The assessment and interpretation of spirometry during the transition from childhood to adulthood.
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Adolescent↗
Biomedical subjects
D L Sherrill
Publications and source records attributed to D L Sherrill.
Continuous oscillation: outcome in critically ill patients.
PURPOSE: To compare turning by an oscillating bed to standard 2-hour turning. Outcomes were survival, length of stay (LOS), duration of mechanical ventilation, and incidence of pneumonia. METHODS: One hundred and three intensive care patients were randomly assigned to standard turning or turning by an oscillating bed. Data, collected at baseline, daily for 7 days, and then three times weekly until study discharge, included demographics, initial Acute Physiology and Chronic Health Evaluation (APACHE II) score, ventilatory/gas exchange parameters, indicators of pneumonia, nursing measures, and chest roentgenograph. RESULTS: There were no significant differences for LOS, duration of ventilation, nor incidence of pneumonia. Higher survival for subjects on the oscillating bed reached borderline significance (P = .056) for subjects with APACHE II greater than or equal to 20. Longitudinal data were analyzed using the random effects model. No differences in ventilatory or gas exchange parameters were identified. Among subjects who developed pneumonia there was a significantly higher respiratory score (nursing acuity scale) for subjects on the oscillating bed. CONCLUSIONS: In selected critically ill patients oscillating therapy may improve survival and improve airway clearance. The frequency and degree of turning needed to prevent complications and improve outcome remains unclear. These newer beds should be used with discrimination so as to not increase hospital costs unnecessarily.
APACHE↗
Longitudinal evaluation of the association between pulmonary function and total serum IgE.
The role of immunoglobulin E (IgE) in the development and course of impaired ventilatory function and chronic obstructive pulmonary disease (COPD) required further study. This role has been examined in the longitudinal Tucson Epidemiological Study of Airways Obstructive Disease, which started in 1972. The association between IgE and longitudinal changes in pulmonary function measures was examined in subjects in the community population sample in Tucson who had an initial age of 35 or more. There were a total of 1,533 such subjects with lung function tests over the 20 yr period who also had IgE determinations. A significant inverse association was found between total serum IgE and FEV1/FVC that was independent of smoking and asthma status. The finding was statistically separate from the relation with age in all but elderly current smokers (age > 55). The magnitude of this effect in nonasthmatic subjects was relatively small. For asthmatic subjects, however, the inverse association was larger in both current and never smokers. Subjects excluded from the current analysis either did not have an IgE measurement and/or had no pulmonary function values after 35 yr of age. These findings suggest that higher IgE levels may indicate the presence of a disease process that may involve inflammation and/or other mechanisms related to IgE production, which impair lung function over time. However, in this study we were not able to account for possible parental or inheritance contributions to increases in total IgE, which have been shown to be important.
Adult↗
Ambulatory monitoring of peak expiratory flow. Reproducibility and quality control.
Eighty-five children and 230 adults from a population study performed ambulatory peak flow readings three times a day for 1 to 2 weeks following a home visit. Three peak expiratory flow (PEF) readings were reported for each of 5,809 test sessions. Within each test session, the third maneuver most frequently (40% of the time) gave the highest PEF reading. This did not vary throughout the day. In subgroups of children and women with a history of asthma or asthma symptoms (hereinafter referred to as "asthma"), the first maneuver during the evening test sessions more frequently gave the highest readings. However, maneuver-induced bronchospasm occurred during less than 5% of the test sessions in both subjects with asthma and in other subjects. The within test session PEF reproducibility was good: overall, the highest and second highest reading matched within one division (10 L/min) 73% of the time and within 30 L/min (9% of the reading) 95% of the time. The best reproducibility was noted after the first two days of testing, during evening and bedtime test sessions (vs morning), and in girls and men. In the group with at least 2 weeks of testing, the coefficient of repeatability (CR) for the week-to-week PEF lability index was 10% for healthy adults and 17% for healthy children. As expected, repeatability was not as good for adults with asthma (CR = 17%) and children with asthma (CR = 28%).
Adult↗
Spirometry and maximal respiratory pressure references from healthy Minnesota 65- to 85-year-old women and men.
OBJECTIVE: To obtain spirometry and maximal respiratory pressure (MRP) reference values for elderly persons. DESIGN: Survey. SETTING: General community. PARTICIPANTS: Four hundred seventy-one healthy ambulatory white women and men age 65+ years. METHODS: A stringent spirometry quality assurance program exceeded American Thoracic Society recommendations. A "healthy" subgroup of 176 women and 112 men between the ages of 65- and 85 years were identified by excluding those with conditions that negatively influenced FEV1 in a multiple regression analysis. Reference equations and normal ranges for FEV1, FVC, FEF25-75%, peak flow, and maximal inspiratory and expiratory pressures (MRPs) were determined from the healthy group with good quality maneuvers. RESULTS: Less than 10% of the subjects were unable to perform three acceptable spirometry maneuvers and ten MRP maneuvers. When the age and height corrected FEV1s from this group were compared with other spirometry reference studies, mean values from the women were nearly identical to those from Morris, while these men had substantially lower FEV1 values (by 0.3- to 0.5L) than elderly men in Crapo's study. Mean peak flow was over 20% higher when compared with previous studies, suggesting greater initial expiratory effort by our subjects. The maximal inspiratory pressure (MIP) values were about 20% higher than those reported by the Cardiovascular Health Study, perhaps because five MIP maneuvers were always performed. CONCLUSION: Spirometry and MRP reference values used for elderly patients should come from population studies using similar techniques and with large numbers of subjects over age 65 years.
Age Distribution↗
Air pollution and upper respiratory symptoms in children from East Germany.
Whereas evidence of adverse effects of air pollution on lower respiratory tract illnesses in children is increasing, little is known about the effects of high and moderate levels of air pollution on the incidence of upper respiratory illnesses. 9 to 11 year old schoolchildren (n = 1,854) living in Leipzig, East Germany were studied. The presence of upper respiratory symptoms was documented by a physician. Daily mean and maximum concentrations of SO2, particulate matter (PM) and NOx, as well as temperature and humidity, were measured. Furthermore, a self-administered questionnaire was distributed to the parents to assess confounding factors. Parents of 1,500 (81%) children returned the questionnaire. When controlling for paternal education, passive smoke exposure, number of siblings, temperature and humidity, increased risks for the development of upper respiratory symptoms were found in the winter months for SO2 mean concentrations (odds ratio (OR) = 1.72; 95% confidence interval (95% CI) 1.19-2.49). NOx mean concentrations (OR = 1.53; 95% CI 1.01-2.31) and PM maximum values (OR = 1.62; 95% CI 1.08-2.45). In the summer months, only NOx mean concentrations were associated with a significantly increased risk (OR = 1.82; 95% CI 1.21-2.73). A combination of high mean levels of different pollutants resulted in the highest risk (OR = 2.10; 95% CI 1.30-3.37 in the winter, and OR = 2.16; 95% CI 1.23-3.81 in the summer). We conclude that high concentrations of SO2, and moderate levels of particulate matters and NOx are associated with an increased risk of developing upper respiratory symptoms in childhood.(ABSTRACT TRUNCATED AT 250 WORDS)
Air Pollutants↗
Lung function development in young adults: is there a plateau phase?
Numerous population studies have reported that pulmonary function following the adolescent growth phase appears to be in a steady-state, where there is little or no growth occurring up to 40 yrs of age. We examined longitudinal forced expiratory volume in one second (FEV1), changes using three different statistical approaches to determine which subjects actually have significant trends during this period. Participants, who were employees at a metal processing plant, underwent quarterly spirometry for up to 10 yrs. Test results up to 33 yrs of age were included in the analysis. Each subject's FEV1 data was first analysed using simple linear regression (SLR) to test for a statistically significant linear slope. Next, each subject's data were fitted using bootstrap sampling (BSS) of their original data, to yield reduced estimates of the slope variances and increase the power of detecting a significant trend. And thirdly, we fitted a regression breakpoint (BKPT) model to the data to find those subjects who may have piecewise linear growth or decline in function. All analyses were stratified, based on smoking status. Subjects included 111 nonsmokers and 110 smokers. Among the nonsmokers, 34 subjects had significant slopes using SLR, an additional three using BSS, and only two with BKPT. Among the smokers, 36 had a significant trend using SLR, 7 were added using BSS, and no additional subjects with BKPT. We conclude that in young adult males lung function is not in a steady-state and that as many as 40% have a significant slope, either positive or negative.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Relationships between total serum IgE, atopy, and smoking: a twenty-year follow-up analysis.
BACKGROUND: A number of cross-sectional studies have demonstrated that higher levels of IgE are found in subjects who currently smoke cigarettes and/or who are atopic and that IgE levels decline with age. OBJECTIVE: This report examines the interactions among atopic status, smoking, and IgE with longitudinal data and methods. METHODS: Subjects were participants in the Tucson Epidemiological Study of Airways Obstructive Disease and were 6 years of age and older. Total serum IgE measures and allergen skin test results were obtained during three surveys spanning a period of up to 20 years. RESULTS: The results showed no significant gender differences between nonatopic nonsmoking subjects, who were considered the reference group. Nonatopic current smokers had IgE levels similar to those of the reference subjects initially, but IgE levels did not decline with age at the same rate as in the reference subjects, causing significant differences at older ages. There was a significant relationship between number of cigarettes smoked and IgE level. CONCLUSIONS: Atopy and smoking are both associated with elevated total serum IgE levels. Although the exact mechanism for elevated IgE levels in smokers is not known, the significant dose relationship is suggestive of a causal association.
Age Factors↗
Longitudinal analysis of the effects of smoking onset and cessation on pulmonary function.
We examined the effects of smoking onset and cessation on FEV1 in participants in the Tucson Epidemiological Study of Airways Obstructive Disease 18 yr of age or older who reported a change in smoking habits during 17 yr of follow-up. Subjects were classified as "new quitters" (n = 288) and "new starters" (n = 45) at each survey on the basis of questionnaire responses concerning current smoking habits. The pulmonary function data were analyzed using a mixed longitudinal or random effects model (REM). We compared FEV1 before and after changing smoking habits in the same subjects while adjusting for important covariables such as height, pack-years, and respiratory symptoms and diseases. The results for smoking cessation showed a beneficial effect related to quitting that was largest for younger subjects and decreased linearly with age. For women, quitting resulted in an improvement in FEV1 of 4.3% at 20 yr of age which decreased to 2.5% by 80 yr of age. Men had an improvement of only 1.2% at 20 yr of age and no improvement at 80 yr of age. After excluding subjects with low initial function (FEV1/FVC in the lowest quartile) and those with only a single observation after quitting, men (n = 70) showed a significantly higher FEV1 improvement of 4% at 20 yr of age that decreased linearly to zero by age 80 yr. In contrast, women in this subgroup (n = 89) had nearly the same degree of improvement at all ages. The onset results showed mean FEV1 values after starting smoking that were higher at the younger ages (< 23 yr) and that decreased more rapidly with age, compared with nonsmoking mean estimates, in both sexes.
Adult↗
Longitudinal effects of passive smoking on pulmonary function in New Zealand children.
In this study we examined the longitudinal effects of smoke exposure on lung function in a cohort of New Zealand children observed from 9 to 15 yr of age. Possible exposures included in utero exposure from mothers smoking during pregnancy, passive smoke from parents, and active smoking by the children. Lung function measures of forced expiratory volume in one second (FEV1) and vital capacity (VC) were measured biennially and ratios (FEV1/VC) were computed. The data were analyzed using longitudinal methodology, and all subjects with at least one pulmonary function test and responses to the questions concerning smoke exposures were included (n = 634). Subjects reporting wheeze or asthma were examined as a separate subgroup. In the whole cohort, no significant detrimental effects were detected for absolute FEV1 or VC in either sex, related to active or passive smoke exposures. Parental smoking was, however, associated with persistent but mild and nonprogressive impairment of the FEV1/VC ratio in males, an effect that was present at the time lung function measurements were first made. This effect was not seen in females. In children with reported wheeze or asthma, parental smoking had progressive, more serious, and clinically significant effects on the FEV1/VC ratio among adolescents of both sexes, causing a mean reduction in FEV1/VC ratios by age 15 of 3.9% in males and 2.3% in females, in contrast to the observed increase in FEV1/VC ratios with age seen in nonexposed wheezing children. We conclude that passive smoking is a major contributing factor to the development and persistence of airflow limitation in wheezing children.
Adolescent↗
Continuous longitudinal regression equations for pulmonary function measures.
The data from a longitudinal population study in Tucson, Arizona, were used to describe the development and decline of maximal expiratory flow-volume (MEFV) measures with age. On the basis of their answers to self-administered questionnaires, in 9 of the first 10 surveys (1972-1988) and having performed at least one MEFV test, 930 nonsmoking healthy subjects were selected, providing 3,848 individual observations. The data were analysed using statistical methods that yield continuous piecewise linear regression equations and allow subjects to have repeated measures which are unequally spaced and at different times for different subjects. In addition, the age intervals for the piecewise linear line segments are estimated for each of the MEFV indices, as part of the modelling procedure. The resulting predicted values are compared between sexes and to previously published cross-sectional results from the same population. All MEFV measures in healthy subjects have an early increase in the rate of development corresponding to the onset of the adolescent growth spurt. This rapid growth period is followed by a plateau phase which lasts around 10 yrs for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in males, in which growth continues, but at a much lower rate. The plateau phase, is followed by a constant rate of decline which lasts throughout adulthood. In contrast, flow measures did not have a detectable plateau period, but did have points of increased rates of decline much later in life.
Adult↗
Methodology for generating continuous prediction equations for pulmonary function measures.
A mathematical procedure is described for fitting piecewise linear equations constrained to join at estimable multiple junctions or breakpoints. The model parameters, a combination of both linear and nonlinear, are estimated using a "Separable Least Squares" algorithm. In this algorithm the linear parameters, estimated using the General Linear Model, are nested within the iterations of a nonlinear optimization routine. This formulation allows additional covariates to be included in the model and can be easily expanded to include any number of line segments, both linear and nonlinear. The procedure is demonstrated by estimating continuous lung function reference equations for healthy normal subjects. Comparison of these reference equations with previously published equations derived for the same subjects, illustrates the advantages of having continuous equations throughout the age range of the data.
Adolescent↗
Respiratory effects of non-tobacco cigarettes: a longitudinal study in general population.
Data from four consecutive surveys of Tucson longitudinal study of airways obstructive disease were used to examine the relation of respiratory symptoms and pulmonary function to non-tobacco cigarette smoking. The surveys were conducted over a six-year period and provided data on 1802 subjects 15-60 years of age, with a total of 5659 individual questionnaires. Estimated odds ratio (OR) of current non-tobacco smoking for chronic cough was 1.73, for chronic phlegm: 1.53, and for wheeze: 2.01 (p less than 0.05). These estimates were adjusted for age, tobacco smoking and occurrence of the symptom in preceding survey. The increased risk of the symptoms was related to the habit continued for several years, and there was no immediate remission of the symptoms after quitting smoking. A significant (p less than 0.05) reduction in pulmonary function (FEV1, Vmax50 and their ratios with FVC) was found a year or more after current non-tobacco smoking was reported. Although the average consumption of non-tobacco cigarettes, believed to be marijuana smoking, was less than one per day, significant effects were still detectable in both pulmonary function and respiratory symptoms.
Adolescent↗
Relationship of respiratory symptoms and pulmonary function to tar, nicotine, and carbon monoxide yield of cigarettes.
The data from consecutive surveys of the Tucson Epidemiologic Study (1981-1988) were used to evaluate the relationship in cigarette smokers of respiratory symptoms and pulmonary function to tar, nicotine, and carbon monoxide (CO) yields of the cigarette. There were 690 subjects who reported smoking regularly in at least one survey, over age 15. After adjustment for intensity and duration of smoking and for depth of inhalation, the risk of chronic phlegm, cough, and dyspnea were not related to the tar and nicotine yields. In 414 subjects with pulmonary function tested in at least one of the three surveys the spirometric indices used were significantly related to the daily dose of tar, nicotine, and CO (product of the cigarette yield and daily number of cigarettes smoked). The effects were more pronounced for past than for current doses. However, the differentiation of pulmonary function due to various yields of cigarettes was small in comparison to the difference in pulmonary function between smokers and nonsmokers.
Age Factors↗
Smoking and symptom effects on the curves of lung function growth and decline.
Numerous studies have examined the natural time course of human lung function growth and decline throughout life. In most of these studies the investigators used statistical models that required a priori assumptions concerning the underlying form or structure of the lung function data, thus introducing possible biases. In this study we used recently developed nonparametric regression (spline) techniques to describe the evolution of lung function measures with age. This procedure yields an optimally fitted smooth curve through the data and estimates of the process velocity and does not require assumptions concerning the underlying shape of the data curves. The lung function growth-velocity curves are used to estimate the age of growth cessation. This technique was applied to the FVC, FEV1, and the FEV1/FVC ratios of 1,295 females and 1,230 males who were tested in at least one of the first nine surveys of the Tucson epidemiologic study of airway obstructive diseases. Data were analyzed stratified according to gender, smoking status, and respiratory symptoms or diseases. The results indicate large differences between the fitted FEV1 and FEV1/FVC smoothed curves of the various subgroups compared with asymptomatic nonsmokers. These differences were most pronounced in the adult symptomatic smokers, who had higher rates of lung function loss that also began at earlier ages, for both sexes. No significant differences were observed between asymptomatic and symptomatic nonsmokers, most likely because of the reduced number of symptomatic nonsmokers, particularly among the males.
Body Height↗
Longitudinal analysis of the effects of acute lower respiratory illnesses on pulmonary function in an adult population.
The data from a longitudinal population study in Tucson, Arizona, were used to evaluate the effects of acute lower respiratory illnesses on pulmonary function in subjects over 25 years of age. In five of nine surveys performed during the first 13 years of follow-up (1972-1985), similar questions were asked concerning chest colds occurring in the past few years. There were 1,151 men and 1,473 women who had questionnaire and spirometric data collected in at least one of these surveys. The random effects longitudinal model with first-order autoregressive error structure was used in the analysis of changes in pulmonary function after the acute illness episode, adjusted for the effects of age, height, cigarette smoking, and chronic respiratory diseases. The analyses indicated that pulmonary function is reduced for several years after a single chest cold in men and after multiple chest colds in women. After an episode of pneumonia, pulmonary flow indices were reduced, with lower values sometimes persisting for several years.
Adult↗
Changes in lung mechanics and reactivity with age after viral bronchiolitis in beagle puppies.
We measured changes with growth in lung function and airway reactivity after acute canine parainfluenza virus type 2 (CPI2, n = 5), canine adenovirus type 2 (CAV2, n = 7), and sequential CAV2-CPI2 (n = 6) infections or no infection (controls, n = 6) in beagle puppies (age approximately 79 days). In the CPI2 and CAV2 groups, a lower respiratory illness developed by day 3 postinfection with clinical recovery by day 14. In the CAV2-CPI2 group, puppies were inoculated initially with CAV2 and 12 days later with CPI2. In this group, illness persisted until day 14 after infection with CPI2. Lung resistance (RL), dynamic (Cdyn) and static (Cst) lung compliance, functional residual capacity (FRC), and responsiveness to aerosolized histamine were measured before infection and at periodic intervals until 239 +/- 43 days of age. Lung function data were analyzed using a longitudinal random effects model. In all groups, FRC, Cst, and Cdyn increased with age. In all infected groups, the regression slopes for Cdyn were steeper than in controls. RL decreased linearly with age without group slope differences. Histamine reactivity increased with age, but there were no differences in slope among groups. Lung pathological studies showed areas of obliterative bronchiolitis and chronic small airways inflammation particularly in the CAV2 and CAV2-CPI2 groups. Thus, viral bronchiolitis produces chronic small airways inflammation in beagle puppies and alters the changes in lung function occurring with growth. Histamine reactivity increases with age and is not modified by viral infection.
Adenoviridae Infections↗
Using smoothing splines for detecting ventilatory thresholds.
A recently developed nonparametric regression technique, called a polynomial smoothing spline, is presented for detecting the ventilatory threshold (VT) and respiratory compensation (RC) points from gas exchange response data taken during an incremental exercise test. This type of curve fitting has the advantage of not requiring investigators to specify, a priori, the form of the underlying model, as is required with all linear regression techniques. This procedure yields a mathematically optimal fitted curve through the O2 uptake (VO2) vs CO2 output (VCO2) data and estimates of the process' first and second derivatives. A breakpoint or threshold is indicated by an increase in the value of the derivative and a peak in the second derivative. To evaluate this approach we analyzed gas exchange data collected on nine healthy subjects during a ramp exercise test (15 W.min-1) to the limits of tolerance. Utilizing this procedure we detected VT and RC breakpoints in four subjects and only VT breakpoints in the remaining five subjects. Our results and those obtained using the more conventional linear regression method were similar for those subjects whose RC points were detected using the smoothing spline procedure. However, using regression techniques for subjects with low or otherwise undetectable RC breakpoints, the linear regression method yielded less reliable results in our hands.
Anaerobic Threshold↗