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[Gr. empyēma, abscess]
A collection of pus in a body cavity, esp. the pleural space.
In the U.S., about 6 people per 100,000 are hospitalized with empyema annually. The number of people with empyema doubled between 1996 and 2008; most of the increase appeared to be caused by a rise in staphylococcal infections.
The disease is usually caused by the local spread of infection from a pneumonia or lung abscess but may be caused by organisms brought to the pleural space via the blood or lymphatic system or an abscess extending upward from below the diaphragm. Streptococcus pneumoniae, Staphylococcus aureus, and Klebsiella pneumoniae are the most common pathogens, but anaerobic organisms also can cause empyema.
SYMPTOMS AND SIGNS
Patients are usually quite ill, with high fevers and sweats, malaise, anorexia, and fatigue. They frequently present with tachycardia, pleurisy, cough, and dyspnea. Depending on the amount of pus and fluid present, physical examination may reveal unequal chest expansion, dullness on percussion, and decreased or absent breath sounds over the involved area. Fibrinous adhesions may fill the pleural space and inhibit lung expansion.
Empyema may be diagnosed indirectly by chest x-rays, computerized tomography, magnetic resonance imaging, or definitively by thoracentesis (insertion of a large-bore needle into the pleural space). Withdrawal of fluid from the pleural space provides material for a culture and sensitivity test of the organism and helps the infection resolve.
The purulent exudate and fluid are drained via thoracentesis, and one or more chest tubes is inserted to underwater-seal chest drainage with suction. Surgical removal of the thick coating over the lung (decortication) or rib resection may be required to allow open drainage and lung expansion. Standard dressing precautions are used if the patient has open drainage. Medications such as urokinase may be injected into the pleural space to minimize fibrous adhesions and to help keep the chest tube stay patent; surgical drainage may be necessary. Intravenous antibiotic therapy is administered based on pathogen sensitivity. Oxygen is administered to treat associated hypoxia.
The patient should be prepared for the procedure and its associated effects, and urged to breathe normally and avoid coughing, sighing, or sudden movement. Vital signs are assessed before, during, and after the procedure, and the patient observed for syncope, respiratory distress, or pneumothorax. Sterile preparation of the chest before insertion of a needle, or any incision, is mandatory. After the fluid is definitively located, e.g., by ultrasonography, the skin on the chest wall is anesthetized, generally with an injection of lidocaine through a small gauge (29 or 30 g) needle. A larger needle is inserted deeper into the soft tissues and guided just above a rib (not below it, where the rib's neurovascular bundle is found). The patient will experience a sudden, intense pain when the needle penetrates the parietal pleura. Another needle with a very wide bore (12 or 14 g) is then used to withdraw fluid from the pleural space. Samples should be labeled immediately with unique patient identifiers and sent to the lab for analysis (pH, cell count, cultures, chemistries, fungi, and acid-fast bacillus stains). After the procedure is completed, the patient's vital signs, oxygen saturation, and symptoms are monitored for evidence of pneumothorax. Patency of any indwelling drainage system is maintained; drainage volume, color, and characteristics are documented; and the patient is protected from accidental dislodgement of the drainage tube. Increased fluid and protein are provided, and adequate pain relief is ensured. Breathing exercises and the use of incentive spirometry are encouraged. The patient may be discharged to home or rehabilitative care with a drainage tube still in place. Home health care is arranged as necessary.