creation date: 2025-05-01 18:51 tags: Pathologies
Chronic Obstructive Pulmonary Disorder
Background
Definitions
COPD is a highly prevalent, heterogeneous lung condition characterized by chronic respiratory symptoms due to airway (bronchitis) and/or alveoli (emphysema) abnormalities. The airway obstruction is persistent, and often progressive.
Chronic bronchitis is characterized by a chronic productive cough over a period of time, typically 3 months.
Emphysema refers to an enlargement of airspaces distal to terminal bronchioles and destruction of the airspace walls manifesting as decreased breath sounds and hyperinflation of the lungs.
Acute exacerbation of COPD occurs when a trigger results in worsening of symptoms of pre-existing COPD. This is discussed separately.
Etiology
COPD is caused by prolonged exposure to harmful particles and/or gases.
The most common cause is cigarette smoking. Other causes include:
- Second-hand smoke
- Environmental/occupational exposures to chemicals, dust, fumes
- Alpha-1 antitrypsin deficiency
Pathogenesis
COPD is an inflammatory condition of the airways, lung parenchyma, and pulmonary vasculature. The inflammatory response is triggered by irritants which causes neutrophils and macrophages to be recruited and release inflammatory mediators.
Oxidative stress and protease-antiprotease imbalances results destruction of the alveolar air sacs (emphysema) which causes obstructive physiology. The obstruction results in a decrease in forced expiratory volume (FEV1) and tissue destruction that leads to further airflow limitations and impaired gas exchange.
Obstruction also causes hyperinflation and air trapping due to airway collapse during exhalation. CO2 retention and subsequent elevation in CO2 levels occur and pulmonary hypertension can occur due to vasoconstriction from hypoexemia.
Environmental irritant or infection (eg. pneumonia) can result in acute exacerbation of COPD which is discussed separately.
Clinical Presentation
Signs & Symptoms
The cardinal symptoms of COPD are:
- Dyspnea
- Chronic cough
- Sputum production
Other symptoms include wheezing and chest tightness.
Early presentation may manifest as exertional dyspnea, which may be very subtle in patients with sedentary lifestyles or who have reduced their exertion due to dyspnea. The dyspnea will often progress with less and less exertion and eventually at rest.
A chronic cough is present often with sputum production. Sputum occurs initially in the morning but can progress to be throughout the day. It is usually mucoid but can become purulent when during exacerbation.
Physical findings vary based on severity.
Mild disease:
- Prolonged expiratory time
- Faint end-expiratory wheezes on forced exhalation Moderate to severe:
- Hyperinflation (increased resonance to percussion)
- Decreased breath sounds
- Wheezes
- Crackles at lung bases
- Distant heart sounds Severe:
- Barrel chest
- Depressed diaphragm
Signs of respiratory failure is discussed with red flags.
History & Physical Exam
History should be used to elucidate pattern of onset. It may not be as clear especially with co-conditions with pulmonary symptoms. Assessment of risk factors and exposures supports the diagnosis.
An assessment of the severity of symptoms should be done in anticipation of management before or after spirometry diagnosis. This can be revisited post-diagnosis for adjustment of management. This consist of the mMRC dyspnea scale:
- Grade 0: only breathless with strenuous exercise
- Grade 1: SOB when hurrying on level ground or walking up slight hill
- Grade 2: slower than people of same age walking due to SOB or have to pause for breath when walking
- Grade 3: stop for breath <100m of walking or after a few minutes on level ground
- Grade 4: too breathless to leave house or SOB when dressing or the COPD assessment test (CAT) which scores and sums the following symptoms from 0-5:
- Cough (no cough - cough all the time)
- Phlegm (no phlegm - completely full of phlegm)
- Chest tightness (none - very tight)
- Breathlessness (none - with one flight of stairs)
- Activities (no limitations - very limited at home)
- Confidence (confident leaving home - not confident)
- Sleep (lots of energy - no energy at all)
A GOLD symptom group can be assigned:
- GOLD Group A:
- <2 moderate exacerbations and no hospitalizations for COPD in past year
- mMRC <2 and CAT <10
- GOLD Group B:
- <2 moderate exacerbations and no hospitalizations in past year
- mMRC ≥2 or CAT ≥10
- GOLD Group E
- ≥2 moderate exacerbations or ≥1 hospitalization for COPD in past year
Physical exams may or may not reveal findings but assessment of respiratory system should be performed.
Risk factors
- Smoking
- Ascertain pack-year smoking history (# packs per day number of smoking years)
- No clear cutoff other than an overall dose-response relationship
- History of fume and dust exposure
- Pulmonary/systemic infections (eg. tuberculosis)
- Possible genetic predisposition
Diagnosis
Criteria
Diagnosis of COPD is made using clinical features, spirometry, and by exclusion of other alternatives.
Clinical features are the presence of respiratory symptoms consistent with COPD.
Spirometry is done prior and following bronchodilator administration to evaluate for airflow limitations and whether it is persistent.
Relevant spirometry measurements are:
- Forced expiratory volume in one second (FEV1)
- Forced vital capacity (FVC)
A postbronchodilator ratio cutoff of FEV1/FVC of <0.7 is generally used for establishing airflow limitation. However, it should be noted that the ratio also decreases with age as as such may be over- and under-diagnosed in older and younger patients, respectively.
An assessment of severity should be made using the GOLD strategy based on FEV1:
- GOLD 1 (mild): FEV1 ≥80% predicted
- GOLD 2 (moderate): 50-80%
- GOLD 3 (severe): 30-50%
- GOLD 4 (very severe): <30%
Further classification of symptoms can be made using the mMRC dyspnea and GOLD symptoms scale discussed above.
In cases where spirometry is not possible, thoracic CT can find emphysema, air trapping, and airway remodelling which would support a diagnosis of COPD. This not routine.
Work-up
Following a clinical suspicion of COPD, spirometry should be done for diagnosis.
Additional testing including bloodwork may be done to rule out alternative diagnoses, especially if there are suspicions that the cause of a specific symptom may not be due to COPD alone.
Chest radiography can be done to evaluate for pulmonary comobidities and other respiratory concerns (incl. heart failure and interstitial lung disease). While they have poor sensitivity, some features that can be on plain film include:
- Rapidly tapering vascular shadows, redistribution of vascular flow to lesser involved upper lobes, increased radiolucency, flat diaphragm, and long narrow heart shadow
- Flat diaphragmatic contour and increased retrosternal airspace on lateral (hyperinflation)
- Bullae: radiolucent area with diameter > 1cm surrounded by arcuate hairline shadows (locally severe disease) - right upper bullae, lung markings compressed to lower lobes
- Other signs of COPD such as pulmonary hypertension
In many patients, a smoking etiology is typically assumed. However, it is reasonable to perform alpha-1 antitrypsin testing as a potential cause or as a contributory factor.
In cases of more severe disease, it may also be beneficial for the patient to undergo exercise capacity and pulmonary function testing.
Differential
With the presence of COPD symptoms, persistent airflow limitation, and absence of radiographic features suggestive of heart failure, the differential is narrowed to:
- Chronic obstructive asthma
- Patients with history of asthma may have chronic airway remodelling
- Presumed diagnosis if patient has long hx of asthma and no risk factors for COPD
- Cannot be differentiated if risk factors for COPD are present
- Bronchiectasis
- Abnormal widening of bronchi associated with recurrent infection
- Tuberculosis
- Can cause airflow obstruction
- Constrictive bronchiolitis
- Submucosal and peribronchiolar fibrosis causing narrowing of bronchiolar lumen
- Seen following inhalation injury, transplantation, rheumatoid lung, IBD
- Diffuse panbronchiolitis
- Predominantly in east Asian males, typically with chronic sinusitis
It should be noted these conditions can coexist with COPD.
Red Flags / Complications
End-stage and chronic respiratory failure manifests as attempts to relieve dyspnea:
- Tripod stance
- Accessory muscle use
- Pursed lip breathing
- Paradoxical chest movements (Hoover sign)
- Cyanosis
- Asterixis
- Enlarged, tender liver (right heart failure)
Management
Lifestyle / Social
Non-pharmacological management should be used whether pharmacological means are used or not.
Patients should be educated/counselled on:
- Smoking cessation
- Correct inhaler technique
- Vaccination to prevent exacerbations
- Healthy weight and nutrition
Pulmonary rehabilitation which includes:
- Exercise
- Promotion of healthy behaviours
- Adherence to treatment
- Psychological support
Pharmacological / Interventional
A pharmacological treatment plan can be created based on the GOLD group as determined above. The goal of treatment is to improve patient symptoms, reduce exacerbations, and improve function and quality of life.
The primary therapy for symptom management are inhaled bronchodilators. Inhaled glucocorticoids can be also added.
In all COPD patients, a short-acting rescue bronchodilator should be prescribed for for relief of episodic dyspnea and early treatment of exacerbations.
For patients taking a long-acting muscarinic antagonist (LAMA), a short-acting beta agonist (SABA) is recommended. A short-acting muscarinic antagonist (SAMA) is not recommended due to the cumulative anticholinergic side effects.
- Salbutamol 2 puffs q4-6h prn
- Levalbuterol prn
For patients not taking a LAMA, a SABA-SAMA option is recommended. Without overlap with the LAMA, the combination is beneficial as muscarinic antagonists predominantly affect proximal large airways while beta agonist act on distal small airways and they have separate mechanisms of action.
- Ipratropium-salbutamol (Combivent Respimat) 1 puff q4-6h prn
GOLD Group A For less symptomatic patients at low risk of exacerbation, a long-acting bronchodilator, either a long-acting beta agonist (LABA) or LAMA, is recommended.
LAMAs are generally preferred over LABAs as they have greater effect but efficacy is comparable enough that choice can be made based on their side effect profiles.
LABA example options:
- Salmeterol 1 puff BID
- Formoterol BID
- Arformoterol one vial neb solution BID LAMA example options:
- Tiotropium (Spiriva) DPI once daily OR SMI two puffs one daily
GOLD Group B For patients with more symptoms at low risk of exacerbation, a LABA-LAMA dual bronchodilator is recommended over single therapy. Use of a fixed-dose combination instead of two separate inhaler may improve adherence as well.
Example options:
- Tiotropium-olodaterol (Spiolto Respimat) 2 puffs once daily
- Umeclidinium-vilanterol (Anoro Ellipta) 1 puff daily
Alternatives to a LABA-LAMA combination can also be:
- LABA or LAMA alone
- LABA plus an inhaled corticosteroid (ICS), especially if the patient has asthma as well (COPD-A)
In cases of stable severe COPD, hypoexmia may be treated using supplemental oxygen. With chronic hypoxemia with SpO2 ≤88% at rest, continuous oxygen therapy for at least 15 hours per day is recommended. A target of 92-95% is generally used.
GOLD Group E In patients with high risk of exacerbation and thus the highest risk of hospitalization and death, use of potent combination therapies are needed.
Initial therapy consist of a LAMA-LABA dual bronchodilator and is generally sufficient.
In patients presenting with elevated eosinophil counts or hospitalizations, it is reasonable to use a LAMA-LABA-ICS as initial therapy as the benefits may outweigh the side effects of the ICS.
References
Tools / Guidelines
GOLD Report 2025 MDCalc - GOLD Groups MDCalc - CAT questionnaire