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Biomedical subjects

P H Quanjer

Publications and source records attributed to P H Quanjer.

At least 19 recordsLinked to original sources
PubMed2004

Inhaled corticosteroids and growth of airway function in asthmatic children.

Airway inflammation and remodelling play an important role in the pathophysiology of asthma. Remodelling may affect childhood lung function, and this process may be reversed by anti-inflammatory treatment. The current study assessed longitudinally whether asthma affects growth of airway function relative to airspaces, and if so whether this is redressed by inhaled corticosteroids (ICS). Every 4 months for up to 3 yrs, lung function was assessed in 54 asthmatic children (initial age 7-16 yrs), who inhaled 0.2 mg salbutamol t.i.d. and 0.2 mg budesonide t.i.d. (beta2-agonist (BA)+ICS), or placebo (PL) t.i.d. (BA+PL) in a randomised, double-blind design. Measurements were carried out before and after maximal bronchodilation. Airway growth was assessed from the change of forced expiratory volume in one second and of maximal expiratory flows (at 60% and 40% of total lung capacity (TLC) remaining in the lung) relative to TLC, as measures of more central, intermediate and more peripheral airways. Growth patterns were compared with the longitudinal findings in 376 healthy children. Airway patency after maximal bronchodilation in patients on BA+PL remained reduced compared to healthy subjects, whereas in patients on BA+ICS a marked improvement was observed to subnormal. No differences between patients and controls could be demonstrated for growth patterns of central and intermediate airway function. Compliance with BA+ICS was 75% of the prescribed dose, resulting in significant, sustained improvement of symptoms and postbronchodilator calibre of central and intermediate airways to subnormal within 2 months, but postbronchodilator small airway patency remained reduced, though improved compared to patients on BA+PL. Anti-inflammatory treatment of asthmatic children is associated with normal functional development of central and intermediate airways. The persistently reduced postbronchodilator patency of peripheral airways may reflect remodelling, or insufficient anti-inflammatory treatment.

Administration, Inhalation↗
PubMed2000

Functional residual capacity and static compliance during the first year in preterm infants treated with surfactant.

Individual lung development during the first year of life was studied in surfactant treated preterm infants with respiratory distress syndrome (RDS) and healthy controls, as well as in a group who subsequently developed chronic lung disease of the newborn (CLDN). Lung development was assessed from functional residual capacity (FRC) and compliance of the respiratory system (Crs). Twenty-one infants with RDS after preterm birth received surfactant treatment. Six of them developed CLDN. Eighteen preterm infants without RDS served as a control group. Lung function measurements were performed at term age and 4, 8, and 12 months afterwards. FRC was obtained by means of the closed-system helium dilution technique whereas static Crs was obtained by means of the weighted spirometer technique. At term age, FRC was lower in the CLDN group compared with uncomplicated RDS and controls (p < 0.05). No significant differences between groups were found in the development of FRC during the first year of life (p = 0.4). No differences were found in Crs during the first year of life in surfactant treated infants who recovered from uncomplicated RDS and the control group. However, lower values were found in the CLDN group (p < 0.05). We conclude that surfactant treated infants without CLDN have similar lung development during the first year of life as control preterm infants.

Functional Residual Capacity↗
PubMed2000

Peak expiratory flow profiles delivered by pump systems. Limitations due to wave action.

Pump systems are currently used to test the performance of both spirometers and peak expiratory flow (PEF) meters, but for certain flow profiles the input signal (i.e., requested profile) and the output profile can differ. We developed a mathematical model of wave action within a pump and compared the recorded flow profiles with both the input profiles and the output predicted by the model. Three American Thoracic Society (ATS) flow profiles and four artificial flow-versus-time profiles were delivered by a pump, first to a pneumotachograph (PT) on its own, then to the PT with a 32-cm upstream extension tube (which would favor wave action), and lastly with the PT in series with and immediately downstream to a mini-Wright peak flow meter. With the PT on its own, recorded flow for the seven profiles was 2.4 +/- 1.9% (mean +/- SD) higher than the pump's input flow, and similarly was 2.3 +/- 2.3% higher than the pump's output flow as predicted by the model. With the extension tube in place, the recorded flow was 6.6 +/- 6.4% higher than the input flow (range: 0.1 to 18.4%), but was only 1.2 +/- 2.5% higher than the output flow predicted by the model (range: -0.8 to 5.2%). With the mini-Wright meter in series, the flow recorded by the PT was on average 6.1 +/- 9.1% below the input flow (range: -23.8 to 2. 5%), but was only 0.6 +/- 3.3% above the pump's output flow predicted by the model (range: -5.5 to 3.9%). The mini-Wright meter's reading (corrected for its nonlinearity) was on average 1.3 +/- 3.6% below the model's predicted output flow (range: -9.0 to 1. 5%). The mini-Wright meter would be deemed outside ATS limits for accuracy for three of the seven profiles when compared with the pump's input PEF, but this would be true for only one profile when compared with the pump's output PEF as predicted by the model. Our study shows that the output flow from pump systems can differ from the input waveform depending on the operating configuration. This effect can be predicted with reasonable accuracy using a model based on nonsteady flow analysis that takes account of pressure wave reflections within pump systems.

Calibration↗
PubMed1999

Diurnal variation in lung function in subgroups from two Dutch populations: consequences for longitudinal analysis.

We studied circadian variation in FVC, FEV1, PEF, TLC, VC, and RV between 9:00 A.M. and 9:00 P.M. and analyzed how this variation affected estimated longitudinal change. Data from 876 adults were obtained in a longitudinal survey of samples from two Dutch areas. Subjects participated in four surveys held at 3-yr intervals between 1975 and 1985. FVC, FEV1, PEF, and VC increased from 9:00 A.M. until noon and decreased afterwards. TLC was constant over the day, whereas RV decreased from 9:00 A.M. to noon. Average variation in FVC, FEV1 and PEF, expressed as percentages of average level, was 4. 8% (200 ml), 2.8% (86 ml), and 3.1% (250 ml/s), respectively. These results are compatible with circadian changes in airway size. No differences in variability were found between men and women. Significantly larger changes between 9:00 A.M. and noon were found in young adults, smokers, and those with respiratory symptoms than in other subgroups. Adjustment for diurnal variation reduced, albeit slightly, residual standard deviations of estimated longitudinal declines. Average diurnal change was large relative to underlying longitudinal change. Its effect on longitudinal change within an individual can therefore be large depending on age, smoking habits, symptomatology, number of visits, time of measurement, and difference in time between measurements. However, when people are measured at random times during the day for at least three visits, or when measurements are made after 11:00 A.M., effects of diurnal variation in pulmonary function on estimated average longitudinal decline are minimal.

Adult↗
PubMed1998

Determination of diffusing capacity by modeling the dynamics of C18O uptake in newborns.

Dynamic modeling of lung C18O diffusion is used to measure the C18O transfer factor (TLCO) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C18O and on changing alveolar ventilation induced by the rebreathing conditions. The model does not involve the volume of the rebreathing bag which is usually needed when applying rebreathing technique and which is a source of error. The equation is discretized and solved for recorded data obtained with equipment adapted to use in newborns. A least-square parameter calculation technique is applied to estimate TLCO. Results show a strong relationship between this index and the biometrical ones and confirm those found in the literature featuring that the measurement duration can be considerably shortened.

Analysis of Variance↗
PubMed1998

The rise and dwell time for peak expiratory flow in patients with and without airflow limitation.

The response of peak expiratory flow (PEF) meters may be affected by the magnitude of PEF, the time taken to get to PEF, and the duration that the peak is sustained. We undertook a retrospective study to define the 10 to 90% rise time (RT) and dwell time for flow above 90% (DT90) and 95% (DT95) of PEF. Blows were analyzed that had been recorded using a pneumotachograph from 912 patients older than 17 yr of age (556 men) who routinely attended a lung function laboratory. For each subject, that blow with the largest PEF was used to derive the PEF, FEV1, FVC, RT, DT90, and DT95. The values for RT, DT90, and DT95 were negatively skewed with the median values for men of 58, 29, and 19 ms, respectively, being significantly shorter than those for the women of 67, 49, and 31 ms. From the 912 subjects, there were 277 (153 men) who had all their spirometric indices within the normal range, and 305 (220 men) had both PEF and FEV1 more than 1. 645 SD below predicted, indicating airflow limitation. For subjects with airflow limitation the median RT was significantly smaller than in the normal subjects (men: 46 versus 72 ms, women: 50 versus 72 ms), and the same was found for DT90 (men: 22 versus 40 ms, women: 27 versus 56 ms) and DT95 (men: 15 versus 26 ms, women: 18 versus 34 ms). We conclude that the dwell times for PEF are shorter in men, and the rise and dwell times are shorter in patients with airflow limitation. Profiles used to test PEF meters should encompass the range of rise and dwell times found in subjects most likely to be using PEF meters, that is, those with airflow limitation.

Adult↗
PubMed1998

References values for forced spirometry. Group of the European Community Respiratory Health Survey.

The European Coal and Steel Community (ECSC) prediction equations exemplify a significant effort carried out approximately 15 yrs ago to provide uniform standards for lung function testing, but this set of equations has not been properly validated as yet. The present study evaluates the ECSC reference values and four other sets of prediction equations, using spirometric data collected in 12,900 nonasthmatic subjects (43% lifetime nonsmokers and 36% active smokers) aged 20-44 yrs from the European Community Respiratory Health Survey (ECRHS). Standardized spirometric measurements were obtained using a common protocol in 34 centres in 14 countries. For each prediction equation, the prediction deviations (i.e. observed minus predicted value) for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were examined for the whole study population and for each centre. For the age range included, the errors about the ECSC equations showed the most prominent underestimation of both predicted FVC (+355 and +360 mL on average in males and females, respectively) and predicted FEV1 (+211 and +200 mL, respectively) among the five studies examined. As expected, FVC and FEV1 in active smokers from the ECRHS were significantly lower than in lifetime nonsmokers (each p<0.01). We conclude that the present European recommendations on lung function reference values should be reconsidered, but further data for nonsymptomatic subjects above the age of 44 yrs are needed.

Adult↗
PubMed1997

Pulmonary function in infants with neonatal chronic lung disease with or without hyaline membrane disease at birth.

We studied whether neonatal chronic lung disease (NCLD), hyaline membrane disease (HMD) and differences in ventilatory support affected pulmonary function during the first year of life, in 65 infants born prematurely. The relationship between body weight and oxygen consumption (V'O2) was also analysed. The study comprised 14 infants without cardiorespiratory disease, 19 infants with HMD but without NCLD, 9 infants with NCLD without prior HMD, and 23 infants with NCLD following HMD. At 6 and 12 months corrected postnatal age, static respiratory system compliance (Crs) was measured by weighted spirometry and the functional residual capacity by closed circuit helium dilution (FRCHe) combined with assessment of ventilation distribution from the mixing index (MI). Ventilatory support during the first 5 days of therapy was quantified from peak inspiratory pressure (PIP), mean airway pressure (MAP) and fractional inspiratory concentration of oxygen (FI,O2). Infants with NCLD had a shorter duration of gestation and lower birth weight than those without NCLD (Wilcoxon, p=0.002 and p=0.001, respectively). Pulmonary function at 6 and 12 months corrected age was not different between NCLD infants with or without HMD at birth. Infants with NCLD had lower Crs and MI than those without NCLD (analysis of variance (ANOVA), p<0.011), but their FRCHe was not different. V'O2 adjusted for body weight was comparable in the four groups. PIP and FI,O2 were higher (Wilcoxon, p<0.01) in the NCLD infants than in those with HMD alone, but MAP was not different. Except for FI,O2, these indices were not different among the infants with NCLD. We conclude that birth weight is the major determinant of the development of neonatal chronic lung disease. At 6 and 12 months corrected age, the abnormal pulmonary function is not associated with prior hyaline membrane disease.

Birth Weight↗
PubMed1996

Pulmonary function and postoperative complications after wedge and flap reconstructions of the main bronchus.

Between 1980 and 1989, 8 wedge and 17 flap main bronchoplasties were done in 24 patients (4 carcinoid tumors, 4 benign lesions, 17 carcinomas). Bronchial anastomotic stenoses, pulmonary function, and survival were evaluated. Preoperative ventilation/perfusion scans with preoperative and postoperative spirometry were done in all patients except two who underwent a wedge bronchoplasty. Postoperative bronchoscopy was done in all patients. Follow-up was complete for the patients with carcinoma (N = 17). In the wedge group bronchial anastomotic stenoses occurred in three (38%) of eight patients. All three patients had serious postoperative complications (persistent atelectasis in one, prolonged ventilatory support in two); one patient died and the other two had impaired postoperative pulmonary function. Complete function recovery occurred in only three (38%) of eight patients who underwent wedge bronchoplasty. In the flap group, bronchostenosis occurred in 3 (18%) of 17 patients. The associated complications (mucus retention, minor atelectasis, partial lobar torsion) were mild. Complete pulmonary function recovery occurred in 13 (76%) of 17 patients who had flap bronchoplasty. Actuarial survival, for the patients with carcinoma, was 88%, 47%, and 41% after 1, 3, and 5 years, respectively. The local recurrence rate was 25% (4/16). In our series, flap main bronchoplasties were effective for the resection of bronchial tumors with local involvement of the adjacent main bronchus. Wedge main bronchoplasties, however, were associated with substantial postoperative complications.

Adult↗
PubMed1996

Lung function and perfusion after bronchial and pulmonary arterial sleeve resection.

Between January 1985 and December 1991, six patients underwent arterial and bronchial sleeve resections of the left upper lobe. Preoperative and postoperative spirometry, preoperative split pulmonary radionuclide ventilation/perfusion (V/Q) scans and postoperative bronchoscopy were obtained in four patients. Postoperative serial digital vascular images (DVI) of the pulmonary artery were obtained in three patients and one patient had a postoperative V/Q scan. For each patient the preoperative and postoperative forced expiratory volume in is (FEV1) were determined to assess the postoperative ventilatory recovery. At bronchoscopy all patients had a patent bronchial anastomosis. At postoperative DVI, in three patients, vascularization of the residual left lung was delayed and less intense compared with the non-operated right lung. Postoperative V/Q scan, in one patient, showed reduced ventilation and perfusion of the residual lung. Preoperative and postoperative FEV1 of the four patients were 2688/1998 ml, 2154/1752 ml, 2618/2100 ml and 2277/2015 ml. Operative mortality was zero. One patient had a postoperative atelectasis of the left lower lobe. In our series, ventilation and vascularization of the reimplanted and revascularized left lower lobe were reduced. But, in our opinion, the preserved residual lung parenchyma was still a relevant advantage.

Aged↗
PubMed1996

Interindividual variation in pubertal growth patterns of ventilatory function, standing height, and weight.

We studied interindividual variation in pubertal growth patterns from peak growth velocities (PGV) and peak growth ages (PGA) of ventilatory function, standing height, and weight in a selection of 144 boys from a longitudinal survey of 404 pupils in a Dutch secondary school. Measurements were made at intervals of approximately 0.5 yr between 1978 and 1985. Between 9 and 14 measurements were available for each selected individual. Average age on enrollment was 12.7 years. 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. PGVs and PGAs were derived from monotonically increased regression splines, fitted to the data of each individual and each variable separately. The 90% percentile ranges of PGA were approximately 4.5 yr in all variables. In almost all boys, the PGA of height occurred earlier than that of ventilatory function, but the magnitude of the time lag varied considerably. Median PGAs agreed well with peak growth ages derived from average growth velocity curves fitted on exactly the same data. However, median PGVs were 1.25 to 1.40 times higher than the corresponding estimates from the average curves. The latter finding implies that in almost all cases, individual development deviates considerably from development suggested by average growth profiles. No differences in PGA and PGV were found between subjects with a prepubertal history of respiratory symptoms and those without. The large interindividual variations in PGA and PGV, and in the time lag between growth of height and of ventilatory function, are not accounted for in cross-sectional reference equations. These equations are therefore not suitable to predict individual development during adolescence.

Adolescent↗
PubMed1996

Pulmonary function during the first year of life following acute viral bronchiolitis.

It has been suggested that acute viral bronchiolitis in infants may result in functional changes that predispose toward chronic pulmonary disease later in life. We assessed pulmonary function (PF) during the acute phase of viral bronchiolitis in infants and up to 12 mo later from static respiratory system compliance (Crs), using weighted spirometry, the distribution of ventilation by the mixing index (MI), and the functional residual capacity (FRC) measured by closed-circuit helium dilution (FRCHe). The study was performed in 24 infants (13 males and 11 females; median [25 to 75% range] age: 11 [9.6 to 13.3] wk; weight: 4.8 [4.3 to 5.0] kg; crown-to-heel length: 57.7 [55.5 to 59.0] cm) at admission and at 2 wk. In 17 infants, measurements were repeated 3 mo and 12 mo later. Predicted values and individual 95% prediction intervals for Crs, MI, and FRCHe were derived from 69 healthy infants (33 boys and 36 girls; median age [25 to 75% range]: 4.7 [2.0 to 21.4] wk; weight: 3.6 [3.0 to 6.9] kg; crown-to-heel length: 51.5 [48 to 61] cm). Data at admission and after discharge were compared by analysis of variance (ANOVA) with those in the healthy controls matched for crown-to-heel length. At admission all three variables gave lower average results than predicted means. Values for each index had attained a normal level 2 wk after admission; normal levels were maintained at 3 and 12 mo. The prevalence of recurrent wheezing (five of the 17 infants) was comparable with that reported in population studies. These findings suggest that in this population acute viral bronchiolitis did not lead to permanent changes in PF.

Acute Disease↗