Biomedical subjects

J Swift

Publications and source records attributed to J Swift.

22 records · Page 2Linked to original sources

PubMed1975

The N2 closing volume test in population studies: sources of variation and reproducibility.

Sources of variation in the nitrogen closing volume test and derived measurements were examined in the results of 13 subjects, each of whom performed 3 sequential trials on 2 occasions 30 to 60 minutes apart, on 2 separate days 1 week apart (156 trials in all). Results were examined to evaluate the relative sensitivity of the various measurements for differences between sujbects and, by implication, their potential value in population studies. Using the ratio of signal (between-subject variance) to noise (within-subject variance) as the criterion, the sensitivities of the ratio of closing volume to vital capacity (CV/VC,%) and the ratio of closing capacity to total lung capacity (CC/TLC,%) were comparable; contrary to expectation, sensitivity decreased rather than increased with side-by-side compared to independent tracing analysis. Comparison of various test schedules showed the greatest sensitivity when the mean of 3 measurements was used, with a single measurement of CV/VC,% being only one-third as sensitive, and a single measurement of CC/TLC,% being one-half as sensitive as the mean. In addition, the validity of the measurements of total lung capacity from nitrogen dilution in a single oxygen breath was confirmed by the demonstration of good agreement with helium dilution values.

Adult↗

PubMed1975

Appraisal of a new test: Between-technician variation in the measurement of closing volume.

To determine the between-technician variation in the measurement of closing volume, 24 subjects were divided into 3 blocks of 8 subjects each. Each block was then tested by a pair of technicians. Each of the 3 technicians involved in the study tested 16 subjects. It was later necessary to reject the tracings of 2 subjects in one of the 3 blocks, leaving 22 for analysis. The N2 method of determining closing volume was used. The statistical analysis was performed separately on the following measures derived from the tracings: expired vital capacity, planimetry of the area under the curve, total lung capacity, closing volume as a per cent of expired vital capacity, and closing capacity as a per cent of total lung capacity. All tracings were assessed by each technician. Two separate analyses of variance were then carried out to determine, respectively, the components of variance in the administration of the test and in the interpretation of the tracings. Because different persons were able to administer the test the same way, it seems that closing volume poses no problem in administration, provided that instructions as to how to perform the test are closely followed. In the interpretation of the tracings, significant differences were found for all measures, except planimetry; however, not all of these have the same practical implications. Some tracings were found "difficult" to interpret and contributed more to the over-all variation than did others. When making use of a new test in a population study, the between-technician variation should be determined before the study is begun.

Humans↗

PubMed1974

Rheumatic complaints and pulmonary response to chrysotile dust inhalation in the mines and mills of Quebec.

In 1967-68 an age-stratified random sample of 1069 current workers in Quebec asbestos mines and mills was surveyed. Questions concerning rheumatic complaints were included in a modified MRC questionnaire used at that time, and on this basis a rheumatic severity gradient was devised. No relationship could be detected between rheumatic complaints and pulmonary radiologic response to chrysotile dust exposure, despite implications in the literature that such a relationship might exist.

Adult↗

PubMedDate not supplied

Auditing mortality from upper gastrointestinal haemorrhage: impact of a high dependency unit.

BACKGROUND: A retrospective audit conducted at our district general hospital indicated that mortality from upper gastrointestinal (GI) haemorrhage was above that reported from nearby centres. OBJECTIVES: To assess the impact of establishing a high dependency unit (HDU) and agreed management protocol on subsequent mortality from upper GI haemorrhage at our hospital. DESIGN: Prospective audits were conducted before and after the establishment of an HDU. All acute admissions, as well as established inpatients with haematemesis and/or melaena, were examined for fitness for endoscopy, comorbidity, underlying diagnosis and the need for surgery. SUBJECT: Over a two-year period, 524 patients were studied in the two audits. Risk scores were calculated and the 30-day mortality from all causes assessed. RESULTS: There was a trend towards higher age and comorbidity during the second audit. Mortality was 9% and 10% during the first and second audits, respectively. CONCLUSIONS: An increasing proportion of patients with bleeding are elderly and have associated comorbidity. Establishment of an HDU and agreed protocol did not reduce mortality at our centre.

Age Factors↗