bubble_chart Overview

If acute empyema is not treated thoroughly and the course of the disease exceeds six weeks, the pus becomes viscous with a large amount of fibrin. This fibrin deposits on both the visceral and parietal layers of the pleura, forming thick fibrous plaques that restrict the expansion of lung tissue. As a result, the abscess cavity cannot shrink further, leading to the formation of chronic empyema.

bubble_chart Etiology

(1) Inadequate treatment of acute empyema or improper management

During acute empyema, inappropriate selection of antibiotics, or failure to timely adjust the dose and switch to sensitive antibiotics during treatment, may result in persistent excessive pus production. If the drainage tube is improperly positioned in terms of height or depth, or if the tube diameter is too narrow, or if the tube is twisted or obstructed, leading to poor drainage, chronic empyema may develop.

(2) Retention of foreign bodies in the pleural cavity

If foreign bodies such as metal fragments, bone chips, or fabric remnants remain in the pleural cavity after trauma, or if surgical foreign bodies are retained, empyema is difficult to cure. Even with thorough and unobstructed drainage, the source of pathogenic bacteria cannot be eliminated due to the retained foreign bodies, preventing recovery.

(3) Failure to cure the primary disease causing empyema

If empyema is secondary to diseases such as lung abscess, bronchial fistula, esophageal fistula, liver abscess, subphrenic abscess, or vertebral osteomyelitis, it is difficult to cure the empyema before the primary condition is resolved, leading to chronic empyema.

(4) Specific infections

Subcutaneous nodular infections, fungal infections, and amoebic empyema are all prone to developing into chronic empyema.

bubble_chart Pathological Changes

In chronic empyema, due to prolonged accumulation of pus, a large amount of fibrin deposits and gradually organizes, forming a fibrous plate that can be 2 cm thick or even thicker. As a result, the chest wall undergoes inward invasion, the ribs become clustered together, the intercostal spaces narrow, and the ribs themselves undergo triangular changes. The spine curves toward the healthy side, and the diaphragm is also immobilized due to the restriction of the thickened pleural fibrous plate. Consequently, respiratory movement is severely affected and significantly weakened. At the same time, due to the contraction of the fibrous plate, the mediastinum is pulled toward the affected side, impairing blood circulation. Patients may develop clubbed fingers (or toes) due to chronic hypoxia.

Patients with chronic empyema may experience hepatomegaly, splenomegaly, and renal dysfunction due to long-term chronic infection. Some cases of empyema may invade the lungs, forming a bronchopleural fistula, or directly penetrate the pleura to invade outward, passing through the intercostal spaces to form a dumbbell-shaped abscess, or even perforate the skin to create a pleurocutaneous fistula.

bubble_chart Clinical Manifestations

Long-term infection and chronic wasting often lead to chronic systemic toxic symptoms in patients, such as low-grade fever, lack of strength, loss of appetite, emaciation, malnutrition, anemia, and hypoproteinemia. Those with bronchopleural fistula cough up large amounts of purulent sputum, which is related to body position.

When combined with a cutaneous fistula, pus may discharge from the fistula opening. Physical examination may reveal depression of the affected chest wall, narrowed intercostal spaces, weakened or absent respiratory movements, dullness on percussion, mediastinal and cardiac shift toward the affected side, diminished or absent breath sounds, scoliosis, and clubbing of fingers (toes).

bubble_chart Diagnosis

Based on the medical history and signs, a preliminary diagnosis can be made.

X-ray: Thickening of the affected pleural membrane, narrowing of the intercostal spaces, and large areas of increased density with hazy, blurred shadows. The mediastinum shifts toward the affected side, and the diaphragm is elevated. High-voltage films or tomograms can reveal the thickened pleural membrane, the abscess cavity, and the condition of the lung tissue. If a fluid level is present, it indicates a history of pulmonary fistula disease with gas or the persistence of a bronchopleural fistula. Combining anteroposterior and lateral chest films can clarify the size and location of the abscess cavity. When a fluid level is present, horizontal projection with the patient lying on the healthy side can reveal the position of the abscess cavity's base.

CT scan: This can further determine whether there are lesions in the lung tissue, such as subcutaneous nodules, bronchiectasis, cysts, or abscesses, which are highly useful for formulating a surgical plan. If there are intrapulmonary lesions, pleural decortication combined with lobectomy or even pneumonectomy, or additional thoracoplasty, may be required.

B-mode ultrasound: In the hypoechoic area of pleural effusion, due to the high cellular content in the fluid, cells often aggregate, forming flocculent material. Therefore, the sonogram shows small echoes of varying intensity and uneven distribution, with slight floating movements. If the patient moves rapidly, the echoes in the fluid exhibit enhanced floating, even tumbling up and down, making them easily identifiable.

The difference between ultrasound findings in empyema and simple pleural thickening is that, after increasing the gain, the hypoechoic area still shows no echoes, whereas the area of pleural thickening exhibits enhanced echoes, displaying characteristics of solid tissue.

For chronic empyema, if thoracentesis or closed thoracic drainage has not been performed, a thoracentesis should be done to aspirate pus for definitive diagnosis, along with bacterial culture and drug sensitivity tests to identify the pathogenic bacteria and select effective antibiotics.

The diagnosis of chronic empyema is not difficult. Based on symptoms, signs, X-ray findings, B-mode ultrasound, and especially the results of thoracentesis, a definitive diagnosis can be made.

bubble_chart Treatment Measures

(1) Chronic empyema often requires surgical treatment

to remove foreign bodies, eliminate the purulent cavity, and preserve and restore lung function as much as possible. Preoperative measures include appropriate nutritional supplementation, correction of hypoproteinemia and anemia, multiple small blood transfusions to enhance the body's resistance, and the use of effective antibiotics to control infection.

(2) High-speed drainage tube for adequate drainage of pus

When systemic toxic symptoms subside, the lung re-expands, and the purulent cavity shrinks or closes, the empyema may heal. If the cavity cannot close or disappear, thorough drainage is also a necessary preparation for radical surgery. In cases of chronic empyema with minimal pus, the closed drainage tube can be shortened and converted to open drainage. After open drainage, the tube should be secured with a safety pin to prevent it from falling into the cavity. As the cavity gradually closes, the drainage tube can be progressively withdrawn and replaced with a thinner one to facilitate closure.

(3) Requirements for drainage of chronic empyema cavities

1. Proper positioning: The drainage tube should be placed at the dependent part of the cavity but not too low, as this may lead to blockage of the tube opening when the cavity shrinks slightly, affecting further drainage.

2. Sufficient tube diameter: The internal diameter should be 1–1.5 cm, inserted about 2–3 cm into the cavity, with side holes to facilitate drainage. In chronic empyema, the intercostal space is narrowed, making tube placement difficult. Therefore, closed thoracic drainage via rib bed incision is often necessary. This involves making a 5 cm incision, cutting through the fascia and muscle layers, removing a segment of rib, incising the rib bed, and excising a small piece of chest wall tissue for pathological examination. The drainage tube is then inserted through the fibrous pleural layer into the cavity, adjusted to the proper position, and the chest wall incision is sutured layer by layer. This ensures the tube is not compressed by the ribs, maintains unobstructed drainage, and minimizes pain caused by tube irritation.

(4) Pleural decortication

This procedure involves stripping the thickened fibrous layers of the parietal and visceral pleura to free the lung tissue from fibrous constraints, allowing re-expansion of the lung, restoration of chest wall respiratory movement, elimination of the purulent cavity, and preservation of the normal thoracic shape.

1. Indications: Chronic empyema with pus largely controlled (daily pus volume <50 ml) but persistent cavity and pus; absence of extensive lung lesions, fibrosis, cavities, bronchiectasis, stenosis, or large bronchopleural fistulas.

2. Surgical method: Performed under general anesthesia with endotracheal intubation. A posterolateral incision is made through the skin, subcutaneous tissue, and muscles. The periosteum is incised, and the 5th or 6th rib is removed. The rib bed is opened, and the pleural fibrous layer is bluntly dissected along the extrapleural space. After sufficient dissection, a rib spreader is used to widen the incision and intercostal space for further decortication. The entire fibrous layer is stripped, though the transition between visceral and parietal layers may be indistinct. The cavity can be opened to remove pus and fibrin, followed by careful visceral decortication. Visceral decortication is often challenging, especially near the primary lesion. To avoid lung injury, some fibrous tissue may be left and scored in a grid pattern to reduce lung constraint and facilitate expansion. Meticulous hemostasis and suturing of large bronchopleural fistulas are essential. Common causes of surgical failure include hemothorax and severe air leaks. Two large drainage tubes (upper and lower) are placed postoperatively to ensure adequate drainage, with negative pressure suction if necessary, to effectively prevent or reduce complications.

(5) Thoracoplasty

Thoracoplasty involves partial rib resection to collapse the chest wall and compress the purulent cavity. For empyema, intrapleural thoracoplasty is used, where ribs are removed and the pleural cavity is opened.

1. Surgical Indications Thoracoplasty is suitable for patients with intrapulmonary lesions, such as severe pulmonary fibrosis, subcutaneous nodule lesions, bronchiectasis, etc., as well as those with bronchopleural fistula.

2. Surgical Method The surgery is performed under general anesthesia with endotracheal intubation. If there is a bronchopleural fistula, a double-lumen tube should be inserted to prevent intraoperative blood from entering the bronchus through the fistula, which could lead to disease dissemination. The surgical incision is determined based on the extent and location of the empyema. For total empyema, the 5th or 6th rib is usually resected first, and the thickened pleural fibrous layer is incised through the rib bed to enter the empyema cavity. Pus and necrotic tissue are aspirated, and depending on the size of the cavity, corresponding ribs and the parietal pleural fibrous layer are removed. Granulation tissue on the visceral pleural fibrous layer is scraped away, hemostasis is carefully achieved, and the area is thoroughly irrigated. One to two or even multiple drainage tubes are placed to ensure adequate drainage, depending on the size of the cavity. The incision muscles and skin are loosely sutured intermittently, followed by pressure dressing with cotton pads and a multi-tailed chest bandage to ensure close apposition of the chest wall muscles and intercostal muscles (including the rib periosteum and intercostal neurovascular bundle) with the visceral pleural fibrous layer, leaving no residual cavity. Postoperatively, antibiotic therapy is intensified, and the drainage tubes are left in place for several days until no further effusion is observed, typically around two weeks post-surgery. Pressure dressing is generally maintained for about five weeks. Premature removal of the dressing may cause the soft tissues of the chest wall to lift, resulting in a residual cavity and surgical failure. This modified surgical method is less traumatic compared to the original extrapleural thoracoplasty, which involved resection of the chest wall muscles, intercostal muscles, and intercostal neurovascular bundle. Postoperatively, nerve innervation and blood supply are preserved, avoiding the drawbacks of severe chest wall numbness and deformity. Since extrapleural thoracoplasty does not remove the parietal pleural fibrous layer, it often fails to completely obliterate the empyema cavity and is rarely used nowadays.

Thoracoplasty generally requires resection of one rib above and below the empyema cavity, with the length exceeding the cavity by 2-3 cm. For large empyema cavities, the surgery can be performed in stages. The first stage involves resection of the 2nd to 6th ribs, and the intermediate stage (second stage) involves resection of the 7th to 10th ribs to avoid excessive trauma from a single surgery, which could hinder postoperative recovery.

(VI) Pleuropneumonectomy

For chronic empyema complicated by extensive pulmonary diseases such as subcutaneous nodular cavities, bronchiectasis, or bronchial stenosis, pleural decortication and thoracoplasty are not suitable and may worsen the pulmonary condition. If the contralateral lung is healthy, pleuropneumonectomy can be performed. This involves en bloc resection of the entire lung and the empyema. Prior pleural decortication is generally unnecessary, though partial fibrous layer resection may be done for surgical convenience. The hilar structures are carefully dissected and freed, taking care to avoid injury to important organs such as the esophagus and superior vena cava. If necessary, the pericardium can be opened to manage major vessels within the pericardium. Pleuropneumonectomy is technically complex, involves significant bleeding, and carries high surgical risks, requiring considerable experience. Therefore, strict indications and thorough preoperative preparation are essential. Meticulous attention to hemostasis and anticipation of organ displacement during surgery are crucial to avoid complications. After resection of the lung and pleural fibrous layer, the thoracic cavity must be thoroughly irrigated. Postoperative antibiotic therapy is intensified, as thoracic infection is a major cause of surgical failure and is difficult to control, often necessitating additional thoracoplasty or even open wound management, leading to prolonged illness and significant patient suffering.

(VII) Pedicled Omental Flap Transplantation

In recent years, some thoracic surgeons have successfully treated chronic empyema and bronchopleural fistula by transplanting a vascularized pedicled omental flap into the thoracic cavity. The omentum has rich blood circulation, strong regenerative capacity, and absorptive function, allowing it to adhere easily to surrounding tissues and form extensive collateral circulation, thereby ensuring surgical success.

The pedicled greater omentum filling the thoracic cavity is suitable for treating various chronic empyemas, including patients with poor constitution who are unsuitable for thoracoplasty, as well as empyemas that are difficult to cure by other methods, such as chronic empyema with bilateral pulmonary lesions. However, patients who have undergone abdominal surgery or have suffered from peritonitis are not suitable for this procedure due to severe omental adhesions that prevent mobilization. The surgery is also more challenging in cases of excessive wasting where the greater omentum is too thin.

The surgical method involves resecting the parietal pleural fibrous layer, scraping away the granulation tissue and necrotic tissue within the abscess cavity, and repeatedly irrigating the abscess cavity. The deformed ribs in the anterior and middle segments (2-3 ribs) are resected subperiosteally. The greater omentum with a vascular pedicle is lifted into the abscess cavity via the left costophrenic angle or the right subcutaneous tissue. For cases with bronchopleural fistula, the surrounding area of the fistula is cleaned, and the fistula is then plugged and sutured in place using the greater omentum. The remaining cavity is filled with intercostal muscle and chest wall muscle tissue. Generally, no drainage tube is placed, except for two rubber drainage strips inserted into the wound. The chest wall is sutured and pressure bandaged.

The greatest advantage of greater omentum thoracic transplantation with a vascular pedicle is that it causes minimal chest deformity and less injury, facilitating recovery.