Spirometry in Chronic Obstructive Lung Disease (COPD)

1 22 SUPPLEMENT TO JAPI FABRUARY 2012 VOL. 60. Spirometry in Chronic Obstructive Lung Disease ( copd ). Vinaya S Karkhanis*, JM Joshi*. Introduction Respiratory Society guidelines (ATS/ERS guidelines) are used for acceptable and reproducible Factors such as cough, T he common criterion recommended for diagnosis of Chronic Obstructive lung Disease ( copd ) is demonstration of progressive irreversible airway obstruction on Spirometry . variable effort, sudden cut off, slow start, inconsistent effort are some of the criteria that may result in fallacies. Spirometry is useful in copd for the following: The Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) has recommended Spirometry as the gold standard for Diagnosis diagnosis of copd . However, Spirometry is not widely available Assessment of severity and spirometric test results are not always optimally recorded or Assessment of response to therapy interpreted except when performed by experienced personnel. Assessment of lung age Experts have differed on spirometric criteria for diagnosis of copd .

2 GOLD1 now recommends that post bronchodilator Detection of upper airway obstruction forced expiratory volume in 1 second/forced vital capacity Pre-operative pulmonary evaluation (FEV1/FVC) ratio of < must be used for diagnosing copd . Demonstration of irreversible airway obstruction absence Diagnosis of bronchodilator reversibility is no more required for diagnosis A typical spirogram (volume versus time recoding) and of copd . Although there is now a consensus; spirometric criteria flow volume loop FVL (flow rate versus volume recording). continue to have limitations. The simplification of Spirometry in copd is as shown in Figures 1 and 2. The interpretation of criteria by GOLD experts is perhaps to encourage Spirometry obstruction in the Spirometry report however remains highly for diagnosis of copd in primary-care settings controversial. The current diagnostic criterion for airflow However; widespread spirometric testing has resulted in a obstruction in copd is a post bronchodilator ratio of FEV1/.

3 Large number of individuals without respiratory symptoms, FVC <70%. Although copd cases usually have no or poor labeled as On the other hand physicians continue to bronchodilator reversibility (Exercise 1), it is well known and diagnose copd based solely on symptoms. Individuals with recognized by GOLD guidelines that some cases may show symptoms but normal Spirometry were earlier included good bronchodilator reversibility (Exercise 2). The predicted as at risk for copd . The revised GOLD guidelines do not FEV1/FVC ratios decrease progressively with age in A. include this group as there is incomplete evidence that these fixed FEV1/FVC ratio thus overestimates airway obstruction in cases always progress to copd . The United States Preventive the elderly and underestimates it in young ,8 Obstructive Services Task Force, an independent panel of experts in primary abnormality is most accurately diagnosed when a reduced care and prevention that systematically reviews the evidence FEV1/FVC ratio is below lower limit of normal (LLN) the of effectiveness and develops recommendations for clinical 5th percentile of the predicted The post-bronchodilator preventive services suggest Spirometry evaluation in a person reference values that are required for accurate interpretation of presenting with shortness of breath, Chronic cough, increased Spirometry have not yet been False normalization of sputum production, wheezing, and/or a family history of the FEV1/FVC ratio that occurs due to a greater reduction in FVC.

4 Alpha1-antitrypsin A combination of symptoms and caused by air trapping in severe airway obstruction may result Spirometry may therefore be a more relevant way of diagnosing in a tendency to diagnose a restrictive ventilatory abnormality copd in individuals exposed to the causative factor. and thus more severe cases being missed (Exercise 3). Therefore Role of Spirometry in copd requires basic understanding Spirometry -based diagnosis of copd and the one size fits all . of Spirometry , its importance in the management of copd spirometric criteria are with knowledge of how to perform Spirometry correctly and its copd patients have an inability to perform a complete or interpretation (Chart). American Thoracic Society and European adequate exhalation, resulting in an underestimate of FVC and Chart: Interpretation of Spirometric Data Volume Volume in liters in liters Time in Seconds Time in Seconds Normal Obstructive abnormality Normal *. Department of Pulmonary Medicine, **Professor and Head, Dept Restrictive abnormality of Pulmonary Medicine, TN Medical College, BYL Nair Hospital, Obstructive abnormality Mumbai 400 008.

5 Fig. 1 : Graphic display of volume versus time spirogram (obstruction in copd dotted lines). Restrictive abnormality SUPPLEMENT TO JAPI FeBRUARY 2012 VOL. 60 23. Flow volume loop Test Predicted Before After Improvement bronchodilator Bronchodilator FVC FVC% 79% 93%. FEV1 +34%, 300ml FEV1% 54% 73%. FEV1/FVC 50% PEFR 476 280 320. Exercise 2: Spirometry of a 60 year old man, Chronic smoker with smoking index of 16 pack years presented with history of Chronic Flow rates airway obstruction showing Obstructive abnormality with good L / sec bronchodilator reversibility. Test Predicted Before After Improvement bronchodilator Bronchodilator Volume in litres FVC FVC% 35% FEV1 10%,16ml FEV1% 55% 57%. FEV1/FVC 90% 96%. PEFR 351 422. Exercise 3: Spirometry of a 50 yr old man, 40 pack years bidi smoker presented with Chronic airway obstruction of 15 years duration Normal showing false normalization of the FEV1/FVC ration, low FVC is related to air trapping. Obstructive abnormality Restrictive abnormality severe <30, rule of 30-50-80 (Table 1).

6 Airway obstruction in copd can be variable which is based on varying degree of smooth Fig. 2 : Flow volume loop (obstruction in copd - dotted lines). muscle contraction. This can be reversed by administering an Test Predicted Before After Improvement inhaled bronchodilator. Hence, the GOLD criteria for copd . bronchodilator Bronchodilator are based on post bronchodilator reversibility values. Also FVC there is no need for the patient to stop regular treatment prior FVC% 46% 51% to post bronchodilator spirometric measurements. copd being FEV1 12%, 80ml progressive Disease leads to worsening of lung function over time. The normal decline of FEV1 ie 30 ml/year gets accelerated in FEV1% 21% 23%. copd patients to 75 to 100 The rate of decline in FEV1. FEV1/FVC 37% 37%. is influenced by number of Thus, FEV1 correlates PEFR 801 266 249. poorly to all the things that matter to patients: symptoms, quality Exercise 1: Spirometry of a 55 year old man, smoker with smoking of life, exacerbation frequency, and exercise copd .

7 Index of 24 pack years and history of Chronic airway obstruction is now recognized to have systemic manifestations that are not showing Obstructive abnormality with poor post bronchodilator reflected by the FEV1. Hence, a simple multidimensional grading reversibility. system the BODE (body mass index, obstruction, dyspnoea, and overestimate of FEV1: FVC ratio. For this reason the measurement exercise tolerance) index16 (Table 2)) has been used to assess of the forced expiratory volume in 6 seconds (FEV6) has been the respiratory and systemic expressions of copd . The BODE. advocated along with the FEV1 In such patients staging system also helps to better predict hospitalization for additional useful information can be obtained by measuring copd . the subdivisions of lung volume. The primary measurement is functional residual capacity (FRC) with a slow vital capacity Assessment of Reversibility with maneuver, and estimation of other lung volumes. Elevated ratio of residual volume (RV) to total lung capacity (TLC) Aerosolized Bronchodilators suggests airflow obstruction.

8 The diffusing capacity of the ATS/ERS guidelines significant reversibility is considered lung for carbon monoxide (DLCO) decreases in the presence of to be an increase in FEV1 of 200ml and 12% after 15 minutes emphysema. Small airway function in copd can be assessed of bronchodilator therapy. Bronchial asthma shows good with the measurement of airway resistance (Raw) using body reversibility with bronchodilators whereas copd often shows plethysmography and total respiratory system resistance (Rrs) poor reversibility. Therefore, traditionally, reversibility testing with forced oscillation technique (FOT) or impulse oscillometry has been used to distinguish copd from bronchial asthma. (IOS). However, in day to day clinical practice a well performed However studies have shown a wide range of reversibility in Spirometry with clinic-radiological correlation is sufficient for clinically well defined was verified in the UPLIFT. diagnosis of copd . (Understanding Potential Long Term Impacts on Function with Tiotropium.)

9 Trial, which included at baseline a reversibility Assessment of Severity test with a combination of high dose ipratropium and GOLD recommends that the assessment of severity of copd . 1 A majority of patients ( ) reached the ATS/. be based on a physiological variable, post bronchodilator FEV1% ERS threshold of reversibility. Roughly 30% of patients with predicted as mild>80, moderate 50-80, severe 30-50 and very copd show significant reversibility and reversibility is greater 24 SUPPLEMENT TO JAPI FABRUARY 2012 VOL. 60. Table1: Classification of Severity (GOLD Guidelines). Class Severity FEV1 / FVC FEV1 (Postbronchodilator). I Mild <70% > 80. II Moderate <70%, 50% - 80%. III Severe <70% 30% - 50%. IV Very Severe <70% <30 % or 30% - 50% + Right Heart Failure Table2: BODE Index Predicts Mortality EXPIRATION INSPIRATION. Bode Index Scoring Points Variables 0 1 2 3. Ptr>Patm Ptr<Patm FEV 1 (%Predicted) > 65 50-64 36-49 < 35. Walk Distance in 6 min (m) > 350 250-349 150-249 < 149.

10 MMRC Dyspnea Scale 0-1 2 3 4. Body Mass Index > 21 < 21. MMRC: Modified Medical Research Council Normal, non 5. susceptible smoker 4. FEV1 L copd . 3. Fig. 4a: Figure showing mechanism for variable extrathoracic upper airway obstruction (VEUAO). 2. EXPIRATION INSPIRATION. 1. 25 35 45 55 65 75 85. Age in years Fig. 3: Figure showing method of assessment of lung age. with anticholinergic Conversely, asthma shows poor Ptr<Ppl Ptr>Ppl reversibility with chronicity and airway remodeling. Hence, bronchodilator reversibility is not a useful criterion for diagnosis of copd and has been removed in the recent GOLD Use of corticosteroids to test reversibility in copd has also not been recommended. Assessment of Lung Age Smoking is attributed as the main cause of copd . A key indicator of copd is a reduced FEV1 compared with predicted Fig. 4b: Figure showing mechanism for variable intrathoracic upper FEV1 value. Hence, Spirometry is a gold standard for diagnosis of airway obstruction (VIUAO).