Clinical Report: Assessing capnography costs in nasogastric tube verification

Overview

A 21-hospital study of 508 patients evaluated capnography for identifying airway placement of nasogastric tubes and modeled savings when radiography was reserved for ETCO₂ above a selected threshold. The correspondence argues that these estimates do not establish the costs of a complete pathway combining capnography with aspirate pH testing, because many patients with negative capnography results lacked aspirate or had pH above 5.5 and may still require radiography.

Background

Nasogastric tube verification must distinguish exclusion of airway placement from confirmation of appropriate tube position. The study assessed capnography alongside aspirate pH testing, but the cost model compared radiography for all patients with radiography only for those exceeding an ETCO₂ threshold. Adult guidance cited in the correspondence describes radiography as a second-line step when aspirate is unavailable or pH exceeds 5.5. The practical and economic implications therefore depend on the subsequent verification steps and the intended use of the tube.

Data Highlights

Key Findings

• The study assessed capnography in 508 patients across 21 hospitals to identify airway placement of nasogastric tubes.
• At an ETCO₂ threshold above 5 mmHg, 23 patients were positive and 485 were negative.
• The reported hypothetical saving of HK$210.3 per patient compared with radiography for all patients excluded radiography costs for the capnography-negative group; the authors distinguished this estimate from a cost-effectiveness analysis.
• Aspirate was unavailable in 241 patients and pH exceeded 5.5 in 61; based on the reported marginal counts, at least 279 capnography-negative patients had one of these findings, although their exact overlap is not reported.
• The correspondence notes that the original table reports aspirate availability by radiographic location but does not provide the joint capnography, aspirate availability, pH, and radiographic-position results needed to calculate costs for a combined pathway.
• The cited adult National Nurses Nutrition Group guidance describes radiography as a second-line confirmation step; the correspondence states that local practice and intended tube use should be considered when specifying the pathway.

Clinical Implications

The correspondence calls for a clearly specified combined verification pathway that defines what follows a negative capnography result when aspirate is unavailable or pH exceeds 5.5, and includes the associated checks, imaging, and repositioning costs. It also proposes comparison with the locally used pathway and clarification of when tube use is permissible, particularly in relation to the proposed reduction in emergency department transfers from care homes.

Conclusion

The reported capnography cost estimate is a hypothetical comparison rather than an evaluation of the full verification pathway. Joint-result data and explicit accounting for subsequent confirmation procedures are needed to assess the resource implications of adding capnography.

Related Resources & Content

1. Chau et al., Critical Care, 2026 — Using capnography to differentiate airway from gastrointestinal placement of nasogastric tubes: a prospective multicentre diagnostic accuracy study
2. National Nurses Nutrition Group, 2023 — Good Practice Guideline: Safe Insertion and Ongoing Care of Nasogastric (NG) Feeding Tubes in Adults
3. Guidelines for Verification of Gastric Tube Location in Adult Hospitalised Patients, 2026 — A Systematic Review
4. AHRQ Patient Safety Network — Misplaced Nasogastric Tube Resulting in Aspiration
5. Critical Care — Real-Time Visualization Techniques for Nasoenteral Tube Insertion in Critically Ill Patients: Insights from a Multicenter Study
6. Critical Care (Springer) — Continuous non-invasive measurement of tidal volume and minute ventilation using a smart nasal cannula
7. Frontiers in Medicine — Respiratory safety and resource utilization in ERCP: a comparative study of high-flow nasal oxygen, conventional mask, and general anesthesia in high-risk populations
8. Frontiers in Medicine — Bronchoscopy-Guided Non-Capping Decannulation Pathway Versus Conventional Capping Trial in Patients with Prolonged Tracheostomy: A Retrospective Comparative Cohort Study
9. Using capnography to differentiate airway from gastrointestinal placement of nasogastric tubes: a prospective multicentre diagnostic accuracy study
10. Good Practice Guideline: Safe Insertion and Ongoing Care of Nasogastric (NG) Feeding Tubes in Adults
11. Guidelines for Verification of Gastric Tube Location in Adult Hospitalised Patients: A Systematic Review
12. Misplaced Nasogastric Tube Resulting in Aspiration
13. Guidelines for Verification of Gastric Tube Location in Adult Hospitalised Patients: A Systematic Review - PMC
14. Misplaced Nasogastric Tube Resulting in Aspiration | PSNet
15. ASPEN Safe Practices for Enteral Nutrition Therapy - Boullata - 2017 - Journal of Parenteral and Enteral Nutrition - Wiley Online Library
16. Ultrasonography to confirm gastric tube placement in critical care and emergency: From diagnostic accuracy to an actionable safety pathway - PMC