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[Flow-volume curves in healthy children and adolescents 10-19 years of age. Reference values and lower limits of the normal].

In 477 healthy children and adolescents (247 boys and 230 girls, aged 10 to 19 years), we measured the vital capacity (VC), the forced expiratory volume in one second (FEV1), the flow between 25 and 75% of expired forced vital capacity (FEF25-75) and the forced expiratory flows when 75, 50 and 25% of forced vital capacity remain to be expired (FEF75, FEF50, FEF25), in order to determine reference values and lower limits of the normal. Regression functions were calculated for girls and boys separately. The best correlations for pulmonary volumes and flows were obtained by taking into account simultaneously height and age in girls, height, age and weight in boys. Power function is the model of regression that fits our data the best. The regression functions determined, as well as the lower limits of the normal and the residual standard deviations, are given by sex for each of the variables measured. These results are discussed and compared with those in literature. They concern clinicians (identification of "abnormal" subjects) and epidemiologists (prevalence of ventilatory troubles, comparison of different populations), and can be used in adolescents of the same age groups.

Adolescent↗
PubMed1995

Spirometric patterns in childhood asthma: peak flow compared with other indices.

The objective of this study was to determine patterns of pulmonary function abnormalities and to evaluate how adequately peak flow monitoring was correlated to other spirometric indices in childhood asthma. Ninety-one children, aged 8-15 years, with moderate-to-severe asthma were repeatedly tested in a summer camp. On-site medical staff permitted 24-hour-a-day supervision. Subjective and objective clinical evaluations of asthma status were made over 14 consecutive days. Detailed clinical history and clinical observations were made by an experienced staff, and a total of 2,663 pulmonary function tests were performed regularly three times daily and whenever a child sensed asthma symptoms. Patterns of obstruction were divided into large airway abnormalities and small airway abnormalities. There was a low concordance between standard large airway measures, such as the peak expiratory flow rate (PEFR) or the forced expiratory volume in 1 second (the FEV1), and measures of small airway obstruction, such as the forced expiratory flow rate 25-75% (FEF25-75). Normal PEFR measurements do not always indicate that all other pulmonary function measures are normal. In fact, 18% of children with a normal PEFR had abnormal FEF25-75 values. Results demonstrated that the FEF25-75 was the most specific and sensitive measure of airway obstruction. PEFR is widely used to monitor asthma symptoms objectively because it is technically simple to perform, relatively inexpensive, and helpful in most cases. It is, therefore, appropriate for asthma education programs to recommend PEFR as an objective measure to guide in making therapeutic decisions. Our data and clinical observations support the "Guidelines for the Diagnosis and Management of Asthma" of the NIH Health Asthma Education Program that suggest that children have more complete pulmonary function testing along with frequent PEFR measures. Many children may appear asymptomatic, while recording normal PEFR measures, and still having significant asthma. Repeated pulmonary function testing and evaluation of the pattern of respiratory obstruction aids in managing this challenging group. We recommend that efforts be made to develop a simple and inexpensive method of measuring FEF25-75 that will allow this measurement to be made even at home.

Adolescent↗
PubMed1996

Value of high-resolution computed tomography in routine evaluation of lung transplantation recipients during development of bronchiolitis obliterans syndrome.

BACKGROUND: Chronic rejection is a major long-term complication after lung transplantation. The purpose of our study was to evaluate the role of repeated high-resolution computed tomographic examinations in monitoring the development of bronchiolitis obliterans syndrome after lung transplantation. METHODS: A total of 126 high-resolution computed tomographic examination in 13 lung transplant recipients was analyzed. During a mean follow-up period of 23 months, bronchiolitis obliterans syndrome developed in eight of the patients. A scoring system from 0 to 10 based on the number of chronic changes on high-resolution computed tomography was developed, and the score of each patient was compared with decline in the forced expiratory volume in 1 second and maximal forced expiratory flow rate of 50% of the forced vital capacity. RESULTS: The score of chronic changes, measured at 1 year after transplantation, correlated inversely with the values of forced expiratory volume in 1 second and maximal forced expiratory flow rate at 50% of the forced vital capacity (p < 0.05). Stage I bronchiolitis obliterans syndrome was associated with scores of 4 to 6 (mean 5.0), stage 2 with scores of 6 to 9 (mean 7.0), and stage 3 with scores of 6 to 9 (mean 7.7). The sensitivity of high-resolution computed tomography was 93% and its specificity was 92% when five chronic changes were used as a cutoff level. CONCLUSIONS: The progress of chronic changes on high-resolution computed tomography occurs concurrently with the development of bronchiolitis obliterans syndrome. High-resolution computed tomography may provide additional morphologic information for noninvasive evaluation of chronic lung rejection.

Adult↗
PubMed1976

The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age.

From a randomly selected population representative of the white population of Tucson, Ariz., satisfactory flow-volume data were obtained for 3,115 persons. Data from the 746 subjects who were totally free of symptoms or history of cardiorespiratory disease and who had never smoked were used in determining "normal" prediction equations for spirometric parameters and maximal expiratory flows. The maximal expiratory flow-volume curve showed considerable intersubject variability, but little change in shape of the mean maximal expiratory flow-volume curve was seen with advancing age when the effects of disease, insult, or injury were excluded.

Adolescent↗
PubMed1985

Flow volume loops.

Explore the source record for details and available documents.

Forced Expiratory Flow Rates↗
PubMed2000

Environmental exposure to air pollution and allergens and peak flow changes.

Laboratory-based studies have shown that ozone and nitrogen dioxide can potentiate the effect of allergen in sensitized asthmatic subjects, but it is not known whether this interaction is important under natural exposure conditions. Thirty-five subjects with clinical diagnoses of asthma or chronic obstructive pulmonary disease and with a provocative dose causing a 20% fall in forced expiratory volume in one second methacholine <12.25 micromol (using the Yan method) kept peak expiratory flow (PEF) records for a 4-week period during late summer, with concurrent measurement of spore and pollen counts and pollution levels. Multiple regression analysis was then used to determine the effect on PEF of aeroallergen, and of the interaction between aeroallergen and pollutant levels. A statistically significant interaction was demonstrated between total spore count and ozone, but not nitrogen dioxide. Mean PEF fell in association with increasing spore count (same-day and 24-h lag level) and PEF variability increased with increasing spore count (24-h lag level only); both changes were greater the higher the prior ozone level. These results suggest that ozone can potentiate the effect of aeroallergens in subjects with bronchial hyperreactivity under natural exposure conditions. However, the effect was small, and the clinical significance of the interaction requires further study.

Adult↗
PubMed1992

Altered epithelial lining fluid parameters in old normal individuals.

Pneumonia is a leading cause of morbidity and death in older patients, and immunosenescence is believed to contribute to their susceptibility. In order to investigate whether age-related changes occur on the epithelial surfaces of the lung, bronchoscopy and bronchoalveolar lavage (BAL) were performed without complication in 19 young (27.7 +/- 4.2 yrs), 6 middle-aged (49.8 +/- 3.5 yrs), and 8 old (74.1 +/- 4.3 yrs) normal, nonsmoking subjects. BAL was performed by instilling and retrieving five 20 ml aliquots of normal saline into three sites. The returns from the first aliquots (the bronchial sample) were analyzed separately from the returns from the subsequent aliquots (the distal sample). Lavage fluid cellularity was characterized and IgA, IgG, and albumin were measured by ELISA. Lavage fluid returns were lower in the elderly group and correlated with spirometric parameters. Significantly elevated numbers of neutrophils were recovered by the bronchial sample fluid from the old group. In contrast, no consistent difference in macrophage recovery by either the bronchial or distal sample was noted. In both the bronchial and distal samples, IgG, but not IgA or albumin, was elevated in the group of old subjects. Alterations occurring in BAL fluid with aging may reflect changes in local host defenses.

Adult↗
PubMed1997

[Forced expiration. Various current concepts, 50 years after Robert Tiffeneau].

One hundred and fifty years after the original description of spirometry by Hutchinson and 50 years after the definition of his famous ratio by Tiffeneau, a certain number of physiological advances have enabled a better understanding of the determinants of the forced expired manoeuvre and to mitigate some of its inconveniences. This review focuses on three of these advances. The first is the influence of an inspiratory manoeuvre which precedes a forced expiration, on the expiratory flow. This influence is probably a consequence of viscoelastic phenomena and impose some strains on standardisation in current practice. The second is the possibility of detecting in a reproducible and simple fashion, without the need for co-operation on the part of the subject, a limitation in expiratory flow by the application of a negative expiratory pressure at the opening of the airways (NEP for negative expiratory pressure). The third is the possibility to verify in a simple fashion the quality of the expiratory performance achieved by the patient and thus to detect an insufficient effort in the force of a falling expiratory flow.

Dyspnea↗
PubMed1987

Effect of effort on measurement of forced expiratory volume in one second.

The American Thoracic Society recommends that the largest FEV1 be reported from a set of forced expiratory vital capacity maneuvers performed with maximal expiratory effort. However, increased expiratory effort can decrease the FEV1. When we evaluated the peak expiratory flow rate (PEFR) in 5 normal subjects, measured from flow-volume curves, as a noninvasive index of expiratory effort, it was positively correlated with indices of effort obtained by using an esophageal balloon. We then measured the difference (dFEV1)between the largest FEV1 and FEV1 from the maneuver with the highest PEFR during 10 test sessions in 10 normal subjects. Thus, dFEV1 was always greater than or equal to 0. The mean dFEV1 was 110 ml for all sessions but decreased to 80 ml when maneuvers with poorly reproducible PEFR or forced expiratory vital capacity values were discarded. We also reviewed 9.471 spirometry sessions from outpatients and found dFEV1 to be greater than 50 ml in 26% of this population and greater than 151 ml in 7%. We concluded that during standard spirometry, FEV1 is inversely dependent on effort. Maximal effort decreases FEV1 because of the effect of thoracic gas compression on lung volume. We recommend that values from spirometry maneuvers that demonstrate submaximal effort, indicated by a decreased PEFR, be discarded. The flow-volume curve display of superimposed efforts facilitates the recognition of submaximal efforts.

Biophysical Phenomena↗
PubMed1990

Tracking of lung function in healthy children and adolescents.

Two hundred twenty-six healthy school children, with a mean age of 8.8 years; 62 girls mean age 8.8, 48 boys mean age 12.6 and 51 girls mean age 12.6 years at the start, were enrolled in a longitudinal study of lung function and tested annually for 5 years. All were free of respiratory symptoms, and none smoked more than five cigarettes per week during the 5 years. Static and dynamic lung volumes (other than residual volume), maximum expiratory and inspiratory flows, and maximum mouth pressures "track," that is, individuals remain at a constant deviation from the sample mean over time. The data indicate that these measurements of lung function in healthy individuals grow in constant proportion relative to other healthy children and adolescents.

Adolescent↗
PubMed1993

Physiologic evaluation of pulmonary function in the candidate for lung resection.

From July 1, 1974, to December 31, 1990, 2340 patients who underwent pulmonary resection were evaluated by comprehensive analysis of pulmonary function. Pulmonary function test criteria for resection were (1) pneumonectomy: forced expiratory volume in 1 second greater than 2 L; forced expiratory flow rate from 25% to 75% greater than 1.6 L; maximum voluntary ventilation greater than 55%; (2) lobectomy: forced expiratory volume in 1 second greater than 1 L; forced expiratory flow rate from 25% to 75% greater than 0.6 L; maximum voluntary ventilation greater than 40%; (3) wedge or segmental resection: forced expiratory volume in 1 second greater than 0.6 L; forced expiratory flow rate from 25% to 75% greater than 0.6 L; maximum voluntary ventilation greater than 35%. Split perfusion lung scan and Reichel exercise stress testing were utilized as indicated. When these values of pulmonary function have been applied, a more precise method of selecting patients for various types of pulmonary resection has resulted in a lower mortality while denying operation to less than 1% of the patients who are considered for surgical resection.

Exercise Test↗
PubMed1996

Effects of lung volume and thoracic gas compression on maximal and partial flow-volume curves.

Comparing isovolume flows, measured at the mouth during forced expiratory manoeuvres as started from maximal or partial lung inflation, is a means of assessing the effects of deep inhalation on airway calibre. The aim of this study was to investigate whether the assessment of the effect of deep inhalation during induced bronchoconstriction is influenced by the lung volume at which it is determined and by volume differences due to thoracic gas compression that occur during forced expiratory manoeuvres. Four healthy subjects and six subjects with mild-to-moderate asthma subjects performed partial and maximal forced expiratory manoeuvres in a flow-type body plethysmograph at control and during a methacholine (MCh) inhalation challenge. Mouth flow (V1) was plotted against both the expired volume (Vmo) and the simultaneous thoracic volume measured by plethysmography (Vpl) changes (V1-Vmo loop and V1-Vpl loop, respectively). The effects of deep inhalation were quantified by determining 1) the ration of maximal to partial expiratory flows (M/P) at 30, 40 and 50% of control forced vital capacity (FVC) both on V1-Vmo loops (M/Pmo) and V1-Vpl loops (M/Ppl) at control and at MCh end-point; and 2) the slope of the linear regression of maximal vs partial expiratory flows at 30, 40 and 50% of control FVC both on V1-Vmo loops (MPst,mo) and V1-Vpl loops (MPsl,pl) over the entire challenge. At control, M/Pmo and M/Ppl were similar. At MCh end-point, M/Pmo and M/Ppl increased more than twofold (p < 0.002), with M/Pmo consistently exceeding M/Ppl (p < 0.001). In addition, both M/Pmo and M/Ppl varied inversely with lung volume (p < 0.001). By contrast, MPsl,mo and MPsl,pl were not significantly different from each other (p = 0.8), and were also similar at the different lung volumes (p = 0.6). We conclude that during induced bronchoconstriction, the bronchodilation following a deep inhalation, expressed as maximal to partial flow ratio is dependent both on lung volume and volume differences due to thoracic gas compression. The use of expired flow and volume measurements may lead to a small but systematic overestimation of the bronchodilator effect of a deep inhalation. On the contrary, maximal to partial flow slope is insensitive either to lung volume or volume differences due to thoracic gas compression and can, therefore, be fairly determined from expired flow-volume loops.

Adult↗
PubMed1995

Gender differences in lung growth.

Annual measurements of lung volumes and forced expiratory flows were made in 281 boys and girls from 8 to 12 years and in another cohort of 287 from 12 to 20 years to measure longitudinal lung growth. Gender differences in growth of lung function were documented, with girls generating greater volume-standardized maximal expiratory flows until age 18.5 years. Beyond that age boys generated higher expiratory flows in proportion to total lung capacity (TLC). There was a time lag of up to 1 year between the age of peak growth velocity in lung volume and peak growth velocity in height. Age at peak growth in flow lagged another year behind that in volume. This was noted more in boys than girls. Dysanaptic lung growth was found with differing rates of growth of maximal expiratory flow compared with TLC or vital capacity (VC).

Adolescent↗
PubMed1996

Pulmonary function after laparoscopic cholecystectomy in the elderly.

The results of laparoscopic cholecystectomy in a group of 52 patients older than 69 years (group 1) were compared with the results of the same operation in a group of 338 younger patients (group 2). In group 1, 23 per cent of patients had acute cholecystitis and 13 per cent were operated on after an episode of acute pancreatitis. In group 2, 8 per cent of patients had acute cholecystitis and 4 per cent were operated on after acute pancreatitis. Pulmonary function was assessed prospectively before operation, 24 h after surgery and on the seventh day after operation, in 20 patients in group 1 and 30 in group 2. In group 1 there was one death (2 per cent); the morbidity rate was 14 per cent and conversion to laparotomy was required in 15 per cent. In group 2 there were no deaths, the morbidity rate was 11 per cent and the conversion rate 4 per cent. No significant differences were found between the two groups in mortality and morbidity rates. Preoperative values of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were significantly lower in group 1 than in group 2 (P < 0.05); the values of FVC, FEV1 and forced expiratory flow at 50 per cent 24 h after surgery were less depressed in group 1 (P < 0.01) and also recovered more quickly in these patients 7 days after operation. Laparoscopic cholecystectomy gives excellent results in geriatric patients and can be recommended as the treatment of choice for symptomatic cholelithiasis in the elderly.

Aged↗