Authors (including presenting author) :
Chan YK(1), Tsoi YK(1), Ho SKS(1)
Affiliation :
(1)Department of Medicine and Geriatrics, Ruttonjee and Tang Shiu Kin Hospitals
Introduction :
Nasogastric tube (NGT) placement is a standard practice in hospital to administer nutrition or medications for people who cannot resume or tolerate oral intake. Unfortunately, misplacement of NGTs is common and can result in detrimental effects including aspiration pneumonia or respiratory failure. Chest X-ray is the gold standard for verifying correct NGT placement in the stomach. However, radiography is not always available conveniently at the bedside and could expose patient to radiation. Another standard method for verifying NGT placement is measurement of aspirates for pH value. However, the accuracy can be suboptimal and often compromised by factors such as inability to aspirate adequate fluids for testing, difficulty in differentiating the colour change in test strips visually, use of antacids, or reflux of gastric contents. Therefore, a reliable and effective alternative bedside test to verify NGT placement is required. An increasing amount of evidence suggests that end-tidal carbon dioxide (ETCO2) detection may be a promising method to verify NGT placement.
Objectives :
The goal of this study is to test the applicability of capnography in confirming NGT placement in clinical setting.
Methodology :
A convenience sampling was used and any patients from 5 geriatric wards who required NGT insertion were eligible for the study. NGT insertion was done as usual practice except a portable EMMA® Capnograph was attached to the NGT during insertion. One designated nurse was responsible for NGT insertion for all recruited patients. The nurse would observe for any reading or waveform developed during NGT insertion. At the end of insertion, gas was aspirated from NGT to detect for any CO2 content. A ETCO2 level > 2 kPa is considered as airway placement of the NGT. The ETCO2 result would then be compared with our current reference standard (i.e. gastric aspirate pH or CXR) to decide the location of NGT.
Result & Outcome :
A total of 39 patients were recruited during May 2020 to Jan 2021. 29 were male and 10 were female. Their age ranged from 35 to 108 with an average of 75.9. During the insertion process, there were 3 cases had ETCO2 > 2 kPa detected and all of them developed clinical signs of airway placement e.g. severe cough, desaturation. NGT had to be withdrawn and reinserted. At the end point, 21 patients had no ETCO2 reading and their NGT was confirmed by gastric aspirate. 15 cases had no ETCO2 reading but nil or negative gastric aspirate. Their NGTs placement were later confirmed by CXR. However, there were 3 cases who had no ETCO2 reading and nil gastric aspirate, CXR showed the NGTs were positioned in oesophagus only.
