Adult Chest Surgery

Chapter 127. Overview 

The diaphragm is a thin, dome-shaped fibromuscular organ that serves a number of anatomic and physiologic purposes. Its primary physiologic function is that of an air pump, whereby it provides the main mechanical forces of ventilation. When the diaphragm contracts in response to stimulation by the phrenic nerve, it descends into the abdominal cavity, thereby establishing a negative intrathoracic pressure. As a result, air is drawn into the lungs through an open glottis. As the muscle relaxes, it moves upward, forcing air out of the glottis in expiration. Anatomically, the diaphragm serves as a barrier between the thoracic and peritoneal cavities. Defects in the barrier permit herniation of abdominal organs into the chest as a result of the relatively negative intrapleural pressure.

The diaphragm is an uncommon site of disease, whether benign or malignant. Intimately associated with vital organs on the thoracic and abdominal surfaces, it can be involved with neoplasms from surrounding structures or diffuse pleural or peritoneal cancers. Less commonly, the diaphragm is invaded by metastasis from distant primary tumors. The most common indication for a partial resection of the diaphragm is local invasion by thoracic or abdominal tumors. The location of the diaphragm also makes it susceptible to trauma by either blunt or penetrating mechanisms. Reconstruction or repair of the diaphragm after resection or injury is essential to maintaining its structural and functional integrity. Usually, the diaphragm can be repaired primarily by using simple running or horizontal mattress sutures. Larger defects may require synthetic or semisynthetic grafts. Reconstruction is arguably more important on the left side than on the right, where the liver may prevent herniation of abdominal contents.

ANATOMY AND EMBRYOLOGY

The diaphragm consists of muscle fibers and a noncontractile central tendon (Fig. 127-1). Its muscle fibers originate from the lumbar spine posteriorly via the external and internal arcuate ligaments, the lower six ribs bilaterally, and the xiphisternum anteriorly. The muscle fibers curve upward and form an aponeurotic sheath known as the central tendon of the diaphragm, which serves as the insertion. The muscle fibers and tendons that comprise the diaphragm are arranged in a crossing pattern and are covered by thin layers of pleura and peritoneum. The diaphragm is the major muscle involved in ventilation, and it serves to divide the thoracic and abdominal compartments. The organ has several distinct apertures, through which a number of structures pass, including the vena cava, aorta, and esophagus. The apertures are usually sealed with thin layers of tissue that prevent communication between the thoracic cavity and the peritoneal cavity (Fig. 127-2). Each of the apertures, along with the multiple areas of fusion that occur during normal embryologic development, offers a potential site for visceral herniation.

Figure 127-1.

 

The muscle fibers of the diaphragm originate from the posterior lumbar spine (arcuate ligaments) and curve upward to form an aponeurotic sheath known as the central tendon. Several thoracic organs and vessels pass through apertures in the diaphragmatic surface.

 

Figure 127-2.

 

Apertures are covered by a thin layer of tissue.

 

The arterial blood supply of the diaphragm is variable but is derived mainly from the aorta and the right and left phrenic arteries. Both the arterial supply and the venous drainage are located on the abdominal surface of the diaphragm (Fig. 127-3). It is along this surface that the inferior phrenic artery divides into anterior and lateral branches shortly after the takeoff of the superior suprarenal arteries.

Figure 127-3.

 

Blood supply and innervation from the abdominal surface of the diaphragm.

 

The diaphragm is innervated solely by the phrenic nerves, which are derived mainly from the fourth cervical ramus, although it has additional contributions from the third and fifth rami. The right nerve passes through the tendinous portion of the diaphragm along the lateral aspect of the inferior vena cava, delivering three branches along the inferior aspect of the diaphragm: the anterior, lateral, and posterior rami. On the left side, the nerve passes through the diaphragm just anterior to the central tendon and lateral to the pericardium and forms similar branches (see Fig. 127-3). On the thoracic surface, the branches of the phrenic nerve assume a "handcuff" distribution, knowledge of which is important when planning incisions of the diaphragm (Fig. 127-4) (see also Chap. 128). Although this anatomy is similar in 75% of patients, numerous variations have been described.The phrenic nerve courses in close proximity to the internal thoracic artery bilaterally, but its relationship to the artery is variable, passing either anterior or posterior to the artery. This makes injury to the nerve possible during mobilization of the internal mammary artery for coronary revascularization (Fig. 127-5).

Figure 127-4.

 

Thoracic surface of the diaphragm.

 

Figure 127-5.

 

A. Close proximity of the phrenic nerves and internal thoracic artery increases the risk of diaphragmatic injury during mobilization of the artery. B. Chest radiograph showing elevation of the right hemidiaphragm after injury to the right phrenic nerve.

 

The lymphatic drainage of the diaphragm is directed toward one of three lymph node centers. The anterior and lateral diaphragmatic lymphatic channels drain into the internal mammary and anterior peridiaphragmatic lymph nodes. The posterior diaphragmatic lymphatics drain into the periaortic and posterior mediastinum lymph nodes. These centers then go on to ascending pathways via the thoracic duct, internal thoracic vessels, and mediastinum to the peritracheobronchial nodes.2

The diaphragm is formed at an early stage in embryonic development. It is created by the fusion of four discrete structures (i.e., septum transversum, pleuriperitoneal membrane, dorsal mesentery, and lateral body wall mesoderm) at the seventh week of development (Fig. 127-6). The diaphragm lies in its normal position at the eighth week, and by the tenth week, the intestines have returned to the abdomen from the yolk sac. At the fourth week of development, the septum transversum lies opposite the third, fourth, and fifth cervical somites. Myoblasts from these somites migrate into the diaphragm. Congenital defects of the diaphragm can arise by failure of any of the preceding processes. Bochdalek hernias are posterolateral and result from failed fusion of pleuriperitoneal folds at the eighth week of gestation. The defect occurs on the left side 75–90% of the time. It is rarely bilateral and occasionally can result in total absence of one hemidiaphragm. Foramen of Morgagni hernias are located posterior to the xiphoid process and are caused by failed migration of the cervical somites. Diaphragmatic eventration is caused by total failure of ingrowth of the cervical myotomes. As a result, the diaphragmatic musculature is entirely replaced by fibroelastic tissue. Congenital defects and hemidiaphragmatic hernias are discussed further in Chaps. 129 and 130, respectively.

Figure 127-6.

 

Embryologic development of the diaphragm at week 7.

PRIMARY TUMORS OF THE DIAPHRAGM

Primary tumors of the diaphragm are rare. Fewer than 200 cases have been reported in the literature. The latest comprehensive review of cases in the adult population was conducted by Olafsson and colleagues in 1971.3In this series, most patients were between 40 and 50 years of age at the time of diagnosis, although the range was quite extensive, including an 80-year-old woman with mesothelioma and a 26-day-old girl with hemangioendothelioma. The ratio of men to women was 1:1.1, and the incidence of right-versus left-sided lesions was equal. Benign lesions outnumbered malignant lesions 61% to 39%.

We performed a literature review of diaphragmatic tumors since the 1971 report, adding to the data from Olaffson and colleagues. The cumulative data show a similar ratio of malignant to benign tumors. The tumors for all patients in our review are subdivided by type and listed in Table 127-1.

Table 127-1. Primary Diaphragm Tumors

Benign

No.

Malignant

No.

Adenoma, adrenocortical

1

Chondrosarcoma

1

Adenoma, hepatic

1

Ewing sarcoma

1

Angiofibroma

4

Fibroangioendothelioma

1

Chondroma

2

Fibromyosarcoma

4

Cyst (bronchial, mesothelial, teratoid)

24

Fibrous histiocytoma

4

Fibroma

5

Hemangioendothelioma

2

Fibrolymphangioma

1

Hemangiopericytoma

2

Fibromyoma

1

Hepatocellular carcinoma

1

Hamartoma

2

Leiomyosarcoma

6

Hemangioma

2

Liposarcoma

1

Leiomyoma

1

Mesenchymoma

1

Lipoma

21

Myosarcoma

2

Lymphangioma, cystic

1

Neurofibrosarcoma

2

Mesothelioma

2

Osteosarcoma

1

Myofibroma

1

Pheochromocytoma

1

Neurilemoma

3

Rhabdomyosarcoma

12

Neurofibroma

5

Sarcoma

5

Rhabdomyofibroma

1

Sarcoma, endothelial

2

Schwannoma

1

Sarcoma, mixed cell

2

 

 

Sarcoma, undifferentiated

2

 

 

Synovioma

1

 

 

Yolk sac tumor

3

Total

79

Total

57

 

The most common type of benign tumors are cysts, whether bronchogenic or mesenchymal (30%) (Fig. 127-7), followed by lipomas (26%) (Fig. 127-8) and fibromas (6%) (Fig. 127-9). Common malignancies include rhabdomyosarcomas (21%) (Fig. 127-10), and leiomyosarcomas (10.5%). It is not surprising that most primary malignancies of the diaphragm are of mesenchymal origin given the embryological origin of the diaphragm.

Figure 127-7.

 

Bronchial cyst.

 

Figure 127-8.

 

Intramuscular lipoma.

 

Figure 127-9.

 

Fibrosarcoma.

 

Figure 127-10.

 

Alveolar rhabdomyosarcoma.

 

The symptoms and signs of diaphragmatic tumors are nonspecific, and most patients are asymptomatic. The tumor usually is discovered incidentally on imaging for another reason. The presenting symptoms of primary diaphragmatic tumors as reported by author are listed in Table 127-2, and as shown, the most common presenting symptom is pain. Pain can be localized to the lower chest or to the upper abdomen and may be pleuritic in nature. Other relatively common symptoms are cough and dyspnea. In children, an abdominal mass may be palpable in a small but significant proportion of patients.

Table 127-2. Presenting Symptoms of Diaphragmatic Tumors

 

Olafsson et al.3

Weiner6

Cada7

Symptom

Chest pain

Chest pain 27%

Chest pain 31%

 

Abdominal pain

Abdominal pain 22%

Abdominal pain 12%

 

Cough

Cough 9%

Cough 15%

 

Dyspnea

Clubbing 9%

Dyspnea 23%

 

Gastrointestinal upset

Fever 4.5%

Abdominal distention 15%

 

 

Back pain 4.5%

 

 

 

Pleural effusion 4.5%

 

 

Asymptomatic 20%

Asymptomatic 36%

 

 

It is important to differentiate a primary diaphragm tumor from either an invasive tumor emanating from an adjacent structure or a metastatic deposit from a distant neoplasm. The structure and position of the diaphragm, however, make diagnostic imaging difficult. Tumors arising in the region of the diaphragm most likely originate from an adjacent organ rather than the diaphragm itself. Thus the initial evaluation of a lesion identified in the thoracoabdominal region should be directed at the adjacent viscera. Once an assessment has been made of the surrounding organ and it is deemed an unlikely source of the tumor, then the diaphragm may be investigated as the primary source.

A great number of tests, such as plain film radiography, fluoroscopy, CT scanning, MRI, and ultrasonography, are used to study tumors of the chest and abdomen. Chest x-rays are rather nonspecific. Nevertheless, they often provide the first indication of a problem in the area of the diaphragm.Tumors found incidentally on chest radiography may cause a deformity in the diaphragmatic contour, but most such irregularities are unlikely to be of clinical significance. More often they represent weaknesses in the diaphragm, variation in the diaphragmatic insertions, or eventrations.CT scanning is becoming the diagnostic imaging modality of choice for masses in the region of the diaphragm. Since the diaphragm is thin and difficult to visualize on cross-sectional imaging, axial images may be complemented by multiplanar reformatting to increase diagnostic yield (Fig. 127-11).

Figure 127-11.

 
 

CT scan without reconstruction fails to visualize a tumor of the diaphragm (A), but reformatted images demonstrate the tumor (B).

SECONDARY TUMORS

Tumors arising from the lungs, liver, and gastroesophageal junction may invade the diaphragm directly. En bloc resection of the diaphragm with the primary tumor is often attempted, and repair of the diaphragmatic defects usually can be performed primarily with running monofilament sutures. Metastasis from a distant primary tumor has been known to involve the diaphragm, although this is a relatively rare phenomenon. The decision to resect the diaphragm is based on the site of the primary tumor and the likelihood that surgical resection will provide a survival advantage. Imaging of the diaphragm is difficult, and it may not be possible to determine before the time of surgery whether the diaphragm is involved. Therefore, whenever a primary tumor is found on or near the diaphragm, one should be prepared to perform a resection with reconstruction (Fig. 127-12).

Figure 127-12.

 

Reconstruction of the diaphragm with Gore-Tex mesh after resection of a diaphragmatic tumor.

Lung Cancer

Advanced lung cancers, either T3 or T4 malignant pleural effusions, are likely to involve the diaphragm and offer potential surgical challenges. For T3 lesions directly involving the diaphragm, en bloc surgical resection of the tumor with the diaphragm provides a chance for long-term survival. A number of reports have focused on locally advanced lung cancers with invasion of the diaphragm, a rare event occurring in fewer than 0.5% of lung cancer cases. Recent debate has focused on the classification and treatment of these tumors, as well as on prognostic factors. Riquet and colleaguesretrospectively reviewed 68 lung cancer patients from multiple centers who underwent thoracotomy for resection of lung cancer involving the diaphragm. The overall survival in patients who received a complete node dissection was 39%. Survival was neither affected by degree of pathologic involvement of the diaphragm or N status. Conversely, Yokoi and colleaguesdid find that prognosis was related to depth of invasion. Five-year survival in patients who had shallow invasion was 33%, whereas patients with tumor invading the muscle or peritoneum had survival of 14%. Invasion of the diaphragm may represent advanced biologic disease because the lymphatic and venous drainage of the diaphragm is so extensive. These tumors may be an indication for neoadjuvant chemotherapy. Others believe that they should be classified as T4.8,9,10

Generally, patients with T4 diaphragmatic involvement, pleural implants, and malignant pleural effusions have a very poor prognosis. Thoracoscopic talc pleurodesis is performed most commonly to provide palliation of malignant pleural effusions.11 Freidberg and colleagues12 performed directed pleural treatment with extrapleural pneumonectomy and achieved survival benefit in a small group of patients, with median survival of 22 months compared with the 4-6 months experienced historically. A multicenter trial is currently under way to determine the role for this aggressive therapy in these often terminal patients.

Hepatocellular Carcinoma

Gross diaphragmatic invasion by tumor is not uncommon for patients undergoing hepatic resection for hepatocellular carcinoma (HCC). Diaphragmatic invasion does not preclude a cure. In a recent surgical series of 640 patient who underwent curative resection for HCC,13 53 patients (8.3%) had gross involvement of the diaphragm at the time of surgery. Of those patients 7 (13.2%) had pathologically proven muscle invasion by tumor, whereas 46 (86.8%) had only fibrous adhesions between the tumor and the diaphragm. Patients underwent primary repair of the diaphragm in 52 cases (98.1%), and one required a mesh repair. There were no differences in operative mortality or postoperative complications between patients who had undergone diaphragmatic resection and those who had not. When matched by tumor stage, there was no difference in survival. In another series, 14 patients with diaphragm involvement by HCC were studied to determine if diaphragm invasion could be reliably identified preoperatively.14 Eight of 14 patients had a contour abnormality of the diaphragm that was termed a hump. A matched control group of 14 patients with HCC then was selected, and radiographs were reviewed. None of the matched patients had the same finding, or hump, on radiography, which led to the conclusion that in patients with HCC situated in the dome of the liver, the presence of a diaphragmatic hump on chest radiography strongly suggests invasion of the diaphragm. The study also showed that further diagnostic studies were not helpful in determining diaphragmatic involvement by HCC, as pre-operative chest CT scan, ultrasonography, and hepatic angiography failed to identify diaphragmatic invasion in any of these cases.

Gastroesophageal Junction Tumors

Tumors of the gastroesophageal junction often can invade the diaphragm at the hiatus, requiring resection of a portion of the crura to obtain a negative margin. Primary repair usually is all that is needed to reconstruct the hiatus, although more extensive resections may require graft or flap reconstruction. Although en bloc resection of the diaphragm with these tumors is technically feasible, the overall prognosis of patients with advanced-stage esophageal carcinoma is poor.

Distant Metastasis

The diaphragm serves as the anatomic barrier between the peritoneal and pleural spaces. Therefore, it is subject to intraperitoneal or intrapleural metastasis of tumors. Carcinomatosis from a number of abdominal neoplasms commonly will seed the diaphragm along with the entire peritoneal cavity. Peritonectomy is an aggressive operation involving the removal of peritoneal metastases for the purpose of cytoreduction. Most of the metastases on the diaphragm are superficial; however, invasive disease does occur.15 Resection of the diaphragm may be included as part of the cytoreduction if the tumors are invasive. Recently, a study of 215 patients undergoing cytoreduction therapy for advanced ovarian cancer16 showed that 74% of diaphragmatic implants were found on the right side. The study also found that the development of new pleural effusions occurred in 60% of patients following diaphragm resection; however, only 13% of patients with effusions required chest tube drainage. Another troublesome complication of cytoreductive surgery is the potential introduction of peritoneal tumor into the chest when the diaphragm is resected.

Although it is rare, the diaphragm also can be involved with isolated metastases. No tumors commonly metastasize to the diaphragm, although there are isolated case reports of renal cell carcinoma17 and colon cancer18 that have directly metastasized to the diaphragm. Other cases have been reported, but most appear to be the result of intrapleural or peritoneal spread. Given the relatively low incidence of involvement of the diaphragm by any specific tumor, the decision concerning resection should be determined on an individual basis. The rules that govern metastasectomy of tumors in other organs should apply when a solitary diaphragmatic nodule is discovered. Resection of an isolated diaphragmatic metastatic lesion should be attempted if the primary tumor is under control, there is no evidence of wide metastatic disease, and if the patient can tolerate the procedure.

Endometriosis

Endometriosis is defined as the presence of normal endometrial glands outside the endometrial cavity and uterine musculature. Implants usually are found in the pelvis, but they can be present almost anywhere. Diaphragmatic endometriosis is relatively rare. The implants, which are also known as chocolate cysts, typically are blue-brown in color and consist of normal endometrial stroma and glands. Most of the endometrial implants are on the right hemidiaphragm.17 Most cases are superficial and do not cause any symptoms, but if symptoms are present, they most likely will be in the form of ipsilateral shoulder, chest, arm, and neck pain that grows worse during menses.19 Cases where diaphragmatic involvement is deep and extension into the pleural space is present may result in catamenial pneumothorax, catamenial hemothorax, or catamenial hemoptysis.20

The diagnosis of diaphragmatic endometriosis requires a high level of suspicion. Patients should be asked about menstrual symptoms of shoulder or chest pain. Patients who have a syndrome of recurring pain thought to be due to endometriosis are commonly managed conservatively with hormonal therapies at first, although, medical therapy alone is not likely to be successful in treating cases of suspected diaphragmatic endometriosis.21 The diagnosis of diaphragmatic endometriosis is a surgical one; CT scanning and MRI are of limited value. The definitive diagnosis typically is made during exploratory laparoscopy, at which time identified lesions can be excised or obliterated and diaphragmatic defects repaired. Full-thickness excision of the diaphragmatic implants is effective and may provide patients with total symptomatic relief, but it may require the conversion to open laparotomy to complete. The use of thoracoscopy for the diagnosis and treatment of this condition has been described. The benefits of such an approach are the improved access to the diaphragm and the relative ease of visualization of the entire hemidiaphragm without the potential conversion to laparotomy.

Mesothelioma

Malignant mesothelioma is a neoplasm that typically arises from the mesothelial layer of the pleural and peritoneal surfaces. Mesothelioma is associated with documented asbestos exposure in most cases. Surgery is important in the treatment of early-stage mesothelioma and has been associated with long-term survival when accompanied by chemotherapy and radiation.

The diaphragm is commonly removed along with the parietal and visceral pleura, pericardium, and phrenic nerve as part of extrapleural pneumonectomy for cytoreduction of mesothelioma (see Chap. 103). Long-term results of patients undergoing trimodal therapy with extrapleural pneumonectomy followed by adjuvant chemotherapy and radiotherapy depend on the stage and cell type of the disease. In patients with favorable factors such as epithelial cell type, margin-negative resections, and extrapleural node-negative resection, the 5-year survival is 46%.22

POROUS DIAPHRAGM SYNDROMES

The disorders now known collectively as the porous diaphragm syndromes were first described and categorized by Kirschner.23 The porous diaphragm is the common pathology shared in conditions where disturbances in the chest are due to processes originating in the abdomen. Fluid, air, and tissues can travel through the diaphragmatic pores and cause pathology in the chest. The numerous porous syndromes are classified by the substance traversing the diaphragm and are listed in Table 127-3. The classification of types of diaphragmatic defects is given in Table 127-4.

Table 127-3. Porous Diaphragm Syndromes

Fluids

Spontaneous ascites

   Cirrhosis of the liver

   Meigs syndrome

   Pancreatic ascites

   Chylous ascites

Iatrogenic ascites

   Peritoneal dialysis

Hemoperitoneum

   Abdominal/tubal pregnancy

   Ruptured spleen

   Ruptured aortic aneurysm

   Operative hemorrhage

   Endometriosis

Gases

Pneumoperitoneum

   Catamenial pneumothorax

   Theraputic peritoneum

   Spontaneous pneumoperitoneum

   Laparoscopic pneumoperitoneum

   Diagnostic pneumoperitoneum

Tissue

Endometriosis

   Catamenial pneumothorax

   Pleural endometriosis

Exudates/secretions

Subphrenic abscess

   Liver abscess

Pancreatic pseudocyst

Biliothorax

Intestinal contents

Perforated peptic ulcer

 

Used with permission from ref. 21.

Table 127-4. Classification of Diaphragm Defects

Type I

No obvious defect

Type II

Blebs lying on the diaphragm

Type III

Fenestrations

Type IV

Multiple gaps (cribriform)

 

The presence of the pores can be either congenital or acquired, which may explain the bimodal incidence of porous diaphragm syndromes. Congenital defects account for the cases of porous syndrome that occur immediately with the onset of abdominal pathology, whereas acquired defects may account for cases in which new thoracic pathology arises in the setting of a long-standing abdominal process.

The development of a porous diaphragm syndrome typically occurs on the right side. Two factors may account for this finding23 (1) the normal flow of peritoneal fluid and (2) pressure created by the liver. The flow of peritoneal fluid has been established. This pattern of flow, or "peritoneal circulation," may cause a relative increase of peritoneal fluid in the subphrenic space on the right side, accounting for greater flow of fluid across right-sided diaphragmatic defects. Furthermore, the liver may increase the pressure on the right side of the diaphragm by compressing fluid against it, causing sufficient stress to create diaphragmatic pores.

Defects found in the diaphragm vary in morphology. Huang and colleagues24 devised a classification system (Table 127-4) of diaphragmatic pores in patients with hepatic hydrothorax based on patients with refractory hydrothorax who underwent thoracoscopic repair. They found that defects were variable in size and often were multiple.

Patients who are found to have blood, air, or infection in the chest as a result of an abdominal process are best managed by treating the primary pathology. Once the primary process is treated, the pleural process should resolve. Identification and treatment of the diaphragmatic defect is usually unnecessary if the source of the pleural pathology is controlled and does not return. However, in patients who have an ongoing condition refractory to treatment, such as patients undergoing continuous peritoneal dialysis or those with ascites secondary to intractable liver disease, establishing the presence of a pore may be more important. The existence of a diaphragmatic defect can be determined relatively safely and easily with the use radioactive tracers or vital dyes such as methylene blue. Pleural fluid is collected shortly after an intraabdominal injection of a tracer agent. Recovery of the tracer in the pleural fluid is diagnostic of a diaphragmatic defect.

If the initial steps taken to control the primary abdominal process fail, identification and treatment of the diaphragmatic defect may provide relief. The treatment includes primary closure of the diaphragmatic defect with or without obliteration of the pleural space by pleurodesis. Defects that are small and are visualized at the time of thoracoscopy may be managed by suture closure with a simple figure-of-eight stitch. Defects that are difficult to visualize may be identified by the intraperitoneal administration of 2 mL of methylene blue in 100–200 mL of normal saline at the time of surgery. The dyed peritoneal fluid may draw attention to pores that otherwise would not have been identified. A few of the more common porous syndromes are detailed below.

Hepatic Hydrothorax

Hepatic hydrothorax is defined as the presence of greater than 500 mL of pleural fluid in patients with liver disease and without cardiopulmonary disease. The incidence of hepatic hydrothorax in cirrhotic patients is estimated to be between 5% and 10%.25 Typically, the development of hydrothorax occurs slowly over time; however, it can present abruptly in the form of tension hydrothorax. This results from a large pleural effusion that displaces the mediastinum to the contralateral side, leading to sudden respiratory distress. The initial treatment of tension hydrothorax is thoracentesis. At the time of thoracentesis, enormous amounts of fluid may be retrieved from the chest, and the abdominal distention caused by ascites can be seen to diminish as fluid is removed from the chest. Conservative management of hepatic hydrothorax is directed at controlling the production of ascites by diuretic administration, salt restriction, and potentially transjugular intrahepatic portosystemic shunt.26

Hepatic hydrothorax refractory to maximal medical therapy may be controlled by repairing the diaphragmatic defect or obliterating the pleural space. Thoracoscopic approaches may be used to close the diaphragmatic defects primarily and may be supplemented with the addition of pleurodesis or onlay of pleura or mesh. Pleurodesis in cirrhotic patients with hepatic hydrothorax after thoracoscopy and the administration of talc is successful in 53–63% of patients.27 Overall success may improve to 80% with the addition of bedside talc slurry in patients who did not achieve pleurodesis after the initial talc application.28 The use of mesh alone to control hepatic hydrothorax also has been reported. In a recent report of patients with Child-Pugh class B-C cirrhosis and hepatic hydrothorax, 10 patients underwent repair of; however, it can present abruptly in the form of diaphragmatic defects with pleura or mesh onlay. At follow-up, none of the patients had recurrence of the hydrothorax, although a few patients died from causes related to their liver disease.29 Other authors have advocated for the use of bioabsorbable mesh in conjunction with fibrin glue and pleurodesis to control the hydrothorax.30

Peritoneal Dialysis

The presence of excess pleural fluid is common in patients with end-stage renal disease and may be due to volume overload, congestive heart failure, infection, or malignancy. Patients who are dependent on peritoneal dialysis also may have collections of fluid within the chest resulting from this type of therapy. This complication occurs in approximately 2% of patients undergoing peritoneal dialysis and is likely due to pleuroperitoneal communication.31 Differentiation of the type of effusion present in a patient undergoing peritoneal dialysis is made by analyzing pleural fluid collected following thoracentesis. The finding of fluid with a composition similar to that of the peritoneal diasylate points toward a diaphragmatic pore as the cause. Conservative management includes temporary interruption of dialysis with successful resolution in over half of cases.32 When interruption of dialysis is not successful, thoracoscopy with mechanical rub or talc pleurodesis may effectively control the communication and permit the majority of patients to resume peritoneal dialysis without further complication.33

Catamenial Pneumothorax

Catamenial pneumothorax is a syndrome defined by recurrent pneumothoraces in women within 72 hours of the onset of menses. Pneumothorax does not necessarily occur with every menses. The etiology of catamenial pneumothorax is unclear. Various mechanisms seeking to explain this phenomenon have been proposed. While all the theories are based on the physiologic changes associated with menses, each is unique in the way it seeks to explain how pneumothorax results. It may be due to intraperitoneal air associated with menses passing through diaphragmatic defects, the spontaneous rupture of blebs, alveolar rupture induced by prostaglandins from endometrial implants, or sloughing of pleural endometrial implants with subsequent air leak.34 The most extensive retrospective review of catamenial pneumothorax involved 229 patients and found that 92% of cases were right-sided, and only 39% had diaphragmatic defects found at thoracoscopy.35 A prospective case series later found that all patients with catamenial pneumothorax had either holes or endometrial implants on the diaphragm.36

Diagnosis and treatment of catamenial pneumothorax can be conducted through thoracoscopy, at which time a thorough evaluation of the thorax may be conducted and any identified lesions treated. Attempts at surgical intervention should be performed during menstruation for optimal identification of endometrial implants on the diaphragm surface.37 Diaphragm defects are best managed by excision and primary closure. Endometrial implants on the diaphragm should not be left behind because they may be responsible for seeding new endometrial implants and creating new defects. Medical management alone, with hormonal therapy such as oral contraceptive pills or gonadotropin-releasing hormone analogues, is unsuccessful in over 50% of patients. The successful treatment of catamenial pneumothorax can be achieved through a combination of thoracoscopy with resection of diaphragmatic defects, concurrent pleurodesis, and the addition of hormonal therapy. Some authors advocate the use of occlusive mesh on-lay of the diaphragm to exclude occult defects that are not identified and treated by resection.37

Diaphragmatic Injuries

Injury of the diaphragm is rare and occurs in approximately 3% of all abdominal injuries.38 Diaphragm injury may be found in 1–5% of patients following a motor vehicle collision and in 10–15% of patients sustaining penetrating injuries to the lower chest.39 Diaphragmatic injury rarely occurs in isolation; it is associated with other injuries in 80–100% of cases.40 Recognition of the injury is difficult and can easily be missed if the patient does not undergo surgery following the trauma. The rate of missed diaphragmatic injuries in patients managed nonoperatively is 12–60%.39 The delayed presentation of diaphragm injury may carry a significant morbidity if visceral herniation and strangulation occur. Therefore, a thorough evaluation of the diaphragm should be performed in any trauma patient with the potential to have such injury. When identified, all diaphragmatic injuries should be repaired because spontaneous closure of the diaphragmatic defect is unlikely owing to the pressure gradient across the diaphragm.

The diaphragm divides the thoracic and abdominal compartments, lying in intimate proximity to organs from both body cavities, making isolated diaphragmatic injury unlikely. The mechanism of trauma, as well as injures identified in adjacent organs, may help to predict diaphragmatic injury. Blunt trauma injuries to the chest, abdomen, and pelvis are associated with an increased likelihood of diaphragmatic injury.41 Injuries to the spleen and liver are most commonly associated with diaphragm injury. Signs and symptoms of diaphragm injury may be subtle; it is therefore unlikely that the symptoms related to diaphragm injury will dominate the clinical picture of a trauma patient. Recognition of the types and locations of injuries that are likely to be associated with diaphragmatic injury is important to guide clinical suspicion and evaluation of the diaphragm.

The type of diaphragm injury depends on the mechanism of trauma. Blunt injuries result in ruptures that typically occur in a congenitally weakened area of the posterior diaphragm. This type of injury usually is the result of pressure differences that occur when rapidly elevated intraabdominal pressure is transmitted across the diaphragm. Injuries generated by high-energy mechanisms such as motor vehicle collisions or falls from great heights may result in large disruptions of the diaphragm that are diagnosed early because of the resulting compromise in respiratory mechanics. The incidence of left-sided diaphragmatic injuries is slightly greater than that of right-sided injuries.42,43 A number of anatomic considerations may explain why the left diaphragm is injured more commonly in blunt trauma. Cadaver studies have demonstrated that the bursting pressure of the left diaphragm is slightly lower.44 The lower bursting pressure would cause the left hemidiaphragm to rupture preferentially. The liver also may be protective because it absorbs and dissipates the forces transmitted to the right hemidiaphragm. Alternatively, it may be that the presence of the liver leads to underdiagnosis of diaphragmatic injuries on the right side.42 In any case, the difference is modest, and the presence or absence of injury on one side cannot be used to determine diaphragmatic integrity on the other side.

Injuries caused by stabbings or gunshots in the area of the diaphragm may produce smaller defects. Injuries caused by penetrating trauma are more likely to be clinically silent at initial presentation; nonetheless, they are capable of causing serious complications in the long term. Left-sided injuries also predominate in penetrating trauma as most assailants are right-handed. Blows from the right hand are more likely to cause injury on the victim's left side.

Long-term complications of diaphragmatic injury and rupture are related to the herniation of abdominal organs through the defect. The symptoms of herniation are variable depending on whether the presentation is acute or chronic, as well as on the degree of herniation present. Acute presentations of diaphragmatic rupture may be predominated by signs and symptoms of respiratory compromise because the herniated viscera embarrass respiration by filling the chest and decreasing thoracic volumes and compliance. Small injuries may have no signs or symptoms in the acute setting. Chronic or delayed presentations are likely to present with signs and symptoms similar to those of bowel obstruction, such as abdominal pain, nausea, and vomiting. If incarceration and strangulation of the hernia contents have occurred, peritonitis also may be present. Thorough evaluation of the diaphragm in patients who are likely to have diaphragmatic injuries will prevent this complication from occurring.

The evaluation of diaphragmatic injuries is at times frustrating. There is no noninvasive means of imaging the diaphragm that is currently considered the "gold standard." Initial evaluation and treatment of diaphragm injuries are guided by a high level of clinical suspicion depending on the mechanism and severity of injury.

The initial evaluation of the diaphragm occurs during trauma resuscitation, when a plain chest radiagraph is performed. This study may be diagnostic, demonstrating a diaphragmatic contour deformity or herniation of visceral contents into the chest. The finding of a nasogastric tube coiled in the chest is highly suggestive of a rupture. Other findings include hemothorax and marked elevation of one hemidiaphragm. Overall sensitivity for plain radiography in detecting diaphragm rupture is in the range of 27–73%.45 Injuries may be masked by other findings, such as atelectasis, pleural effusions, or pulmonary contusions. The importance of serial examinations with chest radiography in patients who are intubated cannot be understated. Negative intrapleural pressure plays a major role in herniation of viscera after diaphragm rupture. In patients who are intubated with positive end-expiratory pressure, the positive intrapleural pressure may prevent herniation of abdominal contents. It may not be until the patient is weaned from the ventilator that the positive peritoneal pressure overcomes the thoracic pressure, and herniation occurs.

Victims of penetrating trauma should be evaluated carefully for diaphragm injury when the wound is in proximity of the diaphragm. Any patient with a stab wound below the level of the nipples and above the costal margins is at risk for having sustained an injury to the shot wounds are capable of penetrating the diaphragm from any entry site depending on the trajectory of the missile. Initial evaluation of the diaphragm in these patients is guided by the overall appearance of the patient. Patients with signs of hemodynamic instability or evisceration of abdominal contents should be taken to the OR emergently for exploratory laparotomy. During laparotomy, the entire diaphragmatic surface should be exposed and evaluated. On the other hand, patients who are hemodynamically stable may undergo further evaluation with chest radiography and CT scanning. As the use of nonoperative management of penetrating injuries increases, the accurate diagnosis of diaphragmatic injury by noninvasive means is even more important.

CT scanning has become the primary diagnostic study in the evaluation of patients sustaining abdominal injuries of any type. Studies focusing on the use of CT scanning for the detection of diaphragm injuries have reported widely variable results. The overall sensitivity of CT scanning in the detection of diaphragm injuries is reported to be between 14% and 82%, and overall specificity is 87%.45 With the use of more advanced helical CT scanners, sensitivity in diaphragm rupture is reported in the range of 71–100%. Diagnostic accuracy of imaging by CT scanning also may be enhanced by multiplanar reformatting.46 When imaging by CT scanning, direct visualization of the injury with herniation of abdominal contents is the most specific finding. Other findings that may be diagnostic are related to disruption of normal diaphragmatic attachments, diaphragmatic thickening, or extravasation of contrast material from the diaphragm. Visualization of the wound tract caused by a missle or a blade on either side of the diaphragm is also diagnostic of diaphragmatic injury. Injuries to the diaphragm are graded according to severity. The classification system was devised as part of the overall Injury Severity Score from the American Association for the Surgery of Trauma. Diaphragm injuries are graded by the degree of laceration and the overall amount of tissue loss. Regardless of the mechanism or grade of injury, ruptures of the diaphragm, however small, are unlikely to close spontaneously. All known diaphragmatic injuries must be repaired to prevent the possibility of long-term complications such as herniation and strangulation of abdominal viscera (Table 127-5).

Table 127-5. Diaphragm Injury Scale

Grade I

Contusion

Grade II

Laceration <2 cm

Grade III

Laceration 2-10 cm

Grade IV

Laceration >10 cm with tissue loss <25 cm2

Grade V

Laceration >10 cm with tissue loss >25 cm2

 

Used with permission from ref. 47.

The surgical approach to the diaphragm in trauma depends on the location of associated injuries and the time to operation. Injuries to the diaphragm that are repaired shortly after the traumatic insult are approached via laparotomy or laparoscopy. This approach facilitates a thorough abdominal exploration and allows for easy reduction of the abdominal viscera. Associated abdominal injuries identified at the initial exploration are also addressed at this time. In contrast to nontraumatic diaphragmatic hernias, a hernia sac is present only occasionally in traumatic hernias. The lack of a hernia sac allows the herniated viscera to become adherent to the thoracic contents. Therefore, surgical repair in cases in which the diagnosis is delayed or the repair is deferred requires a thoracic approach to safely divide the resulting adhesions, reduce the hernia contents, and evaluate the intrathoracic organs. Early repair reduces the likelihood of respiratory compromise and long-term complications associated with incarceration and strangulation of the intraabdominal viscera. In cases in which a clear diagnosis cannot be achieved, exploration of the diaphragm by thoracoscopic evaluation is considered safe and effective and highly sensitive.

The surgical technique for the definitive diaphragm repair will depend on the size of the injury and the degree of tissue loss. Injuries with no tissue loss, grades I–III, may be closed with continuous number 1 or larger monofilament nonabsorbable suture. The edges of the diaphragm are elevated away from surrounding structures and approximated with Allis clamps to facilitate good approximation with minimal risk of injury to other organs. Larger grade IV or V defects are likely the result of severe trauma, and a more complex repair may be necessary to prevent herniation and paradoxical respiratory movement. Prosthetic mesh may be sutured to the perimeter of the defect using running monofilament suture, being careful not to make the closure overly tight. Excessive amounts of tension likely will cause a breakdown of the repair.

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