacute/convalescent/extended care hospitals. End-tidal carbon dioxide (ETCO2) detection by sidestream capnography, which indicates airway intubation of an nasogastric tube when a capnogram waveform or an ETCO2 level > 10 mmHg, will serve as the index test. The reference standards will be the pH value of gastric content aspiration (pH ≤ 5.5 indicates gastric placement) and X-ray performed after the index test. Each participant will be included only once. Sensitivity, specificity, positive predictive value, and negative predictive value, and the area under the receiver operating characteristic curve of capnography will be calculated to assess the diagnostic performance of capnography. The variability in diagnostic accuracy in participants with different characteristics will be compared. The time spent and the cost of the index test and the reference test will be compared. This study will provide evidence on the diagnostic accuracy of capnography in verifying nasogastric tube placement and inform the update of clinical practice guidelines and stakeholders' decisions regarding the adoption of ETCO2 detection as a routine method for verifying nasogastric tube placement.

Official Title
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Diagnostic Accuracy of Using Capnography in Verification of Nasogastric Tube Placement in Hospital Settings

Conditions
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Capnography, Nasogastric Tube, Diagnostic Accuracy

Intervention / Treatment
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* Diagnostic Test: Capnography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years old or above; Admitted to the general medical and geriatric wards, ICUs, or subacute/rehabilitation/infirmary wards in subacute/convalescent/extended care hospitals or visiting AEDs in acute hospitals; Requiring the insertion of an nasogastric tube into the stomach for assessment, nutritional support and medication administration during the study period. Exclusion Criteria: Participants receiving life-saving intervention at the time of recruitment.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Observational group<br>All participants included will be in one observational cohort. | Diagnostic Test: Capnography<br>* Index test: Capnography, which monitors ETCO2, the percentage concentration, or partial pressure of CO2 at the end of exhalation, will serve as the index test. It will be performed by connecting the end of the nasogastric tube with the sensor of the bedside sidestream capnography device. Placement within the airway is defined as detecting a capnogram waveform or an ETCO2 level > 10 mmHg. Reference standard: This study will use radiography (chest/abdominal X-ray) as the reference standard for determining the correct placement of nasogastric tubes. Radiology will be performed as soon as possible and interpreted by a physician. A repeat radiography will be performed if necessary. We will also use pH-Fix-4.5-10 to determine the pH value, and its accuracy is +/- 0.2 pH with minimum increments of 0.5. A pH of 5.5 or below indicates gastric placement.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity of Capnography | True Positive / (True Positive + False Negative) × 100% | Through study completion, an average of 2 year | 
| Specificity of Capnography | True Negative / (True Negative + False Positive) × 100% | Through study completion, an average of 2 year | 
| Positive Predictive Value of Capnography | True Positive / (True Positive + False Positive) × 100% | Through study completion, an average of 2 year | 
| Negative Predictive Value of Capnography | True Negative / (True Negative + False Negative) × 100% | Through study completion, an average of 2 year | 
| Overall diagnostic performance of Capnography | Measured by the area under the receiver operating characteristic curve (AUROC). The test accuracy level is considered high when the AUROC value is ≥ 0.9. | Through study completion, an average of 2 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in the time spent of index test and reference test | Compare the time spent of index test (i.e., capnography) and reference test (i.e., radiography) | Through study completion, an average of 2 year | 
| Difference in the cost of index test and reference test | Compare the cost of index test (i.e., capnography) and reference test (i.e., radiography) | Through study completion, an average of 2 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Capnography, Intubation, gastrointestinal, Diagnostic accuracy