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Table 1: Indications for spirometry. |
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Diagnosis1 • In suspected COPD: – Presence of post-bronchodilator FEV1/FVC < LIN or Z-score with symptoms and risk factors6,7 • In suspected asthma: – It helps during the diagnostic process to document FEV1/FVC below LIN, especially if it reverses post-bronchodilator. Also an increase of > 400 mL post-bronchodilator in FEV1 or FVC – Repeated spirometry (or PEF) in occupational settings may suggest occupational asthma that worsens at work and improves outside of work – If FEV1 increases more than 12% and 200 mL from pre-bronchodilator value or from baseline after four weeks of anti-inflammatory therapy8 – In suspected severe asthma, one of the criteria is the presence of pre-bronchodilator FEV1 < 80% pred (or ≤ 1.64 in Z-score)9 • In suspicion of other respiratory pathology with one or more of the following data:1 – Symptoms: dyspnoea, cough, wheezing, stridor – Signs: rales, thoracic deformity – Abnormal laboratory and laboratory studies: hypoxaemia, hypercapnia, polycythaemia, abnormal chest X-ray • Assessment of pulmonary impact of systemic disease:1 – In any patient with suspected ILD – In any patient with neuromuscular disease and suspected respiratory muscle weakness (SVC may be a better indicator of respiratory muscle weakness than FVC as it is not affected by the coexistence of airflow obstruction)10,11 – Difference > 10% in FVC performed in the sitting-supine position (FVC delta) suggests diaphragmatic weakness; unilateral diaphragmatic paralysis may have delta between 15-25% and bilateral up to 50%12 • Screening: – Not indicated in screening asymptomatic subjects without risk factors13,14 – It is indicated in the intentional search for cases: presence of respiratory symptoms or signs and risk factors (> 35 years and smoking rate > 10 p-a, occupational or occupational exposure to biomass or toxic substances)15 – Decreased FEV1 is a cardiovascular risk factor independent of age, sex and smoking16 • Preoperative risk assessment:1,17 – Respiratory function tests have not been shown to be superior to anamnesis and physical examination in predicting postoperative pulmonary complications in the absence of symptoms and risk factors – Perform in suspected lung disease without prior diagnosis and in procedures close to the diaphragm (thoracic or upper abdominal surgery) – Indispensable before lung resection and transplantation surgery |
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Follow-up1 • Response to therapeutic interventions in lung disease • Prognosis of already diagnosed lung disease:1 – In COPD, at least once a year to identify ‘rapid decliners’ (FEV1 drop > 50-90 mL/year)7,18 – In asthma, at the start of treatment, 3 to 6 months after achieving control (better lung function) and periodically8 – The presence of FEV1 < 60% pred and/or a very significant response to BD in asthmatic patients (even if asymptomatic or with few symptoms) are risk factors for crises8 – In CF, at the start of treatment and every 3 months to identify the pattern of lung function decline19 – The presence of persistent FEV1 < 40% pred in patients with CF is a criterion for advanced lung disease20 – In interstitial lung diseases (of any aetiology) at least during the first 2 years of diagnosis, as it identifies progressive fibrosing phenotype: fall in FVC ≥ 10% or fall in FVC between 5 and 10% and worsening of respiratory symptoms and/or extension of fibrosis on HRCT21 – In muscular dystrophies; if the patient is still walking and < 12 years old, annual is recommended. If the patient is > 12 years, wheelchair user or has an FVC < 80% pred, every 6 months is recommended (FVC < 40% pred is indication for volume recruitment manoeuvres and assisted cough and FVC < 30% pred for non-invasive mechanical ventilation)22-24 • Assessment of functional status during and after an exacerbation of the underlying lung disease:1 – The presence of FEV1 < 60% pred in a patient with an asthma flare-up after 48 hours of inhaler titration is an indication for initiation of OCS8 • Occupational monitoring of subjects exposed to noxious agents:1 – Recommended on admission and annually thereafter. An excessive fall in FEV1 identified by any of the following methods: % from baseline (> 15%), limit of longitudinal decline or linear regression suggests further evaluation of the worker18 • During or after the use of drugs with known pulmonary toxicity: – Patients on chemotherapy regimen (bleomycin, gemcitabine, paclitaxel, platinums, cyclophosphamide, doxorubicin). The presence of a spirometric pattern suggestive of restriction usually occurs in advanced cases, so it is suggested to perform serial DLCO in conjunction with spirometry25 |
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• Disability assessment1 – Admission to rehabilitation programmes – Initial assessment by insurers for risk of respiratory pathology – Initial assessment of lung health in physically demanding occupations – Medico-legal assessments |
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• Other1 – Clinical research – Epidemiological studies – Generation of population reference equations – Assessment of health status prior to strenuous physical activity – General routine respiratory assessment |
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COPD = chronic obstructive pulmonary disease. FEV1 = forced expiratory volume in the first second. FVC = forced vital capacity. %pred = predicted percentage. SVC = slow vital capacity. p-a = pack year. BD = bronchodilator. CF = cystic fibrosis. HRCT = high-resolution tomography. OCS = oral corticosteroids. DLCO = pulmonary diffusion of carbon monoxide. LLN = lower limit of normal. |