Search PubMed⌕ Search

Biomedical subjects

J E Cotes

Publications and source records attributed to J E Cotes.

At least 37 records · Page 2Linked to original sources
PubMed1994

Transit time indices derived from forced expiratory spirograms: repeatability and criteria for curve selection and truncation.

Transit time analysis applied to spirograms truncated with respect to volume, not time, could be informative in population surveys. The present paper asks the questions: How does averaging several forced expirations affect the within subject variability at different levels of truncation? If only one spirogram is analysed, how should it be chosen? Are the results likely to be influenced by prior bronchodilation? The subjects were 46 men, selected by stratified random sampling from a shipyard population. Spirograms were obtained in quintuplicate, on two occasions, an average of nine days apart. Using the three "best" spirograms, transit time indices were calculated from average moments and from single curves selected in eight different ways; the analyses were performed on complete expirations, and after truncation by volume at levels between 75-99% of forced vital capacity (FVC), and by time (at 6 s). Indices from averaged moments were found to be more reproducible and yielded higher intra-class correlations than indices from single curves. Of the latter, the curve selected as having the largest forced vital capacity also yielded acceptable results. Prior inhalation of a bronchodilator aerosol did not reduce the variability. The averaging procedure is recommended for respiratory surveys of working men. For this application, the optimal level of truncation appeared to be by volume at 90% FVC, but on theoretical grounds truncation at 75 and 99% of FVC could also be informative.

Adult↗
PubMed1994

Experience of a standardised method for assessing respiratory disability.

A standardised method of scoring respiratory disability based on measurement and/or estimation of maximal oxygen uptake has recently been developed by the European Society for Clinical Respiratory Physiology. In the present study, we wanted to determine how the results obtained using this objective method compared with those by the more traditional empirical method used in a Medical Boarding Centre (MBC) for Respiratory Diseases. The subjects were 62 men who were claiming industrial injuries benefit on account of prior exposure to a respiratory hazard. The MBC ratings and the disability scores were correlated and, in the case of men with moderate or severe disability, numerically equivalent. The results provided independent confirmation that the MBC ratings were influenced by the forced expiratory volume, radiological category of pneumoconiosis and grade of breathlessness. In subjects in whom the measured and estimated maximal oxygen uptakes were inconsistent, the information obtained during the exercise test could identify which of several factors contributed to the exercise limitation. Since the new method might be expected to reduce the difficulties experienced in assessing respiratory disability, its use is recommended.

Adult↗
PubMed1993

Pre-employment lung function at age 16 years as a guide to lung function in adult life.

BACKGROUND: A study was conducted to find out if pre-employment lung function at age 16 improved the estimation of that between ages 25 to 27 compared with the use of reference values based on smoking history, stature, body mass index, and other concurrent anthropometric variables. METHODS: Apprentices attending a shipyard training school were assessed on six occasions from entry during their 17th year to age 25 to 27; results for 114 such men were analysed. The measurements were of stature, body mass, fat free mass and body fat, thoracic dimensions, forced expiratory volume and indices of forced expiratory flow, total lung capacity, and its subdivisions, transfer factor and KCO. RESULTS: At best about half the variance in the final lung function could be accounted for with the concurrent reference variables. For each lung function index the proportion of explained variance was substantially increased by also including in the prediction equation the pre-employment lung function expressed in standard deviation units. CONCLUSION: Estimation of the longitudinal decline in lung function during adult life should be based on initial and final measurements of which the first should ideally be at age 25 but those at age 16 can be used instead: such measurements have long term value and should be preserved.

Adolescent↗
PubMed1992

Standardization of single-breath transfer factor (TLCO); derivation of breathholding time.

Breathholding time is usually defined using the procedure of Ogilvie et al. or of Jones and Meade; these procedures depend on knowing when inspiration begins and, for the latter, when it ends. Some alternative procedures do not require this information. With a view to standardizing the measurement, transfer factor of the lungs for carbon monoxide (TLCO) was measured in 18 adults with labile airflow obstruction, who were assessed before and after inhalation of salbutamol. The inflection points defining the start and end of inspiration were defined visually (method 1), and by extrapolation of the linear part of the inspiratory limb of the single-breath trace (method 2). The spirograms met recognized standards of quality and were rated by experienced observers. Compared with method 1 the TLCO and related indices by method 2 were lower using the procedure of Jones and Meade and higher using the procedure of Ogilvie et al. in each case by, on average, 1.0%. The within- and between-day variabilities were independent of the method used. Thus, the extrapolation and visual methods yielded interchangeable results when applied by experienced operators. However, extrapolation may be easier for inexperienced operators.

Albuterol↗
PubMed1991

Is respiratory function diminished?

An association between diminished respiratory function and an environmental agent should reflect the magnitude of the exposure and not be due to technical error, bias, confounding factors, or chance. Bias is difficult to avoid; the best course is to make comparisons within a population of exposed individuals, not between them and a control group; the population should be defined and a high response rate achieved. The principal confounding factors are age, smoking, and other environmental exposures; their effects should be fully estimated for the population in question as otherwise they will be wrongly attributed to the environmental agent. Finally, the results should be scrutinized and, if possible, a second independent study should be planned.

Cross-Sectional Studies↗
PubMed1990

Longitudinal respiratory survey of shipyard workers: effects of trade and atopic status.

A respiratory sample survey of 609 shipyard workers was conducted in 1979: the men were reassessed an average of 7.2 years later. The 53 deaths between the surveys were related to age, level of lung function and smoking but not to trade as a welder or caulker/burner. Of the survivors, 488 (88%) were seen, including 425 men who had retired or been made redundant. Redundancy was related to age, smoking, and respiratory symptoms; the average reduction in duration of employment per symptom was 0.44 years. Changes in respiratory symptoms included onset of chronic bronchitis and wheeze on most days (numbers respectively 77 and 109) and increased breathlessness on exertion (n = 89); significant related factors included smoking, previous metal fume fever or pneumonia, and, for breathlessness, trade as a welder or caulker/burner. Electrocardiographic evidence for myocardial ischaemia was also associated with increased breathlessness. The annual declines in FEV1 and other spirometric indices were related to age, to being a smoker at the time of the initial survey, and to trade as a welder or caulker/burner compared with trades that did not involve welding or burning. There was significant interaction between these effects. In a subsample of 124 redundant workers there was also significant interaction between the effects of fumes and atopy (skin test positive to common antigens) or a raised serum IgE concentration. It was concluded that welding fumes interacted with smoking and an atopic constitution to cause respiratory impairment. The results related mainly to exposures in the past and were not necessarily relevant for present day conditions in the industry.

Age Factors↗
PubMed1990

Rating respiratory disability: a report on behalf of a working group of the European Society for Clinical Respiratory Physiology.

A rating procedure for respiratory disability has been developed; it entails measuring the symptom-limited maximal oxygen uptake or estimating the maximal uptake from the results of a submaximal exercise test and other relevant variables. The derivation assumes a linear scale of disability between the limits 0% and 100% which are defined. The percentage disability of 157 men with respiratory limitation of exercise has been used to delineate empirical grades of disability. These are of similar form to those used for grading respiratory impairment. More information is needed with a view to validation.

Disability Evaluation↗