Routine Pulmonary Function Tests Research Articles

Preoperative and Postoperative Abnormalities in Chest X-ray Indices and in Lung Function in Pectus Deformities

In 88 patients with pectus deformities radiologic chest indices and routine pulmonary function tests were measured before and 1 to 20 years after corrective surgery. A combination of anteroposterior indices at the upper and lower level of the chest were investigated to quantitate and to discriminate the different pectus deformities. The study comprised four groups: pectus excavatum, pectus carinatum, pectus deformatum and pectus excavatum with scoliosis. These indices were also assessed in 250 healthy males and females. Generally, several indices showed significant and discriminative changes in the different patient groups and improved again after surgery. Preoperative lung function was decreased in pectus excavatum only. In all groups lung function worsened after surgery. A stepwise discriminant analysis performed on the large group with pectus excavatum indicated that postoperative lung function was decreased if the preoperative value of FEV1 or VC was more than about 75 percent predicted and vice versa, but that it was not related to other factors such as radiologic indices, age at operation or time since operation.

Effect of effort versus volume on forced expiratory flow measurement.

Recently, the validity of the American Thoracic Society (ATS) standards for selection of spirometric test results has been questioned based on the finding of inverse dependence of FEV1 on effort. I carried out a study to determine how the test results of FEV1 and FEF25-75 are affected by use of effort-based criteria (highest PEFR) as compared with the volume-based criteria (largest FVC, largest sum of FVC and FEV1-ATS criteria). Randomly sampled routine pulmonary function test results obtained from 10 normal subjects and 12 patients with COPD were analyzed. Although selection based on the largest FVC yielded test results identical to that obtained by the ATS criteria, selection based on the highest PEFR resulted in a decline of mean FEV1. The latter, however, was accompanied by an even more significant decrease of FVC, suggesting bias of this criterion toward selecting the maneuvers with lower FVC. Furthermore, the individual values of FEV1 were often found to decrease with effort only when the accompanying FVC were also lower. In contrast, FEF25-75 were more prominently affected by the negative effect of effort regardless of the values of accompanying FVC. It appears that fully inflated lungs (the largest FVC) favorably shift the balance of two opposing influences of effort, one of which positively acts on the effort-dependent portion of the flow-volume curve. FEV1 thus is little affected by effort once the lungs are fully inflated. Accordingly, the volume-based selection criteria remain valid. This argument does not apply to FEF25-75, which is prominently affected by the negative effect of effort.

Tests of Respiratory Muscle Function

Respiratory muscle strength and endurance should be assessed when dyspnea, respiratory failure, or poor performance on routine pulmonary function tests are unexplained. Respiratory muscle strength can be measured non-invasively from maximal mouth pressures, but measurement of transdiaphragmatic pressure refines the assessment. The maximal voluntary ventilation test is the only simple index of ventilatory or respiratory muscle endurance. Other tests for endurance and fatigue are more difficult, but some newer techniques may be applicable to the clinical laboratory. Some patients who exhibit tachypnea, marked use of neck inspiratory muscles, and chest-abdomen asynchrony may be developing respiratory muscle fatigue.

A standardised comment scheme for routine pulmonary function test results

Observed values of ventilatory capacity, gas transfer and lung volumes in 840 patients were used to formulate a standardised scheme of descriptive comments. Response to bronchodilators was also difined. Absolute differences between measured and predicted values are used to identify normal and abnormal patterns of results, together with an overall pattern. The algorithms are suitable for computer use. The scheme has been in routine manual use for four years and can be used by any laboratory in which the necessary quality control standards are applied.

Flow-volume loop changes reflecting respiratory muscle weakness in chronic neuromuscular disorders

In order to identify the changes in pulmonary function and in the flow volume loop due to respiratory muscle weakness, two groups of 10 nonsmokers with stable, chronic neuromuscular disease but without respiratory symptoms were studied: one without (Group 1) and one with (Group 2) respiratory muscle weakness as assessed by measurement of maximal static inspiratory and expiratory pressures. In Group 1, pulmonary function was normal except for increased ratio of one second forced expiratory volume to forced vital capacity and forced expiratory flow at 25 to 75 percent forced vital capacity, which may reflect increased elastic lung recoil. Group 2 had mild volume restriction, appropriate for the degree of respiratory muscle weakness, and reduced inspiratory and expiratory flow rates. Pulmonary function was significantly more disturbed in Group 2 than in Group 1, and correlated well with maximal static inspiratory and expiratory pressures. Analysis of the flow-volume loop configuration revealed that four parameters describing effort-dependent portions were significantly related to maximal static inspiratory pressure and maximal static expiratory pressure. These parameters were peak expiratory flow, the slope of the ascending limb of the maximal expiratory curve, a drop of forced expiratory flow near residual volume, and forced inspiratory flow at 50 percent of vital capacity. A flow-volume loop score obtained from these four parameters was significantly higher in Group 2 than in Group 1 (2.8 ± 1.03 versus 1.1 ± 1.37; p <0.01). A flow-volume loop score of 2 or more had 80 percent specificity and 90 percent sensitivity in predicting respiratory muscle weakness in these patients with chronic neuromuscular disease. These data suggest that sensitive assessment of the flow-volume loop configuration as part of routine pulmonary function testing may help to suspect and identify respiratory muscle weakness.

Practical problems in the respiratory care of patients with muscular dystrophy.

THE muscular dystrophies comprise several groups of inherited disorders with a wide variation between the groups in the distribution and severity of muscle involvement.1 The respiratory muscles, in common with other skeletal muscles, are affected in all types of muscular dystrophy, so that patients have an increased risk of respiratory complications and premature death.2 Respiratory insufficiency often remains covert because impaired skeletal-muscle function prevents patients from exceeding their limited ventilatory capacity; however, it can easily be detected with routine pulmonary-function tests. The case for regular pulmonary assessment in neuromuscular disease has recently been cogently argued in the Journal.3 The . . .

Relationship between the result of preoperative pulmonary function test and postoperative pulmonary complications.

Good preoperative screening and evaluation of patients undergoing surgery is necessary because it serves to identify the individual who is at risk of increased intra-operative and postoperative morbidity and mortality. The retrospective study was done in an attempt to determine if abnormalities in preoperative pulmonary function, detected by routine pulmonary function tests, would predict which patients would suffer from pulmonary complications following surgery. Pulmonary complications in the postoperative period included fever, atelectasis and respiratory failure. The overall incidence of pulmonary complications from our 78 patients undergoing surgery was 37 percent based on clinical criteria. This incidence was high in patients with FEV1 less than 1.0 L/sec, MVV less than 40% of predicted value and PCO2 more than 45 mmHg.

What are the implications of high pulmonary compliance?

We studied 19 patients with abnormally high static lung compliances, which had been discovered during a routine pulmonary function test, changes in elastic lung properties and smoking habits after 4 years. We did not observe, as is usually reported in the literature, that cessation of smoking normalizes lung compliance. A falsely normalized lung compliance may be due to lung zones that cease to ventilate. High lung compliances in nonsmoking patients, without clinical and radiological pulmonary abnormalities, are not always pathological but must be supervised.

Partial and Maximal Expiratory Flow-Volume Curves in Normal and Asthmatic Subjects Before and After Inhalation of Metaproterenol

The effects of deep inspiration upon expiratory flow rates and response to inhaled metaproterenol were studied in normal and asthmatic subjects using partial (PEFV) and maximal (MEFV) expiratory flow volume curves. Routine pulmonary function tests and specific conductance were also measured. Prior to administration of metaproterenol, 18 of 24 normal subjects and 11 of 24 asthmatic subjects (p 0.05) had higher flow rates on MEFV than on PEFV curves. The 11 volume history responsive asthmatic subjects showed better lung function and more density-dependence of expiratory flow than the other 13 asthmatic subjects; furthermore, the effect of lung inflation was significantly larger in the volume history responsive asthmatic subjects than in the volume history responsive normal subjects. Responses to inhaled metaproterenol were much larger on PEFV than MEFV curves; nevertheless, differences between normal and asthmatic subjects in metaproterenol responsiveness were less using PEFV curves. Thus, the use of PEFV curve measurement did not facilitate the detection of individual asthmatic responses to inhaled metaproterenol.

Moment analysis of multibreath nitrogen washout in young children.

The purpose of this study was to determine whether on-line computerized moment analysis of multibreath N2 washout (MBNW) could be used as a method of estimating lung function in children too young to cooperate with routine pulmonary function testing. The limits of normal variability were determined from results obtained from duplicate studies performed on 36 healthy children ages 3-6 yr. Five healthy adults were studied for comparison. Test sensitivity was estimated by comparing the results in the healthy group to those of 10 age-matched children with cystic fibrosis (CF). Outcome variables of interest included functional residual capacity, the first-to-zeroth moment ratio (M1/M0), the second-to-zeroth moment ratio (M2/M0), and the lung clearance index. Test precision in the healthy group was high with the intrasubject coefficient of variation for all variables being less than 10%. There was no difference in mean within- or among-subject variability between the healthy children and the older, theoretically more cooperative, healthy adults. Mean M1/M0 and M2/M0 were both higher in CF than in the healthy group, 2.69 vs. 2.32 and 13.04 vs. 9.31, respectively (P less than 0.001). Moment ratios in CF showed good negative correlations with Shwachman scores; thus those CF patients with the most advanced lung disease had the highest moment ratios and vice versa. Moment analysis of MBNW has promise as a means of quantifying lung function in young children, since the method is noninvasive, low in inherent variability, requires only quiet breathing, and has the sensitivity required to detect rather mild ventilation inhomogeneity.

Exercise Capacity as a Predictor of Post-thoracotomy Morbidity1–3

Although severe impairment on routine pulmonary function tests will identify patients with a high post-thoracotomy morbidity, cardiopulmonary complications often develop in patients with only a mild-to-moderate impairment in pulmonary function. To determine whether the preoperative exercise capacity can prospectively identify those at risk of developing complications, 22 patients scheduled for thoracotomy (mean age, 55.7 +/- 2 yr) underwent an incremental exercise test on a cycle ergometer to determine their maximal O2 uptake (VO2max) prior to thoracotomy. Routine pulmonary function tests were performed and postoperative forced expiratory volume in one second (FEV1) was predicted from split function perfusion lung scan in all subjects. Eleven of the 22 patients had no cardiopulmonary complications postoperatively. The age, history of prior cardiovascular disease, degree of impairment on routine pulmonary function tests, and predicted postoperative FEV1 were similar in those who did and those who did not experience complications. However, those without complications had a significantly higher VO2max than did those who experienced complications (22.4 +/- 1.4 versus 14.9 +/- 0.9 ml/kg/min, p less than 0.001). Only 1 of 10 patients with a VO2max greater than 20 ml/kg/min had a complication, whereas all 6 patients with a VO2max less than 15 ml/kg/min had a complication. We conclude that exercise testing is a useful adjunct in the evaluation of operative risk for thoracotomy.

The 12-min walking distance; its use in the pre-operative assessment of patients with bronchial carcinoma before lung resection.

The 12-min walking distance was measured as part of the pre-operative evaluation of 30 patients with carcinoma of the bronchus consecutively admitted to hospital for lung resection. Of the 22 who had a resection, 7 suffered post-operative ventilatory complications. There was no significant difference in distance walked, both in absolute terms and when standardised for effort, between these patients and the 15 who did not suffer post-operative complications. The empirically derived level of maximum separation between the complication and non-complication groups was in the region of 1,100 m. This approach also failed to provide significant separation between the two groups. Significant separation was achieved by discriminant analysis of simple pulmonary function tests but this separation was not enhanced by entry of values from the 12-min walk into the analysis. These results suggest that there is little to be gained from adding exercise testing to routine pulmonary function tests in pre-operative assessment before lung resection, and that the use of exercise tolerance as a final arbiter of fitness for operation should be viewed with caution.

Serial Pulmonary Function in Patients With Acute Heart Failure

This study delineates the effects of congestive heart failure on routine pulmonary function tests and assesses the changes in pulmonary function as congestive heart failure was treated. Twenty-eight patients had spirometry, lung volumes, and diffusing capacity measurements initially and at frequent intervals after their initial hospitalization for congestive heart failure. Initially the patients had both obstructive (mean forced expiratory volume in 1 s [FEV1], 48.2% +/- 13% predicted) and restrictive (mean forced vital capacity [FVC], 5.6% +/- 15.7% predicted) ventilatory dysfunction, but a normal carbon monoxide diffusing capacity. With treatment, pulmonary function rapidly improved initially and there was no further significant improvements in the mean pulmonary function after two weeks of treatment. However, there was marked interindividual variability and several patients took months to reach their best level of pulmonary function. Even with treatment, the patients retained evidence of obstructive ventilatory dysfunction and at the time of their best spirometry 53% (8/15) of nonsmokers still had an abnormally low FEV1/FVC ratio.

Role of Pulmonary Function Tests in the Prevention of Bleomycin Pulmonary Toxicity During Chemotherapy for Metastatic Testicular Teratoma

Thirty-eight men were treated for metastatic teratoma with up to four courses of chemotherapy, each containing 90 mg bleomycin. Routine pulmonary function tests (PFTs) were performed before each course to assess their value in detecting bleomycin pulmonary toxicity. PFTs were repeated 2-5 yr after completion of chemotherapy in 10 disease-free survivors. Analysis of changes in individual PFT values showed a fall in the carbon monoxide diffusing capacity (DLco) after 90 mg bleomycin (P less than 0.005). The DLco remained depressed with subsequent doses of bleomycin, but there was no further statistically significant fall. There was no significant change in any other PFT. Similarly, late PFT values showed no significant change. There was no correlation between changes in the visible extent of metastases as assessed from the chest radiography and changes in serial PFTs. It is concluded that routine PFTs are unnecessary if the total bleomycin dose in less than or equal to 360 mg, unless there are particular risk factors. Late drug-induced pulmonary damage is unlikely to develop after treatment withdrawal.

The Interstitial Lung Diseases

The interstitial lung diseases are a heterogenous group of diseases grouped together because of common clinical, roentgenographic, physiologic, and pathologic features. 1 Fulmer JD Crystal RG Interstitial lung diseases. in: Simmons DE Current pulmonology. Houghton-Mifflin Publishers, Boston1979: 1-65 Google Scholar , 2 Weinberger SE Kelman JA Elson NA Young RC Reynolds HY Fulmer JD et al. Bronchoalveolar lavage in interstitial lung disease. Ann Intern Med. 1978; 89: 459-466 Crossref PubMed Scopus (151) Google Scholar , 3 Crystal RG Gadek JE Ferrans VJ Fulmer JD Line BR Hunninghake GW Interstitial lung disease: current concepts of pathogenesis, staging and therapy. Am J Med. 1981; 70: 54-67 Abstract Full Text PDF Scopus (344) Google Scholar , 4 Crystal RG Roberts WC Hunninghake GW Gadek JE Fulmer JD Line BR Pulmonary sarcoidosis: a disease characterized and perpetuated by activated lung T-lymphocytes. Ann Intern Med. 1981; 94: 73-94 Crossref PubMed Google Scholar Most patients present with insidious breathlessness and have a diffuse infiltrative pattern on chest roentgenogram (Fig 1A). Not uncommonly, an isolated reduction in carbon monoxide diffusing capacity (Dco) on routine pulmonary function testing is the first indication of underlying interstitial disease. The pathology of these diseases is characterized by an inflammatory cellular infiltration and an apparent increase in connective tissue of alveolar septae; in some, there are inflammatory cells within alveolar airspaces (Fig 1B). Many of the interstitial diseases also have disease of airways, pulmonary vasculature, and sometimes pleural disease. 1 Fulmer JD Crystal RG Interstitial lung diseases. in: Simmons DE Current pulmonology. Houghton-Mifflin Publishers, Boston1979: 1-65 Google Scholar , 3 Crystal RG Gadek JE Ferrans VJ Fulmer JD Line BR Hunninghake GW Interstitial lung disease: current concepts of pathogenesis, staging and therapy. Am J Med. 1981; 70: 54-67 Abstract Full Text PDF Scopus (344) Google Scholar , 4 Crystal RG Roberts WC Hunninghake GW Gadek JE Fulmer JD Line BR Pulmonary sarcoidosis: a disease characterized and perpetuated by activated lung T-lymphocytes. Ann Intern Med. 1981; 94: 73-94 Crossref PubMed Google Scholar

Role of pulmonary function tests in the prevention of bleomycin pulmonary toxicity during chemotherapy for metastatic testicular teratoma

Thirty-eight men were treated for metastatic testicular teratoma with up to four courses of chemotherapy, each containing 90 mg bleomycin. Routine pulmonary function tests (PFTs) were performed before each course to assess their value in detecting bleomycin pulmonary toxicity. PFTs were repeated 2–5 yr after completion of chemotherapy in 10 disease-free survivors. Analysis of changes in individual PFT values showed a fall in the carbon monoxide diffusing capacity (DL CO) after 90 mg bleomycin ( P < 0.005). The DL CO remained depressed with subsequent doses of bleomycin, but there was no further statistically significant fall. There was no significant change in any other PFT. Similarly, late PFT values showed no significant change. There was no correlation between changes in the visible extent of metastases as assessed from the chest radiograph and changes in serial PFTs. It is concluded that routine PFTs are unnecessary if the total bleomycin dose is ≤ 360 mg, unless there are particular risk factors. Late drug-induced pulmonary damage is unlikely to develop after treatment withdrawal.

Hidden asthma in childhood.

An unusual manifestation of asthma occurred in 11 children who had chronic cough and no wheezing. Initial, routine pulmonary function tests gave normal results in most cases. The diagnosis of asthma was confirmed by an exercise provocation test in ten children and/or a successful therapeutic trial with bronchodilators. The asthma in these cases had previously remained undiagnosed (hidden) for years, during which time the patients were treated unsuccessfully with antibiotics, antitussives, and antihistamines. Earlier diagnosis of this asthmatic illness assisted by exercise provocation testing will result in more effective management.

Measurement of oxygen consumption and carbon dioxide production rates by a tracer-bolus method.

A new method for measuring oxygen consumption and carbon dioxide production is described. The method is based on the injection of a helium bolus into the inspired gas for repeated breaths; the helium can be delivered through the mouth or through a nostril (the injection system being controlled by the integrated flow signal or by the signal of a thermistor, respectively). Compared with the conventional gas-collection technique, the tracer-bolus method allows more rapid and frequent measurements. The method does not necessarily require an airtight respiratory circuit, so that it can be conveniently applied in less cooperative subjects, including children. The results of validation studies based on a comparison with the standard gas-collection technique are presented; these results indicate that the measurements by the tracer-bolus method are accurate in normal subjects. In patients with obstructive lung disease, the determinations are associated with a systematic error, which is expected, the tracer-bolus method being based on a single-compartment, uniformly ventilated and perfused lung model; the error is, however, predictable from the degree of functional impairment and can be corrected using equations based on routine pulmonary function tests.

Effects of Breathing Retraining in Patients With Chronic Obstructive Pulmonary Disease

Subjects with severe chronic obstructive pulmonary disease (COPD) were studied to evaluate the effects of breathing retraining (BRT) on exercise tolerance. Twenty-two subjects exercised on a treadmill three times weekly for six weeks. Twelve of the subjects (controls) then exercised for three more weeks; the other ten subjects received three more weeks of exercise reconditioning plus BRT. Results of routine pulmonary function and exercise tests were similar in both groups at the beginning of the study and after six weeks of exercise. However, in the last three weeks of the study, increments in exercise performance were significantly greater in the BRT subjects than in controls (P less than .002). Following BRT, respiratory rate during exercise decreased (P less than .005) and tidal volume and PaO2 during exercise increased (P less than .05). Thus, these data suggest that BRT increases exercise performance in subjects with severe COPD.

Functional correlates of lung involvement in Wegener's granulomatosis: Use of pulmonary function tests in staging and follow-up

To examine the usefulness of pulmonary function testing in the clinical management of patients with Wegener's granulomatosis, 22 subjects with biopsy proved disease were evaluated using routine functional parameters. Although reduced lung volumes and diffusing capacity occurred frequently, the most common abnormality was in obstruction to airflow. Comparison of these functional parameters with roentgenographic and clinical findings revealed that reduced lung volumes were useful in detecting focal infiltrates, mass or cavitary lesions and diffuse interstitial involvement whereas airflow measurements were useful in detecting focal large airway lesions. In people with evidence of limitation of airflow, respiratory complications frequently developed in the form of acute tracheal obstruction or lobar collapse. In addition, serial evaluation of lung function during treatment revealed that although in most patients lung volumes and airflow obstruction improved or stabilized, a reduction of diffusing capacity was common. These studies suggest that routine pulmonary function testing may be a useful tool in the staging of patients with Wegener's granulomatosis and in following responses to therapy.