Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Total Lung Capacity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1992

Predictive equations for total lung capacity and residual volume calculated from radiographs in a random sample of the Michigan population.

BACKGROUND: Published predicted values for total lung capacity and residual volume are often based on a small number of subjects and derive from different populations from predicted spirometric values. Equations from the only two large studies gave smaller predicted values for total lung capacity than the smaller studies. A large number of subjects have been studied from a population which has already provided predicted values for spirometry and transfer factor for carbon monoxide. METHODS: Total lung capacity was measured from standard posteroanterior and lateral chest radiographs and forced vital capacity by spirometry in a population sample of 771 subjects. Prediction equations were developed for total lung capacity (TLC), residual volume (RV) and RV/TLC in two groups--normal and total. Subjects with signs or symptoms of cardiopulmonary disease were combined with the normal subjects and equations for all subjects were also modelled. RESULTS: Prediction equations for TLC and RV in non-smoking normal men and women were square root transformations which included height and weight but not age. They included a coefficient for duration of smoking in current smokers. The predictive equation for RV/TLC included weight, age, age and duration of smoking for current smokers and ex-smokers of both sexes. For the total population the equations took the same form but the height coefficients and constants were slightly different. CONCLUSION: These population based prediction equations for TLC, RV and RV/TLC provide reference standards in a population that has provided reference standards for spirometry and single breath transfer factor for carbon monoxide.

Adult↗
PubMedDate not supplied

Reevaluation of the radiographic method for measurement of total lung capacity.

To clarify whether the radiographic estimate of total lung capacity (TLC) using the method of Barnhard et al., as modified by Loyd et al., yields accurate values, we measured TLC in 20 young healthy subjects with the above technique (Vb). We compared it to the more sophisticated radiologic method of Pierce et al. (Vp) and to plethysmographic measurements (Vbox). Plethysmographic results, 7.38 +/- 0.94 l (mean +/- SD) or 101.7% of predicted, were significantly higher than Vb (mean difference 0.53 +/- 0.68 l; p less than 0.005 by paired t test), but were not significantly different from Vp (mean difference 0.13 +/- 0.52 l). Based on these and previous data, we conclude that the Pierce et al. approach yields more accurate results than the Barnhard and Loyd method, although individual data, in both methods, should be interpreted cautiously.

Adult↗
PubMed1997

Radiographic determination of total lung capacity in patients with pneumonectomy.

To determine whether total lung capacity (TLC) can be measured from plain chest radiographs in patients with pneumonectomy, we examined 20 such patients (17 male, 3 female) who had pneumonectomy for lung carcinoma. In 16 patients the right lung was preserved, and in 4 the left. The TLC was measured with the helium dilution method and by planimetry of the anterior and lateral projections of the lung on chest radiographs, summing the anterior and lateral projected areas of the lung to a single value, S. The correlation between S and TLC by helium gas dilution was r = 0.95. Linear fit of TLC to S explained 99.5% of the variance in TLC, with the equation. The side resected did not influence the predictive value (p < 0.001). The interquartile range of the residual error was +/-130 ml, and standard error was 64 ml. Therefore in patients with pneumonectomy, TLC of the preserved lung may be estimated within +/-130 ml by planimetry of the anterior and lateral chest radiographs.

Aged↗
PubMed1992

Roentgenographic determination of total lung capacity in normal Chinese children.

Roentgenographic determination of total lung capacity (TLC) in children, rarely mentioned in the past, differs from the determination of TLC using helium dilution method in that it does not need the measurement of functional residual capacity. Therefore, it is useful for hospitals where pulmonary function testing (PFT) is not available. In this study, 87 out of 125 normal children completed both chest radiographs and PFT. Ellipsoid method which divides the lung field into several sections was used to calculate TLC from chest radiographs. The correlation coefficient of TLC measured by both chest radiographs and PFT was 0.7680, and paired Student's t-test of the mean values of the two groups showed P value greater than 0.05. Among the variables of height, weight, age and body surface area, height alone was able to predict the normal reference value of TLC. Line of regression between TLC and height was expressed as "TLC = 52.776 x Height- 4404.998", and correlation coefficient was 0.8013. Intersubject reproducibility was also verified. It is concluded that chest radiographs can be used to determine TLC in children.

Adolescent↗
PubMed1980

Validity of total lung capacity determination by the single breath nitrogen technique.

Total lung capacity (TLC) derived from the single breath oxygen test (dilution of alveolar nitrogen) was compared with the plethysmographic TLC in 40 healthy males aged 25 to 55 years and in 16 patients with chronic obstructive respiratory disease. In healthy subjects TLC02 was 8% less (P less than 0.001) than TLC pleth. The two results were highly correlated (r = 0.89; P less than 0.001); their difference tended to increase with age and correlated significantly with the slope of phase III (P less than 0.01). In patients TLC02 underestimated the lung volume by 5 to 50% (average 28%) (P less than 0.001), and the relation between the two measurements were weaker (r = 0.59; P less than 0.02). The TLC02/TLC pleth. ratio was significantly related to FEV1.0% predicted (r = 0.68) and to specific conductance (r = 0.60), and highly significantly (P less than 0.001) related to obstructive ventilatory impairment (r = 0.77), to distribution unevenness (r = -0.85) and overinflation (r = 0.94). Although an overestimation of lung volume by plethysmography in the presence of severe obstruction cannot be excluded, most of the discrepancy reported is to be ascribed to underestimation by single breath nitrogen dilution due to impaired distribution of ventilation.

Adult↗
PubMed1990

A simple method for correcting single breath total lung capacity for underestimation.

The single breath method underestimates total lung capacity by comparison with the multiple breath method (TLCmb) because of inhomogeneity of ventilation distribution. This study proposes a simple correction for the single breath TLC (TLCsb), using inert gas phase III slope to account for the effects of uneven ventilation distribution. A model of a non-uniform lung ventilation was designed, composed of a serial dead space and two alveolar compartments arranged in parallel, whose relative ventilations were determined from the phase III plateau. Before correction TLCsb was 104-44% of TLCmb in 64 subjects (17 with diffuse interstitial disease, 42 with chronic obstructive pulmonary disease, and five healthy subjects). The limit of acceptability for the correction (TLCcorr) was determined from the 95% confidence interval of TLCsb/TLCmb in the healthy subjects. The correction resulted in a significant increase in TLCsb (p less than 0.004). TLCcorr remained under the limit of acceptability for only 12 patients with emphysema, and all 12 showed a large improvement in the TLC estimate. The presence of poorly ventilated zones during a single breath in these patients may explain this partial correction.

Adult↗
PubMed1980

Roentgenologic determination of total lung capacity.

Geometric analysis of the chest roentgenogram allows calculation of estimated gas volume. If roentgenograms are made on individual patients or in epidemiologic studies in which relatively expensive nitrogen meters or body plethysmographs are not available, the thoracic roentgenogram provides an economical alternative. This study compares two roentgenographic methods of estimating total lung capacity in 154 subjects who also had total lung capacity estimated by the 7-minute nitrogen-washout technique or by total-body plethysmography. Results with the roentgenographic techniques were closely comparable with each other and with those of the gas-dilution and total-body plethysmograph methods in normal subjects. The planimetric method consistently estimated higher total lung capacity than the elliptic method in men and women with total lung capacity of 7.75 liters or less. In patients with severe obstructive lung disease, the roentgenographic methods were more closely comparable with body plethysmography, which is believed to be the most accurate, whereas the nitrogen-rinsing and similar gas-dilutional methods tended to underestimate the true volumes. The roentgenographic techniques also proved to be reliable in a small group of patients with varying degrees of pulmonary fibrosis.

Female↗
PubMed1989

Radiographic measurement of total lung capacity in acute asthma.

The thoracic cage appears to be large during attacks of asthma. Lung volume measurements by body plethysmography and helium dilution have suggested that total lung capacity may be increased during an acute attack of asthma, but doubt has been cast on the accuracy of these measurements in the presence of airflow obstruction. The change in total lung capacity has therefore been investigated during and after an acute attack of severe asthma in 32 patients by a radiographic technique. There was a small decrease (0.29 l) in mean total lung capacity between admission and follow up, though a quarter of the subjects showed a slight increase. There was no correlation between change in total lung capacity and change in expiratory flow rates, arterial carbon dioxide tension on admission, body mass index, and length of stay in hospital. Our findings agree with previous reports of a decrease in total lung capacity with improving airway obstruction, but the changes were small and inconsistent.

Acute Disease↗
PubMed2004

On defining total lung capacity in the mouse.

Maximal lung volume or total lung capacity in experimental animals is dependent on the pressure to which the lungs are inflated. Although 25-30 cm H2O are nominally used for such inflations, mouse pressure-volume (P-V) curves show little flattening on inflation to those pressures. In the present study, we examined P-V relations and mean alveolar chord length in three strains (C3H/HeJ, A/J, and C57BL/6J) at multiple inflation pressures. Mice were anesthetized, and their lungs were degassed in vivo by absorption of 100% O2. P-V curves were then recorded in situ with increasing peak inflation pressure in 10-cm H2O increments up to 90 cm H2O. Lungs were quickly frozen at specific pressures for morphometric analysis. The inflation limbs never showed the appearance of a plateau, with lung volume increasing 40-60% as inflation pressure was increased from 30 to 60 cm H2O. In contrast, parallel flat deflation limbs were always observed, regardless of the inflation pressure, indicating that the presence of a flat deflation curve cannot be used to justify measurement of total lung capacity in mice. Alveolar size increased monotonically with increasing pressure in all strains, and there was no evidence of irreversible lung damage from these inflations to high pressures. These results suggest that the mouse lung never reaches a maximal volume, even up to nonphysiological pressures >80 cm H2O.

Animals↗
PubMed1981

Comparison of hydrostatic weighing at residual volume and total lung capacity.

Hydrostatic weighing (HW) was performed at both residual volume (RV) and total lung capacity (TLC) (both measured on land) to determine if underwater weighting at extreme lung volumes affected the measurement of body density. Subjects were 72 middle-aged males (mean age = 43.4 yr) and 51 middle-aged females (mean age = 40.2 yr). Subjects were first assessed for underwater weight at RV for at least 10 trials. Subjects were than instructed to inspire maximally and hold their breath underwater for as long as they could. Three trials at TLC were used for assessment of underwater weight. Forced vital capacity and residual volume (oxygen dilution) were determined separately on land. Small but statistically significant differences in body density (Db) were observed with the use of RV (1.0354 g/ml for men and 1.0196 g/ml for women) vs TLC (1.0367 g/ml for men and 1.0221 g/ml for women) (p less than 0.05). Percent fat values for the RV and TLD data differed by only 0.5% for men and 0.9% for women. Results indicated that the difference between percent fat determination by HW at RV and TLC, was negligible. It was concluded that HW at TLC may be the method of choice for subjects who are uncomfortable with performing the technique of underwater weighing at RV.

Adipose Tissue↗
PubMed1983

Roentgenographic determination of total lung capacity: normal values from a National Population Survey.

Planimetric measurements of total lung capacity (TLC) were made from posteroanterior and lateral chest roentgenograms obtained during a nationwide survey of the civilian, noninstitutionalized United States population. Regression equations for TLC, residual volume (RV), and the ratio of RV to TLC for healthy, nonsmoking participants are presented. The equations predict values that agree closely with previously published normal values obtained by other methods.

Adult↗
PubMedDate not supplied

[Closing volume of the respiratory airways and total lung capacity during 7-day antiorthostatic hypokinesis].

By mass spectrography and pneumotachography structural variations in total lung capacity (TLC) were investigated in 7 test subjects during 7-day head-down tilt at -15 degrees. By the 7th hour of head-down tilt TLC, vital lung capacity (VLC), functional residual capacity (FRC) and residual volume (RV) decreased significantly and closing volume (CV) increased insignificantly. The CV/FRC ratio grew from 0.82 +/- 0.03 to 1.24 +/- 0.08 (P less than 0.01), indicating the closure of respiratory pathways in certain lung structures within the tidal volume. These changes in the TLC structure persisted till day 7 but the CV/FRC ratio fell down to 1.01 +/- 0.07. The above findings can clarify the mechanism responsible for a lower oxygenation of arterial blood in the head-down position. The expiratory closure of the airways within the tidal volume causes regional changes in alveolar ventilation and ventilation-perfusion relations and, consequently, a larger venous admixture and a smaller oxygen saturation of arterial blood.

Adult↗
PubMed1976

The mechanism of increase in total lung capacity during acute asthma.

In order to investigate the mechanism underlying the increased total lung capacity (TLC) observed during an acute asthmatic attack, we measured respiratory mechanics in a specially trained, exercise-induced, asthmatic. During the acute attack his TLC (determined plethysmographically) increased from 7.8 to 9.2 liters. The static pressure-volume curve of the lung shifted to the left and expiratory compliance increased from 0.24 to 0.55 liter/cm H2O. There was a parallel shift of the static pressure-volume curve of the chest wall resulting in an increase in the outward recoil of this structure. The maximum inspiratory pressure-volume curve of the total respiratory system was shifted so that the inspiratory muscles were able to generate greater pressures at any given lung volume during the attack. The findings indicate that the increase in TLC during acute bronchospasm results from the combination of loss of lung recoil, increased outward recoil of the chest wall and increased strength of contraction of the inspiratory muscles.

Acute Disease↗
PubMedDate not supplied

Standard values of the maximal expiratory flow-volume curve normalized by total lung capacity.

Standard values for the maximal expiratory flow-volume (MEFV) curve normalized by total lung capacity (TLC) were obtained in one hundred and fifty healthy men. We compared age dependency and the coefficient of variation of parameters of the MEFV curve, obtained at given percentages of the vital capacity and normalized by height to those of parameters obtained at given percentages of TLC and normalized by TLC (V %TLC/TLC). At low lung volumes, every parameter showed a larger age dependency and a larger coefficient of variation than at high lung volumes. V %TLC/TLC showed almost the same age dependency and almost the same coefficient of variation than the other parameters. However, in pulmonary patients, V %TLC/TLC seems to detect obstructive impairment more readily in spite of the changes in lung volume. It is suggested that V %TLC/TLC would be more helpful in screening for airflow limitation in various pulmonary disorders than other parameters.

Adult↗
PubMed1978

Problems in the plethysmographic assessment of changes in total lung capacity in asthma.

We studied the effect of abdominal gas compression on plethysmographically determined total lung capacity (TLC) in asthmatic patients before, during, and after treatment of induced bronchospasm. TLC was derived from panting maneuvers near residual volume, at functional residual capacity, and near TLC. Significant differences among these "derived TLC" values increased significantly during bronchospasm. Whether or not TLC appeared to increase, and by how much, depended on the level of the vital capacity from which it was derived. Individual increases in TLC during bronchospasm could not be explained by increases in abdominal gas volume or in the extent to which it was compressed and decompressed during panting. We postulate that during the Boyle's Law panting maneuver, pleural, and therefore alveolar, pressure swings may be nonhomogeneous and greater over lung regions subtended by closed airways than over regions in communication with the mouth. This would result in an underestimation of alveolar pressure swings as measured at the mouth and an overestimation of thoracic gas volume, and would account in large part for the observed increase in discrepancies between the "derived TLC" values in asthma as well as the dependence of apparent TLC changes on the level of the VC at which the panting maneuver is performed.

Asthma↗
PubMed1985

Regional lung strain in dogs during deflation from total lung capacity.

Regional lung distortion during deflation from total lung capacity to functional residual capacity (FRC) in intact supine and prone anesthetized dogs was determined from the displacement of multiple metallic markers embedded in the lung parenchyma. Distortion was expressed as strain (epsilon), which is related to fractional length changes. In the supine position, transverse strain (epsilon yy) was larger than vertical strain (epsilon xx) and cephalocaudal strain (epsilon zz) in the upper lobe. The FRC of the lower lobe was smaller than FRC of the upper lobe and all strains were larger, but epsilon zz increased most and became equal to epsilon yy. In the prone position, epsilon yy was largest in all upper lobes and in three of four lower lobes. Strains and volumes of the upper and lower lobes were similar. The upper and lower lobes rotated slightly around different axes, indicating that interpleural fissures allow additional degrees of freedom for the lungs to conform to the thoracic cavity. In the prone position, there were no consistent gradients of strain or volume. These results indicate that, in determining the regional distribution of FRC in the recumbent dog, in addition to the effect of gravity on the lung, there are important interactions between lung and thoracic cavity shapes.

Animals↗
PubMedDate not supplied

[Plethysmographic and radiologic measurement of the total lung capacity during acute attack of bronchial asthma].

There is controversy on the behavior of total lung capacity (TLC) during an acute asthma attack because the severe airflow obstruction causes an overestimation of the intrathoracic gas measured by plethysmography. We measured plethysmographic and radiologic TLC (TLCpl, TLCrx) in 17 patients with acute asthma, at admission and 3-5 days later when clinical and spirometric improvement was seen. TLCrx was measured planimetrically from routine chest X-rays in postero-anterior and lateral projection. Patients had a mean age of 32 +/- 15 years (ranging from 8-53) and six were males. FEV1 and FVC increased significantly in the second evaluation (1.36 +/- 0.7 vs 1.99 +/- 0.7 L, and 1.97 +/- 0.9 vs 2.6 +/- 1 L respectively, p less than 0.05), whereas airway resistance decreased (13.4 +/- 5.3 vs 9.8 +/- 3.4 cm H2O/L/s, p less than 0.05). On the other hand, we did not find a significant change in TLCpl (4.4 +/- 1.1 vs 4.6 +/- 1.2 L) nor in TLCrx (4.2 +/- 0.9 vs 4.1 +/- 0.8 L). We found no significant difference between TLCpl and TLCrx.

Acute Disease↗
PubMed1988

Total lung capacity. An insensitive measure of impairment in patients with asbestosis and chronic obstructive pulmonary disease?

The total lung capacity (TLC) is frequently used as a measure of respiratory impairment in patients with asbestosis. Because asbestosis and chronic obstructive pulmonary disease (COPD) exert opposite effects on the TLC, it may be an insensitive measure of impairment in patients with both abnormalities. To assess this, we compared asbestos-exposed patients with functional evidence of COPD and radiographic evidence of interstitial fibrosis (group 1) to those with interstitial fibrosis alone (group 2). Despite the two groups being comparable in degree of radiographic "fibrosis," no case of restrictive impairment (reduced TLC) was identified among those with both interstitial fibrosis and COPD (group 1), compared to 33 percent of those with interstitial fibrosis alone (group 2). In addition, those patients with both interstitial fibrosis and COPD, compared to those with interstitial fibrosis alone, were found to have greater impairment as measured by alveolar-arterial oxygen difference and diffusing capacity. We conclude that the TLC is an insensitive measure of impairment due to asbestosis in patients with the common setting of coexistent asbestosis and COPD.

Aged↗