Introduction:
A variety of methods have been used to assess Nasogastric tube (NGT) placement. Only gastric aspirate pH checking 5.5 & X-ray imaging are considered as gold standard method and widely accepted as the most reliable test. The study will collect information to demonstrate the reliability of colorimeter testing/ capnography monitor. It helps to serve as an additional screening tool for identification of tube placement, when the patient fails to collect gastric aspirate for testing.
Objectives:
To ascertain the accuracy of colorimeter/ capnography, with radiographic examination as the reference standard; as well as to assess the time lag from change of NGT to resume feeding of patient.
Methodology:
This is a prospective descriptive study. 71 samples are recruited from three Medical Extended wards by convenience sampling for colorimeter test. 12 samples were recruited from old age homes for a pilot study on capnography monitor with 15 trails of NGT insertion. The colorimeter test/ capnography monitor does not involve any invasive procedures & will not cause any short-term or long-term discomfort to the patient. Without getting gastric aspirate, by clinical judgement found no tube coiling inside the mouth, positive auscultation “Whoosh Test”, and the colorimeter test/ capnography monitor is performed. Then, comparing of result with X-ray imaging without leading to skipping procedures in usual clinical practice. (The Joanna Briggs Institute, 2016).
Result & Outcome:
There were 26 patients in the study with a mean age of 74.07 years (SD = 16.33). Fifteen (57.7%) of them were male. The final sample consisted of 71 doubtful NGT placements and none of them was misplaced. The specificity of CO2 colorimeter was 98.6%, and the negative predictive value was 100% while the sensitivity and positive predictive value were unable to determine. The patient waiting time required for X-ray imaging verification ranged from 51 to 1095 minutes (mean = 380.75 mins., SD = 179.51).
15 trails of NGT insertion performed for the pilot study of capnography monitor. The ETCO2 waveform were all present at nostril area before NGT insertion; none of the episodes detected ETCO2 and crisp waveforms after verify of tube placement in the stomach by the “Whoosh test”.
Conclusion:
CO2 colorimeter has high specificity and negative predictive value in verification of doubtful NGT placement. Using it to replace X-ray imaging verification may speed up resumption of NGT feeding. Meanwhile, further study to enhance the diagnostic accuracy of ETCO2 detection for inpatient in general ward is needed.
