Authors (including presenting author) :
Cheng PPP (1), Lee FKI (2)
Affiliation :
(1) Department of Medicine, Yan Chai Hospital, Kowloon West Cluster
(2) Nethersole Institute of Continuing Holistic Health Education, Alice Ho Miu Ling Nethersole Charity
Introduction :
The gastric aspirate pH checking 5.5 & X-ray imaging are considered as Gold Standard and widely accepted as the most reliable test to assess Nasogastric tube (NGT) placement. This study aims to demonstrate the reliability of colorimeter to serve an additional screening tool for identification of tube placement if the gastric aspirate could not be obtained.
Objectives :
To ascertain the accuracy of colorimeter, with radiographic examination as the reference standard, to verify the NGT placement for patients
To assess the time lag from change of NGT to resume feeding of the patient.
Methodology :
A prospective descriptive study was approved by KWC/REC in November 2018.
By convenience sampling, doubtful NGT placements were obtained from extended-care wards. Each case would be verified by both x-ray imaging and CO2 colorimeter. The test did not involve any invasive procedures or skipping procedures in usual clinical practice.
For patient without getting gastric aspirate, found no tube coiling inside the mouth, acquired positive auscultation “Whoosh Test”, the colorimeter was tested for the presence of carbon dioxide.
Result & Outcome :
There were 26 patients in the study (mean = 74.07years; SD = 16.33), 15 (57.7%) of them were male. The final sample consisted of 71 doubtful NGT placements, none of them was misplaced.
The specificity of CO2 colorimeter was 98.6%, the negative predictive value was 100% while the sensitivity and positive predictive value were unable to determine.
The average waiting time required for X-ray verification ranged from 51 to 1,095 minutes (mean = 380.75 min., SD = 179.51). In all, the patients would resume feeding in 6 – 7 hours after change of NGT.
The 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 and helps to minimize patient unnecessary exposure to radiation
