Disorders of the Pleural Space: Gas, Liquid, and Solid

Empyema remains a challenge for modern medicine. Cases not amenable to lung decortication are particularly di ﬃ cult to treat, requiring prolonged hospitalizations and mutilating procedures. This paper presents the current role of thoracomyoplasty procedures, which allow complete and deﬁnitive obliteration of the infected pleural space by a combination of thoracoplasty and the use of neighbourhood muscle ﬂaps (latissimus dorsi, serratus anterior, pectoralis, rectus abdominis, omentum, etc). Recent publications show an overall rate of success of 90%, with a quick and deﬁnitive healing. Although rarely indicated in our days, this kind of procedures remain in the armamentarium of modern thoracic surgery. The importance of thoracomyoplasty derives from the fact that it may be a simple and deﬁnitive solution for complicated cases of chronic empyema not amenable to standard decortication. The radiological manifestations of the aberrant air surrounding the pleura are varied because of the air outlining the organs in and out of the visceral space. The continuity of the visceral space from the neck, mediastinum to the retroperitoneum is originated from embryological development, which is compatible with the ﬁndings through laboratory experiments, cadaveric anatomy, and thoracic computer tomography image. We reviewed the embryo development to understand the anatomy of body cavity, which can determine the radiological ﬁndings of pneumomediastinum and pneumothorax. Pleural e ﬀ usions can present in 40% of patients with pneumonia. Presence of an e ﬀ usion can complicate the diagnosis as well as the management of infection in lungs and pleural space. There has been an increase in the morbidity and mortality associated with parapneumonic e ﬀ usions and empyema. This calls for employment of advanced treatment modalities and development of a standardized protocol to manage pleural sepsis early. There has been an increased understanding about the indications and appropriate usage of procedural options at clinicians’ disposal. We investigate the mechanism of talc pleurodesis (TP) in 20 patients with recurrent malignant pleural e ﬀ usion and 10 patients with nonmalignant pleural e ﬀ usions. We measured IL-8 levels before and 6 h after TP and ﬁnd a signiﬁcant threefold increase (2.26ng/mL ± 0.7 to 6.5ng/mL 0.1), which explains the recruitment of inﬂammatory cells in these patients. We hypothesize that TP is enable by stimulating the mesothelial cells (MS) to secrete FGF. A signiﬁcant tenfold increase in FGF-b (0.05ng/mL ± 0.02 to 0.44ng/mL 0.6) was seen 24 h after talc instillation ( P < 0 . 04). In order to examine whether FGF-b is secreted by MS cells, MS recovered from CHF patients with recurrent pleural e ﬀ usions were cultured for 48 h in the presence or absence of increasing concentrations of talc (from 100ng/mL to 1mg/mL). They produced signiﬁcant levels of FGF-b in a dose dependent manner ( P < 0 . 005). We hypothesized that a successful pleurodesis involves an early enhanced recruitment of inﬂammatory cells through a rise of IL-8 followed by enrollment of ﬁbroblasts from the submesothelial space through increased mesothelial FGF-b production. Pleural ﬂuid analysis yields important diagnostic information in pleural e ﬀ usions in combination with clinical history, examination, and radiology. For more than 30 years, the initial and most pragmatic step in this process is to determine whether the ﬂuid is a transudate or an exudate. Light’s criteria remain the most robust in separating the transudate-exudate classiﬁcation which dictates further investigations or management. Recent studies have led to the evaluation and implementation of a number of additional ﬂuid analyses that may improve the diagnostic utility of this method. This paper discusses the current practice and future direction of pleural ﬂuid analysis in determining the aetiology of a pleural e ﬀ usion. While this has been performed for a few decades, a number of other pleural characteristics are becoming available suggesting that this diagnostic tool is indeed a work in progress. Background . Tube thoracostomy is widely used throughout the medical, surgical, and critical care specialities. It is generally used to drain pleural collections either as elective or emergency. Complications resulting from tube thoracostomy can occasionally be life threatening. Aim . To present an update on the complications and management of complications of tube thoracostomy. Methods . A review of the publications obtained from Medline search, medical libraries, and Google on tube thoracostomy and its complications was done. Results . Tube thoracostomy is a common surgical procedure which can be performed by either the blunt dissection technique or the trocar technique. Complication rates are increased by the trocar technique. These complications have been broadly classiﬁed as either technical or infective. Technical causes include tube malposition, blocked drain, chest drain dislodgement, reexpansion pulmonary edema, subcutaneous emphysema, nerve injuries, cardiac and vascular injuries, oesophageal injuries, residual/postextubation pneumothorax, ﬁstulae, tumor recurrence at insertion site, herniation through the site of thoracostomy, chylothorax, and cardiac dysrhythmias. Infective complications include empyema and surgical site infection. Conclusion . Tube thoracostomy, though commonly performed is not without risk. Blunt dissection technique has lower risk of complications and is hence recommended.

This special issue focuses on the pleural space, a unique region of the human body affected by some of the earliest described maladies in medical science yet remaining a mystery in both purpose and function. The two pleural spaces, defined by the bony thorax, diaphragm, and mediastinum, are each occupied by the lungs. Consequently, the pathophysiologic disorders of the space involve not only benign and malignant disorders that take the form of solid masses or effusions, but also gaseous disorders as well.
Ongoing air leakage through the surface of a lung will result in collapse and, if ongoing, will result in a fatal pneumothorax. These are some of the most common problems encountered in the pleural space and are treated, along with other maladies, with tube access of the pleural space. Although a common procedure, it requires technical precision and judgment to avoid potentially disastrous complications, as detailed in this special issue. Embryologic development of the pleural structures, discussed in this special issue, results in planes of dissection and paths of least resistance that can result in unusual and unexpected patterns of air accumulation when the air leaks within the lungs.
The net negative pressure within the pleural space and the positive pressure in the pulmonary arterial circulation and the lymphatic circulation maintain a dynamic equilibrium in pleural space, the net effect being a minimal amount of fluid at any given time despite a high flow from the visceral to parietal pleural surfaces. Perturbation of this delicate balance results in fluid accumulation. Because of the extraordinary number of factors involved in maintaining this balance, it can be very difficult to diagnose the reason for the fluid buildup. Within the context of the overall clinical picture, the diagnosis is often rendered by analysis of the fluid itself. As described in this special issue, there are many tests and criteria accessible to the clinician to diagnose the etiology of the fluid accumulation. When the fluid is caused by a malignancy or noninfectious benign process, it is typically necessary to intervene and stop the fluid accumulation. The most common approach remains pleurodesis, affecting a symphysis between the visceral and parietal pleural surfaces for the purpose of obliterating the space. Using talc for this purpose remains one of the most common, and arguably best, techniques and is described in this special issue.
When the fluid does accumulate and becomes infected, it is called an empyema, and this too can easily escalate into a fatal condition without prompt and appropriate treatment. Although drainage, as first described by Hippocrates over 2000 years ago, remains a critical element of the treatment, there are now multiple tools and techniques available to the clinician to combat this common and lethal disorder. A review of this important topic is covered in this special issue. Although the pleural space is highly resistant and resilient in the face of infectious challenges, the ultimate clearance and recovery most often hinges on full lung expansion with pleural-pleural apposition. When an empyema is not drained early enough, the lung can become encased in a fibrous peel that precludes reexpansion and results in a chronic space. Ideally, the fibrous peel can be surgically resected to reexpand the lung and fill the space. At times, however, the lung will no longer fill space, and this results in a challenging and deadly situation that warrants surgical intervention. As described in this special issue, this can take the form of opening the space to allow full drainage to obliterating the space by filling it with healthy vascularized tissue and/or collapsing the chest wall to meet the lung surface.
The pleural space is a fascinating and enigmatic region of the body maintained in balance by a symphony of homeostatic mechanisms. Perturbation of this balance by benign or malignant processes can lead to a myriad of problems, unique to the pleural space. Addressing these problems requires an understanding of the embryology, anatomy, and physiology and then combining this knowledge with sound judgment, scientific analysis, meticulous technique, and, at times, a dash of detective work. We hope you enjoy this special issue as it explores these topics.

Joseph S. Friedberg
Takashi Nakano