Biomedical subjects
N Metheny
Publications and source records attributed to N Metheny.
Detection of inadvertent respiratory placement of small-bore feeding tubes: a report of 10 cases.
Documented inadvertent respiratory placement of small-bore feeding tubes was identified in 10 patients over a 2-year period in five intensive care units and two general wards. Types and effectiveness of bedside methods used by clinicians to test tube position were described. The most frequently used methods were observation for respiratory distress and auscultation of the abdomen during air insufflations through the tubes. It was concluded that commonly used bedside methods to test feeding tube placement often gave false reassurance that the tubes were properly positioned.
Effect of tube-feeding osmolality on serum sodium levels.
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Re: 'Effectiveness of the auscultatory method in predicting feeding tube location'.
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Effectiveness of the auscultatory method in predicting feeding tube location.
A clinical study was conducted to determine the extent to which sounds generated by air insufflations through feeding tubes could be used to predict where the tubes' ports ended in the gastrointestinal tract (esophagus, stomach or proximal small intestine), and to differentiate between gastric and respiratory placement. Sounds generated by a series of air insufflations through the tubes of 85 acutely-ill adult subjects were recorded. One hundred fifteen usable tape-recordings of sound sequences were obtained. The principal investigator later played the tapes for the research team members (who were also skilled clinicians) so that they could independently record their impressions of the sounds. (No identification of subjects or tube positions were given on the tapes; however, each site of auscultation was announced.) The results were collated and compared against the hypotheses and actual tube location (as determined by X-ray). Overall, the average percentage of correct classifications of each tape was 34.4%. Descriptive data were reported for three subjects with feeding tubes inadvertently positioned in the respiratory tract; air insufflations were clearly audible in 2 of the 3 cases. Clinicians should not rely on the auscultatory method to differentiate gastric from intestinal placement, nor gastric from respiratory placement of feeding tubes.
Effectiveness of pH measurements in predicting feeding tube placement.
The extent to which pH values of aspirates from feeding tubes could be used to differentiate between (a) gastric and intestinal placement, and (b) gastric and respiratory placement were determined in a clinical study. The sample consisted of 181 adult subjects, 94 with small-bore nasogastric tubes and 87 with nasointestinal tubes. Data were collected at the time of initial tube placement and again, when possible, after one or two days of tube feedings. Using color coded pH-paper, a total of 247 readings were made concurrently with x-rays to determine feeding tube position. Findings indicated that pH readings were often effective in differentiating between gastric and intestinal placement (p less than .0001). For example, approximately 81% of the aspirates from nasogastric tubes had pH values ranging from 1 through 4, while almost 88% of the aspirates from nasointestinal tubes had pH values of 6 or greater. Only one aspirate from a tube inadvertently placed in the lung was tested; as expected it had an alkaline pH.