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J E Cotes

Publications and source records attributed to J E Cotes.

159 records · Page 9Linked to original sources
PubMedDate not supplied

Modelling the lung function of Caucasians during adolescence as a basis for reference values.

BACKGROUND: In childhood the relationship between lung size and stature changes during the adolescent growth spurt. This is not allowed for in models of lung function based on stature alone. For spirometric indices inclusion of an age x stature interaction (A x St) can overcome the difficulty. AIM: The study tested the hypothesis that this simple, interactive model might also be effective for total lung capacity and its subdivisions and the single breath transfer factor for carbon monoxide. SUBJECTS AND METHODS: Data were available for 695 asymptomatic non-smokers (Caucasians) aged 7-20 years (440 boys, 255 girls). Each lung function index was described using the above model and the fit was compared with that from a linear, power or polynomial model based on stature alone. RESULTS: After allowing for stature, the A x St interaction term was significant for almost all indices. The improved fit was most apparent for the lung function of older adolescent boys. Reference values using the model are reported. CONCLUSIONS: A simple model based on stature and an interaction between stature and age can account for the changing relationship between body habitus during the growth spurt and lung size and transfer factor in a single equation encompassing children and adolescents. Its use is recommended for deriving reference values when the explanatory variables are limited to stature and age.

Adolescent↗
PubMedDate not supplied

Sitting height, fat-free mass and body fat as reference variables for lung function in healthy British children: comparison with stature.

The ventilatory capacity, total lung capacity and transfer factor with their respective subdivisions have been measured on 254 healthy British boy and girl twins aged 8-16 yrs. The logarithmic regression relationships of lung function on stature have been compared with those on sitting height and on stature plus indices of body muscle and fat. The regressions on stature and on sitting height describe the results with similar precision, but stature is marginally better; either index may be used as the reference variable. For the description of inspiratory capacity and of all indices which include this volume (e.g. vital capacity, total lung capacity and transfer factor), additional precision is secured by adding to the regression equation on stature a term for fat-free mass or body mass divided by the square of the stature; for the description of functional residual capacity, the inclusion of a term for % body fat similarly reduces the variance about the regression equation. The difference in lung function between boys and girls is smaller when the function is related to stature than to sitting height. It is further reduced when fat-free mass/sature and % body fat are also included in the prediction equations. The equations may be used to obtain reference values for indices of lung function in similar subjects.

Adipose Tissue↗
PubMedDate not supplied

Genetic and environmental determinants of the cardio-respiratory response to submaximal exercise--a six-year follow-up study of twins.

The fat-free mass and the ventilatory and cardiac frequency responses to submaximal exercise have been assessed longitudinally over six years in a total of 65 identical and non-identical boy and girl twin pairs. Exercise ventilation at rates of work below the anaerobic threshold was independent of the genetic and environmental factors which were investigated. The anaerobic threshold increased with age. The fat-free mass and the exercise cardiac frequency were subject to both genetic and environmental control with the genetic component predominating initially. The subsequent environmental component was larger for non-identical than for identical twin pairs and for boys than for girls. It is concluded that in identical twin boys by the time they reach adolescence the performance during submaximal exercise has a material environmental component. There appears to be interaction between the genetic and environmental components.

Adolescent↗
PubMedDate not supplied

Respiratory and cardiac function tests in relation to occupational lung diseases.

Tests of lung function have a number of important roles in occupational medicine but the results need to be of high technical quality if they are to be useful. On this account, as well as careful supervision and scrutany of results, only appropriate tests should be applied. The choice will vary with circumstances; it is likely to be made from a limited number of procedures including those recommended in Respiratory function tests in pneumoconioses (I.L.O., 1966). Tests of maximal and near maximal exercise are seldom indicated. Care should be taken over the selection of reference values and of mathematical treatments for the results.

Disability Evaluation↗
PubMedDate not supplied

Transit time analysis of spirograms: which blow is best?

Moment analysis applied to the forced expiratory spirogram describes the distribution of fractions of the forced vital capacity with respect to time (t). The first three moments (based on t1, t2 and t3) are used to derive respectively the mean transit time (MTT), its standard deviation, also related indices and an index of skewness. The moments are all obtained from the same spirogram (out of 3 or 5), but the criteria for selection have not been defined. We have looked to see which curve yields the most reproducible indices. 46 naive male volunteers performed five forced expirations on two occasions nine days apart. The spirograms were truncated with respect to volume at 99% of forced vital capacity, the time of which was taken as forced expiratory time (FET), and separately at 6 s when FET exceeded this. The absolute values and reproducibility between days of the first three moments were not significantly different for the first three compared with all five blows. Transit time indices were extracted from the first three blows in nine different ways; they included deriving a mean curve from the averaged moments, taking the curve with the shortest MTT, that with the largest FVC, etc. Reproducibility was best when the indices were calculated from the averaged moments; that for the curve with the shortest MTT was nearly as good. The curve with the shortest FET, largest peak expiratory flow, largest FEV1/FVC ratio or largest area under the flow-volume curve were for most indices equally reproducible, but the absolute results were not always interchangeable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗