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PubMed1985

Reference equations for the single-breath diffusing capacity. A cross-sectional analysis and effect of body size and age.

A longitudinal study was implemented in an unpolluted rural area of northern Italy (near Venice), before the start of the operation of a large oil-burning thermoelectric power plant, in order to investigate the effects of the future exposure to air pollution and to elucidate the natural history of obstructive airways diseases. During the first cross-sectional survey, a sample of the general population (n=3,300, 8 to 64 yr of age) performed several lung function tests, and information on risk factors and on the presence of respiratory symptoms were obtained by a standardized questionnaire. There were 712 subjects who were classified as normal on the basis of rigid criteria and who were able to perform satisfactorily a single-breath CO diffusing capacity (DLCOsb) test. The DLCOsb values showed an increase with height and age early in life and a later decrease with age. Two age groups were selected to determine an age at which DLCOsb stopped increasing and began to decline. Reference equations were computed (using age and height) in these 2 different age groups in each of the sexes. Similar equations were calculated for the total lung capacity derived from single-breath helium dilution measurements. The DLCOsb values in this study were higher than reported by other investigators. The method of selection of the study population, the strict criteria for normal, as well as technical, differences probably explain this finding. Reference equations for diffusing capacity corrected to lung volume (DL/VA) were computed only for adults (much greater than 20) in both sexes, because age and height coefficients in young subjects were insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Small airway disease is associated with elastic recoil changes in excised human lungs.

We studied 54 excised human lungs, 15 with no emphysema and 39 with varying degrees of emphysema, to examine the relationship of small airway disease and elastic recoil. We found a negative correlation between the total small airway pathology score and the mean internal bronchiolar diameter (r = -0.309, p = less than 0.03), as well as with other measurements of small airway size. The internal bronchiolar diameter correlated well with both the elastic recoil expressed as a percentage of predicted values at 70% of total lung capacity (r = 0.533, p less than 0.001) and elastic recoil expressed as an exponential constant k (r = -0.370, p less than 0.01). Fibrosis of the small airways was associated with a reduced internal bronchiolar diameter (r = 0.460, p less than 0.001), as well as the percentage of predicted elastic recoil at 70% of total lung capacity (r = -0.382, p less than 0.01) and elastic recoil expressed as an exponential constant k (r = 0.348, p less than 0.02). We have concluded that changes in elastic recoil seen in these lungs and fibrosis of small airways may be related by a common inflammatory process.

Bronchi↗
PubMed1994

Clinical and functional assessment of patients with idiopathic pulmonary fibrosis: results of a 3 year follow-up.

The purpose of this study was to analyse the information provided by different techniques used in the assessment of patients with idiopathic pulmonary fibrosis (IPF) and their role in the prediction of lung function decline with the decline. Twenty seven subjects with IPF (55 +/- 14 (mean +/- SD) yrs) were studied at the initial staging. Nineteen of them (70%) were included in a follow-up over 3 yrs (32 +/- 6 months), whilst the remaining 8 patients were lost to follow-up. During the period of the study, 6 of the 19 patients died. A significant correlation between diffusing capacity of the lungs for carbon monoxide (DLCO) (and carbon monoxide transfer coefficient (KCO) = DLCO/alveolar volume (VA)) and the increase in alveolar-arterial oxygen tension difference (A-aPO2) during exercise (delta A-aPO2) was observed at diagnosis (r = -0.58). Despite the treatment with prednisone (1 mg.kg-1 daily during 4 weeks, tapered to an individualized maintenance daily dose of 15-30 mg), the 13 patients controlled throughout the whole period of the study showed a marked impairment in lung volumes; forced vital capacity (FVC) -0.46 +/- 0.09 l, from 69 +/- 16 to 52 +/- 11% of predicted, and total lung capacity (TLC) -0.39 +/- 0.11 l, from 75 +/- 16 to 62 +/- 14%, and in DLCO -0.6 +/- 0.2 mmol.min-1.kPa-1, from 56 +/- 15 to 47 +/- 18%, predicted. By contrast, both mean arterial oxygen tension (PaO2) and A-aPO2 at rest remained unchanged throughout the 3 yrs follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1996

Effects of surfactant on the in vivo alveolar surface-to-volume ratio.

To investigate how pulmonary surfactant influences alveolar structure in vivo, we examined the alveolar surface area-to-lung volume (S/V) ratio of the lung parenchyma of a live dog by light-scattering stereology before and after saline lavage. We measured the backscattered light pattern produced by applying a laser beam to the pleural surface of a ventilated animal and obtained the S/V [equivalent to the inverse of the optical mean free path (lambda)]. After saline lavage, V at transpulmonary pressure (P) of 30 cmH2O (defined as total lung capacity) decreased by 11.1 +/- 3.1% (SD) and the P-V curve shifted to a lower V. The lambda-V curve was shifted to a higher lambda and to a lower V after saline lavage. S/V decreased after saline lavage (lambda increased by 38 +/- 27% on the deflation limb at a V of 80% of control total lung capacity). The alveolar surface tension increased after saline lavage, and the increase in surface tension was greater on inflation than on deflation. We conclude that depletion of pulmonary surfactant increases the alveolar surface tension in vivo, resulting in a decrease in S/V.

Animals↗
PubMed1997

The time course of pulmonary transfer factor changes following heart transplantation.

OBJECTIVE: The pulmonary transfer factor for carbon monoxide (TLCO) has been reported to decline following heart transplantation, but the time course of this decline is not well documented. The aim of this study was to define the longitudinal changes in TLCO after heart transplantation. METHODS: Single breath TLCO, lung volumes and expiratory flow rates were prospectively measured in 57 patients (mean age 49 years, range 19-61) before and at least once after heart transplantation. Thirty seven of the 57 patients had four post-transplant assessment which were performed at 6 weeks, 3, 6 and 12 months in 26 patients and at 12, 18, 24 and 36 months in 11 patients. Results were compared with data from 28 normal subjects (mean age 40 years, range 19-61). RESULTS: Before transplantation there was a mild impairment of lung volumes and expiratory flow rates. At 6 weeks after transplantation, there was a further reduction in the forced expiratory volume in one second, forced vital capacity, residual volume and total lung capacity, but all of these increased in the subsequent measurements to exceed their pre-transplant values at about 1 year after transplantation. Haemoglobin-corrected TLCO was also reduced before transplantation compared to normal controls (74.3% and 98.6% of predicted respectively, P < 0.001). Although TLCO per unit alveolar volume (KCO) was relatively preserved in heart transplant candidates, it was still significantly lower than that of normal controls (92.6% and 105.3% of predicted respectively, P < 0.05). After transplantation, mean haemoglobin-corrected TLCO and KCO declined by 12% and 20% of predicted respectively) with the majority of patients having reductions greater than 10% of predicted. The decline in TLCO and KCO was evident at 6 weeks after transplantation with no further changes in the subsequent measurements. CONCLUSIONS: TLCO is reduced in heart transplant candidates and declines further after heart transplantation despite improvement in lung volumes and airway function. The early and non-progressive nature of TLCO decline suggests an aetiology exerting its effect on TLCO within the first 6 weeks after transplantation.

Adult↗
PubMed1985

Effects of mitral valve surgery on static lung function and exercise performance.

Lung function at rest was assessed in 50 patients before and six months after mitral valve surgery. There were small increases in spirometric volumes (FEV1 and vital capacity) with decreases in total lung capacity and residual volume, but no change in carbon monoxide transfer factor or transfer coefficient (KCO). Progressive exercise tests performed before and after operation in 19 of the patients confirmed an improved exercise capacity after surgery. The patients with the greatest symptomatic improvement in breathlessness were also those who achieved the greatest increase in maximum work load and the greatest decrease in ventilation for a given oxygen consumption. Depression of the ST segment of the electrocardiogram and frequent ventricular ectopic beats on exercise remained common after surgery and may have been due to digoxin treatment.

Adult↗
PubMed1981

Increased lung stiffness of persons with pleural plaques.

Forty-five men with asbestos-related pleural plaques detected at a health screening centre were investigated with measurement of lung volumes, airways resistance, ventilatory capacity, transfer factor, gas distribution, closing volume and static recoil pressures of the lung. The men were subjectively healthy, had confirmed exposure to asbestos and had normal chest radiograms apart from the presence of pleural plaques. Most of the men had been exposed to small or moderate amounts of asbestos with a mean duration of 39 years since first exposure. Sixty-seven per cent of the men were smokers or ex-smokers. The lung function was evaluated using regression formulas which included smoking variables. The results clearly demonstrate the presence of lung parenchymal involvement with increased stiffness of the lungs and decreased lung volumes. The change in elastic recoil pressure of the lungs, in total lung capacity and residual volume show significant correlation with measures of asbestos exposure and extent of pleural changes. No synergistic effects between tobacco smoking and asbestos exposure on lung function could be demonstrated. Measurements of the static elastic lung recoil (Pst(max) and Cst/TLC) and total lung capacity were the most sensitive tests for separating the pleural plaque carriers from the controls.

Aged↗
PubMed1994

Prediction of sensitization to flour allergens.

The purpose of the present study was to investigate the factors that may contribute to the sensitization to flour in baker's apprentices, and to predict this type of sensitization with a stepwise logistic regression model. Of the total of 258 baker's apprentices, 54 (20.9%) exhibited specific IgE development against flour allergens (wheat, rye, and/or barley). Allergologic variables, such as the total IgE level and IgE specific to grass pollen, tree pollen, weed pollen, molds, and animal dander, were found to correlate strongly with the sensitization to flour. However, the correlation between the presence of other manifest allergies and the sensitization to flour was weak. The presence of shadowing of the paranasal sinuses on the radiograph (mucosal thickening, opacity, air/fluid levels, and/or polypous shadowing) correlated with flour sensitization as well as with the leukocyte and lymphocyte counts in peripheral blood. Of the lung function data, only total lung capacity (in percentage of the predicted values) weakly correlated with the sensitization to flour. We were able to predict flour sensitization with a sensitivity of 63%, a specificity of 90%, and an efficiency of 84% by using the parameters that allow for the presence or absence of IgE specific to grass pollen and tree pollen, the presence or absence of radiographic shadowing, and total lung capacity in percentage of the predicted values.

Allergens↗
PubMed1999

Cardiovascular effects of the breathhold used in determining pulmonary diffusing capacity.

BACKGROUND: The single-breath technique for determination of the diffusion capacity of the lung for CO (DlCO) requires a 10-s breathhold at total lung capacity. The assumption has been that this breathhold does not alter the components of DlCO, i.e., the diffusion capacity of the membrane (Dm) and the pulmonary capillary blood volume (Qc), and therefore measurement of these variables during breathhold represents these variables as they exist during normal breathing. The purpose of this study was to determine the effect of the 10-s breathhold on cardiac output (Q) and Qc while supine and standing. The hypothesis was that the standing posture would have a greater influence on Q and Qc during the breathhold than would the supine posture. METHODS: Twelve male subjects participated. Q, stroke volume (SV), heart rate (HR), BP (MAP), and total peripheral resistance (TPR) were determined before and during the 10-s breathhold determination of DlCO, Qc, and Dm. RESULTS: Results while supine were compared with those while standing. DlCO was reduced on standing, due mainly to a reduction in Qc. SV and Q decreased significantly during the 10-s breathhold in both postures. Both SV and Q decreased more when standing (-53% and -49.5%, respectively) than when supine (-40.5% and -36.5%, respectively). Thus, the 10-s breathhold caused significant reductions in Q and therefore may alter the measurement of DlCO and Qc. CONCLUSIONS: The greater decline in Q during the measurement of DlCO when standing would suggest that the DlCO and Qc values while breathing might be underestimated in the upright posture.

Adult↗
PubMed1994

Changes in lung function and perfusion after irradiation in patients with lung cancer.

The changes in lung function were prospectively studied for patients with lung carcinoma who were treated with relatively high doses of irradiation. Their dyspnoea score, lung volume spirometry, diffusion capacity and ipsilateral hemithorax perfusion were measured at presentation, again between 5 and 6 months after irradiation (Group 1, 36 evaluable patients), and once more between 11 and 12 months (Group 2, 16 evaluable patients). There was a worsening of the dyspnoea score from 1 to 2, in a large percentage of patients, but only 6% developed a dyspnoea score of 3. The largest change in lung function tests was a decrease in the diffusion capacity (DLCO) to 14% at 6 months and 12% at 12 months (statistically significant, P < 0.0001 paired t-test). The forced vital capacity (FVC) and the total lung capacity (TLC) showed a lesser decrease at 6 and 12 months, and the smallest decrease, which was not statistically significant, was in the forced expiratory volume in 1 s (FEV1). There was also a statistically significant decrease in the ipsilateral hemithorax lung perfusion of 16% at 6 months and 20% at 12 months. There was a weak correlation between the decrease in the DLCO and the FEV1 at follow-up. There was no statistically significant correlation between initial perfusion or decreased perfusion and the decrease in lung function. Lung irradiation should be regarded as an ablative form of therapy, analogous to surgery, in patients with a projected survival of 6 months or more. The DLCO is the most sensitive indicator of clinical damage and its pretreatment assessment should be useful in predicting clinical tolerance to irradiation.

Dyspnea↗
PubMed1999

Nonreversible airflow obstruction in life-long nonsmokers with moderate to severe asthma.

The aim of this longitudinal study was to assess the frequency of nonreversible airflow obstruction (NRAO) among adults with moderate to severe asthma, and to compare the decline of forced expiratory volume in one second (FEV1) in asthmatics with reversible and nonreversible airflow obstruction. Ninety-two (31 males) life-long nonsmokers with asthma participated in a 10-yr follow-up study; mean age 37 yrs (range 18-64) and duration of asthma 16 yrs (range 2-60) at enrolment. Case history, including use of asthma medication, was obtained, and pulmonary function, including diffusion capacity, was measured using standard techniques. At enrolment, all patients had typical symptoms and reversible airflow obstruction. (NRAO) was defined as FEV1 <80% predicted and change in deltaFEV1 after 5 mg salbutamol <9% pred. A total of 21 (23%) patients (mean age at enrolment 32 yrs) fulfilled the criteria for NRAO at the time of follow-up; current therapy was inhaled steroids (n=21, mean daily dose 1.5 mg), oral steroids (n=14), theophylline (n=20), oral beta2-agonist (n=6) and inhaled beta2-agonist. The patients with NRAO (n=21) had a steeper decline in FEV1 than the remaining patients (n=71, reversible airflow obstruction (RAO)), mean+/-SD 53+/-23 mL x yr(-1) and 36+/-21 mL x yr(-1), respectively (p<0.003). Increasing degree of bronchodilator reversibility (deltaFEV1% pred) at enrolment (p=0.002) and long-term treatment with oral corticosteroids (p=0.009) were associated with an increased risk for the presence of NRAO at follow-up. The comparison of data for NRAO and RAO patients (at follow-up) revealed no significant differences in mean values for total diffusion capacity (TL,CO), diffusion constant (KCO), or total lung capacity. The findings suggest that a subgroup of asthmatics may experience very steep rates of decline in forced expiratory volume in one second leading to severe nonreversible airflow obstruction, whereas no indication was found that long-standing asthma may lead to the development of emphysema.

Adolescent↗
PubMed2002

Physiological characterization of variability in response to lung volume reduction surgery.

This paper examines potential physiological mechanisms responsible for improvement after lung volume reduction surgery (LVRS). In 25 patients (63 +/- 9 yr; 11 men, 14 women), spirometry [forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC)], lung volumes [residual volume (RV) and total lung capacity (TLC)], small airway resistance, recoil pressures, and respiratory muscle contractility (RMC) were measured before and 4-6 mo after LVRS. Data were interpreted to assess how changes in each component of lung mechanics affect overall function. Among responders (DeltaFEV(1) > or = 12%; 150 ml), improvement was primarily due to an increase in FVC, not to FEV(1)-to-FVC ratio. Among nonresponders, FEV(1), FVC, and RV/TLC did not change after surgery, although recoil pressure increased in both groups. Both groups experienced a reduction in RMC after LVRS. In conclusion, LVRS improves function in emphysema by resizing the lung relative to the chest wall by reducing RV. LVRS does not change airway resistance but decreases RMC, which attenuates the potential benefits of LVRS that are generated by reducing RV/TLC. Among nonresponders, recoil pressure increased out of proportion to reduced volume, such that no increase in vital capacity or improvement in FEV(1) occurred.

Adult↗
PubMed2001

Effect of changes in lung volume on acoustic transmission through the human respiratory system.

The variation of acoustic attenuation with lung density was determined in experimental studies on seven healthy human volunteers, using a change of lung volume as a means of varying lung density. White noise between 50 and 680 Hz was introduced into the mouth and the transmitted signals were recorded with four microphones on the posterior chest wall (left/right, top/base) at 24, 40, 60 and 80% of total lung capacity. The change in lung volume had a frequency-dependent effect on acoustic attenuation in all subjects. A frequency between 177 and 243 Hz was identified, where altering the lung volume between 24 and 80% of total lung capacity induced a change in attenuation of only 1.0 (+/-0.5) to 2.7 (+/-1.8) dB, while at a frequency of 364-436 Hz marked variations in attenuation 8.9 (+/-2.0) to 21.5 (+/-4.8) dB occurred with similar lung volume changes.

Acoustics↗
PubMed1988

Thoracoabdominal restriction in supine men: CT and lung function measurements.

Thoracoabdominal restriction was brought on by means of a corset, and the subsequent effects on thoracic dimensions and lung tissue were studied by computerized tomography (CT) and by various lung function tests in supine healthy volunteers (mean age 30 yr). Restriction caused reductions in total lung capacity (helium equilibration) from mean 6.84 to 4.80 liters, in functional residual capacity (FRC) from 2.65 to 2.08 liters, and in vital capacity from 5.16 to 3.45 liters. Closing capacity (single-breath N2 washout) fell from 2.42 to 1.88 liters, thus matching the reduction in FRC. The static pressure-lung volume curve was shifted to the right by 1.5 cmH2O at 50% of total lung capacity. However, no change in the slope of the curve was observed. The diaphragm was moved cranially by 1.2 cm, and the thoracic cross-sectional area was reduced by a mean 32 cm2 at a level just above the diaphragm. No changes in the lung tissue were seen on CT scanning. Gas exchange, as assessed by multiple inert gas elimination technique and arterial blood gas analysis, was unaffected by restriction. It is concluded that in supine subjects, thoracoabdominal restriction that reduces FRC by 0.6 liter is not accompanied by atelectasis (normal CT scan). In this respect the result differs from that found in anesthetized supine subjects who show the same fall in FRC and atelectasis in dependent lung regions.

Abdomen↗
PubMed1993

Nocturnal oxygen saturation and sleep quality in long-term survivors of thoracoplasty.

The extent and the predictors of nocturnal hypoxemia were studied in 9 men and 11 women treated for pulmonary tuberculosis by thoracoplasty 30-54 years previously. The patients had a scoliotic (Cobb) angle of 4-53 degrees. Median values for pulmonary function were: forced expiratory volume in 1 s 1.2 liters (49% of the predicted value), vital capacity 1.9 liters (54%), total lung capacity 3.6 liters (62%), and supine waking partial pressure for arterial oxygen 9.7 kPa. Four patients were hypercapnic. The patients' mean nocturnal SaO2 ranged from 83 to 94% (median 91.8%), and the SaO2 level below which the patients spent 10% of the total nocturnal recording time ranged from 78 to 92% (median 89.4%). A multiple stepwise linear regression analysis identified supine waking SaO2 as a significant predictor of nocturnal O2 desaturation, accounting for about 80% of the variability in nocturnal SaO2 levels; lung function values and Cobb angle were not significant independent predictors. The sleep quality, assessed by EEG, was good. It is concluded that in thoracoplasty patients with mild hypoxemia during wakefulness, the degree of sleep-related oxygen desaturation was modest and closely related to the waking level of SaO2.

Aged↗
PubMed1987

Effects of swim training on lung volumes and inspiratory muscle conditioning.

Lung volumes and inspiratory muscle (IM) function tests were measured in 16 competitive female swimmers (age 19 +/- 1 yr) before and after 12 wk of swim training. Eight underwent additional IM training; the remaining eight were controls. Vital capacity (VC) increased 0.25 +/- 0.25 liters (P less than 0.01), functional residual capacity (FRC) increased 0.39 +/- 0.29 liters (P less than 0.001), and total lung capacity (TLC) increased 0.35 +/- 0.47 (P less than 0.025) in swimmers, irrespective of IM training. Residual volume (RV) did not change. Maximum inspiratory mouth pressure (PImax) measured at FRC changed -43 +/- 18 cmH2O (P less than 0.005) in swimmers undergoing IM conditioning and -29 +/- 25 (P less than 0.05) in controls. The time that 65% of prestudy PImax could be endured increased in IM trainers (P less than 0.001) and controls (P less than 0.05). All results were compared with similar IM training in normal females (age 21.1 +/- 0.8 yr) in which significant increases in PImax and endurance were observed in IM trainers only with no changes in VC, FRC, or TLC (Clanton et al., Chest 87: 62-66, 1985). We conclude that 1) swim training in mature females increases VC, TLC, and FRC with no effect on RV, and 2) swim training increases IM strength and endurance measured near FRC.

Adolescent↗
PubMed1989

Dimensions of the trachea to age 6 years related to height.

In an effort to establish normal values for both investigational and patient care purposes, computed tomography was used to determine the length, diameters, cross-sectional area, and volume of the tracheas of 34 children up to the age of 6 years. The measurements were taken when patients were asleep or resting quietly during tidal breathing, at perhaps 30-60% of total lung capacity. The results were related to body height (in infancy, to body length). There was virtually no difference between boys and girls. Each mean diameter correlated well with mean cross-sectional area. Tracheal diameters and area were reasonably constant over the length of individual tracheas. The slopes of the functions relating height to tracheal dimensions in these 34 infants and young children were slightly less steep than those previously measured near total lung capacity in 90 older children and adolescents.

Analysis of Variance↗
PubMed1991

Lung mechanics and gas exchange in steroid treated pulmonary sarcoidosis. A seven year follow-up.

Fifteen patients with pulmonary sarcoidosis, representing the functionally most severely affected quartile of referred patients, were prescribed steroids during one year. During this period and after 7 years on average, measurements were made of lung volumes, the static elastic pressure/volume (PstL/V) curve and lung resistance (RL). Lung mechanics and arterial blood gases were studied at exercise. Within months static compliance (CstL) and the arterial partial pressure of oxygen improved along with radiography. A modest positive trend continued throughout the follow-up. The vital capacity followed CstL changes closer than did the total lung capacity, which remained low. Though CstL improved, transpulmonary pressure at maximal inspiration increased and the upper part of the PstL/V curve became flatter. RL remained moderately increased. The course of the physiologic findings may be explained by fairly stable parenchymal and peribronchial fibrosis after cessation of active inflammation, and by regress of reflex inhibition of inspiration. Thus most subjects showed modest improvement during and after treatment. The initial study of lung function provided important prognostic information. The study does not allow conclusive evidence with respect to long term benefit of treatment, but encourages continued use of steroids under the guidance of function tests.

Adult↗