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At least 649 records · Page 36Linked to original sources
PubMed1980

A general purpose microprocessor for spirometry.

A portable, inexpensive microprocessor is described for on-line spirographic analysis of FVC and its time derivatives and MVV, using a primary flow or volume signal. Resolution is +/- 0.02 L and maximal collection time 66 seconds. Algorithms according to the Snowbird Conference recommendations include back extrapolation, "end of test" determination and the selection criteria for satisfactory tests, and best FVC, FEV1 and other flow rates. Differentiation is digital and flow-volume outputs are available. Actual, predicted and percent predicted values for children or adults are displayed, or can be printed together with an interpretation and a flow-volume loop. Four hundred tests with a Stead-Wells spirometer, a pneumotachograph and a turbinometer using an explosive decompression FVC simulator showed standard deviations of +/- 0.04 L or L/sec or less, except for peak flow. Differences between microprocessor values and tracing analyses were less than 0.04 L. MVV with a reciprocating pump equalled exactly the MVV calculated from stroke volume and frequency (r = .999) from 8 to 325 L/min. Tests of 168 patients were comparable to the calibration devices.

Computers↗
PubMed1983

Spirometry: what paper speed?

Controversy still exists regarding the paper speed necessary for accurate measurements from records of maneuvers for forced vital capacity. Twenty-four spirometric wave forms of known characteristics were plotted by a computer at 1, 2, and 3 cm/sec and were measured in random order by 12 experienced readers. We found that all readers made a surprisingly large number of major errors. The speed of the paper was found to be an important determinant for accurately measuring the forced expiratory volume in one second and the mean forced expiratory flow during the middle half of the forced vital capacity. A minimum paper speed of at least 3 cm/sec is important if spirograms are to be accurately measured by hand. Human errors in measurement may be minimized by obtaining results from at least three acceptable curves, by making duplicate reading of curves, and by making use of validated computerized measurement systems.

Forced Expiratory Volume↗
PubMed1988

Spirometry and chest wall dimensions in achondroplasia.

Standard values for pulmonary function in short-limbed dwarfism are not available. Therefore, chest diameters and expiratory spirograms were measured in 58 female and 44 male subjects between 7 and 60 years of age with achondroplasia, the most common form of dwarfism. Standing height in adults was 49.6 +/- 3.2 (SD) inches with a sitting/standing height ratio of 0.66 (normal 0.52-0.53). Despite extremely short stature, only AP chest diameters in males were smaller than control subjects of similar age. The following equations were derived for forced vital capacity (FVC): males (under 25 years), FVC(L) = -3.56 + 0.162 X sitting height (in) + 0.067 X age (yrs); males (over 25 years), FVC(L) = -0.73 + 0.162 X sitting height (in) -0.047 X age (yrs); females (under 20 years), FVC(L) = -3.56 + 0.150 X sitting height (in) + 0.067 X age (yrs); females (over 20 years), FVC(L) = -1.92 + 0.150 X sitting height (in) -0.016 X age (years). Similar prediction equations were derived for FEV1 and FEF25-75%: FEV1/FVC % was 84.2 (+/- 6.5) for females and 88.0 (+/- 6.5) for males. We also compared the observed FVC measurements to values calculated using standing heights derived from the subject's sitting height, assuming a normal body proportion. The observed vital capacity in achondroplasia was only 67.6 (+/- 19.2) percent of that predicted for normally proportioned females and 72.4 (+/- 13.6) percent for males, suggesting reduced vital capacity in achondroplasia, due to reduced chest wall compliance or abnormal lung growth.

Achondroplasia↗
PubMed1988

Spirometry and maximal expiratory flow-volume curve reference standards for Polynesian, European, and Chinese teenagers.

Lung function was compared and reference standards were determined in 1,007 Polynesian, European, and Chinese teenagers attending school in Tahiti (517 boys, 490 girls; mean age, 14.4 years). Spirometric study results and maximal expiratory flow-volume curves were measured using techniques recommended by the American Thoracic Society. Age, standing height, and weight were chosen as the independent variables for males, and age and standing height for females. Regression equations constructed with logarithmically transformed dependent variables provided accurate predictions. We observed significant racial differences: in the Europeans, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were higher than the mean values predicted for the whole study population, while forced expiratory flow during the middle half of the FVC (FEF25-75%) and maximal expiratory flows after 25, 50, and 75 percent of FVC had been exhaled (V max 25, 50, and 75, respectively) were about equal to the mean values; in the Polynesians, volumes and flows were mostly lower than the mean; in the Chinese, FVC in boys and girls, and FEV1 in girls only, were lower, while the other flows were higher. The FEV1/FVC, FEF25-75%/FVC, Vmax25/FVC, Vmax50/FVC, and Vmax75/FVC were significantly higher than the mean in the Chinese boys and girls and often lower in the Europeans.

Adolescent↗
PubMed1989

Differences in plethysmographic lung volumes. Effects of linked vs unlinked spirometry.

Determination of absolute lung volumes in patients is most reliable when measured with body plethysmography. Many laboratories use data obtained with a spirometer not directly linked to the plethysmograph to calculate total lung capacity (TLC) and residual volume (RV) from thoracic gas volume (Vtg) measured at functional residual capacity (FRC) in the plethysmograph. The reliability of these calculations depends on the stability of FRC between these separate devices. We examined the differences in TLC and RV values calculated with linked and unlinked spirometers in 220 patients and found them statistically significant (p less than 0.05). Additionally, differences exceeding the 95 percent confidence intervals for repeated, linked determinations occurred in more than 5 percent of patients. The large-volume differences in TLC were often associated with differences in expiratory reserve volume (ERV) in the opposite direction, suggesting a shift in FRC. However, clinical diagnoses were infrequently (4/220) altered by these differences, and recognition of the shift in FRC should further reduce this error. Therefore, the unlinked method appears acceptable.

Adolescent↗
PubMed1990

Long-term reproducibility of tests of small airways function. Comparisons with spirometry.

We used a tracking index to measure the reproducibility of single breath nitrogen test variables (CV/VC, CC/TLC, delta N2/L) and spirometric variables (FEV1 and FEV1/FVC) and to compare the characteristics of individuals whose pulmonary function tracks well with those whose pulmonary function tracks poorly. Data were derived from two cohorts followed longitudinally over a 9-11 year period. All variables were adjusted for age, sex and height by expressing them as Z-scores. In all smoking groups and in both cohorts, the tracking index was highest for FEV1, indicating that this variable was the most reproducible over the period of follow-up; delta N2/L and FEV1/FVC had very similar but slightly lower tracking indices; CV/VC consistently had the lowest tracking indices. Tracking indices were generally higher in smokers than in nonsmokers. The reproducibility of CC/TLC increased over the period of follow-up whereas the FEV1 reproducibility remained constant. We found no significant difference between those with high tracking indices and those with low indices in terms of sex, smoking status, prevalence of respiratory symptoms, history of respiratory disease, and rate of decline of FEV1. We conclude that FEV1 is the most reproducible of the variables examined, both within and between individuals, and that poor tracking or reproducibility are not related to smoking or to the presence of respiratory symptoms or disease.

Adult↗
PubMedDate not supplied

[Basic spirometry measurements in workers on pig farmers].

INTRODUCTION: Many epidemiological and clinical studies have demonstrated an increased risk for the symptoms of respiratory disorders consistent with chronic bronchitis and asthma and alterations of pulmonary function tests in pig farmers. AIM: The aim of this study was to determine basic pulmonary function values in workers in swine confinement buildings and to compare them with the same values in the control group of unexposed persons. The next aim was to examine the association between these values with duration of professional exposure, cigarette smoking, age, and sex of the examined persons. METHODS: We randomly selected for examination 145 workers of both sex who had worked for at least 2 previous years in pig farms and spent at least 3 hours per day, 6 days per week in a swine confinement building. The farmers worked at 6 different farms with 12,383 pigs on average on each farms. The subject was eligible for the study if he had had no history of atopic disease nor any serious chronic disease, and no acute respiratory infection within 3 previous months. As control group we examined 156 subjects who had lived and/or worked in the same areas and had had no history of exposure to farming environment or any other known occupational air pollutants. In both groups the study comprised cigarette smokers and persons who had never smoked. Pulmonary function data were collected according to the standard protocol with a Micro Spirometer, (Micro Medical Ltd, England, UK). The registered parameters were FEV1 and FVC. At least three satisfactory forced maximal expirations were performed by each subject and the best value was accepted for analyses. The results were also expressed as a percentage of predicted values and FEV1/FVC x 100 was calculated. RESULTS: There were no differences in the main demographic characteristics between two examined groups (Table 1). Mean duration of work in pig farming was 11.6 years (SD=8.5; range 2-40). The average values of examined pulmonary function tests are shown in table 2. The values of FEV1 and FVC in each groups were between 92% and 97% of predicted values, and FEV1/FVC x 100 was not lower than 82%. There were no differences in the average values of FEV1 (p=0.574) and FEV1 % predicted (p=0.653) between pig farmers and control subjects. Pearson coefficient of correlation and Spearman nonparametric correlation test revealed a high level of correlation of FEV1 values with sex and age and no correlation of pig farming exposure with cigarette smoking as predictor variables (Table 3). The analysis by linear regression method showed that all examined predictor variables had the effect on the value of FEV1 (Table 4). After the elimination of the two least significant predictor variables it was possible to make the equation for prediction of FEV1 values. DISCUSSION: In the present study there are no significant alterations in the values of the basic pulmonary function tests in pig farmers. In the majority of previous similar studies the differences in the average values of FEV1 and FVC between pig farmers and control subjects were also not found. However, in some studies the alterations in several more specific lung function parameters were registered. The decreased values of FEV1 during workshift were also found and they are probably connected to the bronchial hyperreactivity registered in many studies in pig farmers. Longer exposure to swine confinement environment caused more decline in FEV1 and FVC and accelerated mean age-related annual decline in FEV1 was observed reaching to 44 ml/yrs more than expected. The correlations between values of FEV1 with pig farming exposure and cigarette smoking in this study were not found. However, the analysis by linear regression method showed that all examined predictor variables had the effect on the value of FEV1. In a few previous bronchoscopic, BAL and sputum studies some signs of inflammation and morphological changes of the respiratory tract were observed. The absence of important alterations in the basic spirometric measures in this and the majority of the previous studies suggests that early airway injuries may not be readily apparent using spirometric measures of lung function. CONCLUSION: In contrast to other world studies, our study comprised an important number of women farmers, but alterations associated to sex were not found. To assess the lung function in these pig farmers after several years may be of great importance.

Adolescent↗