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P J Merkus

Publications and source records attributed to P J Merkus.

At least 19 recordsLinked to original sources
PubMed2006

Computed tomographic estimation of lung dimensions throughout the growth period.

The aim of the current study was to use computed tomography (CT) to estimate airway wall and lumen, and arterial and parenchyma dimensions in children throughout the growth period, and to provide normative data to study alterations caused by pulmonary disease. Clinical CT scans reported as normal that were performed in children for nonpulmonary and noncardiac reasons were analysed for lung weight, gas volume, lung expansion, lung surface/volume ratio, airway wall area, airway lumen area, airway lumen perimeter, arterial area and airway surface length/area ratio. The age range of the 50 subjects was 0-17.2 yrs. The data showed only little increase in lung expansion throughout childhood (n = 32). There was substantial variability in lung expansion between subjects. Airway wall and lumen and arterial area were exponentially associated with subjects' height (n = 50). Airway surface length/area ratio was linearly associated to alveolar surface/volume ratio. The data from the current study provide normative computed tomography estimates of airway wall and lumen, and arterial and parenchyma dimensions throughout the growth period that may be useful for the study of alterations in disease.

Adolescent↗
PubMed2003

[Beta 2 agonists in infants and young children with a wheeze: often ineffective].

Wheezing is a common symptom in infants and young children, for which the treatment of choice is beta 2-agonists. However, the efficacy of beta 2-agonists in children aged 2 years and younger is not evidence based. Approximately 60% of wheezy infants do not have asthma, but a transient condition related to airway obstruction that is associated with coughing, wheezing and/or stuffiness: so-called infant asthma. In infants, beta 2-agonists may make the airways more compliant, resulting in more severe airway obstruction. In addition to this, beta 2-agonists increase the metabolism and cause ventilation-perfusion mismatch in the lung which may lead to a decrease in the oxygen saturation. Since it is unclear which infants will benefit from beta 2-agonists, a trial treatment is justified and this should be critically evaluated. Beneficial clinical effects of beta 2-agonists are a reduction in breathing frequency, reduction in or disappearance of retractions or the use of accessory respiratory muscles during breathing and possibly an increase in oxygen saturation. beta 2-agonists are effective and safe for the treatment of asthma. However, there is no basis for continuing the treatment in the case of infants and young children with an airway obstruction unless there is a clinically favourable effect.

Adrenergic beta-Agonists↗
PubMed2003

[Guideline 'Treating asthma in children' for pediatric pulmonologists (2nd revised edition). II. Medical treatment].

The second revision of the guidelines for the treatment of asthma in children is largely based on the evidence of comparative studies. Short-acting beta 2-sympathicomimetics are the medication of choice for acute exacerbations and should therefore be prescribed to each patient. Inhaled corticosteroids (ICS) are the medication of choice for maintenance treatment. Starting with a high dose of ICS which is then reduced to a lower but effective level on the basis of the complaints (step-down approach) is no longer recommended, as this strategy is not more effective than a constant dosage schedule. If asthmatic symptoms persist despite ICS maintenance treatment then 3 therapeutic options are available in the following order: doubling the ICS dose, the addition of a long-acting beta 2-sympathicomimetic, and the addition of a leukotriene receptor antagonist.

Administration, Inhalation↗
PubMed2003

Estimation of lung growth using computed tomography.

Anatomical studies suggest that normal lungs grow by rapid alveolar addition until about 2 yrs of age followed by a gradual increase in alveolar dimensions. The aim of this study was to examine the hypothesis that normal lung growth can be monitored by computed tomography (CT). Therefore, the gas volume per gram of lung tissue was estimated from measurements of lung density obtained from CT scans performed on children throughout the growth period. CT scans were performed on 17 males and 18 females, ranging in age from 15 days-17.6 yrs. CT-measured lung weight was correlated with predicted post mortem values and CT measured gas volume with predicted values of functional residual capacity. The median value for lung expansion was 1.86 mL x g(-1) at 15 days, decreased to 0.79 mL x g(-1) by 2 yrs and then increased steadily to 5.07 mL x g(-1) at 17 yrs. Computed tomography scans can be used to estimate lung weight, gas volume and expansion of normal lungs during the growth period. The increase in the lung expansion after the age of 2 yrs suggests progressive alveolar expansion with increasing lung volume.

Adolescent↗
PubMed2001

Interrupter resistance in preschool children: measurement characteristics and reference values.

There is a need for quick, reliable, and noninvasive lung function tests to assess airway obstruction in preschool children both for pediatric pulmonary care as well as for research purposes. We studied feasibility, reproducibility, and validity of measurements of the respiratory system using the interrupter technique (interrupter resistance [Rint]) and obtained reference values in children from a general population, 2 to 7 yr of age. Accuracy was studied by comparisons of Rint with plethysmographic airway resistance (Raw) in 20 patients (7 to 14 yr) with mild to severe chronic airways obstruction and was satisfactory in patients with FEV(1) > 60% predicted. The technique proved sensitive enough to detect changes in airway caliber within a small group of 12 children who developed mild respiratory tract infections. Among children from a general population, subgroups with mild respiratory symptoms or mild respiratory disease had higher mean Rint values. Airway obstruction was better detected using expiratory rather than inspiratory interruptions, both programmed at peak tidal ventilatory flow. Reproducibility within subjects was satisfactory (intraclass correlation 0.82 and 0.79). The same applied to interobserver agreement (intraclass correlation 0.98). The interrupter technique proves to be a reliable and practical test of airway function, suitable for clinical and epidemiologic studies in preschool children.

Age Factors↗
PubMed2001

Rescue use of DNase in critical lung atelectasis and mucus retention in premature neonates.

Excessive or thick pulmonary secretions are a common clinical challenge in the neonatal population. Mucus accumulation can cause many life-threatening complications, including plugging of the endotracheal tube and increasing the risk of pulmonary infections. We report 3 premature neonates who had critical pulmonary collapse secondary to mucous plugging. Different conventional methods to liquefy mucus and facilitate removal of secretions were exhausted to no avail. The rescue use of DNase was effective in reestablishing airway patency. Thus, this drug could be a valuable tool in treating atelectasis and mucus-plugging in mechanically ventilated, premature neonates.

Administration, Inhalation↗
PubMed2001

DNase treatment for atelectasis in infants with severe respiratory syncytial virus bronchiolitis.

Respiratory insufficiency due to respiratory syncytial virus (RSV) bronchiolitis is partly due to the abundance of thickened mucus and the inability to clear it from the airways. Mucus in RSV bronchiolitis contains necrotic inflammatory and epithelial cells. The viscoelastic properties of purulent airway secretions are largely due to the presence of highly polymerized deoxyribonucleic acid (DNA). Recombinant human deoxyribonuclease (rhDNase) is known to liquefy such mucus in patients with cystic fibrosis, whereas case reports described a beneficial effect in other respiratory disorders. The authors hypothesized that rhDNase would diminish atelectasis and mucus plugging in infants with severe RSV bronchiolitis. Two infants with RSV bronchiolitis with massive unilateral atelectasis in whom mechanical ventilation was imminent due to exhaustion, and three mechanically ventilated infants (two neonates, one with bronchopulmonary dysplasia) with RSV bronchiolitis with pneumonia received treatment with 2.5 mg nebulized rhDNase twice daily. Following administration of nebulized recombinant human deoxyribonuclease, clinical and radiological parameters improved quickly. Mechanical ventilation could be avoided in two infants while in three infants on artificial ventilation, clinical recovery started following the first dose of the drug. A therapeutic trial of recombinant human deoxyribonuclease may be an option in the treatment for atelectasis in severe or complicated respiratory syncytial virus bronchiolitis in infancy.

Administration, Inhalation↗
PubMed2000

A family with extrinsic allergic alveolitis caused by wild city pigeons: A case report.

We describe a family in which the mother died of unresolved lung disease and whose 5 children, some of whom had previous signs of asthma, were subsequently affected by extrinsic allergic alveolitis caused by contact with wild city pigeon antigens. The children received systemic corticosteroids for 1 month and inhaled steroids for 24 months, while antigen exposure was reduced as much as feasible. This was followed by a quick clinical recovery and a slow normalization of chest radiographs and pulmonary function indices, especially of diffusion capacity, during a follow-up of 24 months. Because pigeon-breeder's lung caused by free-roaming city pigeons has not been previously described, it remains unclear whether this family developed the disease because of high antigen exposure or because of increased susceptibility. None of the supposedly high-risk human leukocyte antigen types were found in the children. Whether human leukocyte antigen B7 in 1 child played a role in the course of the illness remains speculative. It is unknown to what extent pigeon-breeder's lung caused by nondomestic birds remains undetected and misdiagnosed as difficult or steroid-resistant asthma. The question remains whether free-roaming city pigeons are indeed a public health risk. We suggest that atypical outdoor antigens be considered in all patients with nonresolving chest disease or therapy-resistant asthma.

Adolescent↗
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

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

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↗