Criteria
Global Initiative for Chronic Obstructive Lung Disease classification of severity of airflow limitation and assessment of exacerbation risk[1]
In pulmonary function testing, a postbronchodilator FEV1/FVC ratio of <0.70 is commonly considered diagnostic for COPD. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) system categorizes airflow limitation into stages.
In patients with FEV1/FVC <0.70:
GOLD 1 - mild: FEV1 ≥80% predicted
GOLD 2 - moderate: 50% ≤ FEV1 <80% predicted
GOLD 3 - severe: 30% ≤ FEV1 <50% predicted
GOLD 4 - very severe: FEV1 <30% predicted.
The GOLD guideline uses a combined COPD assessment approach to group patients according to symptoms and previous history of exacerbations. Symptoms are assessed using the Modified British Medical Research Council (mMRC) or COPD assessment test (CAT) scale. GOLD cautions against the use of the mMRC dyspnea scale alone for assessing patients, as symptoms of COPD go beyond dyspnea alone. For this reason, the CAT is preferred. However, GOLD acknowledges that the use of the mMRC scale is widespread, and so a threshold of an mMRC grade ≥2 is still included to define "more breathless" patients in its assessment criteria.[1]
Group A: low risk (0-1 exacerbation per year, not requiring hospitalization) and fewer symptoms (mMRC 0-1 or CAT <10)
Group B: low risk (0-1 exacerbation per year, not requiring hospitalization) and more symptoms (mMRC ≥2 or CAT ≥10)
Group C: high risk (≥2 exacerbations per year, or one or more requiring hospitalization) and fewer symptoms (mMRC 0-1 or CAT <10)
Group D: high risk (≥2 exacerbations per year, or one or more requiring hospitalization) and more symptoms (mMRC ≥2 or CAT ≥10).
GOLD classification of exacerbation severity:[1]
Mild: requires treatment with short-acting bronchodilators only
Moderate: requires treatment with short-acting bronchodilators plus antibiotics and/or oral corticosteroids
Severe: patient requires hospital admission or visit to the emergency room. Acute respiratory failure may also occur in severe exacerbation.
GOLD classification of hospitalized patients with acute exacerbations of COPD:[1]
No respiratory failure
Respiratory rate 20 to 30 breaths/minute
No use of accessory muscles of respiration
No changes in mental status
Hypoxemia improves when supplemental oxygen is given via Venturi mask at 28% to 35% inspired oxygen (FiO2)
Partial pressure of carbon dioxide (PaCO2) is not increased.
Acute respiratory failure - nonlife threatening
Respiratory rate >30 breaths/minute
Using accessory muscles of respiration
No changes in mental status
Hypoxemia improves when supplemental oxygen is given via Venturi mask at 24% to 35% FiO2
Hypercarbia occurs: PaCO2 is increased relative to baseline or is elevated (50 mmHg-60 mmHg).
Acute respiratory failure - life threatening
Respiratory rate >30 breaths/minute
Using accessory muscles of respiration
Acute changes in mental status
Hypoxemia does not improve when supplemental oxygen is given via Venturi mask, or FiO2 >40% is required
Hypercarbia occurs: PaCO2 is increased relative to baseline or is elevated (>60 mmHg), or acidosis is present (pH ≤7.25).
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