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© SUPPLEMENT TO JAPI • FABRUARY 2012 • VOL. 60
Spirometry in Chronic Obstructive Lung Disease
(COPD)
Vinaya S Karkhanis*, JM Joshi*
Introduction
T
he common criterion recommended for diagnosis of chronic
obstructive lung disease (COPD) is demonstration of
“progressive irreversible airway obstruction” on spirometry.
The Global Initiative for Chronic Obstructive Pulmonary Disease
(GOLD) has recommended spirometry as the gold standard for
diagnosis of COPD. However, spirometry is not widely available
and spirometric test results are not always optimally recorded or
interpreted except when performed by experienced personnel.
Experts have differed on spirometric criteria for diagnosis of
COPD. GOLD1 now recommends that post bronchodilator
forced expiratory volume in 1 second/forced vital capacity
(FEV1/FVC) ratio of <0.70 must be used for diagnosing COPD.
Demonstration of “irreversible airway obstruction” i.e. absence
of bronchodilator reversibility is no more required for diagnosis
of COPD. Although there is now a consensus; spirometric criteria
continue to have limitations. The simplification of spirometry
criteria by GOLD experts is perhaps to encourage spirometry
for diagnosis of COPD in primary-care settings worldwide.2
However; widespread spirometric testing has resulted in a
large number of individuals without respiratory symptoms,
labeled as COPD.3 On the other hand physicians continue to
diagnose COPD based solely on symptoms. Individuals with
symptoms but normal spirometry were earlier included
as “at risk” for COPD. The revised GOLD guidelines do not
include this group as there is incomplete evidence that these
cases always progress to COPD. The United States Preventive
Services Task Force, an independent panel of experts in primary
care and prevention that systematically reviews the evidence
of effectiveness and develops recommendations for clinical
preventive services suggest spirometry evaluation in a person
presenting with shortness of breath, chronic cough, increased
sputum production, wheezing, and/or a family history of
alpha1-antitrypsin deficiency.4 A combination of symptoms and
spirometry may therefore be a more relevant way of diagnosing
COPD in individuals exposed to the causative factor.
Role of spirometry in COPD requires basic understanding
of spirometry, its importance in the management of COPD
with knowledge of how to perform spirometry correctly and its
interpretation (Chart). American Thoracic Society and European
Respiratory Society guidelines (ATS/ERS guidelines) are used for
acceptable and reproducible spirometry.5 Factors such as cough,
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:
•
Diagnosis
•
Assessment of severity
•
Assessment of response to therapy
•
Assessment of lung age
•
Detection of upper airway obstruction
•
Pre-operative pulmonary evaluation
Diagnosis
A typical spirogram (volume versus time recoding) and
flow volume loop –FVL (flow rate versus volume recording)
in COPD is as shown in Figures 1 and 2. The interpretation of
obstruction in the spirometry report however remains highly
controversial. The current diagnostic criterion for airflow
obstruction in COPD is a post bronchodilator ratio of FEV1/
FVC <70%. Although COPD cases usually have no or poor
bronchodilator reversibility (Exercise 1), it is well known and
recognized by GOLD guidelines that some cases may show
good bronchodilator reversibility (Exercise 2). The predicted
FEV1/FVC ratios decrease progressively with age in adults.6 A
fixed FEV1/FVC ratio thus overestimates airway obstruction in
the elderly and underestimates it in young adults.7,8 Obstructive
abnormality is most accurately diagnosed when a reduced
FEV1/FVC ratio is below lower limit of normal (LLN) i.e. the
5th percentile of the predicted value.9 The post-bronchodilator
reference values that are required for accurate interpretation of
spirometry have not yet been developed.10 False normalization of
the FEV1/FVC ratio that occurs due to a greater reduction in FVC
caused by air trapping in severe airway obstruction may result
in a tendency to diagnose a restrictive ventilatory abnormality
and thus more severe cases being missed (Exercise 3). Therefore
spirometry-based diagnosis of COPD and the “one size fits all”
spirometric criteria are inappropriate.11
COPD patients have an inability to perform a complete or
adequate exhalation, resulting in an underestimate of FVC and
Chart: Interpretation of Spirometric Data
Volume
in liters
Volume
in liters
Time in Seconds
Time in Seconds
*
Department of Pulmonary Medicine, **Professor and Head, Dept
Normal
of Pulmonary Medicine, TN Medical College, BYL Nair Hospital,
Obstructive
abnormality
Mumbai 400 008
Restrictive abnormality
Normal
Obstructive abnormality
Restrictive abnormality
Fig. 1 : Graphic display of volume versus time spirogram
(obstruction in COPD –dotted lines).
© SUPPLEMENT TO JAPI • FeBRUARY 2012 • VOL. 60 Flow volume loop
Volume in litres
Normal
Obstructive abnormality
Restrictive abnormality
Fig. 2 : Flow volume loop (obstruction in COPD- dotted lines).
Predicted
FVC
FVC%
FEV1
FEV1%
FEV1/FVC
PEFR
3.75
3.07
801
Before
After
Improvement
bronchodilator Bronchodilator
1.73
1.92
46%
51%
0.63
0.71
12%, 80ml
21%
23%
37%
37%
266
249
Exercise 1: Spirometry of a 55 year old man, smoker with smoking
index of 24 pack years and history of chronic airway obstruction
showing obstructive abnormality with poor post bronchodilator
reversibility.
overestimate of FEV1: FVC ratio. For this reason the measurement
of the forced expiratory volume in 6 seconds (FEV6) has been
advocated along with the FEV1:FEV6ratio.12 In such patients
additional useful information can be obtained by measuring
the subdivisions of lung volume. The primary measurement
is functional residual capacity (FRC) with a slow vital capacity
maneuver, and estimation of other lung volumes. Elevated
ratio of residual volume (RV) to total lung capacity (TLC)
suggests airflow obstruction. The diffusing capacity of the
lung for carbon monoxide (DLCO) decreases in the presence of
emphysema. Small airway function in COPD can be assessed
with the measurement of airway resistance (Raw) using body
plethysmography and total respiratory system resistance (Rrs)
with forced oscillation technique (FOT) or impulse oscillometry
(IOS). However, in day to day clinical practice a well performed
spirometry with clinic-radiological correlation is sufficient for
diagnosis of COPD.
Assessment of Severity
GOLD recommends that the assessment of severity of COPD
be based on a physiological variable, post bronchodilator FEV1%
predicted as mild>80, moderate 50-80, severe 30-50 and very
1
Test
Predicted
FVC
FVC%
FEV1
FEV1%
FEV1/FVC
PEFR
3.5
2.3
476
Before
After
Improvement
bronchodilator Bronchodilator
2.5
2.95
79%
93%
1.15
1.55
+34%, 300ml
54%
73%
50%
67.4%
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
airway obstruction showing obstructive abnormality with good
bronchodilator reversibility.
Flow rates
L / sec
Test
23
Test
Predicted
FVC
FVC%
FEV1
FEV1%
FEV1/FVC
PEFR
3.38
2.94
Before
After
Improvement
bronchodilator Bronchodilator
1.20
1.74
35%
53.1%
1.62
1.68
10%,16ml
55%
57%
90%
96%
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
showing false normalization of the FEV1/FVC ration, low FVC is
related to air trapping.
severe <30, “rule of 30-50-80” (Table 1). Airway obstruction in
COPD can be variable which is based on varying degree of smooth
muscle contraction. This can be reversed by administering an
inhaled bronchodilator. Hence, the GOLD criteria for COPD
are based on post bronchodilator reversibility values. Also
there is no need for the patient to stop regular treatment prior
to post bronchodilator spirometric measurements. COPD being
progressive disease leads to worsening of lung function over
time. The normal decline of FEV1 ie 30 ml/year gets accelerated in
COPD patients to 75 to 100 ml/year.13 The rate of decline in FEV1
is influenced by number of exacerbations.14 Thus, FEV1 correlates
poorly to all the things that matter to patients: symptoms, quality
of life, exacerbation frequency, and exercise intolerance.15 COPD
is now recognized to have systemic manifestations that are not
reflected by the FEV1. Hence, a simple multidimensional grading
system the BODE (body mass index, obstruction, dyspnoea, and
exercise tolerance) index16 (Table 2)) has been used to assess
the respiratory and systemic expressions of COPD. The BODE
staging system also helps to better predict hospitalization for
COPD.
Assessment of Reversibility with
Aerosolized Bronchodilators
ATS/ERS guidelines significant reversibility is considered
to be an increase in FEV1 of 200ml and 12% after 15 minutes
of bronchodilator therapy. Bronchial asthma shows good
reversibility with bronchodilators whereas COPD often shows
poor reversibility. Therefore, traditionally, reversibility testing
has been used to distinguish COPD from bronchial asthma.
However studies have shown a wide range of reversibility in
clinically well defined COPD.This was verified in the UPLIFT
(Understanding Potential Long Term Impacts on Function with
Tiotropium.) trial, which included at baseline a reversibility
test with a combination of high dose ipratropium and
salbutamol.17 A majority of patients (53.9%) reached the ATS/
ERS threshold of reversibility. Roughly 30% of patients with
COPD show significant reversibility and reversibility is greater
24
© SUPPLEMENT TO JAPI • FABRUARY 2012 • VOL. 60
Table1: Classification of Severity (GOLD Guidelines)
Class
I
II
III
IV
Severity
Mild
Moderate
Severe
Very Severe
FEV1 / FVC
<70%
<70%,
<70%
<70%
Table2: BODE Index Predicts Mortality
FEV1 (Postbronchodilator)
> 80
50% - 80%
30% - 50%
<30 % or 30% - 50% + Right Heart Failure
EXPIRATION
INSPIRATION
Bode Index Scoring
Variables
FEV 1 (%Predicted)
Walk Distance in 6 min (m)
MMRC Dyspnea Scale
Body Mass Index
0
> 65
> 350
0-1
> 21
Points
1
2
50-64
36-49
250-349 150-249
2
3
< 21
3
< 35
< 149
4
Ptr>Patm
Ptr<Patm
MMRC: Modified Medical Research Council
Normal, non
susceptible smoker
5
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
Age in years
75
85
Fig. 3: Figure showing method of assessment of lung age.
with anticholinergic therapy.18 Conversely, asthma shows poor
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 update.1
Use of corticosteroids to test reversibility in COPD has also not
been recommended.
Ptr<Ppl
Ptr>Ppl
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
FEV1 value. Hence, spirometry is a gold standard for diagnosis of
COPD. It can also be used for assessing the “lung age” (measured
FEV1) of the patient of COPD as compared to the predicted FEV1
as per his chronological age.This can illustrate the likely negative
impact of continued smoking on lung function. Demonstration
of graphic illustration e.g. 45-year old man with COPD with a
“lung age” of an 80 year old is shown in figure 3. Estimation of
lung age is also helpful in encouraging smokers to quit smoking.
In the Lung Health Study, 6000 middle age smokers were
randomized to smoking cessation program and followed for 5
years.19Sustained quitters had a rate of decline of FEV1 of 31ml/
year compared with 62ml/year in those continued to smoke.
Detection of Upper Airway
Obstruction (UAO)
The most common etiology for COPD being smoking,
Fig. 4b: Figure showing mechanism for variable intrathoracic upper
airway obstruction (VIUAO).
these patients are at high risk of laryngeal, pharyngeal and
lung malignancies. Spirometric flow volume loop assessment
helps to identify evidence of upper airway obstruction, helping
in prioritizing management plans. Flow volume loop is a
graphic expression of flows at different lung volumes. It helps
in identifying variable as well as fixed UAO at various levels
(Figure 4a, b, c). Miller and Hyatt defined three classic patterns
of flow volume loop contours (Figure 5) in the patients with
upper airway obstruction, depending on the location of the
obstruction and whether the obstruction was fixed or variable.20
UAO can be diagnosed by clinical and radiological correlation
along with inspection of the pattern of flow volume loop and
calculation of indices.
Empey’s index: FEV1 in ml/Peak expiratory flow (PEF) in L/
min
© SUPPLEMENT TO JAPI • FeBRUARY 2012 • VOL. 60 25
EXPIRATION
Fig. 4c: Figure showing mechanism for fixed upper airway
obstruction.
INSPIRATION
Fig. 6a : Figure showing “biphasic flow volume loop” or “two can
effect”
Variable Extrathoracic UAO
Variable intrathoracic UAO
Fixed UAO
Fig. 6b : Figure showing “biphasic flow volume loop” or “two can
effect”
Indices of UAO
● FEV1 (ml) / PEF (L / m) = > 8 (Empey’s index)
● FEF50 / FIF50 = <0.3 or > 1
Fig. 5: Figure showing upper Airway Obstruction (UAO): Flow
volume loop interpretation.
FEF50/FIF50 (ratio of flow at 50% of expiration and flow at
50% of inspiration)
Indices further help confirm presence and identify the type
of UAO.
Presence of UAO is indicated by Empey’s index>/=8.
Type is determined by:
FEF50/FIF50=1 in fixed UAO
FEF 50 /FIF 50 >1 in variable extrathoracic upper airway
obstruction
the inspiratory flow, it is easy to diagnose. But if it is variable
intrathoracic upper airway obstruction, it is difficult as both
COPD and variable intrathoracic UAO cause expiratory flow
changes. Effort dependent high flow portion of flow –volume
loop near TLC is the first to be distorted in the UAO.Patients
presenting with obstructed main bronchus(figure6a) show
“biphasic flow volume loop” or “two can effect” due to slow
emptying and filling of the affected lung (Figure 6b).
Role of Spirometry in Pre-Operative
Pulmonary Evaluation
COPD is a well known independent risk factor for the
development of post operative pulmonary complications after
thoracic or non thoracic surgery.21 It should be performed
in patients requiring thoracic surgery or in non thoracic
(particularly thoracic or upper gastro intestinal surgery) only if
history of tobacco smoking, cough, dyspnoea are present and if
clinical or radiological findings suggest pulmonary abnormality.
FEF 50/FIF 50< 0.3 in variable intrathoracic upper airway
obstruction
Thoracic surgery
Patients with severe COPD, even a significant tracheal
stenosis may not be apparent on flow volume loop and also
FEV1 is a poor indicator of large airway obstruction. If COPD
patients develop variable extrathoracic UAO, compromising
Role of spirometry is well defined in pre-operative evaluation
of thoracic surgery. Predicted postoperative (ppo) values should
be calculated by deducting the volume to be resected from the
pre-operative values. For this purpose “rule of five” can be
26
Test
Predicted
FVC
FVC%
FEV1
FEV1%
FEV1/FVC
PEFR
4L
3L
Before
After
bronchodilator Bronchodilator
3L
3L
75%
75%
1.85L
2L
61%
66%
61%
66%
600
620
PPO FEV1
1.20L
Exercise 4: Preoperative spirometry assessment of a 45-year old
man with COPD and left lung collapse due to left main bronchus
mass. Predicted postoperative ppo FEV1> 1 L, therefore fit for left
pneumonectomy.
used which assumes one-fifth function for each lobe. A simpler
method is the “rule of fives”, where one fifth function is
attributed to each lobe. Postoperative FEV 1 is calculated
by deducting the volume contributed by the lung to be
resected. For example, if the preoperative FEV 1 is 2.5 liters
and a right upper lobectomy is planned (1/5 of 2.5), i.e. 0.5
liters is deducted from 2.5 liters which gives a predicted
postoperative FEV 1 of 2 liters (Exercise 4) Perfusion scans
may be performed to determine exact contribution of the lobe/
lung to be resected.Predicted postoperative FEV1 less than 40%
predicted contraindicates any lung resection.
Non thoracic Surgery
Spirometry is not routinely indicated in non thoracic
surgeries. Pre-operative evaluation is done to assess the risk of
postoperative pulmonary complications and to minimize them
by optimal treatment.22 Smoking cessation for at least 8 weeks
prior to surgery and vigorous pulmonary hygiene in the 48 to
72 hours before surgery along with optimized bronchodilator
therapy helps to reduce postoperative pulmonary complications
in COPD. In patients with COPD, FEVI/FVC less than 50%,
maximum voluntary ventilation <50%, or a high PaCO2 place
the patient at a higher risk for postoperative complications.
National Emphysema Treatment Trial (NETT), FEV1 or DLCO
values < 20% of predicted were associated with an unacceptably
high postoperative mortality.23 Patients described as high risk
by spirometry can undergo surgery with an acceptable risk for
postoperative pulmonary complications. Risk is also indirectly
proportional to the distance of surgical site from the thorax.
In conclusion, spirometry is an important tool in diagnosis
and management of COPD and its appropriate use must be
encouraged in specialist as well as primary care settings.
References
1.
© SUPPLEMENT TO JAPI • FABRUARY 2012 • VOL. 60
Global Initiative for Chronic Obstructive Lung Disease. Global
strategy for the diagnosis, management, and prevention of chronic
obstructive pulmonary disease. (Updated 2010). http://www.
goldcopd.org
5.
Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates
A, Crapo R, Enright P, et al. Standardisation of Spirometry: ATS/
ERS TASK FORCE: Standardization of Lung Function Testing. Eur
Respir J 2005;26:319–338.
6.
Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B. Changes in the
normal maximal expiratory flow-volume curve with growth and
aging. Am Rev Respir Dis 1983;127:725–734.
7.
Hardie JA, Buist AS, Vollmer WM, Ellingsen I, Bakke PS, Morkve
O. Risk of over-diagnosis of COPD in asymptomatic elderly neversmokers. Eur Respir J 2002; 20:1117-1122.
8.
Pena VS, Miravitlles M, Gabriel R, Jiménez-Ruiz CA, Villasante
C, Masa JF, et al. Geographic variations in prevalence and
underdiagnosis of COPD: results of the IBERPOC multicentre
epidemiological study. Chest 2000;118:981-989.
9.
Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi
R, et al. Interpretative strategies for lung function tests. Eur Respir
J 2005;26:948–968.
10. Lindberg A, Jonsson A, Ronmark E. Prevalence of Chronic
Obstructive Pulmonary. Disease according to BTS, ERS, GOLD
and ATS Criteria in Relation to Doctor’s Diagnosis, Symptoms,
Age, Gender, and Smoking Habits. Respiration 2005;72:471-479.
11. Culver B H. Interpretation of Spirometry: We Can Do Better Than
the GOLD Standard. Respiratory Care 2006;51:719-721.
12. Enright RL, Connett JE, Bailey WC. The FEV1/FEV6 predicts lung
function decline in adult smokers. Respir Med 2002;96:444-449.
13. Sandford AJ, Chagani T, Weir TD, Connett JE, Anthonisen NR, Pare
PD. Susceptibility genes for rapid decline of lung function in the
lung health study. Am J Respir Crit Care Med 2001;163:469-473.
14. Donaldson GC, Seemungal TAR, Bhowmik A, Wedzicha JA.
Relationship between exacerbation frequency and lung function
decline in chronic obstructive pulmonary disease. Thorax
2002;57:847-852.
15. Kerstjens HA. The GOLD classification has not advanced
understanding of COPD. Am J Respir Crit Care Med 2004;170,212-213.
16. Celli BR, Cote CG, Marin JM, Casanova C, Montes de Oca M,
Mendez RA, et al. The body-mass index, airflow obstruction,
dyspnea, and exercise capacity index in chronic obstructive
pulmonary disease. N Engl J Med 2004;350:1005-12.
17. Tashkin DP,Celli B, Decramer M,Liu D, Burkhart D, Cassino C,
Kesten S. Bronchodilator responsiveness in patients with COPD.
Eur Respir J 2008;31:742-750.
18. Brusasco V, Hodder R, Miravitlles M, Korducki L, Towse L, Kesten
S. Health outcomes following treatment for six months with once
daily tiotropium compared with twice daily salmeterol in patients
with COPD. Thorax 2003;58:399-404.
19. Scanlon PD, Connett JE, Waller LA, Altose MD, Bailey WC, Buist
AS. Smoking cessation and lung function in mild-to-moderate
chronic obstructive pulmonary disease. The Lung Health Study.
Am J Respir Crit Care Med 2000;161:381-390.
20. Miller RD, Hyatt RE. Evaluation of obstructing lesions of the trachea
and larynx by flow- volume loops. Am Rev Respir Dis 1973;108:475481.
2.
Crapo RO, Jensen RL. Standards and interpretive issues in lung
function testing. Respir Care 2003;48:764–772.
21. Bapoje SR, Whitaker JF, Schulz T, Chu ES, Albert RK. Preoperative
Evaluation of the Patient with Pulmonary Disease.Chest
2007;132:1637-1645.
3.
Wilt, TJ, Niewoehner, D, Kim, C, for the Agency for Healthcare
Research and Quality (AHRQ). Use of spirometry for case finding,
diagnosis, and management of COPD. August 2005 Agency
for Healthcare Quality and Research. Rockville, MD: AHRQ
Publication No. 05-E017–1.
23. National Emphysema Treatment Trial Research Group. Patients at
high risk of death after lung-volume-reduction surgery. N Engl J
Med 2001;345:1075.
4.
Lin K, Watkins B, Johnson T, Rodriguez JA, Barton MB. Screening for
chronic obstructive pulmonary disease using spirometry: summary
of the evidence for the US Preventive Services Task Force. Ann Intern
Med 2008;148:535-43.
22. Joshi J M. Post operative pulmonary evaluation. Ind J Chest Dis and
Allied Sci 1999;41:35-42.