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Biomedical subjects

P H Quanjer

Publications and source records attributed to P H Quanjer.

At least 55 records · Page 3Linked to original sources
PubMed1993

Variability of bronchodilator response and effects of inhaled corticosteroid treatment in obstructive airways disease. Dutch CNSLD Study Group.

BACKGROUND: In the day to day care of obstructive airways diseases (asthma and chronic obstructive pulmonary disease) important decisions such as disease classification and choice of therapy are based on assessment of the bronchodilator response. However, surprisingly little is known of the long term course of the bronchodilator response in patients with obstructive airways disease. METHODS: Data from a multicentre trial were used in which 274 patients aged 18-60 years with airways obstruction were selected with PC20 < 8 mg/ml and FEV1 < 95% CI of predicted. FEV1 was measured before and 20 minutes after 1000 micrograms terbutaline and 40 minutes after an additional 80 micrograms ipratropium bromide. Data were analysed from 185 patients who were followed up for 21 months (five measurements). Four different expressions of bronchodilator response (BDR) were examined for change under long term therapy, long term variability, and prognostic value in predicting response to inhaled corticosteroids. RESULTS: There was a significant reduction in BDR of 117 ml after three months of treatment with a beta 2 agonist plus a corticosteroid (BA + CS), but not after bronchodilators only. Significant reductions with BA + CS were also found in BDR as a percentage of initial FEV1, and in BDR as a percentage of predicted FEV1. Bronchodilator tests were quite variable (SD 186 ml or 11% of initial value) and less than half of the patients could consistently be classified as "irreversible" with recommended cutoff levels. The bronchodilator response at the start of the study proved to be a poor predictor of improvement in FEV1 under BA + CS treatment (correct prediction 60%). CONCLUSIONS: Bronchodilator responses decrease substantially with inhaled corticosteroid therapy, and within subject variability is considerable both in asthma and chronic obstructive pulmonary disease. Dichotomous decisions on whether patients are "irreversible" according to any single bronchodilator measurement should therefore be made with great caution. The bronchodilator response cannot be used accurately as a predictor of response to inhaled corticosteroids in obstructive airways disease.

Administration, Inhalation↗
PubMed1993

Water-sealed spirometer for measurements in newborns and infants.

Details are given of two spirometers for use in neonates and infants < 12 mo old. The minimum volumes are 520 and 670 ml, respectively. The maximum volume changes that can be recorded are 250 and 450 ml, respectively. The minimal detectable volume changes are 0.4 and 0.6 ml, respectively. Rebreathing of dead space gas is prevented by a fan producing a flow of 6.2 and 10.2 l/min, respectively; 100% gas mixing after injecting a gas bolus in the two spirometers is achieved in 5.7 and 6.6 s, respectively. Resistance to airflow is 0.2 kPa.l-1.s (2 cmH2O.l-1.s) at 150 ml/s in both spirometers. The frequency response of both instruments is flat to 6 cycles/s. The instruments can be easily cleaned and are suitable for bedside measurements.

Humans↗
PubMed1993

Growth of airways and air spaces in teenagers is related to sex but not to symptoms.

To determine growth patterns of the lung and airways in adolescents, we analyzed maximal expiratory flow-volume curves, closing capacity, and residual volume. They were obtained every 6 mo for up to 7 yr in 430 boys and 125 girls (11-19 yr), of whom 143 boys and 36 girls were classified as symptomatic; symptoms were most often minor and limited to childhood. Development of flows vs. volumes was used to investigate growth of the airways relative to lung size. A model of isotropic growth of the airways and air spaces (J. Appl. Physiol. 65: 822-828, 1988) was modified for increasing elastic recoil pressure with growth. Growth of airways relative to volume occurred faster in teenage boys than in teenage girls and was compatible with isotropic growth in 92% of asymptomatic boys and in 44% of asymptomatic girls: dysanaptic growth in teenage girls seems to be a normal phenomenon and not a unique characteristic of symptomatic subjects. Subjects with respiratory symptoms in childhood and/or adolescence have lower flows for a given lung size and airway closure at a greater lung volume when they enter adulthood. However, no difference in patterns of lung growth was observed in association with the presence of respiratory symptoms.

Adolescent↗
PubMed1993

Pubertal growth curves of ventilatory function: relationship with childhood respiratory symptoms.

This study describes longitudinal growth patterns of ventilatory function in relation to the growth of standing height and weight of boys and girls aged 12.5 to 18 yr with or without a positive history of prepubertal respiratory symptoms. Ventilatory function was characterized by FVC, FEV1, peak expiratory flow (PEF) and maximal expiratory flow at 50% of the FVC (MEF50), derived from maximum expiratory flow volume (MEFV) curves. Data on respiratory symptoms and MEFV curves were obtained in a longitudinal survey of 404 children from a Dutch secondary school. Measurements were made at 6-month intervals between 1978 and 1985. The subjects selected for analysis comprised 151 boys and 118 girls for whom between nine and 14 measurements were available. In asymptomatic boys, the average peak growth rate of standing height occurred at about 14 yr, whereas the growth rates of the ventilatory function indices peaked about 0.8 (FVC) to 1.5 (MEF50) yr later. Weight growth paralleled that of FVC and FEV1. In girls, growth rates of all indices decreased over the whole age range. Adolescents with a positive history of prepubertal respiratory symptoms exhibited lung growth parallel to asymptomatic subjects, but at a lower level. In symptomatic boys, and to a lesser extent in girls, we found consistently lower levels of FVC, FEV1, and MEF50. We conclude that adolescents with a positive history of prepubertal respiratory symptoms, even if they lose their symptoms, remain at a disadvantage with respect to their ventilatory function when they reach adulthood.

Adolescent↗
PubMed1993

Large lungs after childhood asthma. A case-control study.

Several studies have suggested that the TLC after childhood asthma is increased compared wtih that in healthy subjects. The aim of this study was to assess whether TLC is increased after childhood asthma and whether this is associated with an increased growth of the lung during adolescence. During a mean period of 29 months we studied 53 patients and 106 healthy control subjects who were matched for sex, age, and standing height. The patients had had asthma for a mean period of 10 yr. We found that in asthmatics TLC was increased in both sexes by about 7% predicted compared with that in the matched control subjects. The growth of TLC in ml/yr during adolescence was less in patients; this can be accounted for by a delay in pubertal development. When corrected for the delay in growth of stature, growth of TLC in ml/cm in asthmatics was similar to that found in control subjects. These findings support the hypothesis of a developmental change of enhanced lung growth during childhood asthma; they do not support a mechanism with progressive loss of elastic recoil of the lung.

Adolescent↗
PubMed1993

Validity of the forced rebreathing method in the measurement of residual volume in patients with airflow limitation.

The validity of the forced rebreathing method (FRM) in the measurement of residual volume (RVn) was assessed in two groups (28 and 12) of patients with significant airflow limitation. The mean FEV1% FVC% were 48.28%, SD = 8.91% and 54.3%, SD = 0.23% respectively. Patients performed at least 30 forced rebreathings into a bag and bottle system at about 28 breaths per minute. RVn per breath was regressed on breath and gas dilution was considered complete at the breath number where the regression line deviated from the nitrogen washout curve. Residual volume computed four breaths after the breath number where the regression line deviated from the curve were compared with results derived from helium dilution (RVHe), mouth (RVmo) and oesophageal (RVOeS) pressure changes in the body plethysmograph. The mean RVn was similar to RVHe (P > 0.98) and correlated well with RVHe (r = 0.908, P < 0.001). RVn and RVHe were significantly smaller than RVmo and RVoes (P < 0.001). The difference between RVn and RVmo was smaller than the difference with RVoes. RVmo was larger than RVoes (P < 0.001) and correlated well with RVoes (r = 0.939, P < 0.001). It is concluded that the FRM can be used with reasonable accuracy to measure residual volume in patients with airflow limitation, and has advantages over the plethysmographic and conventional helium dilution methods.

Adult↗
PubMed1993

Long-term effect of inhaled corticosteroids on growth rate in adolescents with asthma.

BACKGROUND: Growth in stature in asthmatic adolescents may be delayed compared to normals as a result of treatment with inhaled corticosteroids (CS) or because of a delay in puberty. However, growth rates in asthmatic children have never been studied when treatment with CS was randomized and when growth was compared with that of matched healthy control subjects. OBJECTIVE: To assess the long-term effect of CS treatment on growth rates in asthmatic adolescents. METHODS: Participants were 40 asthmatic teenagers (mean age 12.8 years) who received randomized treatment with 0.2 mg of albuterol (salbutamol) with either placebo three times a day (BA + PL) or 0.2 mg of budesonide three times a day (BA + CS) for a median period of 22 months in a double-blind controlled study. Growth rates were compared with those of 80 control subjects who were matched for sex, age, height, and duration of follow-up. RESULTS: Growth rates in male patients, but not in female patients, were significantly less than in control subjects (P < .05), a finding consistent with a delay of puberty due to asthma. The mean difference (95% confidence interval) in growth rates between patients treated with BA+PL and their controls was -0.70 (-1.62, 0.22) cm/y; that between patients treated with BA + CS and their controls was -0.44 (-1.25, 0.37) cm/y. The observed mean (SEM) case-control difference between treatment groups was +0.27 (0.58) cm/y in favor of BA + CS. CONCLUSION: Growth retardation observed in adolescents with asthma may be due to a delay in puberty but not to the prescription of 0.6 mg of budesonide daily.

Administration, Inhalation↗
PubMed1993

Assessment of bronchodilator response in children with asthma. Dutch CNSLD Study Group.

The bronchodilator response (BDR) in forced expiratory volume in one second (FEV1) is routinely assessed to estimate the reversibility of airways obstruction. However, there is no consensus on how the BDR should be expressed, and recommendations applying to children are lacking. Similarly, the relationship between BDR and nonspecific bronchial hyperresponsiveness to histamine (BHR) has not been elucidated. These questions were addressed in 116 children, 7-16 yrs of age, with stable asthma after withdrawal of all pulmonary maintenance medication. Inclusion criteria were an initial FEV1 between 55-90% predicted, and/or FEV1/forced vital capacity (FVC) between 50-75%, as well as a fall in FEV1 of 20% or more when challenged with up to 150 micrograms histamine. The change in FEV1 (delta FEV1) 20 min after inhalation of 800 micrograms salbutamol was expressed in four ways: as an absolute difference (delta FEV1(l)), as a percentage of predicted FEV1 (delta FEV1%pred) or initial FEV1 (delta FEV1%init), and as a percentage of the deficit in FEV1 (delta FEV1%(pred-init)). delta FEV1%init and delta FEV1%pred were not related to age and stature of the children; delta FEV1%(pred-init) was related to stature, whilst delta FEV1(l) was related to both age and stature. All indices correlated with initial FEV1. However, this is an artefact introduced by relating change to initial value, rather than to the mean of initial and final value. In fact, BDR, expressed as delta FEV1%pred, was only slightly greater in children with the lowest initial airway calibre (p = 0.08), unlike delta FEV1%init. BDR was weakly related to BHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Assessment of bronchodilatation after spontaneous recovery from a histamine challenge in asthmatic children.

BACKGROUND: It would be convenient to be able to measure airway responsiveness to histamine and to bronchodilator drugs on the same day, but whether this can be done reliably is unknown. METHODS: The effect of a prior histamine challenge on the bronchodilator response to salbutamol after spontaneous recovery of FEV1 to 95% of the prechallenge level was studied in two groups of asthmatic children. Fourteen children inhaled 400 micrograms salbutamol after spontaneous recovery from a histamine challenge, followed by a further 100 micrograms salbutamol 20 minutes later. In a second group of eight asthmatic children the study was repeated with 800 micrograms salbutamol, followed by a further 200 micrograms 20 minutes later. RESULTS: After histamine challenge FEV1 returned to baseline in 70 minutes or less on all occasions. The FEV1 20 minutes after 400 micrograms salbutamol was significantly lower after the histamine challenge than on the control day. After the further 100 micrograms salbutamol FEV1 values were similar after the histamine challenge and on the control day. FEV1 values after 800 micrograms salbutamol and the further 200 micrograms dose were not influenced by a prior histamine challenge. CONCLUSIONS: In children with stable asthma in whom FEV1 has returned to baseline after a histamine challenge the FEV1 achieved after 800 micrograms salbutamol is not affected by the histamine challenge. Histamine and bronchodilator responsiveness can thus be assessed reliably on the same day in patients with stable asthma. This has clear advantages for patient care.

Adolescent↗
PubMed1992

Interpretation of bronchodilator response in patients with obstructive airways disease. The Dutch Chronic Non-Specific Lung Disease (CNSLD) Study Group.

BACKGROUND: There is no agreement on how a bronchodilator response should be expressed. Ideally, the index used should be able to distinguish asthma from chronic obstructive lung disease and be independent of initial FEV1. METHODS: Two hundred and seventy four adults (aged 18-60 years) outpatients with obstructive airways disease were studied. Patients were divided into syndrome groups on the basis of a standardised history: asthma (n = 99), asthmatic bronchitis (n = 88), and chronic obstructive lung disease (n = 51); 36 subjects could not be attributed to any subgroup. FEV1 was measured before and 20 minutes after inhalation of 1000 micrograms terbutaline. Different expressions of bronchodilator response (delta FEV1) were compared with respect to their dependence on initial FEV1 and their efficacy in separating subjects with asthma from those with chronic obstructive lung disease. delta FEV1 was expressed as a percentage of initial FEV1 (delta FEV1%init), absolute value (delta FEV1[1]), percentage of predicted FEV1 (delta FEV1%pred), standardised residual (delta SR-FEV1), and percentage of maximal possible increase (delta FEV1%[pred-init]). RESULTS: delta FEV1%init was more dependent on initial FEV1 (p = -0.405) than delta FEV1[1] (r = -0.145), delta FEV1%pred (r = -0.166), and delta SR-FEV1 (r = -0.127). delta FEV1%[pred-init] reached infinity when initial FEV1 approached predicted levels. delta FEV1%pred had a higher likelihood ratio (1.71) for separating patients with asthma from those with chronic obstructive lung disease than other expressions of bronchodilator response. Asthmatic patients had larger mean bronchodilator responses than patients in other subgroups; this difference was largest for delta SR-FEV1 (F = 9.19) and delta FEV1%pred (F = 9.03); it was much smaller for delta FEV1%init (F = 5.89). Despite significant differences in mean response, there was a large overlap of individual responses between diagnostic subgroups. The bronchodilator response was continuously and unimodally distributed for all expressions. CONCLUSIONS: delta FEV1%pred appears to be the most useful method of expressing bronchodilator response, both for clinical and for research purposes. Reversibility of airways obstruction in response to a bronchodilator is a continuous variable and not a dichotomous triat. Any cut off level of a "positive" bronchodilator response is therefore arbitrary.

Adolescent↗