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Biomedical subjects

G Polgar

Publications and source records attributed to G Polgar.

At least 19 recordsLinked to original sources
PubMed1987

Cold air challenge of airway hyperreactivity in children: dose-response interrelation with a reaction plateau.

A previous study of cold air challenge (CACh) in children with asthma produced indirect evidence for the existence of a reaction plateau. To examine directly this phenomenon, 17 children, mean age 13 1/2 years, were challenged by isocapnic hyperventilation with -10 degrees C air at 75% of maximal voluntary ventilation for 10 minutes (extended CACh [ECACh]). Each minute FEV1 and maximum expiratory flow at 25% remaining vital capacity (V25) were measured. During "recovery" these measurements were repeated every minute for 10 minutes. Analysis of the cumulative dose-response curves constructed from the measurements revealed that a reaction plateau was reached in the last minutes of the challenge by both functions in each child. Induced changes in absolute terms were similar for both functions (FEV1: -28 +/- 12% predicted; V25: -29 +/- 17% predicted), but V25 started at a lower baseline (FEV1: 81 +/- 15% predicted; V25: 48 +/- 27% predicted) and thus arrived at a higher degree of obstruction (FEV1: 53 +/- 19% predicted; V25: 19 +/- 13% predicted). Together with the reaction plateau developing faster for V25, this indicated a dose-response influenced by baseline small airway obstruction. Although the size of the reaction differed from one child to the other (FEV1: -5% to -50% predicted; V25: -4% to -77% predicted), interindividual variability in the development of the reaction decreased toward the end of the challenge and was minimal at the plateau and in the early minutes of "recovery."(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Bronchodilators increase airway instability in cystic fibrosis.

Supramaximal flow transients of partial expiratory flow-volume curves are caused by a rapidly emptying compartment. By superimposing a maximal and a series of partial expiratory flow-volume curves, the volume of the flow transient equivalent for the maximal curve was estimated (volume of airway contribution = VACMEFV). This flow transient equivalent is caused by an extra dead space, created in the large airways by a full inspiration. In 18 children with cystic fibrosis (CF), routine pulmonary functions and VACMEFV were measured before and after bronchodilator medication. Baseline VACMEFV correlated directly with the curvilinearity of the flow-volume curve and inversely with the clinical and radiologic score. Significantly, bronchodilator medication improved FVC, FEV1, FEF25-75, VC, PEF, Raw, and also VACMEFV. In 6 children, VEmax25 increased as a result of apparent peripheral bronchodilation. In 3 others, end-expiratory flow increased slightly but the expanded VACMEFV included the measuring point invalidating the measurement. In the remaining 9 patients, VEmax25 decreased after bronchodilator. As an apparent discrepancy, FEV1, FVC, PEF, VC, FEF25-75 increased, and Raw decreased in 4 to 9 patients. The volumes and flow rates measured early in forced expiration and the end-expiratory flow behaved differently because VACMEFV expanded beyond the measuring points of early expiratory and mid-expiratory flow rates. As the bronchodilator rendered the compliant large airways still more distensible, the amount of air emptied from the dead space in early forced expiration increased. Simultaneously, end-expiratory flow decreased because of enhanced airway compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Cold air challenge of airway hyperreactivity in children: practical application and theoretical aspects.

In 23 children with asthma and 18 healthy controls, cold air challenge ( CACh ) was done twice during the same half day, and in the asthmatics a third time together with a histamine challenge (HCh) 2 wk later. Pulmonary functions were tested before and after each challenge. No overlapping of individual responses to CACh in seven forced expiratory flow tests proved the power of discrimination of this technique in children. The limits of "normal" reactions ranged from minus 9% for larger airway-related to 26% for smaller airway-related flows. Short-term reproducibility of induced changes, in percentage of baseline, was excellent (r = 0.815-0.954); in percentage of predicted postchallenge abnormality it was even better (r = 0.926-0.975). The response in small airway-related flow rates (-43.1 +/- 12.8 to -51.9 +/- 16.8% of baseline) was much larger than in others (-27.6 +/- 14.6 to -32.1 +/- 17.3% of baseline). This, the different baseline-to-response correlations in various measurements, and the divergent dose response to colder versus less cold air in large (60.7 +/- 21.9 versus 65.4 +/- 21.5% predicted, postchallenge values) and small airway-related tests (28.9 +/- 18.7 versus 29.5 +/- 15.1% predicted, postchallenge values) in asthmatic children suggest a predetermined, small airway-related limitation of individual reactivity, which is independent of the baseline situation. All asthmatics responded positively to HCh but quantitative results of the two methods did not correlate. Responses to CACh also better characterized the clinical severity of asthma than those of HCh.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Current concepts of respiratory diseases in childhood: the significance of physiological development.

Recent advances in pulmonary physiology have led to new concepts in the understanding of childhood respiratory disorders. The functional development of the respiratory system appears responsible for most of the age-related attributes of pediatric lung diseases. Increased understanding of the altered physiology of these disorders creates a new and improved basis for supportive care and therapy. The recognition of long lasting functional disturbances caused by some seemingly trivial childhood respiratory disorders suggests a close relationship to chronic obstructive pulmonary disease in adulthood. Relevant developmental risk factors are defined; their influence on the manifestation of common pediatric respiratory disorders is discussed.

Child↗
PubMed1981

Cystic fibrosis diagnosed in a black adolescent with long-standing, unstable diabetes mellitus.

A case is reported of a black youth whose marked diabetic lability was stabilized subsequent to establishing the diagnosis of cystic fibrosis and treatment of the pancreatic exocrine deficiency. The patient had no evidence of pulmonary involvement secondary to cystic fibrosis, but had a partial immunoglobulin A deficiency. A possible common etiology for diabetes mellitus and cystic fibrosis is discussed.

Adolescent↗
PubMed1979

Measurement of regional lung function by tetrapolar electrical impedance plethysmography.

This study demonstrates the clinical feasibility of atraumatically measuring dynamic regional lung function with tetrapolar electrical impedance plethysmography (EIP) in the pediatric age group. A tetrapolar electrode system was used because of its ability to detect local baseline and pulsatile impedance changes, minimal electrode-tissue impedance interference, and uniform current distribution. Studies performed on 4 children 4 to 15 years old with various pulmonary diseases are presented. The information obtained on their regional ventilation and pulsatile perfusion by EIP was found to agree closely with pulmonary ventilation and perfusion scans. In one case, EIP detected pulsatile perfusion abnormalities which were not apparent in the non-pulsatile perfusion scan but were demonstrated by cineangiography. It is concluded that tetrapolar EIP can provide safe, reliable regional information about ventilation and perfusion in diseased lungs, and because of its atraumatic approach, is technically most suitable for use in children.

Adolescent↗
PubMed1976

Pulmonary function in survivors of Wilm's tumor. Patterns of impairment.

Whole-lung irradiation in Wilms' Tumor patients has been given prophylactically and for treatment of metastasis. Thirty-three children with Wilm's tumor who have survived for 4 to 20 years from the time of diagnosis were avaiable for study. Whole-lung irradiation was given in doses from 1163 to 1370 rads (orthovoltage). Eighteen patients (Group N) received no irradiation to the lungs. The remaining 15 patients were divided according to whether pulmonary irradiation was given for metastatic disease (Group M--10 patients) or for prophylactic treatment (Group P--five patients). All but five patients in Group N received at least one course of actinomycin D. A routine set of pulmonary function tests was done to assess possible abnormalities of lung volume and the mechanics of breathing. Group N was normal. The findings in Group M suggested moderately reduced lung volumes and may have also reflected obstruction of the large airways and/or a limited expiratory effort. Group P had essentially normal lung volumes but also appeared to have obstruction of the larger airways. Abnormalities were generally not severe; only two patients, in Group M, were symptomatic. Excess irradiation, presence of metastatsis, additional lung irradiation, and pneumonitis may have contributed to morbidity.

Child↗
PubMed1974

The influence of pulmonary growth and development on paediatric respiratory diseases.

The mortality, morbidity and symptomatology of respiratory diseases in infants and children may be partially related to age specific phenomena of structure and function. Such are the comparatively smaller functional residual capacity and respiratory surface area; the difference in growth velocity of alveolar numbers and size; the smaller number of intrapulmonary communications; the larger resistance of the peripheral airways accentuated by fewer muscular elements and larger number of mucous glands in the same; and the smaller elastic recoil pressure of the lung in children as compared to adults. Many factors compensate, partially or totally, for these apparent handicaps, but the influence of growth and development on disease processes can certainly not be disregarded.

Adolescent↗