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Biomedical subjects

P H Quanjer

Publications and source records attributed to P H Quanjer.

At least 37 records · Page 2Linked to original sources
PubMed1996

Peak expiratory flow and the resistance of the mini-wright peak flow meter.

The purpose of this study was to examine whether the resistance of the peak flow meter influences its recordings. One hundred and twelve subjects, (healthy nonsmokers and smokers and subjects with lung diseases) performed three or more peak expiratory flow (PEF) manoeuvres through a Fleisch pneumotachograph with and without a mini-Wright peak flow meter added in random order as a resistance in series. The results were as follows. In comparison with a pneumotachograph alone, peak flow measured with an added mini-Wright meter had a smaller within-test variation, defined as the difference between the highest and second highest values of PEF in a series of blows. The mean (SE) variation was 14 (1.3) L.min-1 and 19 (1.5) L.min-1 with and without meter added, respectively. In comparison with the pneumotachograph alone, the addition of the mini-Wright meter caused PEF to be underread, especially at high flows. The difference (PEF with meter minus PEF without meter) = -0.064 (average PEF) -8 L.min-1; R2 = 0.13. The mean difference was -7.8 (1.1) %, and increased numerically for a given PEF, when maximal expiratory flow when 75% forced vital capacity remains to be exhaled (MEF75%FVC) decreased. The reproducibility criteria for repeated measurements of peak flow are more appropriately set at 30 L.min-1 than the commonly used 20 L.min-1, because a within-test variation of less than 30 L.min-1 was achieved in 76% of the subjects without PEF meter inserted and in 88% with meter inserted, with no difference between healthy untrained subjects and patients. The resistance of the peak expiratory flow meter causes less variation in recordings but reduces peak expiratory flow, especially at high values and when the peak is large as compared with the rest of the maximal expiratory flow-volume curve.

Adolescent↗
PubMed1995

Spirometric reference values for white European children and adolescents: Polgar revisited.

We analyzed six spirometric data sets collected in the Netherlands, Austria, the United Kingdom, Spain, and Italy. The objectives were to establish whether (1) it was possible to describe spirometric indices from childhood to adulthood, taking into account the adolescent growth spurt, and (2) there are systematic differences in ventilatory function between children and adolescents in different parts of Western Europe. The study comprised 2,269 girls and 3,592 boys, aged 6-21 years. The range in standing height was 110-185 in girls, 110-205 in boys. The model applicable to all data sets was ln FVC or ln FEV1 = a + (b + c x A) x H, where H = standing height and A = age; this model prevents the phase shift between the adolescent growth spurt in length and lung volume from leading to an age-dependent bias in predicted values. There was surprising agreement between most of the data sets; systematic differences are probably due to technical factors arising from ATPS-BTPS corrections and from defining the end of breath with pneumotachometer systems. Taking those into account, prediction equations for FVC, FEV1, and FEV1%FVC were developed with "lower limits of normal" which should be applicable to children and adolescents of European descent. It is proposed that the approach of analyzing available data sets should also be applied to other ventilatory indices, data collected in adults and elderly subjects, or in other ethnic groups, and that an international data base be set up to that end.

Adolescent↗
PubMed1995

Biochemical lung maturity, static respiratory compliance, and pulmonary gas transfer in intubated preterm infants with and without respiratory distress syndrome.

We investigated the relationship between tests of biochemical lung maturity [lecithin/sphingomyelin ratio (L/S ratio)], static compliance of the respiratory system (Crs), and estimates of pulmonary gas transfer [venous admixture and arterial/alveolar (a/A) ratio] in a group of intubated preterm infants with and without respiratory distress syndrome (RDS). Thirty infants were studied once (n = 26) or twice (n = 4). The L/S ratio was obtained by means of high-performance thin-layer chromatography and determination of the phosphorus content. Crs was obtained by the multiple occlusion technique. Transcutaneous blood gases and the percentage of oxygen in the inspired gas were recorded and estimates of pulmonary gas transfer were calculated using algorithms. L/S ratio and Crs correlated well (r = 0.73), indicating a higher compliance in biochemically more mature lungs. Both the a/A ratio and venous admixture correlated significantly with the L/S ratio and Crs (P < 0.001). Crs, L/S ratio, and a/A ratio decreased with increasing severity of radiological RDS, and the percentage venous admixture increased (P < 0.001). Sequential measurements in four infants during the acute phase and after RDS resolved indicated that clinical improvement coincided with improvements in biochemical lung maturity, Crs, and estimates of pulmonary gas transfer.

Chromatography, High Pressure Liquid↗
PubMed1995

Respiratory illness in families of preterm infants with chronic lung disease.

AIMS--To examine the relation, based on two types of questionnaires, between (1) chronic lung disease of the newborn (CLDN) and lower respiratory illness (LRI) in siblings, and between (2) CLDN and asthma, chronic obstruction pulmonary disease (COPD), or allergy in parents and grandparents. METHODS--Data from 209 children born before 32 weeks of gestation were randomly taken from the records of three neonatal units. Taking into account age and gender, the excess of LRI was calculated for each family compared with the average of all families. Subsequently whether CLDN was associated with an excess of LRI in the family was tested. RESULTS--Thirty one (14.8%) children were diagnosed as having CLDN. The family probability index for LRI did not differ between children with or without CLDN. The prevalence of COPD, asthma, and allergy in parents of children with CLDN was similar to that of children without CLDN. The prevalence of LRI was 18.1% in study children, 29.6% in children with CLDN, and 16.9% in children without CLDN (P < 0.01). These prevalences were higher compared with that of a group of term siblings (9.3%) (P = 0.05). CONCLUSIONS--These findings suggest that CLDN in preterm children is not related to a genetic or familial predisposition towards asthma, COPD, or allergy.

Asthma↗
PubMed1995

Strength of the Breuer-Hering inflation reflex in term and preterm infants.

The effect of the presence of the respiratory distress syndrome (RDS) or related factors (static compliance of the respiratory system and transcutaneous blood gases) and gestational age on the strength of the Breuer-Hering inflation reflex (BHIR) was studied in three groups of infants. Twenty-six ventilated preterm infants with and without RDS were studied 6 h after birth (group 1). In 24 preterm infants, we followed the development of reflex strength during the first year of life (group 2). Twenty-one healthy nonintubated term infants were studied within the first week of life (group 3). The BHIR was initiated by end-inspiratory occlusions, and the strength was characterized by the ratio of expiratory time after and without preceding airway occlusion. The static compliance of the respiratory system in ventilated infants was assessed by the multiple-occlusion technique. In group 1, reflex strength declined with increasing gestational age; in the presence of RDS or low respiratory compliance, the decline was less. Transcutaneous blood gases did not affect reflex strength. At term age, reflex strength was similar in spontaneously breathing preterm (group 2) and term infants (group 3). The BHIR decreased in strength during the first year after preterm birth. We conclude that 1) the strength of the BHIR decreases with increasing gestational and postnatal ages and 2) RDS, due to changes in respiratory system mechanics, causes an increase in reflex strength.

Age Factors↗
PubMed1995

Pulmonary function during the first year of life in healthy infants born prematurely.

Premature birth is associated with increased respiratory morbidity. We investigated cross-sectionally, in 69 healthy infants who had never had cardiorespiratory problems, whether premature birth is associated with diminished pulmonary function. The study comprised 26 healthy infants born prematurely (PT), median gestational age 32 (26-36) weeks, and 43 healthy controls born full-term (FT), median gestational age 40 (37-42) weeks. Static respiratory system compliance (Crs) was assessed by weighted spirometry, combined with the measurement of the functional residual capacity by closed circuit helium dilution (FRCHe) and with assessment of ventilation distribution from the mixing index (MI). Repeatability of these indices was also assessed. Premature and full-term infants had the same length-corrected FRCHe; their Crs was different, but the difference disappeared when gestational age was taken into account. Mixing index was unrelated to body size and was not different between full-term and premature infants. Crown-heel length and lung volume were not different for any postconceptional age. However, infants born prematurely were smaller and had smaller lung volume at any postnatal age compared to those born at term. Repeatability of the indices was fair. These findings suggest that gestational age < 37 weeks is associated with normal respiratory system mechanics for body size, and normal distribution of ventilation in healthy infants who never had cardiorespiratory problems.

Body Constitution↗
PubMed1995

Frequency response of variable orifice type peak flow meters: requirements and testing.

Little is known about the response of variable orifice peak flow meters to high frequency flow input. The purpose of this study was to define and test dynamic requirements for such peak flow meters. In a population sample we measured peak expiratory flow (PEF), rise time (tr), from 10-90% PEF and the duration of the flow in excess of 97.5, 95 and 90% of PEF, by use of a carefully calibrated Fleisch pneumotachograph with known and adequate frequency response. Three peak flow meters (Mini Wright, Vitalograph and Ferraris) were tested with an explosive decompression calibrator adjusted to values for PEF and tr as close as possible to the 95th and 5th percentile values, respectively, both for males and females, and with peak durations between 5 and more than 100 ms. The 95th percentile values of PEF were 597 L.min-1 for females and 894 L.min-1 for males. The 5th percentile values of tr were, respectively 55 and 45 ms. The duration of flow in excess of 95% PEF was longer than 10 ms in 99% of the subjects. For all meters, the deviation of PEF corrected for alinearity were less than 5% at a peak duration of 10 ms. We conclude that PEF, rise time, and peak duration can be used for description of dynamic properties of variable orifice meters, and that the tested meters had a satisfactory frequency response for recording PEF in mostly normal subjects.

Adult↗
PubMed1994

Dust-related decline in lung function among animal feed workers.

The study describes results of the first part of a follow-up study among 50 animal feed and grain elevator workers. The initial results suggest that the change in lung function over a 5 year period is related to the dust exposure. Workers in the high exposure category showed a greater decline in lung function than workers in the low exposure category. The decline in lung function was strongest for workers who were low exposed at the beginning of the study and who became high exposed during the follow-up period.

Adult↗
PubMed1994

Dust- and endotoxin-related acute lung function changes and work-related symptoms in workers in the animal feed industry.

Reported respiratory and related symptoms during work were compared between 265 exposed animal feed workers and a control group consisting of 175 external controls and nonexposed workers in the animal feed industry. Symptoms indicating respiratory and nasal irritation were significantly increased in the animal feed workers. Prevalences ranged from 9% (cough) to 21% (sneezing). Reported cough after work was also significantly increased. In 119 workers, a total of 457 across-shift spirometric lung function changes were measured. Almost all lung function variables showed a decrease during the work shift, as could be expected since the circadian rhythm is in a downward phase during the measurement period (2 p.m.-10 p.m.). When the workers were grouped into dust and endotoxin exposure categories according to their job titles, and exposure-response trend was seen for maximum mid-expiratory flow (MMEF) and maximum expiratory flow rate at 50% of vital capacity (MEF50). The effect of endotoxin was stronger than that of dust, both in magnitude and significance. For the same lung function variables and for forced expiratory volume in 1 second (FEV1) and MEF25, a significant across-week change was also detected. The results of this study are in concordance with other studies that indicate acute effects on lung function and elevated prevalences of respiratory symptoms during work caused by exposure to grain dust.

Adult↗
PubMed1994

Discrepancies between longitudinal and cross-sectional change in ventilatory function in 12 years of follow-up.

We compared the age dependence of cross-sectional and longitudinal changes in ventilatory function. FEV1, FVC, and data on chronic respiratory symptoms were obtained from 4,395 adults in a longitudinal survey of normal populations in two different areas in the Netherlands. They participated in up to five surveys at 3-yr intervals between 1972 to 1973 and 1984 to 1985. The ventilatory function in the oldest cohorts is substantially lower than might have been expected from the longitudinal change in the youngest cohorts. This holds for males and females, smokers and nonsmokers, subjects with or without symptoms, and for both survey populations. The robustness of the findings is demonstrated by various data-analytic strategies or omitting one or two of the five surveys from the analysis. Selective loss to follow-up cannot explain the discrepancy. It is concluded that the main differences between our longitudinal and cross-sectional findings may be due to a cohort effect. The implication is that in longitudinal studies of populations at risk, reference equations based on cross-sectional surveys may overestimate longitudinal change and hence lead to underestimating effects of exposure. Similarly, in clinical studies, accelerated decline in ventilatory function may be underrated if it is compared with cross-sectional standards. In older people at any one age the ventilatory function seems to improve in successive birth cohorts.

Adult↗
PubMed1994

Validity of ECSC prediction equations for spirometric indices in Dutch conscripts.

A study was performed to determine whether prediction equations issued by the European Community for Steel and Coal (ECSC) and the European Respiratory Society (ERS) fit spirometric data in young adult males. The study comprised 246 randomly selected Dutch conscripts, who participated in the study on the basis of informed consent. A questionnaire was used to assess respiratory symptoms and smoking habits. Maximal expiratory flow-volume curves were obtained with a rolling seal spirometer, and summary statistics selected according to ECSC/ERS recommendations. In addition, standing height and body weight were obtained. We analysed the data of 100 conscripts of European descent, with no history of respiratory symptoms. They were all life-long nonsmokers. Their mean (SD) age was 18 (0.12) yrs (range 17.9-19.0 yrs), with a mean (SD) standing height of 1.84 (0.06) m (range 1.68-2.00 m). The data for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximal mid-expiratory flow (MMEF) agreed well with ECSC predictions; 95% confidence intervals (95% CI) of differences between measured and predicted values were -0.174 to 0.044 l, -0.012 to 0.174 l.s-1 and -0.114 to 0.302 l.s-1, respectively. Peak expiratory flow was systematically larger than predicted, as was FEV1 % FVC (95% CI 0.74 to 1.31 l.s-1 and 2.50 to 5.24%, respectively), due to the intercept being inappropriate. The residual standard deviation in the conscripts was somewhat less than in the ECSC/ERS predictions equations, except for peak expiratory flow (PEF).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Changes of respiratory system mechanics in ventilated lungs of preterm infants with two different schedules of surfactant treatment.

We investigated the time course of changes in the static respiratory system compliance and resistance in relationship to surfactant administration by means of single-breath and multiple-occlusion techniques. The study comprised 12 infants receiving a high-dose schedule (200 mg/kg, maximum 600 mg/kg) and 13 infants receiving a low-dose schedule (100 mg/kg, maximum 300 mg/kg) of porcine surfactant. Eight healthy preterm infants served as a comparison group. Respiratory mechanics were studied before and at 1.5, 8, and 72 h after surfactant administration. Results were related to changes in gas transfer, including an estimate of venous admixture. Static compliance improved after surfactant instillation, and changes were similar in the two treatment groups during the first eight h (0.8 In.(hour + 1) mL.kPa-1). The compliance values remained below the values of the healthy comparison group during the whole study period, but resistance remained at the same level. There was a considerable delay in changes of respiratory mechanics in relationship to the rapid fall of the venous admixture, from 27 to 19%, and the rapid increase of the transcutaneous oxygen pressure/fraction of inspired oxygen ratio from 13 to 27 kPa within the hour. There were no clues that short-term changes in compliance were masked by breathing at a higher and flatter portion of the pressure-volume curve. Both treatment schedules resulted in a similar improvement of compliance within 72 h and the two groups benefited similarly in terms of venous admixture.

Airway Resistance↗