40: Chronic Obstructive Pulmonary Disease

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CHAPTER 40 Chronic Obstructive Pulmonary Disease

Howard J. Miller, MD

1 Define chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a spectrum of diseases that includes emphysema, chronic bronchitis, and asthmatic bronchitis. It is characterized by progressive increased resistance to breathing. Airflow limitation may be caused by loss of elastic recoil or obstruction of small or large (or both) conducting airways. The increased resistance may have some degree of reversibility. Cardinal symptoms are cough, dyspnea, and wheezing.

2 What are the features of asthma and asthmatic bronchitis?

Asthma

image This heterogeneous disorder is characterized by reversible airway obstruction.
image Precipitating factors include exercise, dander, pollen, and intubation.
image Symptoms improve with bronchodilator and immunosuppressive therapy.

Asthmatic bronchitis

image It consists of airway obstruction, chronic productive cough, and episodic bronchospasm.
image It can result from progression of asthma or chronic bronchitis.
image There is less improvement with bronchodilator therapy; some degree of airway obstruction at all times.

3 Describe chronic bronchitis and emphysema

image Chronic bronchitis: Characterized by cough, sputum production, recurrent infection, and airway obstruction for many months to several years. Patients with chronic bronchitis have mucous gland hyperplasia, mucus plugging, inflammation and edema, peribronchiolar fibrosis, airway narrowing, and bronchoconstriction. Decreased airway lumina caused by mucus and inflammation increase resistance to flow of gases.
image Emphysema: Characterized by progressive dyspnea and variable cough. Destruction of the elastic and collagen network of alveolar walls without resultant fibrosis leads to abnormal enlargement of air spaces. In addition, the loss of airway support leads to airway narrowing and collapse during expiration (air trapping).

4 List contributory factors associated with the development of chronic obstructive pulmonary disease

image Smoking: Smoking impairs ciliary function, depresses alveolar macrophages; leads to increased mucous gland proliferation and mucus production; increases the inflammatory response in the lung; leading to increased proteolytic enzyme release; reduces surfactant integrity; and causes increased airway reactivity.
image Occupational and environmental exposure: Animal dander, toluene and other chemicals, various grains, cotton, and sulfur dioxide and nitrogen dioxide in air pollution.
image Recurrent infection: Bacterial, atypical organisms (mycoplasma), and viral (including human immunodeficiency virus, which can produce an emphysema-like picture).
image Familial and genetic factors: A predisposition to COPD exists and is more common in men than women. α1-antitrypsin deficiency is a genetic disorder resulting in autodigestion of pulmonary tissue by proteases and should be suspected in younger patients with basilar bullae on chest x-ray film. Smoking accelerates its presentation and progression.

5 What historical information should be obtained before surgery?

image Smoking history: number of packs per day and duration in years
image Dyspnea, wheezing, productive cough, and exercise tolerance
image Hospitalizations for COPD, including the need for intubation and mechanical ventilation
image Medications, including home oxygen therapy and steroid use, either systemic or inhaled
image Recent pulmonary infections, exacerbations, or change in character of sputum
image Weight loss that may be caused by end-stage pulmonary disease or lung cancer
image Symptoms of right-sided heart failure, including peripheral edema, hepatomegaly, jaundice, and anorexia secondary to liver and splanchnic congestion

6 What features distinguish pink puffers from blue bloaters?

Pink puffers (emphysema) Blue bloaters (chronic bronchitis)
Usually older (>60 years) Relatively young
Pink in color Cyanotic
Thin Heavier in weight
Minimal cough Chronic productive cough; frequent wheeze

7 List abnormal physical findings in patients with chronic obstructive pulmonary disease

image Tachypnea and use of accessory muscles
image Distant or focally diminished breath sounds, wheezing, or rhonchi
image Jugular venous distention, hepatojugular reflux, and peripheral edema suggest right heart failure
image Palpation of peripheral pulses is an indirect measure of stroke volume

8 What laboratory examinations are useful?

image White cell count and hematocrit: Elevation suggests infection and chronic hypoxemia, respectively.
image Electrolytes: Bicarbonate levels are elevated to buffer a chronic respiratory acidosis if the patient retains carbon dioxide. Hypokalemia can occur with repeated use of β-adrenergic agonists.
image Chest x-ray film: Look for lung hyperinflation, bullae or blebs, flattened diaphragm, increased retrosternal air space, atelectasis, cardiac enlargement, infiltrate, effusion, masses, or pneumothorax.
image Electrocardiogram: Look for decreased amplitude, signs of right atrial (peaked P waves in leads II and V1) or ventricular enlargement (right axis deviation, R/S ratio in V6 ≤1, increased R wave in V1 and V2, right bundle-branch block), and arrhythmias. Atrial arrhythmias are common, especially multifocal atrial tachycardia and atrial fibrillation.
image Arterial blood gas: Hypoxemia, hypercarbia, and acid-base status, including compensation, can be evaluated.
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