Authors: (including presenting author): :
Sze SYM(1), Chau JPC(2), Tong DWK(3), Lai PCK(4), Chung JYM(5), Lo SHS(2), Kwok MLM(3), Lam HKC(3), Choi KC(2), Fan YH(6), Chien WT(2), Au PWP(3)
Affiliation: :
(1) Shatin Hospital, Hospital Authority, Hong Kong (2) The Nethersole School of Nursing, The Chinese University of Hong Kong, Hong Kong (3) Nursing Services Department, Hospital Authority, Hong Kong (4) Queen Mary Hospital, Hospital Authority, Hong Kong (5) Alice Ho Miu Ling, Nethersole Hospital & Tai Po Hospital, Hong Kong (6) Prince of Wales Hospital, Hospital Authority, Hong Kong
Keyword 2: :
Nasogastric tube
Keyword 3: :
Pulmonary placement
Introduction: :
Inadvertent insertion of a nasogastric tube (NGT) into the airway can result in pulmonary aspiration and death. X-ray confirmation is considered gold standard for confirming correct tube placement, but it is not always available. Previous systematic reviews suggest that capnography, the measurement of end-tidal carbon dioxide (ETCO2), may have comparable diagnostic accuracy to radiography in differentiating between respiratory and gastrointestinal tube placement.
Objectives: :
(1) To determine the diagnostic accuracy of ETCO2 detection using capnography for verifying the correct placement of NGTs; (2) to determine the average cost incurred by the participants when radiography alone is used versus when capnography is used in conjunction with radiography.
Methodology: :
A prospective observational diagnostic study was conducted, and a total of 508 adult patients were recruited from medical wards, intensive care units, and emergency departments across 21 Hospital Authority hospitals. The sensitivity, specificity, positive predictive value, and negative predictive value of capnography, the index test, were evaluated using radiography as the reference standard. The average cost saved per patient by using each capnography test compared with using radiography only was estimated together with a confidence interval based on a bias-corrected and accelerated bootstrapping method with 20,000 replications.
Result & Outcome: :
Among all the study participants, there was only one patient (0.2%) identified with airway placement of NGT (ETCO2=32 mmHg). Capnography demonstrated a sensitivity of 100% (95% CI 2.5% to 100%) and a specificity of 97.6% (95% CI 95.9% to 98.8%) for detecting airway placement using an ETCO2 cutoff of 15 mmHg. The average cost per patient for using radiography only was HK$405.9±168.9 and HK$188.3±68.7 for capnography combined with radiology. The average cost would be saved per patient compared with using radiography only was HK$217.5 (95% CI: 203.1 to 232.6). This is the first study to provide evidence on the diagnostic accuracy and cost data of using capnography in detecting pulmonary placement of NGTs among diverse patient populations. Given the positive outcomes and the simplicity of capnography measurement, capnography can be considered a first-line tool to detect pulmonary placement of NGTs, and it can be included in the decision-making process for inserting a NGT in adults, both in hospital and community settings.
