Pulmonary Heart Disease (Cor Pulmonale)
Cor pulmonale is a condition in which the right ventricle of theheart enlarges (with or without right-sided heart failure) as a re-sult of diseases that affect the structure or function of the lung or its vasculature. Any disease affecting the lungs and accompanied by hypoxemia may result in cor pulmonale. The most frequent cause is severe COPD, in which changes in the air-way and retained secretions reduce alveolar ventilation. Other causes are conditions that restrict or compromise ventilatory function, leading to hypoxemia or acidosis (deformities of the thoracic cage, massive obesity), or conditions that reduce the pul-monary vascular bed (primary idiopathic pulmonary arterial hypertension, pulmonary embolus). Certain disorders of the ner-vous system, respiratory muscles, chest wall, and pulmonary arterial tree also may be responsible for cor pulmonale.
Pulmonary disease can produce physiologic changes that in time affect the heart and cause the right ventricle to enlarge and even-tually fail. Any condition that deprives the lungs of oxygen can cause hypoxemia and hypercapnia, resulting in ventilatory insuf-ficiency. Hypoxemia and hypercapnia cause pulmonary arterial vasoconstriction and possibly reduction of the pulmonary vascu-lar bed, as in emphysema or pulmonary emboli. The result is in-creased resistance in the pulmonary circulatory system, with a subsequent rise in pulmonary blood pressure (pulmonary hyper-tension). A mean pulmonary arterial pressure of 45 mm Hg or more may occur in cor pulmonale. Right ventricular hypertrophy may result, followed by right ventricular failure. In short, cor pul-monale results from pulmonary hypertension, which causes the right side of the heart to enlarge because of the increased work re-quired to pump blood against high resistance through the pul-monary vascular system.
Symptoms of cor pulmonale are usually related to the underlying lung disease, such as COPD. With right ventricular failure, the patient may develop increasing edema of the feet and legs, dis-tended neck veins, an enlarged palpable liver, pleural effusion, as-cites, and a heart murmur. Headache, confusion, and somnolence may occur as a result of increased levels of carbon dioxide (hyper-capnia). Patients often complain of increasing shortness of breath, wheezing, cough, and fatigue.
The objectives of treatment are to improve the patient’s ventila-tion and to treat both the underlying lung disease and the mani-festations of heart disease. Supplemental oxygen is administered to improve gas exchange and to reduce pulmonary arterial pres-sure and pulmonary vascular resistance. Improved oxygen trans-port relieves the pulmonary hypertension that is causing the cor pulmonale.
Better survival rates and greater reduction in pulmonary vas-cular resistance have been reported with continuous, 24-hour oxygen therapy for patients with severe hypoxemia. Substantial improvement may require 4 to 6 weeks of oxygen therapy, usu-ally in the home. Periodic assessment of pulse oximetry and arte-rial blood gases is necessary to determine the adequacy of alveolar ventilation and to monitor the effectiveness of oxygen therapy.
Ventilation is further improved with chest physical therapy and bronchial hygiene maneuvers as indicated to remove accu-mulated secretions, and the administration of bronchodilators. Further measures depend on the patient’s condition. If the pa-tient is in respiratory failure, endotracheal intubation and me-chanical ventilation may be necessary. If the patient is in heart failure, hypoxemia and hypercapnia must be relieved to improve cardiac function and output. Bed rest, sodium restriction, and di-uretic therapy also are instituted judiciously to reduce peripheral edema (to lower pulmonary arterial pressure through a decrease in total blood volume) and the circulatory load on the right side of the heart. Digitalis may be prescribed to relieve pulmonary hypertension if the patient also has left ventricular failure, a supraventricular dysrhythmia, or right ventricular failure that does not respond to other therapy.
ECG monitoring may be indicated because of the high inci-dence of dysrhythmias in patients with cor pulmonale. Any pul-monary infection must be treated promptly to avoid further impaired gas exchange and exacerbations of hypoxemia and pul-monary heart disease. The prognosis depends on whether the pulmonary hypertension is reversible.
Nursing care of the patient with cor pulmonale addresses the underlying disorder leading to cor pulmonale as well as the prob-lems related to pulmonary hyperventilation and right-sided car-diac failure. If intubation and mechanical ventilation are required to manage ARF, the nurse assists with the intubation procedure and maintains mechanical ventilation. The nurse assesses the pa-tient’s respiratory and cardiac status and administers medications as prescribed.
During the patient’s hospital stay, the nurse instructs the pa-tient about the importance of close monitoring (fluid retention, weight gain, edema) and adherence to the therapeutic regimen, especially the 24-hour use of oxygen. Factors that affect the pa-tient’s adherence to the treatment regimen are explored and addressed.
Most of the care and monitoring ofthe patient with cor pulmonale is performed by the patient and family in the home because it is a chronic disorder. If supple-mental oxygen is administered, the nurse instructs the patient and the family in its use. Nutrition counseling is warranted if the pa-tient is on a sodium-restricted diet or is taking diuretics. The nurse teaches the family to monitor for signs and symptoms of right ventricular failure and about emergency interventions and when to call for assistance. Most importantly, the nurse urges the patient to stop smoking.
A referral for home care may be warranted forthe patient who cannot manage self-care or for the patient whose physical condition warrants close assessment. During the home visit, the home care nurse evaluates the patient’s status and the patient’s and family members’ understanding of the therapeutic regimen and their adherence to it. If oxygen is used in the home, the nurse determines if it is being administered safely and as pre-scribed. It is important to assess the patient’s progress in stopping smoking and to reinforce the importance of smoking cessation with the patient and family. The nurse identifies strategies to as-sist with smoking cessation and refers the patient and family to community support groups. In addition, the patient is reminded about the importance of other health promotion and screening practices.
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