24. Obstructive (Ventilatory) Lung Diseases

, DENISE R. FORTENBERRY and GLADYS D. FIELD



The authors would like to acknowledge David A. Miller for his contributions that remain unchanged from the first edition.




CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)




I. Definition


A. COPD is a mixture of diseases, including emphysema, chronic bronchitis, and bronchospastic airway disease, all of which are characterized by limitation of expiratory air flow.


B. Acute exacerbations are superimposed upon chronic symptoms.


II. Etiologies/incidence


A. Tobacco smoking (cigarettes, cigars, pipes) is the most common cause.


1. Most persons who smoke a pack of cigarettes per day for longer than 40 years will have manifestations of COPD.


2. Note: One pack of cigarettes per day multiplied by the number of years smoked equals the number of pack-years of cigarettes smoked.


B. Inhalation of environmental pollutants (e.g., oxides of sulfur and nitrogen): Incidence depends on exposure in heavily polluted areas.


C. Occupational exposure to inorganic chemicals (chlorine, fluorine) and organic chemicals (toluene, for example) may result in airway obstruction.



IV. Physical examination findings


A. General


1. Respiratory rate is normal or increased.


2. Mental status should be alert and oriented.


3. Note sitting position for the presence of classic “emphysema stance.”


a. The patient sits with the chest forward and the arms straightened.


b. The upper body is lifted to allow for greater expansion of the chest as gravity pulls the abdominal contents downward and away from the diaphragm.


4. Inspect for clubbing of the nail beds (chronic bronchitis, bronchiectasis) and for pursed-lip breathing.


B. Chest inspection


1. Increase in the anteroposterior diameter of the chest


a. Gives rise to a “barrel” configuration


b. Normally, the diameter of the chest from axilla to axilla is about twice the anteroposterior diameter.


2. Use of accessory muscles of respiration


a. Sternocleidomastoids


b. Intercostals


C. Chest percussion


1. Hyperresonance


2. Low diaphragm


D. Chest auscultation


1. Diminished breath sounds throughout the chest


2. Prolonged forced expiratory time (Auscultation while the patient forcibly exhales shows that the effort needed to exhale the air requires longer than 3 seconds.)


3. Rhonchi on inspiration and/or expiration, especially when secretions are increased


4. Occasional wheezing on expiration


a. Asthma


b. Chronic bronchitis


V. Laboratory/diagnostic findings


A. Pulmonary function testing


1. Expiratory flow rates are reduced.


a. Early disease: reduction in small airway flow rates


b. Late disease: reduction in FEV1 (forced expiratory volume in 1 second, a measure of the potential for severe complications of COPD)


2. Lung volume changes


a. Air trapping indicated by increased residual volume


b. Hyperinflation indicated by increased total lung capacity


c. Forced vital capacity may be reduced by air trapping.


d. The reduction in forced vital capacity is, on a percentage of normal basis, less than the percentage reduction in predicted expiratory air flow.


B. Arterial blood gases and pulse oximetry


1. Earlier in the course of disease, and often during the later stages, both studies show normal oxygenation and arterial blood gases (ABGs) show no evidence of chronic respiratory acidosis.


2. Seen more frequently later in the course of disease, or during exacerbations of moderately severe disease


a. Hypoxemia (PaO2 [partial pressure of oxygen in arterial blood] less than 55 mmHg)


b. Hypercarbia (chronic respiratory acidosis)


3. During acute exacerbations of COPD, hypoxemia and acute hypercarbia may be seen.


a. Assessment requires at least one ABG analysis.


b. Increasing respiratory distress and changes in mental status (confusion, stupor) require more frequent checks of ABGs.


4. Pulse oximetry


a. Used frequently to assess for adequacy of oxygen transport within the blood at rest and during exertion


b. Adequate oxygenation is implied when SaO2 (oxygen saturation) is greater than 88% when the hemoglobin level is above 10 g/dl.


C. Other laboratory values


1. Hemoglobin and hematocrit


a. Hemoglobin less than 10 g/dl may be suboptimal for oxygen transport.


b. Hematocrit greater than 55 ml/dl indicates secondary polycythemia due to chronic hypoxemia.


2. Serum bicarbonate is elevated with chronic hypercarbia.


D. Chest x-ray


1. Air trapping


2. Blebs and bullae (dilated air spaces within the pulmonary parenchyma)


3. Flattened diaphragm



VII. Pharmacologic management


A. Anticholinergic agents


1. Decrease airway secretions and airway smooth muscle tone


2. Agent of choice in COPD: ipratropium bromide (Atrovent), 2 puffs 4 times a day; also premixed in saline for use in handheld nebulizer


a. Mainstay of therapy for COPD


b. Adverse effects: dry mouth and dry, hacking cough or oral candidiasis (teach patient to rinse mouth after use)


B. Bronchodilators


1. Beta2-adrenergic receptor agonists


a. Relax smooth muscle tone and improve air flow.


b. Stimulate ciliary motion to promote secretion mobilization.


2. Short-acting inhaled beta2 agonists: used for episodic symptom exacerbations or before exercise for exercise-induced bronchospasm


a. Albuterol (Proventil, Ventolin); also premixed in saline for handheld nebulizer use


b. Metaproterenol (Alupent); premixed in saline for heldheld nebulizer use


c. Pirbuterol (Maxair)


d. Terbutaline (Brethine), 2 puffs 3 times a day


3. Long-acting inhaled beta2 agonists: used for maintenance therapy only; bronchodilation for up to 12 hours


a. Salmeterol (Serevent Diskus): Prolonged receptor binding requires patient education about proper use to avoid induction of cardiac arrhythmias.


4. Oral preparations of beta2 agonists


a. Albuterol (Volmax), 2-4 mg 3 times a day


b. Albuterol extended-release (Proventil, Repetab), 4 mg every 12 hours

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Mar 3, 2017 | Posted by in NURSING | Comments Off on 24. Obstructive (Ventilatory) Lung Diseases

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