Current Respiratory Symptoms Research Articles

Follow−up of asthma from childhood to adulthood: Influence of potential childhood risk factors on the outcome of pulmonary function and bronchial responsiveness in adulthood

The outcome of asthma in 406 children, aged 8 to 12 years, was studied. Follow−up in adulthood was 86%, with a mean age of 24.7 years and a mean interval of follow−up of 14.8 years. The predictive value of gender and various childhood variables on the adult level of pulmonary function (forced expiratory volume in 1 second [FEV 1]) and bronchial responsiveness in adulthood was assessed. An increase in mean percent predicted FEV 1 from childhood to adulthood was found, both in subjects with (76%) and without (24%) current respiratory symptoms. The only childhood variable predictive of adult level of FEV 1 was the level of percent predicted FEV 1 ( p < 0.01). The proportion of subjects with a histamine provocative concentration causing a 10% decrease in FEV 1 less than or equal to 16 mg/ml decreased significantly in adulthood. The degree of bronchial responsiveness had increased slightly in adults with symptoms ( p = 0.87), whereas it had decreased significantly in subjects without symptoms ( p < 0.01). Female subjects were significantly more responsive in adulthood than male subjects ( p = 0.047). The childhood degree of bronchial responsiveness significantly predicted the presence of bronchial responsiveness in adulthood ( p = 0.02). We conclude that childhood percent predicted FEV 1 is relevant to predict the outcome of the adult pulmonary function level, whereas female gender and the childhood degree of bronchial responsiveness are important for the prediction of adult degree of bronchial responsiveness among children with asthma (J A LLERGY C LIN I MMUNOL 1994; 93:575−84.)

Reference ranges for respiratory rate measured by thermistry (12-84 months).

Previous studies of respiratory rate in children have had a number of methodological problems. The aim of this study was to construct age specific reference ranges for respiratory rate. Respiratory rate in children attending childcare centres, kindergartens, and schools was measured using a nasal thermocouple to obtain respiratory waveforms. Reference ranges were constructed using data from 293 awake children between 12 and 84 months, and from 123 sleeping children between 12 and 60 months. The mean respiratory rate declined with increasing age and was significantly lower, with lower variability, during sleep than wakefulness. Neither the awake nor sleeping reference ranges were significantly affected by sex, nor by the presence of past respiratory nor current respiratory symptoms.

Airway response to exercise and methacholine in children with respiratory symptoms.

Thirty atopic and 30 non-atopic subjects were identified from a population of 7-8 year old children with current respiratory symptoms. The response of the airways to exercise and provocation by methacholine were compared. In these children, who had symptoms but were not necessarily asthmatic, there was no significant correlation between the two stimuli. The atopic children were, however, significantly more responsive than the non-atopic children to both. For the whole group, odds ratios derived for atopy and for an increased response to methacholine (expressed as a PD20--the dose that caused the forced expiratory volume in one second (FEV1) to fall by 20%--of less than 6.4 mumol/l), a positive exercise test (greater than 15% fall in FEV1), and the presence of asthma were 13.5, 3.3, and 21.0, respectively; that for positive response to methacholine and positive exercise challenge was 1.5. Thus though increased bronchial responsiveness to methacholine and exercise challenge are both associated with a diagnosis of asthma, the association between the two stimuli is complex, and supports the view that they reflect entirely different components of airways dysfunction.

Change in airway responsiveness to inhaled house dust from childhood to adulthood

Between 1966 and 1969, housedust (HD) inhalation provocation tests were performed in 119 children with asthma. Between 1984 and 1987, 101 of the 119 subjects (85%) were reinvestigated. Thirty-one of these 101 adults who participated in a study on the outcome of childhood asthma were rechallenged with HD after a mean interval of 16 years to establish the change in airway responsiveness to HD from childhood to adult life. In the childhood study in these 31 subjects, six had no response (NAR); six, an early response (EAR); eight, a late (LAR); and eleven subjects, an EAR followed by an LAR (dual asthmatic response [DAR]) to the inhalation of HD. In the second survey, two of the subjects with NAR in the first study had a bronchoconstrictor response to HD. Five subjects with an EAR or an LAR response in childhood had NAR as an adult. The eleven subjects with a DAR during childhood also had a response to HD as an adult; five had an EAR, and six adults again had a DAR. Eleven of the 13 adults (85%) with current respiratory symptoms had a repsonse to HD during the second survey. Although they were symptom free, 11 of the other 18 adults (61%) responded on inhalation of HD. One of the 18 subjects without (6%), and six of the 13 subjects (46%) with current respiratory symptoms, had a provocative concentration of histamine in FEV 1 10% of baseline ≤16 mg/ml. We conclude that, although respiratory symptoms disappear in one half the children with asthma and although adults may believe that they have outgrown their disease, adults still have the potency to respond to inhaled allergens. Most children do outgrow their respiratory symptoms but not the susceptibility of their airways to allergens.

Pulmonary function in children after neonatal meconium aspiration syndrome.

Eighteen children aged 6 to 11 years old who fulfilled criteria for the diagnosis of neonatal meconium aspiration syndrome were investigated to find out the prevalence of previous and current respiratory symptoms, and abnormal pulmonary function tests, chest radiographs, and ventilation scans. Eleven of the 18 had no respiratory symptoms and eight of these had normal pulmonary function on testing. Two had mild limitation of expiratory airflow that did not respond to treatment with bronchodilators, and one had exercise induced bronchospasm that responded to treatment with bronchodilators. Seven of the 18 had recurrent cough and wheezing compatible with a diagnosis of asthma, and five of these had appreciable exercise induced bronchospasm that responded to treatment with bronchodilators. None of the children with symptoms had a personal or family history of atopy or had had acute bronchiolitis. All chest radiographs were normal. We found a much higher prevalence of asthmatic symptoms and abnormal bronchial reactivity among survivors of neonatal meconium aspiration syndrome than in the general childhood population. Aspiration of meconium may have long term consequences for the developing respiratory tract and is associated with abnormal respiratory function in later childhood.

RESPIRATORY SYMPTOMS, LUNG FUNCTION AND BRONCHIAL REACTIVITY AFTER PERTUSSIS IN INFANCY

In a field survey, children with a history of pertussis, were more likely to have had other chest illnesses, and to have current chest symptoms, but did not differ from controls in spirometry. We have done more detailed laboratory lung function tests, allergy prick skin tests and histamine bronchial challenges on 45 of the 74 cases who were admitted to hospital with pertussis in infancy, and 42 case control children all enlisted from the original survey. Cases (mean age 9.9 yrs) had had more respiratory symptoms in the past year than controls (mean age 10.0 yrs), e.g. ‘day or night cough’ 27% v. 12%, p = 0.08; ‘ever wheezy’ 22% v. 5%, p = 0.02. Cases were more likely than controls to have positive allergy skin tests but there was no difference in the histamine PC2O (concentration of histamine to produce a 20% fall in FEV1) between the two groups. Likewise there were no differences in any index of lung function derived as a percent of predicted for height from spirometry, flow-volume curves and single breath nitrogen washout analysis. We conclude that a history of pertussis in infancy is associated with increased current respiratory symptoms but does not cause any detectable deficit in lung function or increased bronchial reactivity in later childhood.

Respiratory morbidity and lung function after whooping-cough.

360 primary-school children with a history of whooping-cough were shown to have experienced an excess of other chest illnesses compared with 711 controls. This susceptibility may, however, have antedated the whooping-cough. Current respiratory symptoms were also more common in children who had had whooping-cough, though no differences were found on physical examination. No differences were found in lung function between cases and controls. Whooping-cough, as experienced by British children in recent years, is unlikely to cause subsequent respiratory morbidity and does not result in impaired lung function in later childhood.

Ventilatory function in Nigerian coal miners.

Ventilatory capacity has been measured in 675 Nigerian colliery employees classified in three groups according to occupation: coalface workers, other underground workers with low exposure to dust, and surface workers in administrative and clerical jobs. Men with current respiratory symptoms were excluded, as were ex-miners. The faceworkers were a slightly older group who smoked less, and they were presumed to be more active. Faceworkers had a highest forced vital capacities (adjusted for age and stature) but the lowest values for indices reflecting maximal expiratory airflows, (FEV1/FVC, PFR FEF, and FMF). Apparently coalface work is associated with an 8% impairment of maximum expiratory airflow, probably due to dust exposure, but also with a modest enhancement in FVC, possibly due to training of the respiratory muscles. Regression coefficients on age for the airflow indices are significantly more negative in faceworkers than in the other groups. Smoking and duration of service did not significantly affect the pattern of results. FEV1 does not vary among the occupational groups in the colliery, and the mean value is close to that predicted on the basis of reference equations previously obtained for non-miners in Nigeria.

UK Naval Dockyards asbestosis study: survey of the sample population aged 50-59 years.

As part of a general morbidity study of all civilian employees in the four Royal Naval Dockyards, the clinical, radiological and physiological effects of exposure to asbestos in 1200 men aged 50-59 years were studied in detail. The sample included all men on the Register of Asbestos Workers, one in three of those currently in occupations where intermittent exposure to asbestos may occur, and one in 30 of the remainder. The conclusions are mainly in accord with those of the comprehensive morbidity study of all the civilian dockyard workers, and show that smoking played a large part in increasing prevalence rates of radiographic, clinical, and physiological abnormalities in this population. A sub-group of 39 men, who were working as asbestos laggers or sprayers before 1957, was identified. These men showed much more extensive disease than any other sub-group, yet, even so, the smokers were worse than the non-smokers. Of these smokers, 48% had small opacities of category 1/1 or more, 76% reported that they coughed during the day and 53% had crepitations; forced expiratory volume and transfer factor were also markedly reduced in these 21 smokers. Although asbestos exposure had been intermittent for the majority of the population, the prevalences of pleural thickening, small opacities, current respiratory symptoms and crepitations were shown to be related to duration of exposure to asbestos.

Chronic effect of fire fighting on pulmonary function.

Pulmonary function was studied in 1430 Boston fire fighters during the period 1970 to 1972. Questionnaire information on exposures, current respiratory symptoms and smoking habits was also collected. Forced vital capacity and forced expiratory volume in one second were measured on two occasions. The rate of loss in pulmonary function observed for the entire population was more than twice the expected rate (77 vs. 30 ml for forced vital capacity). These changes were significantly related to frequency of fire exposure (p < 0.01) and could not be explained by differences in age, smoking habits or ethnic background. This study strongly suggests that occupational exposures are contributing to chronic impairment of pulmonary function in fire fighters. (N Engl J Med 291:1320–1322, 1974)