Search PubMed⌕ Search

Biomedical subjects

N Metheny

Publications and source records attributed to N Metheny.

At least 19 recordsLinked to original sources
PubMed2001

Statistical estimation and pedigree analysis of CCR2-CCR5 haplotypes.

As more SNP marker data becomes available, researchers have used haplotypes of markers, rather than individual polymorphisms, for association analysis of candidate genes. In order to perform haplotype analysis in a population-based case-control study, haplotypes must be determined by estimation in the absence of family information or laboratory methods for establishing phase. Here, we test the accuracy of the Expectation-Maximization (EM) algorithm for estimating haplotype state and frequency in the CCR2-CCR5 gene region by comparison with haplotype state and frequency determined by pedigree analysis. To do this, we have characterized haplotypes comprising alleles at seven biallelic loci in the CCR2-CCR5 chemokine receptor gene region, a span of 20 kb on chromosome 3p21. Three-generation CEPH families (n=40), totaling 489 individuals, were genotyped by the 5'nuclease assay (TaqMan). Haplotype states and frequencies were compared in 103 grandparents who were assumed to have mated at random. Both pedigree analysis and the EM algorithm yielded the same small number of haplotypes for which linkage disequilibrium was nearly maximal. The haplotype frequencies generated by the two methods were nearly identical. These results suggest that the EM algorithm estimation of haplotype states, frequency, and linkage disequilibrium analysis will be an effective strategy in the CCR2-CCR5 gene region. For genetic epidemiology studies, CCR2-CCR5 allele and haplotype frequencies were determined in African-American (n=30), Hispanic (n=24) and European-American (n=34) populations.

Alleles↗
PubMed1991

I.V. inquiry.

Explore the source record for details and available documents.

Humans↗
PubMed1990

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.

Adult↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

Measures to test placement of nasogastric and nasointestinal feeding tubes: a review.

A literature review regarding commonly recommended bedside measures to test nasogastric and nasointestinal feeding tube placement is presented in this article. Among the methods discussed are: aspiration of recognizable gastrointestinal contents, auscultation of insufflated air, measurement of pH of gastrointestinal secretions, and observing for coughing and choking, inability to speak, and the appearance of bubbles from the end of the tube when it is held under water. Fallibilities in these methods as well as discrepancies in recommendations for their implementation and interpretation are discussed along with implications for current practice and needed areas for research.

Auscultation↗
PubMedDate not supplied

Effect of feeding tube properties and three irrigants on clogging rates.

An experimental study was conducted on 3 consecutive 12-hour days to determine if selected physical properties of feeding tubes (material and diameter) affect tube clogging. Effectiveness of three irrigant fluids (cranberry juice, Coca-Cola, and water) in preventing tube clogging was studied. One hundred eight tubes were connected to gravity flow feeding bags containing isotonic enteral formula; 54 polyurethane and 54 silicone tubes were equally divided as to external diameters of 8 French (Fr), 10 Fr, and 12 Fr. At 4-hour intervals, flow regulators on the feeding bags were adjusted to a rate of 50 ml/hour. Fluid volumes delivered per minute were measured for each tube at 2-hour intervals. One set of tubes at each station was irrigated periodically with cranberry juice, Coca-Cola, or water. On each of the 3 days, analyses revealed significant, p less than .05, effects for tube material, cranberry juice contrasted with Coca-Cola and water as irrigants, and time. Polyurethane was consistently superior to silicone as a tube material, and cranberry juice was consistently inferior to both Coca-Cola and water as an irrigant. Tube diameter had no significant effect on the incidence of tube clogging.

Beverages↗
PubMedDate not supplied

Visual characteristics of aspirates from feeding tubes as a method for predicting tube location.

A sample of 880 feeding tube aspirates were classified as being primarily clear or cloudy and as having one of six colors. Gastric aspirates were most frequently cloudy and green, tan or off-white, or bloody or brown. Intestinal fluids were primarily clear and yellow to bile-colored. In the absence of blood, pleural fluid was usually pale yellow and serous, and tracheobronchial secretions were usually tan or off-white mucus. However, respiratory aspirates often contained blood and therefore failed to have the expected characteristics of respiratory fluid. Staff nurses were shown photographs of a sample of 106 aspirates and asked to predict tube position. Their ability to identify 50 gastric aspirates improved significantly after reading a list of suggested characteristics of feeding tube aspirates (81.33% to 90.47%, p < .0001). Similarly, their ability to identify 50 intestinal aspirates improved from 64.07% to 71.53% after reading the list of criteria. However, nurses were often unable to identify respiratory aspirates; the accuracy of their predictions decreased after reading the list of suggested characteristics (from 56.67% to 46.11%). The appearance of aspirates is often helpful in distinguishing between gastric and intestinal placement, but is of little value in ruling out respiratory placement.

Adult↗
PubMedDate not supplied

Effectiveness of pH measurements in predicting feeding tube placement: an update.

This paper reports further findings from an ongoing clinical study designed to evaluate the extent to which pH values of aspirates from feeding tubes can be used to differentiate between gastric and intestinal tube placement and gastric and respiratory tube placement. The sample consisted of 405 aspirates from small-bore nasogastric tubes and 389 aspirates from nasointestinal tubes, which were obtained from 605 subjects ranging in age from 18 to 94 years. Data were collected at the time of initial placement and again, when possible, after feedings were initiated. A total of 794 pH-meter readings were made concurrently with X-rays to determine feeding tube position. Gastric placement was successfully distinguished from intestinal placement of the feeding tubes on the basis of pH-meter readings (p < .0001). Approximately 85% of the 405 pH-meter readings from gastric fluid were between 0 and 6.0, while over 87% of the 389 pH-meter measurements performed on intestinal aspirates were greater than 6.0. Four aspirates from feeding tubes inadvertently placed in the respiratory tract (two in the pleural space and two in the tracheobronchial tree) were tested with a pH-meter, all had pH values greater than 6.5.

Adolescent↗