Clinical Application of Pulmonary Function and Exercise Tests in the Management of Patients with Interstitial Lung Disease

Cardiopulmonary exercise testing in interstitial lung diseases and the value of ventilatory efficiency

Interstitial lung diseases (ILDs) are diverse parenchymal pulmonary disorders, primarily characterised by alveolar and interstitial inflammation and/or fibrosis, and sharing pathophysiological similarities. Thus, patients generally harbour common respiratory symptoms, lung function abnormalities and modified exercise adaptation. The most usual and disabling complaint is exertional dyspnoea, frequently responsible for premature exercise interruption. Cardiopulmonary exercise testing (CPET) is increasingly used for the clinical assessment of patients with ILD. This is because exercise performance or dyspnoea on exertion cannot reliably be predicted by resting pulmonary function tests. CPET, therefore, provides an accurate evaluation of functional capacity on an individual basis. CPET can unmask anomalies in the integrated functions of the respiratory, cardiovascular, metabolic, peripheral muscle and neurosensory systems in ILDs. CPET uniquely provides an evaluation of all above aspects and can help clinicians shape ILD patient management. Preliminary evidence suggests that CPET may also generate valuable prognostic information in ILDs and can be used to shed light on the presence of associated pulmonary hypertension. This review aims to provide comprehensive and updated evidence concerning the clinical utility of CPET in ILD patients, with particular focus on the physiological and clinical value of ventilatory efficiency (V˙_E/V˙_CO2 ).

The correlation of symptoms, pulmonary function tests and exercise testing with high-resolution computed tomography in patients with idiopathic interstitial pneumonia in a tertiary care hospital in South India

CONTEXT

For the follow-up of patients with idiopathic interstitial pneumonias (IIP), it is unclear which parameters of pulmonary function tests (PFT) and exercise testing would correlate best with high-resolution computed tomography (HRCT)..

AIM

To find out the correlation of symptom scores, PFTs and exercise testing with HRCT scoring in patients diagnosed as idiopathic interstitial pneumonia.

SETTINGS AND DESIGN

Cross-sectional study done in pulmonary medicine outpatients department of a tertiary care hospital in South India.

MATERIALS AND METHODS

Consecutive patients who were diagnosed as IIP by a standard algorithm were included into the study. Cough and dyspnea were graded for severity and duration. Pulmonary function tests and exercise testing parameters were noted. HRCT was scored based on an alveolar score, an interstitial score and a total score. The HRCT was correlated with each of the clinical and physiologic parameters. Pearson's/Spearman's correlation coefficient was used for the correlation of symptoms and parameters of ABG, PFT and 6MWT with the HRCT scores.

RESULTS

A total of 94 patients were included in the study. Cough and dyspnea severity (r = 0.336 and 0.299), FVC (r = -0.48), TLC (r = -0.439) and DLCO and distance saturation product (DSP) (r = -0.368) and lowest saturation (r = -0.324) had significant correlation with total HRCT score. Among these, DLCO, particularly DLCO corrected % of predicted, correlated best with HRCT score (r = -0.721)..

CONCLUSION

Symptoms, PFT and exercise testing had good correlation with HRCT. DLCO corrected % of predicted correlated best with HRCT.

Pulmonary impairment and disability

Respiratory disorders, including occupational and environmental lung diseases, are prevalent. Physicians are frequently called upon to determine impairment and aid in the assessment of disability caused by these conditions, either as the treating physician or as an independent medical examiner. In this article we reviewed the role of physicians in determining the presence and severity of pulmonary disorders. A comprehensive clinical assessment and appropriate standardized tests, to objectively characterize the severity of impairment, are the key elements of the evaluation. This assessment may also include the physician's opinion regarding causative factors. Finally, disability determination is made by nonclinicians, through administrative means, based on the degree of impairment and a review of circumstances specific to the individual. Knowledge of these components of disability evaluation will help physicians to better serve their patients and supply appropriate data to the adjudicating system.

Pulmonary function tests in interstitial lung disease: what role do they have?

Pulmonary function tests have been widely accepted and utilized in the management of interstitial lung diseases. Although the tests performed have changed little over the past several decades, extensive literature has been published highlighting their clinical role in the diagnosis, staging, prognostication, and follow-up of patients with a wide variety of interstitial lung diseases.

Pulmonary function tests at work

Occupational exposures remain an important cause of lung disease. A number of PFTs are used in the occupational setting, including spirometry, PEF recordings, methacholine challenge testing, lung volume, and DL(CO). These tests are used in a number of situations, including the clinical evaluation and management of patients with possible occupational lung disorders, preplacement and fitness-for-duty examinations, medical screening of exposed workers, impairment and disability evaluations, and research. The diagnosis of occupational lung disease has serious consequences for a worker and, in addition to a careful occupational history, usually requires objective assessment using PFTs. Serial PFTs are useful in following such patients and screening exposed populations of workers for respiratory conditions.

Single-breath carbon monoxide diffusing capacity

Measurement of DL(CO) remains a clinically useful way to assess transfer of gases across the lung. It is important, however, to be vigilant in controlling the sources of variation and to be aware of those that remain when interpreting the measured values.

The role of pulmonary function testing in pulmonary fibrosis

Interstitial lung diseases are characterized by disruption of the distal pulmonary parenchyma. The clinical history manifestations, cough and dyspnea, and physical exam manifestations, inspiratory crackles, are nonspecific. Pulmonary function testing aids in the evaluation and management of patients with interstitial lung disease although the pattern of abnormality is nonspecific. Pulmonary function testing can provide an estimate of histologic severity but not a definitive quantification of histologic fibrosis or inflammation. Pulmonary function tests can provide a baseline estimation of prognosis and be used to monitor disease progression or response to therapy. The forced vital capacity and diffusion capacity are the most valuable serial measurements, but further data are required to examine composite scoring and exercise gas exchange.

Idiopathic pulmonary fibrosis: current concepts

Idiopathic pulmonary fibrosis (IPF) is generally defined as a progressive, fibrosing inflammatory disease of the lung parenchyma of unknown cause. It is characterized by slowly increasing dyspnea, diffuse interstitial lung infiltrates, restrictive lung dysfunction, and impaired gas exchange. Ultimately, it is fatal in most patients, and treatment options remain unsatisfactory. The advent of high-resolution computed tomography of the chest and modifications in the histopathologic classification of interstitial pneumonias have reshaped the concept of IPF. Although initially thought to be a relatively specific clinicopathologic entity, it seems likely that IPF as previously defined is a heterogeneous disorder consisting of several clinicopathologic entities with differing histopathologic patterns, clinical course, response to therapy, and prognosis. The most common histologic pattern in cases previously defined as IPF is usual interstitial pneumonia, which is associated with a median survival of less than 3 years. For accurate prognosis and optimal management of patients, the clinician should attempt to be as precise as possible in distinguishing various clinicopathologic entities that have been included under the clinical heading of IPF. In the future, we recommend that the use of the term "idiopathic pulmonary fibrosis" be restricted to patients with usual interstitial pneumonia and that clinicians recognize the fact that other idiopathic interstitial pneumonias do not have the same prognostic effect traditionally ascribed to IPF.

Idiopathic pulmonary fibrosis: predicting response to therapy and survival

Idiopathic pulmonary fibrosis (IPF) is associated with significant morbidity and mortality despite aggressive therapy. Thirty-eight patients with biopsy-proven IPF were studied to identify pretreatment features that could be used to predict short-term improvement in pulmonary function and improved longer term survival. In all patients, a pretreatment clinical (dyspnea), radiographic (chest radiograph), and physiologic (pulmonary function including exercise saturation) score was generated (CRP). A high-resolution CT scan (HRCT) was independently scored by four radiologists for ground glass (CT-alv) and linear opacity (CT-fib) on a scale of 0-4. Open lung biopsy samples were scored for cellular infiltration, interstitial fibrosis, desquamation, and granulation by an experienced pulmonary pathologist. All patients were treated with 3 mo of high-dose steroids and the CRP scoring repeated. Patients were divided into three groups: responders with a greater than 10-point drop in CRP (n = 10); stable with +/- 10 point change in CRP (n = 14); and nonresponders with > 10 point rise in CRP or death (n = 14). Those responding to steroids were treated for 18 mo in a tapering fashion. In all others, steroids were tapered quickly and oral cyclophosphamide prescribed. Responders (10 of 38) had a lower age (45.1+/-4.3 yr) than nonresponders (61.4+/-3.5 yr) or those remaining stable (53.1+/-3.3 yr) (p = 0.01). Pretreatment CRP was higher in responders (58.8+/-5.6) than nonresponders (40.5+/-4.7) or stable individuals (37.6+/-4.7) (p = 0.01). Cellular infiltration score of the open lung biopsies was higher in responders (7.6+/-0.6) than stable individuals (5.7+/-0.5) (p = 0.04). The CT-alv scores were higher and CT-fib scores were lower in responders than nonresponders. Receiver operating curve (ROC) analysis was employed to identify pretreatment features of longer term survival (follow-up of 29.1+/-2.3 mo). Only CT-fib (p = 0.009) and pathology fibrosis score (p = 0.03) were able to predict mortality. A pretreatment CT-fib score > or = 2.0 demonstrated 80% sensitivity and 85% specificity in predicting survival. Those patients who did not respond to initial steroid therapy demonstrated a worse long-term survival and greater likelihood of decreased pulmonary function. We demonstrate that pretherapy pulmonary function, pathologic and radiographic parameters are different in individuals who respond to initial prednisone therapy. Only HRCT imaging and pathologic fibrosis were able to reliably predict long-term survival in patients with biopsy-proven IPF.

Management and outcome of pregnant women with interstitial and restrictive lung disease

OBJECTIVE

Our purpose was to describe our experience with management and outcome of restrictive lung disease in pregnancy.

STUDY DESIGN

Between 1981 and 1994 nine pregnant women with interstitial and restrictive lung disease were prospectively managed and delivered at the University of Washington Medical Center.

RESULTS

Three patients had severe disease, characterized by vital capacity < or = 1.5 L (50% predicted) or diffusing capacity < or = 50% predicted. Five patients had exercise-induced oxygen desaturation, and four required supplemental oxygen. Five patients required corticosteroids. One patient had an adverse outcome; she was delivered at 31 weeks and required mechanical ventilation for 72 hours. All other patients were delivered at or beyond 36 weeks with no adverse intrapartum or postpartum complications. All babies were at or above the 30th percentile for growth.

CONCLUSIONS

Restrictive lung disease is tolerated in pregnancy. Exercise intolerance is common and patients may require early oxygen supplementation. Adequate fetal growth can be achieved.