Transcript
Chapter 11: Alterations in Pulmonary Function
Chapter Summary
Restrictive diseases interfere with lung expansion and are characterized by decreased lung volumes and compliance, and decreased TLC and TV. Obstructive diseases interfere with expiratory airflow and are characterized by normal or increased lung volumes, normal or increased lung compliance, air trapping, and reduced expiratory flow rates.
Acute respiratory failure (ARF) is a life-threatening medical emergency that can cause global tissue hypoxia and MODS. ARF can be divided into two components—failure to oxygenate and failure to ventilate—with one component often being the primary trigger.
ARDS is a severe inflammatory lung disorder characterized by nonhydrostatic pulmonary edema and refractory hypoxemia. It can be triggered by local or distant predisposing factors. The most common predisposing factors include sepsis, pneumonia, gastric aspiration, and posttrauma injury with shock. Diagnosis is usually based on the ARDS consensus criteria or the Modified Lung Injury Score.
ARDS clinical presentation is fairly predictable. Pathogenesis involves injury to the pulmonary alveolar–capillary membrane associated with inflammatory cells with their products. ARDS treatment strategies are primarily supportive, centering on improving gas exchange through mechanical ventilation, and may include positioning therapy, drug therapy (e.g., iNO or corticosteroids), and conservative fluid management.
There are four major types of pulmonary emboli (PE): thrombus, fat, amniotic, and venous air. In addition, other bloodborne substances such as vegetative bacterial growths or sloughing dead tissue can become emboli. Thromboembolism is the major cause of PE, and DVT is the major source of thromboembolism. Predisposing factors for DVT are those noted in Virchow’s triad. Common signs and symptoms of PE include dyspnea, tachypnea, pleuritic pain, cough, wheeze, crackles, and unilateral leg pain and swelling.
A preliminary risk assessment should be completed on all patients suspected of having PE. A variety of tests can help make the diagnosis, including D-dimer assay, spiral CT scan, and ECG. The pulmonary angiogram is the definitive test. Early assessment of DVT risk and implementation of interventions to prevent DVT during hospitalization are crucial for all high-risk patients.
Treatment of PE is focused on anticoagulant therapy. Fibrinolytic therapy or mechanical clot removal may be used for severe cases. Oxygen therapy is common, and shock protocols are initiated as needed with severe PE.
Pneumonia is the leading cause of death from infection in the United States. Pneumococcal pneumonia is the most common CAP in the United States. The classic signs and symptoms are acute onset of cough, fever, chills, purulent sputum, pleuritic chest pain, and shortness of breath.
Aspiration syndromes may result when contaminants enter the lower airways. Aspiration pneumonitis results from aspiration of caustic, low-pH gastric contents into the lungs, which sets up the inflammatory process and causes damage. Aspiration pneumonia develops when oropharyngeal or colonized gastric secretions enter the lungs, setting up infection. Dysphagia and altered level of consciousness are major factors in aspiration. Poor oral hygiene contributes to the contamination of oral secretions.
Influenza pneumonia is a potentially severe complication of influenza infection. The clinical presentation of viral pneumonia includes prolonged flu symptoms with progressive dyspnea and fever.
Pneumonia prevention strategies include pneumococcal and influenza vaccines and smoking cessation. Strategies for prevention of aspiration include evaluation of swallowing by speech pathologists, recognition of signs of aspiration, and feeding techniques to enhance safe swallowing.
Common disorders requiring thoracic surgery include lung cancer, emphysema, localized infection of the lung and pleura, lung transplantation, and chest wall deformities. Lung resections are categorized by the amount of lung removed. Postoperatively, pneumonectomy patients may be positioned supine or lying on the operative side, never on the nonoperative side.
Postthoracic surgery pain control and pulmonary hygiene are priorities in the postoperative phase to prevent complications, primarily atelectasis, and pneumonia. Modified cough techniques and splinting the incision are used to improve cough. Chest tube insertion is often required when the integrity of the pleural linings has been compromised, causing a loss of negative intrapleural pressure. Pneumothorax or hemothorax may result from an internal or external insult.
The location of the chest tube insertion depends on the problem being treated. A pneumothorax tube is placed high on the anterior chest to facilitate removal of air, whereas a hemothorax tube is placed lower on the chest near the midaxillary line to drain the lower lung field. Management of the patient with a chest tube includes monitoring chest drainage system status, controlling pain, and promoting pulmonary hygiene.
