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PubMed1980

Lung growth and airway function after lobectomy in infancy for congenital lobar emphysema.

To characterize the outcome of lobectomy in infancy and the low expiratory flows which persist after lobectomy for congenital lobar emphysema, 15 subjects with this history were studied at age 8-30 yr. Total lung capacity was normal in all, but higher values (P < 0.05) were observed in nine subjects with upper lobectomy than in five subjects with right middle lobectomy. Ratio of residual volume to total lung capacity was correlated (P < 0.05) with the amount of lung missing as estimated from normal relative weights of the respective lobes. Xe(133) radiospirometry in eight subjects showed that the operated and unoperated sides had nearly equal volumes at total lung capacity, but that the operated side was larger than the unoperated side at residual volume. Perfusion was equally distributed between the two sides. Similar findings were detected radiographically in four other subjects. Forced expiratory volume in 1 s and maximal midexpiratory flow rate averaged 72 and 45% of predicted, respectively. Low values of specific airway conductance and normal density dependence of maximal flows in 12 subjects suggested that obstruction was not limited to peripheral airways. Pathologic observations at the time of surgery and morphometry of the resected lobes were not correlated with any test of pulmonary function. These data show that lung volume can be completely recovered after lobectomy for congenital lobar emphysema in infancy. The volume increase occurs on the operated side, and probably represents tissue growth rather than simple distension. The response to resection is influenced by the particular lobe resected and may be associated with decreased lung recoil near residual volume. Low expiratory flows in these subjects could be explained by several mechanisms, among which a disproportion between airway and parenchymal growth in infancy (dysanaptic growth) is most compatible with our data.

Adolescent↗
PubMed1988

Indomethacin and cromolyn sodium alter ozone-induced changes in lung function and plasma eicosanoid concentrations in guinea pigs.

Male Hartley guinea pigs were given either indomethacin (IN), cromolyn sodium (CS), or no drug (ND) and then exposed either to filtered air or to 1 ppm ozone (O3) for 1 hr. At 2 or 24 hr postexposure, ventilation, respiratory mechanics, lung volumes, carbon monoxide-diffusing capacity (DLCO), and alveolar volume (VA) were measured, and in separate groups of animals, plasma eicosanoids (EC) were measured. Both drugs blocked the increase in flow resistance noted at 2 hr after O3 and prevented O3-induced increases in the wet lung weight to body weight ratio seen at 2 and 24 hr in the ND group. In the ND animals O3 also decreased total lung capacity (TLC), vital capacity (VC), functional residual capacity (FRC), and residual volume (RV). IN as well as CS blocked reductions in FRC and RV at both 2 and 24 hr after O3. TLC was reduced by both drug treatments in air- and O3-exposed animals. CS treatment also decreased VC in all groups. IN blocked reductions in VA after O3 but did not prevent decreases in DLCO. CS blocked reductions in both VA and DLCO after O3, but the drug decreased DLCO in air-exposed animals. The prostaglandins PGF2 alpha and 6-keto PGF1 alpha were largely unaffected by O3 exposure or drug treatment. Prostaglandin E1 (PGE1) was not affected by O3, but both drugs significantly increased PGE1 in all exposure groups. Effects on plasma thromboxane B2 (TxB2) were variable although in most groups TxB2 was lower than in the O3-exposed ND groups. Although our findings suggest that both drugs block some effects of O3 exposure on the lungs and on plasma EC concentrations, the degree to which EC contribute to O3-induced pulmonary effects is not clearly apparent.

Animals↗
PubMed1996

[Clinical effects of four weeks of respiratory muscle stretch gymnastics in patients with chronic obstructive pulmonary disease].

We developed a program of respiratory muscle stretch gymnastic (RMSG), and measured lung function, exercise capacity, dyspnea, and quality of life before and after 4 weeks of training with this program. Thirteen patients with chronic obstructive pulmonary disease (mean FEVi, 1.24 liters) began the program. They participated in three sessions of RMSG each day. Twelve patients completed all 4 weeks. RMSG significantly (p < 0.01) decreased functional residual capacity (from 4.19 +/- 1.27 to 3.88 +/- 1.03 liters), total lung capacity (from 5.98 +/- 1.35 to 5.66 +/- 1.20 liters), residual volume (from 3.29 +/- 1.16 to 2.89 +/- 0.89 liters), and residual volume as a percent of total lung capacity (from 53.9 +/- 11.2% to 50.6 +/- 9.74%). The distance walked in 6 min increased by an average of 43 +/- 30 meters (+ 15%, p < 0.01). Dyspnea after a 6-minute walk (measured with a 150-mm visual analog scale) decreased significantly (from 65.1 +/- 40.8 to 36.1 +/- 36.8, p < 0.05). Quality of life was measured with the Chronic Respiratory Disease Questionnaire of Guyatt, et al., and was found to have improved significantly. Respiratory muscle stretch gymnastics may be useful in pulmonary rehabilitation.

Aged↗
PubMed1977

Pulmonary arteriovenous fistulas: increase in shunt at high lung volume.

Intrapulmonary shunt measured in the sitting position by the oxygen breathing method increased at total lung capacity in 7 of 8 patients with pulmonary arteriovenous fistulas. This may explain the clinically noted increased murmur over a fistula on inspiration. The finding of an increased intrapulmonary shunt at total lung capacity might suggest the diagnosis in equivocal cases and provide a convenient test for follow-up after surgery.

Arteriovenous Fistula↗
PubMed1997

Airway hyperreactivity in children with sickle cell disease.

Progressive restrictive defect with increasing age, obstructive lung disease, and bronchodilator responsiveness have been reported in sickle cell disease (SCD). Because airway hyperreactivity (AHR) can be underestimated when assessed by bronchodilator responsiveness in patients with normal baseline lung function, the aim of this study was to investigate the prevalence of AHR in SCD by cold-air bronchial provocation testing, and to assess whether AHR can be present in symptom-free patients with SCD. Forty patients aged 6 to 19 years (mean, 10.7 years +/- 3.5 SD) performed pulmonary function tests. Eighteen were known to have a history of reactive airway disease (RAD group), and 22 had no known history of RAD (non-RAD group). A control group, aged 6 to 7 years (mean, 10.5 +/- 3.1 years), consisted of 10 siblings of the non-RAD SCD group. There were no significant differences in age and height among the groups. If the forced expiratory volume in 1 second (FEV1) was greater than 70%, cold air challenge (CACh) was performed; if the FEV1 was less than 70%, aerosolized bronchodilator therapy was given. A decrease in FEV1 of more than 10% after CACh or an increase in FEV1 of 12% or greater after bronchodilator inhalation was considered evidence of AHR. In the RAD group, the total lung capacity was 88.9% +/- 14.0% of race-corrected predicted values, the forced vital capacity was 91.2% +/- 12.6%, and FEV1 was 85.3% +/- 16.2%. The mean maximal percent fall in FEV1 after CACh (n = 13) was 18.5% +/- 9.6% and was greater than 10% in 11 of 13 patients. The mean increase in FEV1 after bronchodilator therapy (n = 5) was 11.5% +/- 8.3%, and it was greater than 12% in 4 of 5 patients. In the non-RAD group the baseline total lung capacity was 101.6% +/- 11.7%, forced vital capacity was 95.5% +/- 10.2%, and FEV1 was 93.3% +/- 13.2%. The mean maximal percent fall in FEV1 after CACh (n = 19) was 14.1% +/- 8.8% and was greater than 10% in 13 of 19 patients. The mean increase in FEV1 after bronchodilator therapy (n = 3) was 14.7% +/- 11.3%, and was 12% of greater in 1 of 3 patients. In the control group the baseline total lung capacity was 105.7% +/- 12.1%, forced vital capacity was 96.2% +/- 11.1%, and FEV1 was 92.9% +/- 10.3%. The mean maximal percent fall in FEV1 was 5.0% +/- 2.5%, and was greater than 10% in none of 10 patients. The prevalence of AHR in the control group, the RAD group, and the non-RAD group was zero, 83%, and 64%, respectively (p < 0.0001). The overall prevalence in the SCD group was 73%. We conclude that there is a high prevalence of AHR in children with SCD and that airway hyperreactivity may exist in patients with SCD even in the absence of the clinical symptoms of RAD. AHR may be a significant component of sickle cell lung disease.

Administration, Inhalation↗
PubMed1986

Pulmonary functional and morphological changes induced by a 4-week exposure to 0.7 ppm ozone followed by a 9-week recovery period.

Male Fischer-344 rats (control, C = 12; experimental, E = 11) were subjected to pulmonary-function testing procedures. The experimental group was then exposed to 0.7 ppm ozone for 28 d, 20 h/d, and both groups were tested at the termination of the exposure and after 4 and 9 wk of recovery in clean filtered air. Another group of animals (C = 6, E = 12) was similarly treated, but at each test point one-third were sacrificed for microscopic evaluation. When percent changes from preexposure values were compared to controls at each time point, the ozone exposure produced obstructive changes in the lung, including significant decreases (p less than 0.05) in forced expiratory flows (MEF25 40.3%, MEF10 70.7%), lung volumes (IC 22.5%, FVC 21.8%), and DLCO (20.7%); and a significant increase in functional residual capacity (FRC 61.1%). The total lung capacity (IC + FRC) was not significantly changed by the ozone. Microscopic examination revealed characteristic lesions in the region of terminal bronchioles and central acinar alveoli marked by peribronchiolar edema, bronchiolization of alveolar duct epithelium, and type II cell proliferation in involved alveoli with increased numbers of macrophages and a few leucocytes. Clearly discernable was a focal interalveolar-alveolar duct reaction made up of fibroblasts, a few inflammatory cells, and conspicuous mast cells, all embedded in a loose metachromatic matrix. After 4 wk of recovery, all measurements of lung volume and DLCO had returned to the values of the control group; however, even after 9 wk some of the measurements of lung flow (MEF25, MEF10) remained significantly although less depressed (27.9 and 40.1%, respectively). Histologically, after 4 wk recovery, there remained only a slight unevenly disturbed inflammatory reaction. In these foci there was often a residual, narrower, more condensed band of eosinophilic material, presumably collagen, that sometimes contained interspersed mast cells. After 9 wk, this collagen accumulation within the thickened wall of the alveolar duct could occasionally still be noted. These data suggest that the florid response seen at the end of exposure was related to the obstructive changes measured and that, with recovery, the residual central acinar-alveolar duct thickening may be responsible for the persistently diminished air flows.

Animals↗
PubMed1996

Office evaluation of pulmonary function: beyond the numbers.

Pulmonary function testing is useful in evaluating dyspnea, wheezing and cough, determining the severity of pulmonary disease, monitoring the response to therapy and assessing preoperative pulmonary risk. Accurate office spirometry requires routine preventive maintenance, cleaning and calibration of equipment and quality control measures. To obtain a flow-volume loop, the seated or standing patient is instructed to inspire maximally to total lung capacity, exhale as hard, fast and completely as possible (forced vital capacity [FVC]), and inhale quickly and deeply to total lung capacity (TLC). Spirometry reveals both obstructive and restrictive airway disease. Obstruction is characterized by reduced forced expiratory volume in one second (FEV1) and FEV1/forced vital capacity (FEV1/FVC%), and normal to increased TLC and residual volume. Restriction is characterized by reduced TLC and residual volume and normal FEV1/FVC%. Spirometry may also reveal abnormalities of the upper airway, including the nasopharynx, vocal cords, trachea and proximal large airways.

Humans↗
PubMed1999

Alveolar epithelial surface area-volume relationship in isolated rat lungs.

In vitro studies of the alveolar epithelial response to deformation require knowledge of the in situ mechanical environment of these cells. Because of the presence of tissue folding and crumpling, previous measurements of the alveolar surface area available for gas exchange are not equivalent to the epithelial surface area. To identify epithelial deformations in uniformly inflated lungs representative of the in vivo condition, we studied isolated Sprague-Dawley rat lungs (n = 31) fixed by perfusion with glutaraldehyde on deflation after cycling three times at high lung volume (10-25 cmH2O). The epithelial basement membrane in 45 electron micrographs (x12,000)/rat was traced, digitally scanned, and analyzed. Epithelial basement membrane surface area (EBMSA) was computed from a morphometric relationship. EBMSA was found to increase 5, 16, 12, and 40% relative to EBMSA at 24% total lung capacity at lung volumes of 42, 60, 82, and 100% total lung capacity, respectively. The increases in EBMSA suggest that epithelial cells undergo significant deformations with large inflations and that alveolar basement membrane deformation may contribute to lung recoil at high lung pressures.

Air Pressure↗
PubMed1997

On the causes of lung hyperinflation during bronchoconstriction.

Airway obstruction in asthma and chronic obstructive pulmonary disease (COPD) is often associated with lung hyperinflation. In this review, we examine the mechanisms that may cause functional residual capacity (FRC), residual volume (RV) and total lung capacity (TLC) to increase during acute and chronic airway obstruction. Normally, FRC at rest is determined by the static characteristics of the lung and chest wall. When airways narrow, FRC may be also be determined by dynamic factors. There are data suggesting that expiratory flow limitation during tidal breathing represents the starting trigger for FRC to increase, in order to allow breathing at higher flows. Indeed, the increase in FRC during induced bronchoconstriction in asthma is closely associated with the occurrence of flow limitation, i.e. the achievement of maximum flow during tidal breathing. Conversely, the decrease in FRC following bronchodilatation in COPD is closely associated with flow limitation disappearing or occurring at lower lung volumes. In normal young people, RV is determined by the static characteristics of the chest wall. During bronchoconstriction RV may also be determined by dynamic factors; therefore, changes in flow or airway calibre at low lung volumes may modulate RV during bronchoconstriction. During acutely induced bronchoconstriction, RV achieved with an expiration from TLC is less than with an expiration from tidal breathing, and this effect appears to be linked to the bronchodilator effect of the deep inhalation. The reasons for the increase in TLC during airway narrowing are not clear, but the duration of the bronchoconstriction by itself may play a role.

Bronchoconstriction↗
PubMedDate not supplied

Value of spirometry in detecting volume restriction in interstitial lung disease patients. Spirometry in interstitial lung diseases.

BACKGROUND: Restriction is a typical functional abnormality in interstitial lung disease (ILD) patients, but is not always present, especially in the early stage of the disease. The greater reduction of vital capacity (VC; %pred.) than total lung capacity (TLC; %pred.) is regarded as a typical pattern of lung function disturbances in ILD patients. STUDY OBJECTIVES: To explore the diagnostic value of spirometry in a detection restrictive pattern the relative volume loss assessed by TLC and VC in large series of patients with a diagnosis of ILD referred for lung function tests was evaluated. METHODS: Retrospective, cross-sectional analysis of pulmonary function data was done. The sampleconsisted of 1,173 patients with the diagnosis of different interstitial lung diseases investigated during a period of 5 years. Only patients without airway obstruction (normal FEV1%VC) were included. In all cases spirometry and whole body plethysmography were performed by experienced staff using MasterLab - 'Jaeger' equipment according to ERS standards. Reference values according to ERS guidelines were applied. RESULTS: The mean value of TLC expressed as %pred. was significantly (p < 0.001) lower than VC in all patients (93.7 +/- 18.6 vs. 98.0 +/- 21.4%pred.). The frequency of abnormal (lowered) TLC results was also higher than lowered VC (22.8 vs. 17.8%). Sensitivity of VC reached 69.3% and the positive predictive value was 88.5% in detecting volume restriction as compared to TLC measurement. CONCLUSION: The relative loss of TLC was greater than VC in our large group of patients. Measurement of TLC should be part of functional assessment of ILD patients, irrespective of whether they present or do not present a restrictive pattern in spirometry.

Adolescent↗
PubMedDate not supplied

Bronchiectasis in systemic sclerosis. A study using high resolution computed tomography.

OBJECTIVE: To detect noninvasively the presence of bronchiectasis in patients with systemic sclerosis (SSc), through the use of high resolution chest computed tomography (HRCT). METHODS: Twenty two patients with SSc, of whom 13 with diffuse and 9 with limited disease, besides a complete history, physical and routine laboratory and immunologic profile, were evaluated by pulmonary function testing and HRCT. The chi square test with Yates' correction, the Fisher's exact test, the Fisher's test (F test) and the "t" test were used for statistical analysis of the results. RESULTS: Eleven patients (50.0%) had decreased carbon monoxide diffusing lung capacity (DLCO) and, out of these, four had restrictive lung disease, based on a combined decrease of forced vital capacity (FVC) and total lung capacity (TLC). Another two patients exhibited this pattern without DLCO impairment. HRCT revealed a ground glass picture in 15 patients (68.2%), fibrosis in 9 (40.9%) (of which 5 with ground glass as well), and cylindrical bronchiectasis in 13 (59.1%). Bronchiectasis was more common in diffuse than in limited SSc, and the difference approached but did not reach the level of statistical significance. On the other hand, it was not correlated with either decreased DLCO, presence of ground glass and fibrosis, or with patients' age and disease duration. CONCLUSION: Although the number of patients included in our study is relatively small, our data, for the first time in the literature, indicate a significant association between scleroderma and bronchiectasis. Bronchiectasis should be included in the list of pulmonary manifestations of SSc, and SSc in the list of conditions causing bronchiectasis.

Adult↗
PubMedDate not supplied

Reduced work of breathing after single lung transplantation for emphysema.

BACKGROUND: Pulmonary emphysema, with or without chronic bronchitis, has emerged as the most common indication for successful single lung transplantation. Although gas exchange can be expected to improve after successful transplantation, such changes do not adequately explain the improvement in dyspnea experienced by these patients and resulting in improved quality of life. METHODS: We prospectively studied the respiratory mechanics of 14 single lung transplantation recipients with pulmonary emphysema, of whom 10 have been followed up beyond 1 year. The mean age of the group was 48.8 years (range, 42 to 60 years) for the seven men and seven women. Average donor-predicted total lung capacity was 0.6 L (+0.2 [standard error]) greater than recipient-predicted total lung capacity. Comparison of pulmonary resistance, dynamic lung compliance, and static lung compliance were taken to examine the possible role of reduced airways resistance and of improved elastic recoil in the reduced work of breathing. Results were analyzed by means of a one-tailed paired Student t test and linear regression analysis (both stepwise and multivariate); results are tabulated by mean (+/- 1 [standard error]). RESULTS: Between preoperative measurements and 12 months postoperatively, maximum lung elastic recoil increased from 8.1 (+/- 0.7) to 11.3 (+/- 1.0) cm H2O, p < 0.01; pulmonary resistance fell from 8.3 (+/- 0.8) to 5.4 (+/- 0.7) cm H2O sec/L, p < 0.01. Dynamic lung compliance fell from 0.23 (+/- 0.04) to 0.12 (+/- 0.02) L/cm H2O, p < 0.02, and static lung compliance fell from 0.66 (+/- 0.13) to 0.22 (+/- 0.05) L/cm H2O, p < 0.001. CONCLUSIONS: The decline in lung compliance after single lung transplantation reflects the importance of improvement in elastic recoil and reduced chest wall distention, improving the work of breathing. The 67% decline in static lung compliance (300% increase in elastic recoil) is probably the single most important mechanical factor leading to reduced dyspnea after single lung transplantation for emphysema.

Airway Resistance↗
PubMed1980

Pulmonary function abnormalities in thalassemia patients on a hypertransfusion program.

Pulmonary function tests were performed in 12 thalassemia patients on a hypertransfusion program (age 18.4 +/- 2.6 SEM years) to determine the presence of any abnormalities of lung function. These included spirometry, expiratory flow rates, body plethysmography, single-breath nitrogen washout, single breath carbon monoxide diffusing capacity, and arterial blood gases. Only one patient had normal pulmonary function. Arterial hypoxemia was present in ten of 12 patients at rest. The total lung capacity (TLC) was normal. The residual volume was abnormally increased in five of 12 patients. The slope of phase III of single breath nitrogen washout curve was abnormal in five of 12 patients, but the closing volume was normal. The maximal expiratory flow rate at 60% total lung capacity was decreased in four of 12 patients, suggesting the presence of small airway disease. The single breath carbon monoxide diffusing capacity was normal in all patients. These pulmonary function abnormalities did not correlate with age or the cumulative amount of iron via blood transfused. The small airway obstruction, hyperinflation; and hypoxemia observed in thalassemia patients on a hypertransfusion program may result from the basic disease, iron deposition in the lungs, or other factors.

Adolescent↗
PubMed1994

Oxygen and 99mTc-MAA shunt estimations in patients with pulmonary arteriovenous malformations: effects of changes in posture and lung volume.

BACKGROUND: Patients with arteriovenous malformations are routinely monitored with arterial oxygen saturation (SaO2) estimations (breathing air) from which an oxygen shunt fraction can be calculated. This simple estimation has been compared with an anatomically defined estimate of the right to left shunt using a radioisotopic method. The fall in SaO2 which occurs in patients with pulmonary arteriovenous malformations in the erect posture and at high lung volumes was used to test the ability of SaO2 alone to follow changes in right to left shunt. METHODS: Radiolabelled albumin macroaggregates (99mTc-MAA) or microspheres (MS) were injected intravenously and kidneys and lungs were imaged. The shunt fraction (QS/QTTc) in the supine position at functional residual capacity (baseline) was obtained by quantifying right kidney radioactivity. On standing or while breath holding at total lung capacity, shunt fraction was calculated from baseline QS/QTTc and from lung counts and the injected dose. Arterial oxygen saturation (SaO2) was recorded by a pulse oximeter for calculation of the oxygen shunt (QS/QTO2) (breathing air). RESULTS: In the postural study (n = 8) SaO2 decreased from a mean (SD) value of 89 (5)% supine to 80 (6)% erect, corresponding to QS/QTO2 28 (8)% and 44 (8)% respectively. QS/QTTc increased from 28.7 (10.3)% to 39 (14.3)%. In the lung volume study (n = 8) QS/QTTc increased from 16.6 (11.5)% at functional residual capacity to 23.3 (11.9)% at total lung capacity while QS/QTO2 increased from 19.5 (7.5)% to 25.9 (10.6)% respectively. When all measurements were compared for QS/QTTc% and QS/QTO2% (n = 32) the difference in the mean values was 2.5% (absolute) and the limits of agreement between the two methods were +38% to -18% (relative). In neither the postural nor the volume study did delta (QS/QTO2) reliably predict delta (QS/QTTc)%. CONCLUSIONS: In pulmonary arteriovenous malformations the simple physiological shunt calculated from SaO2 breathing air agreed well with the anatomical right to left shunt measured with 99mTc-MAA, but predicted poorly the changes in anatomical shunt induced by postural or lung volume changes.

Adult↗
PubMed1981

Understanding pulmonary function tests.

Lung volume measurements include vital capacity, inspiratory capacity, expiratory reserve volume, functional residual capacity, residual volume, total lung capacity and tidal volume. Minute ventilation and forced vital capacity help to determine the patient's ability to move air. Other tests measure parameters such as diffusion across the alveolocapillary membrane and gas distribution. Combined with blood gas measurements, these tests are invaluable in the study of dyspneic patients and patients undergoing major surgery, in monitoring of pulmonary disease and in selection of therapy.

Humans↗
PubMed2003

Comparison of a new desktop spirometer (Spirospec) with a laboratory spirometer in a respiratory out-patient clinic.

BACKGROUND: The performance of spirometers is often evaluated under ideal conditions with computer-generated waveforms or in vivo testing with healthy subjects. Real-life conditions are less ideal because of comorbidities, age of the subjects, and a variety of air flow limitations. Evaluation of new spirometry equipment can also be performed under these less favorable conditions. The Spirospec is a new desktop spirometer that is commercially available, but its accuracy has not been evaluated in a clinical setting. OBJECTIVE: Test the Spirospec with subjects with normal and pathologic pulmonary function. METHODS: A group of 45 patients (mean age 38.4 years, 27 male) booked for evaluation in the pulmonary function laboratory of a tertiary care university hospital were tested with both a Spirospec and a standard Jaeger Masterlab 4.0 spirometer, according to the guidelines of the American Thoracic Society. Three subgroups (normal spirometry, obstructive air flow limitation, and restrictive air flow limitation) of 15 consecutive subjects each underwent spirometry. RESULTS: Pulmonary function measurements from the Spirospec correlated closely (r = 0.95-0.99) with those from the Masterlab 4.0, showing good limits of agreement and differences between the 2 devices: forced vital capacity 0.03 L, forced expiratory volume in the first second (FEV(1)) -0.01 L, peak expiratory flow -0.41 L/s, peak inspiratory flow 0.43 L/s, forced expiratory flow at 50% of total lung capacity 0.13 L/s, and forced expiratory flow at 75% of total lung capacity 0.12 L/s. With the exception of forced vital capacity and FEV(1), these differences were statistically significant (p < 0.05). CONCLUSION: The Spirospec is comparable to the Masterlab 4.0, with high accuracy for FEV(1) and forced vital capacity and clinically acceptable differences in the measured flow variables.

Adult↗
PubMed1994

Assessment of hyperinflation in children with cystic fibrosis.

BACKGROUND: Radiological estimates of hyperinflation are used in several clinical and radiographic scoring systems for cystic fibrosis, but it is not known if these estimates of hyperinflation are related to measured total lung capacity. METHODS: Comparison was made of independent clinical estimates of hyperinflation from chest radiographs with objective plethysmographic and radiographic measurements of total lung capacity in 25 children with cystic fibrosis. RESULTS: There was good agreement between plethysmographic and radiographic measurements. Clinical estimation correctly predicted the extremes of hyperinflation, but grading was no more than 50% accurate in all other groups. CONCLUSION: The degree of hyperinflation cannot be estimated by inspecting chest radiographs in many children with cystic fibrosis. This does not invalidate the scoring systems, but suggests that a better term than "hyperinflation" should be sought.

Adolescent↗
PubMed1993

Costal diaphragm curvature in the dog.

The curvature of the midcostal region of the diaphragm in seven dogs was determined at functional residual capacity (FRC) and end inspiration during spontaneous breathing and mechanical ventilation and at total lung capacity in the prone and supine positions. Metallic markers were attached to muscle fibers on the abdominal surface of the diaphragm, and the dog was allowed to recover from surgery. The three-dimensional positions of the markers were determined by biplane videofluoroscopy. A quadratic surface was fit to the bead positions. The principal axes of the quadratic surface lie nearly along and perpendicular to the muscle fibers. In both the supine and prone positions, the values of the principal curvatures were similar at FRC and end inspiration during spontaneous breathing, when muscle tension and transdiaphragmatic pressure both increase with increasing lung volume, and during mechanical ventilation and passive inflation to total lung capacity, when both decrease relative to their magnitude at FRC. No abrupt change of curvature, which might be expected at the edge of the zone of apposition, was apparent. The curvature along the muscle fiber was 0.35 +/- 0.07 cm-1; the curvature perpendicular to the muscle fiber was much smaller, 0.06 +/- 0.01 cm-1. The costal region of the diaphragm displaces and shortens as lung volume increases, but its shape, as described by its curvatures, does not change substantially.

Animals↗