THE EFFECT IN PATIENTS OF STREPTOCOCCAL FIBRINOLYSIN (STREPTOKINASE) AND STREPTOCOCCAL DESOXYRIBONUCLEASE ON FIBRINOUS, PURULENT, AND SANGUINOUS PLEURAL EXUDATIONS

Intrapleural Fibrinolytic Interventions for Retained Hemothoraces in Rabbits

Bleeding within the pleural space may result in persistent clot formation called retained hemothorax (RH). RH is prone to organization, which compromises effective drainage, leading to lung restriction and dyspnea. Intrapleural fibrinolytic therapy is used to clear the persistent organizing clot in lieu of surgery, but fibrinolysin selection, delivery strategies, and dosing have yet to be identified. We used a recently established rabbit model of RH to test whether intrapleural delivery of single-chain urokinase (scuPA) can most effectively clear RH. scuPA, or single-chain tissue plasminogen activator (sctPA), was delivered via thoracostomy tube on day 7 as either one or two doses 8 h apart. Pleural clot dissolution was assessed using transthoracic ultrasonography, chest computed tomography, two-dimensional and clot displacement measurements, and gross analysis. Two doses of scuPA (1 mg/kg) were more effective than a bolus dose of 2 mg/kg in resolving RH and facilitating drainage of pleural fluids (PF). Red blood cell counts in the PF of scuPA, or sctPA-treated rabbits were comparable, and no gross intrapleural hemorrhage was observed. Both fibrinolysins were equally effective in clearing clots and promoting pleural drainage. Biomarkers of inflammation and organization were likewise comparable in PF from both groups. The findings suggest that single-agent therapy may be effective in clearing RH; however, the clinical advantage of intrapleural scuPA remains to be established by future clinical trials.

Fibrinolytic Agents in Thromboembolic Diseases: Historical Perspectives and Approved Indications

Fibrinolytic agents catalyze the conversion of the inactive proenzyme plasminogen into the active protease plasmin, degrading fibrin within the thrombus and recanalizing occluded vessels. The history of these medications dates to the discovery of the first fibrinolytic compound, streptokinase, from bacterial cultures in 1933. Over time, researchers identified two other plasminogen activators in human samples, namely urokinase and tissue plasminogen activator (tPA). Subsequently, tPA was cloned using recombinant DNA methods to produce alteplase. Several additional derivatives of tPA, such as tenecteplase and reteplase, were developed to extend the plasma half-life of tPA. Over the past decades, fibrinolytic medications have been widely used to manage patients with venous and arterial thromboembolic events. Currently, alteplase is approved by the U.S. Food and Drug Administration (FDA) for use in patients with pulmonary embolism with hemodynamic compromise, ST-segment elevation myocardial infarction (STEMI), acute ischemic stroke, and central venous access device occlusion. Reteplase and tenecteplase have also received FDA approval for treating patients with STEMI. This review provides an overview of the historical background related to fibrinolytic agents and briefly summarizes their approved indications across various thromboembolic diseases.

Causes, management and treatment of empyema

Infections in the pleural space have been a significant problem since ancient times and continue to be so today, with an incidence of 52% in patients with post-pneumonia syndrome. Typically, these effusions require a combination of medical treatment and surgical drainage, including debridement and decortication. Researchers have been studying the use of intrapleural fibrinolytics in managing complicated pleural effusions and empyema, but there is still ongoing debate and controversy among clinicians. Empyema has traditionally been considered a surgical disease, with antibiotics and chest tube drainage being the initial treatment modality. However, with advances in minimally invasive procedures such as video-assisted thoracoscopic surgery (VATS) and the use of intrapleural fibrinolytics, medical management is now preferred over surgery for many cases of empyema. Surgical options, such as open thoracotomy, are reserved for patients who fail conservative management and have complicated or chronic empyema. This comprehensive review aims to explore the evolution of various management strategies for pleural space infections from ancient times to the present day and how the shift from treating empyema as a surgical condition to a medical disease continues.

Diagnosis and management of pleural infection

Pleural infection remains a medical challenge. Although closed tube drainage revolutionised treatment in the 19th century, pleural infection still poses a significant health burden with increasing incidence. Diagnosis presents challenges due to non-specific clinical presenting features. Imaging techniques such as chest radiographs, thoracic ultrasound and computed tomography scans aid diagnosis. Pleural fluid analysis, the gold standard, involves assessing gross appearance, biochemical markers and microbiology. Novel biomarkers such as suPAR (soluble urokinase plasminogen activator receptor) and PAI-1 (plasminogen activator inhibitor-1) show promise in diagnosis and prognosis, and microbiology demonstrates complex microbial diversity and is associated with outcomes. The management of pleural infection involves antibiotic therapy, chest drain insertion, intrapleural fibrinolytic therapy and surgery. Antibiotic therapy relies on empirical broad-spectrum antibiotics based on local policies, infection setting and resistance patterns. Chest drain insertion is the mainstay of management, and use of intrapleural fibrinolytics facilitates effective drainage. Surgical interventions such as video-assisted thoracoscopic surgery and decortication are considered in cases not responding to medical therapy. Risk stratification tools such as the RAPID (renal, age, purulence, infection source and dietary factors) score may help guide tailored management. The roles of other modalities such as local anaesthetic medical thoracoscopy and intrapleural antibiotics are debated. Ongoing research aims to improve outcomes by matching interventions with risk profile and to better understand the development of disease.

The Fibrinolytic System and Its Measurement: History, Current Uses and Future Directions for Diagnosis and Treatment

The fibrinolytic system is a key player in keeping the haemostatic balance, and changes in fibrinolytic capacity can lead to both bleeding-related and thrombosis-related disorders. Our knowledge of the fibrinolytic system has expanded immensely during the last 75 years. From the first successful use of thrombolysis in myocardial infarction in the 1960s, thrombolytic therapy is now widely implemented and has reformed treatment in vascular medicine, especially ischemic stroke, while antifibrinolytic agents are used routinely in the prevention and treatment of major bleeding worldwide. Despite this, this research field still holds unanswered questions. Accurate and timely laboratory diagnosis of disturbed fibrinolysis in the clinical setting remains a challenge. Furthermore, despite growing evidence that hypofibrinolysis plays a central role in, e.g., sepsis-related coagulopathy, coronary artery disease, and venous thromboembolism, there is currently no approved treatment of hypofibrinolysis in these settings. The present review provides an overview of the fibrinolytic system and history of its discovery; measurement methods; clinical relevance of the fibrinolytic system in diagnosis and treatment; and points to future directions for research.

Fibrinolysis Shutdown and Hypofibrinolysis Are Not Synonymous Terms: The Clinical Significance of Differentiating Low Fibrinolytic States

Low fibrinolytic activity has been associated with pathologic thrombosis and multiple-organ failure. Low fibrinolytic activity has two commonly associated terms, hypofibrinolysis and fibrinolysis shutdown. Hypofibrinolysis is a chronic state of lack of ability to generate an appropriate fibrinolytic response when anticipated. Fibrinolysis shutdown is the shutdown of fibrinolysis after systemic activation of the fibrinolytic system. There has been interchanging of these terms to describe critically ill patients in multiple settings. This is problematic in understanding the pathophysiology of disease processes related to these conditions. There is also a lack of research on the cellular mediators of these processes. The purpose of this article is to review the on and off mechanisms of fibrinolysis in the context of low fibrinolytic states to define the importance in differentiating hypofibrinolysis from fibrinolysis shutdown. In many clinical scenarios, the etiology of a low fibrinolytic state cannot be determined due to ambiguity if a preceding fibrinolytic activation event occurred. In this scenario, the term "low fibrinolytic activity" or "fibrinolysis resistance" is a more appropriate descriptor, rather than using assumptive of hypofibrinolysis and fibrinolysis shutdown, particularly in the acute setting of infection, injury, and surgery.

Tissue plasminogen activator with prolonged dwell time effectively evacuates pleural effusions

OBJECTIVES

Fibrinolytic therapy can be effective for management of complex pleural effusions. Tissue plasminogen activator (tPA, 10 mg) and deoxyribonuclease (DNAse) every 12 h with a dwell time of one hour is a common strategy based on published data. We used a simpler protocol of tPA (4 mg) without DNAse but with a longer dwell time of 12 h, repeated daily. We reviewed our results.

METHODS

Charts were reviewed and demographics, clinical data and treatment information were abstracted. Outcomes were assessed based on radiographic findings and need for surgery.

RESULTS

Two hundred and fifteen effusions in 207 patients (8 bilateral) were identified. 85% were either infectious or malignant. Two hundred and forty nine chest tubes were used: 84% were 10 Fr or 12 Fr and 7% were PleurX®. Five hundred and thirty one doses of tPA were given. The median number of doses per effusion was 2 (range 1-10), and 84% of effusions were treated with three or fewer doses. There were no significant bleeding complications. Median time to chest tube removal was 6 days (range 1 to 98, IQR 4 to 10). Drainage was considered complete for 78% of effusions, while 6% required decortication.

CONCLUSIONS

Low dose tPA daily with a 12 h dwell time may be as effective as the standard regimen of tPA and DNAse twice daily with one hour dwell. For most patients only three doses were required, and small pigtail catheters were sufficient. This regimen uses less medication and is logistically much easier than the current standard.

From Chest Wall Resection to Medical Management: The Continued Saga of Parapneumonic Effusion Management and Future Directions

Pleural space infections have been described since the time of Hippocrates and to this day remains a significant pathology. Every year in the USA approximately there are one million hospital admissions for pneumonia with 20%-40% associated with some form of pleural space infections leading to pleural effusions with increased morbidity and mortality. Often, management of these effusions mandate combination of medical treatment and surgical drainage with debridement and decortication. There has been a lot of ongoing research regarding the safety and efficacy of intrapleural fibrinolytics in the management of complicated pleural effusions and empyema. Till this day, areas of debate and controversies exist among clinicians treating pleural space infection. Empyema is historically considered a surgical disease. There have been societies and guidelines for the management of infected parapneumonic effusions with antibiotics and chest tube drainage as an initial empiric treatment modality. With the advances in the use of Intrapleural fibrinolytics and minimally invasive procedures such as video-assisted thoracoscopic surgery (VATS), empyema a surgical disease is now more favoring medical management. Surgical option, such as open thoracotomy, is reserved for patients who failed conservative management and chronic empyema. The aim of this comprehensive review is to shed light on the evolution of various management strategies from the era of Hippocrates to current day practice and how there continues to be a paradigm shift in treating empyema as a surgical condition to a medical disease.

Efficacy and safety of intrapleural streptokinase in tubercular empyema thoracis - old wine in new wineskin

Tubercular empyema thoracis continues to be one of the leading causes of morbidity in low-income countries. Despite antitubercular therapy (ATT) and thoracostomy, empyema drainage is hampered by multiple septations, loculations, debris, and blood clots leading to complications. In a comparative experimental study to estimate the efficacy and safety of intrapleural streptokinase (IPSTK) in tubercular empyema, 30 cases of chronic multiloculated tubercular empyema were compared by radiological improvement by chest radiography, duration and volume of fluid drained, and degree of dyspnoea according to the modified Borg scale, depending on whether streptokinase was used or not. The former scored on all counts; we therefore conclude that intrapleural streptokinase is a safe, efficacious intervention in tubercular empyema. It decreases morbidity and reduces the need for surgery.

Parapneumonic Effusion and Empyema

The rising incidence and high morbidity of pleural infection remain a significant challenge to health care systems worldwide. With distinct microbiology and treatment paradigms from pneumonia, pleural infection is an area in which the evidence base has been rapidly evolving. Progress in recent years has revolved around characterizing the microbiome of pleural infection and the addition of new strategies such as intrapleural enzyme therapy to the established treatment pathway of drainage and antibiotics. The future of improving outcomes lies with personalizing treatment, establishing optimal timing of intrapleural agents and surgery, alongside wider use of risk stratification to guide treatment.

Thrombolytic Enzymes of Microbial Origin: A Review

Enzyme therapies are attracting significant attention as thrombolytic drugs during the current scenario owing to their great affinity, specificity, catalytic activity, and stability. Among various sources, the application of microbial-derived thrombolytic and fibrinolytic enzymes to prevent and treat vascular occlusion is promising due to their advantageous cost-benefit ratio and large-scale production. Thrombotic complications such as stroke, myocardial infarction, pulmonary embolism, deep venous thrombosis, and peripheral occlusive diseases resulting from blood vessel blockage are the major cause of poor prognosis and mortality. Given the ability of microbial thrombolytic enzymes to dissolve blood clots and prevent any adverse effects, their use as a potential thrombolytic therapy has attracted great interest. A better understanding of the hemostasis and fibrinolytic system may aid in improving the efficacy and safety of this treatment approach over classical thrombolytic agents. Here, we concisely discuss the physiological mechanism of thrombus formation, thrombo-, and fibrinolysis, thrombolytic and fibrinolytic agents isolated from bacteria, fungi, and algae along with their mode of action and the potential application of microbial enzymes in thrombosis therapy.

Management of complex pleural disease in the critically ill patient

Disorders of the pleural space are quite common in the critically ill patient. They are generally associated with the underlying illness. It is sometimes difficult to assess for pleural space disorders in the ICU given the instability of some patients. Although the portable chest X-ray remains the primary modality of diagnosis for pleural disorders in the ICU. It can be nonspecific and may miss subtle findings. Ultrasound has become a useful tool to the bedside clinician to aid in diagnosis and management of pleural disease. The majority of pleural space disorders resolve as the patient’s illness improves. There remain a few pleural processes that need specific therapies. While uncomplicated parapneumonic effusions do not have their own treatments. Those that progress to become a complex infected pleural space can have its individual complexity in therapy. Chest tube drainage remains the cornerstone in therapy. The use of intrapleural fibrinolytics has decreased the need for surgical referral. A large hemothorax or pneumothorax in patients admitted to the ICU represent medical emergencies and require emergent action. In this review we focus on the management of commonly encountered complex pleural space disorders in critically ill patients such as complicated pleural space infections, hemothoraces and pneumothoraces.

Management of Pleural Infection

Pleural infection is a millennia-spanning condition that has proved challenging to treat over many years. Fourteen percent of cases of pneumonia are reported to present with a pleural effusion on chest X-ray (CXR), which rises to 44% on ultrasound but many will resolve with prompt antibiotic therapy. To guide treatment, parapneumonic effusions have been separated into distinct categories according to their biochemical, microbiological and radiological characteristics. There is wide variation in causative organisms according to geographical location and healthcare setting. Positive cultures are only obtained in 56% of cases; therefore, empirical antibiotics should provide Gram-positive, Gram-negative and anaerobic cover whilst providing adequate pleural penetrance. With the advent of next-generation sequencing techniques, yields are expected to improve. Complicated parapneumonic effusions and empyema necessitate prompt tube thoracostomy. It is reported that 16-27% treated in this way will fail on this therapy and require some form of escalation. The now seminal Multi-centre Intrapleural Sepsis Trials (MIST) demonstrated the use of combination fibrinolysin and DNase as more effective in the treatment of empyema compared to either agent alone or placebo, and success rates of 90% are reported with this technique. The focus is now on dose adjustments according to the patient's specific 'fibrinolytic potential', in order to deliver personalised therapy. Surgery has remained a cornerstone in the management of pleural infection and is certainly required in late-stage manifestations of the disease. However, its role in early-stage disease and optimal patient selection is being re-explored. A number of adjunct and exploratory therapies are also discussed in this review, including the use of local anaesthetic thoracoscopy, indwelling pleural catheters, intrapleural antibiotics, pleural irrigation and steroid therapy.

The Fibrinolytic System: Mysteries and Opportunities

The deposition and removal of fibrin has been the primary role of coagulation and fibrinolysis, respectively. There is also little doubt that these 2 enzyme cascades influence each other given they share the same serine protease family ancestry and changes to 1 arm of the hemostatic pathway would influence the other. The fibrinolytic system in particular has also been known for its capacity to clear various non-fibrin proteins and to activate other enzyme systems, including complement and the contact pathway. Furthermore, it can also convert a number of growth factors into their mature, active forms. More recent findings have extended the reach of this system even further. Here we will review some of these developments and also provide an account of the influence of individual players of the fibrinolytic (plasminogen activating) pathway in relation to physiological and pathophysiological events, including aging and metabolism.

An interview with A. Koneti Rao: Editor of Platelets (1990-2018)

Professor A. Koneti Rao has made many critical contributions to the field of platelet research for over forty years. He joined the editorial board of Platelets as a Principal Editor in 1989 before the start of the journal and the appointment of Stan Heptinstall, who was Editor-in-Chief for 25 years. Professor Rao retired from the editorial board in 2018. This article is based on an interview with Professor Rao that took place prior to the Platelets Editorial Board meeting and lunch in 2019 during the ISTH Congress in Melbourne. Professor Rao was presented with a plaque in recognition of his service to the journal. The article is a reflection on Professor Rao's personal life and his career in science, along with his views on the past and future of Platelets. Professor Rao continues to serve as a referee for the journal.

Fibrinolysis: A Primordial System Linked to the Immune Response

The fibrinolytic system provides an essential means to remove fibrin deposits and blood clots. The actual protease responsible for this is plasmin, formed from its precursor, plasminogen. Fibrin is heralded as it most renowned substrate but for many years plasmin has been known to cleave many other substrates, and to also activate other proteolytic systems. Recent clinical studies have shown that the promotion of plasmin can lead to an immunosuppressed phenotype, in part via its ability to modulate cytokine expression. Almost all immune cells harbor at least one of a dozen plasminogen receptors that allows plasmin formation on the cell surface that in turn modulates immune cell behavior. Similarly, a multitude of pathogens can also express their own plasminogen activators, or contain surface proteins that provide binding sites host plasminogen. Plasmin formed under these circumstances also empowers these pathogens to modulate host immune defense mechanisms. Phylogenetic studies have revealed that the plasminogen activating system predates the appearance of fibrin, indicating that plasmin did not evolve as a fibrinolytic protease but perhaps has its roots as an immune modifying protease. While its fibrin removing capacity became apparent in lower vertebrates these primitive under-appreciated immune modifying functions still remain and are now becoming more recognised.

Use of fibrinolytics and deoxyribonuclease in adult patients with pleural empyema: a consensus statement

Although our understanding of the pathogenesis of empyema has grown tremendously over the past few decades, questions still remain on how to optimally manage this condition. It has been almost a decade since the publication of the MIST2 trial, but there is still an extensive debate on the appropriate use of intrapleural fibrinolytic and deoxyribonuclease therapy in patients with empyema. Given the scarcity of overall guidance on this subject, we convened an international group of 22 experts from 20 institutions across five countries with experience and expertise in managing adult patients with empyema. We did a literature and internet search for reports addressing 11 clinically relevant questions pertaining to the use of intrapleural fibrinolytic and deoxyribonuclease therapy in adult patients with bacterial empyema. This Position Paper, consisting of seven graded and four ungraded recommendations, was formulated by a systematic and rigorous process involving the evaluation of published evidence, augmented with provider experience when necessary. Panel members participated in the development of the final recommendations using the modified Delphi technique. Our Position Paper aims to address the existing gap in knowledge and to provide consensus-based recommendations to offer guidance in clinical decision making when considering the use of intrapleural therapy in adult patients with bacterial empyema.

Short-course intrapleural alteplase and DNase in complex effusion with bleeding risk

Pleural infection is an important clinical problem with significant morbidity. In poorly draining complex pleural effusions, the current management favours a less invasive image-guided placement of smaller bore catheters and adjunctive intrapleural fibrinolysis therapy (IPFT). We describe our experience of using IPFT in three patients with different bleeding risks with complex pleural effusions. The first was a 30-year-old with transfusion-dependent β-thalassemia with haemoglobin of 7.8 g/dL; second was an 87-year-old on dabigatran with haemoglobin of 10 g/dL; and the third was an 80-year-old with diffuse large B-cell lymphoma with haemoglobin of 8.6 g/dL. All three patients received three doses of alteplase and deoxyribonuclease (DNase) without any adverse effects of bleeding and had resolution of the effusion. This case series is an addition to the current literature on the safety of IPFT and we highlight the use of IPFT in patients with low baseline haemoglobin and on anticoagulation therapy.

Intrapleural Tissue Plasminogen Activator for Traumatic Retained Hemothorax

Objective: To describe the efficacy, safety, dosing regimen, and administration technique of intrapleural alteplase for the treatment of retained hemothorax. Data Sources: A PubMed, EMBASE, and Google Scholar search (January 2000 to February 2019) was conducted with the search terms intrapleural, fibrinolytic, fibrinolysis, alteplase, tissue plasminogen activator, and hemothorax. Study Selection and Data Extraction: Articles were included if they described the use of intrapleural alteplase in adult patients with a retained hemothorax; single patient case reports and abstracts were excluded. Data Synthesis: A total of 6 retrospective reviews and 1 meta-analysis were identified for inclusion. A variety of dosing strategies have been defined for the administration of intrapleural alteplase ranging from 6 to 100 mg, volume of fluid from 50 to 120 mL of normal saline, and the number of total doses has ranged from 1 to 8 over the treatment course. A majority of studies showed a greater than 80% success rate and less than 7% bleeding rate. Relevance to Patient Care and Clinical Practice: Because of the paucity of data for use of alteplase in retained hemothorax and administration of a high-risk medication, this review provides dosing and administration recommendations based on reported safety and efficacy. Conclusion: Administration of intrapleural alteplase should be considered in patients with retained hemothorax as an alternative to surgical intervention. In contrast to intrapleural alteplase administration for other indications such as empyema, higher doses and volumes of alteplase are recommended for retained hemothorax.

Fibrinolysis Shutdown in Trauma: Historical Review and Clinical Implications

Despite over a half-century of recognizing fibrinolytic abnormalities after trauma, we remain in our infancy in understanding the underlying mechanisms causing these changes, resulting in ineffective treatment strategies. With the increased utilization of viscoelastic hemostatic assays (VHAs) to measure fibrinolysis in trauma, more questions than answers are emerging. Although it seems certain that low fibrinolytic activity measured by VHA is common after injury and associated with increased mortality, we now recognize subphenotypes within this population and that specific cohorts arise depending on the specific time from injury when samples are collected. Future studies should focus on these subtleties and distinctions, as hypofibrinolysis, acute shutdown, and persistent shutdown appear to represent distinct, unique clinical phenotypes, with different pathophysiology, and warranting different treatment strategies.

Phase 1 trial of intrapleural LTI-01; single chain urokinase in complicated parapneumonic effusions or empyema

BACKGROUND

Current dosing of intrapleural fibrinolytic therapy (IPFT) in adults with complicated parapneumonic effusion (CPE) / empyema is empiric, as dose-escalation trials have not previously been conducted. We hypothesized that LTI-01 (scuPA), which is relatively resistant to PA inhibitor-1 (PAI-1), would be well-tolerated.

METHODS

This was an open-label, dose-escalation trial of LTI-01 IPFT at 50,000-800,000 IU daily for up to 3 days in adults with loculated CPE/empyema and failed pleural drainage. The primary objective was to evaluate safety and tolerability, and secondary objectives included assessments of processing and bioactivity of scuPA in blood and pleural fluid (PF), and early efficacy.

RESULTS

LTI-01 was well tolerated with no bleeding, treatment-emergent adverse events or surgical referrals (n=14 subjects). uPA antigen increased in PFs at 3 hours after LTI-01 (p<0.01) but not in plasma. PF saturated active PAI-1, generated PAI-1-resistant bioactive complexes, increased PA and fibrinolytic activities and D-dimers. There was no systemic fibrinogenolysis, nor increments in plasma D-dimer. Decreased pleural opacities occurred in all but one subject. Both subjects receiving 800,000 IU required two doses to relieve pleural sepsis, with two other subjects similarly responding at lower doses.

CONCLUSION

LTI-01 IPFT was well-tolerated at these doses with no safety concerns. Bioactivity of LTI-01 IPFT was confirmed, limited to PFs where its processing simulated that previously reported in preclinical studies. Preliminary efficacy signals including reduction of pleural opacity were observed.

Pleural infection: a closer look at the etiopathogenesis, microbiology and role of antibiotics

INTRODUCTION

Pleural infection is a condition that continues to pose a significant challenge to respiratory physicians. We hypothesize that the main barriers to progress include limited understanding of the etiopathogenesis, microbiology,and role of antibiotics in the pleural space. Areas covered: PubMed was searched for articles related to adult pleural infection using the terms 'pleural infection', 'empyema' and 'parapneumonic'. The search focused on relevant literature within the last 10 years, with any older citations used only to display context or lack of progress. Tuberculous pleural infection was excluded. We chose to give specific attention to the etiopathogenesis of pleural infection, including recent advances in diagnostics and biomarkers. We discuss our understanding of the pleural microbiome and rationalize the current use of antibiotics in treating this condition. Expert commentary: Understanding of key events in the development of this condition remains limited. The microbiology is unique compared to the lung, and highly variable. Higher culture yields from pleural biopsy may add new insights into the etiopathogenesis. There is little evidence into achievable effective antibiotic concentration within the pleura. Research into issues including the relevance of biofilm formation and significance of pleural thickening is necessary for treatment progress.

Recent developments in the management of pleural infection: A comprehensive review

OBJECTIVES

Pleural infection is a condition commonly encountered by the respiratory physician. This review aims to provide the reader with an update on the most recent data regarding the epidemiology, microbiology, and the management of pleural infection.

DATA SOURCE

Medline was searched for articles related to pleural infection using the terms "pleural infection," "empyema," and "parapneumonic." The search was limited to the years 1997-2017. Only human studies and reports in English were included.

RESULTS

A rise in the incidence of pleural infection is seen worldwide. Despite the improvement in healthcare practices, the mortality from pleural infection remains high. The role of oral microflora in the etiology of pleural infection is firmly established. A concise review of the recent insights on the pathogenesis of pleural infections is presented. A particular focus is made on the role of tPA, DNAse and similar substances and their interaction with inflammatory cells and how this affects the pathogenesis and treatment of pleural infection.

CONCLUSION

Pleural infection is a common disease with significant morbidity and mortality, as well as a considerable economic burden. The role of medical management is expanding thanks to the widespread use of newer treatments.

Fibrin turnover and pleural organization: bench to bedside

Recent studies have shed new light on the role of the fibrinolytic system in the pathogenesis of pleural organization, including the mechanisms by which the system regulates mesenchymal transition of mesothelial cells and how that process affects outcomes of pleural injury. The key contribution of plasminogen activator inhibitor-1 to the outcomes of pleural injury is now better understood as is its role in the regulation of intrapleural fibrinolytic therapy. In addition, the mechanisms by which fibrinolysins are processed after intrapleural administration have now been elucidated, informing new candidate diagnostics and therapeutics for pleural loculation and failed drainage. The emergence of new potential interventional targets offers the potential for the development of new and more effective therapeutic candidates.

Precision-guided, Personalized Intrapleural Fibrinolytic Therapy for Empyema and Complicated Parapneumonic Pleural Effusions: The Case for the Fibrinolytic Potential

Complicated pleural effusions and empyema with loculation and failed drainage are common clinical problems. In adults, intrapleural fibrinolytic therapy is commonly used with variable results and therapy remains empiric. Despite the intrapleural use of various plasminogen activators; fibrinolysins, for about sixty years, there is no clear consensus about which agent is most effective. Emerging evidence demonstrates that intrapleural administration of plasminogen activators is subject to rapid inhibition by plasminogen activator inhibitor-1 and that processing of fibrinolysins is importantly influenced by other factors including the levels and quality of pleural fluid DNA. Current therapy for loculation that accompanies pleural infections also includes surgery, which is invasive and for which patient selection can be problematic. Most of the clinical literature published to date has used flat dosing of intrapleural fibrinolytic therapy in all subjects but little is known about how that strategy influences the processing of the administered fibrinolysin or how this influences outcomes. We developed a new test of pleural fluids ex vivo, which is called the Fibrinolytic Potential or FP, in which a dose of a fibrinolysin is added to pleural fluids ex vivo after which the fibrinolytic activity is measured and normalized to baseline levels. Testing in preclinical and clinical empyema fluids reveals a wide range of responses, indicating that individual patients will likely respond differently to flat dosing of fibrinolysins. The test remains under development but is envisioned as a guide for dosing of these agents, representing a novel candidate approach to personalization of intrapleural fibrinolytic therapy.

Intrapleural Fibrinolytic Therapy for Residual Coagulated Hemothorax After Lung Surgery

BACKGROUND

Many studies have described the use of intrapleural fibrinolytics for the treatment of complex pleural processes and traumatic hemothorax, but data are scarce regarding their use for hemothorax after lung surgery.

OBJECTIVE

To evaluate the utility of intrapleural fibrinolytic therapy with urokinase for residual coagulated hemothorax (blood clot accumulation in the pleural cavity) after lung surgery.

METHODS

From July 2009 to November 2013, 46 patients (33 males; mean age, 56.9 ± 10.7 years) were treated with intrapleural urokinase (250,000 IU per dose) for residual hemothorax after lung surgery. Complete response was defined as clinical improvement with complete drainage of the retained collection shown by chest X-ray, and partial response as substantial resolution with minimal residual opacity (<25 % of the thorax). Follow-up was at least 30 days.

RESULTS

The procedure was successful in 42 patients (91.3 %), with complete response observed in 35/46 patients (76.1 %) and partial response in 7/46 (15.2 %). These 42 patients did not require re-intervention for fluid accumulation in the pleural cavity. Treatment failed in 4 patients (8.7 %): one developed bronchopleural fistula that later resolved spontaneously and three (6.5 %) required thoracoscopic drainage for pleural cavity fluid accumulation and lung collapse. No patient required thoracotomy for total decortication. Intrapleural urokinase administration was not associated with serious adverse events, including bleeding complications or allergic reactions.

CONCLUSIONS

Intrapleural fibrinolytic agents should be considered a useful therapeutic option for the treatment of postoperative residual hemothorax. This method appears to be safe and effective in >90 % of patients with postoperative hemothorax.

A History of Thrombolytic Therapy

Thrombolytic therapy has been available for the last 5 decades, but the modern era of thrombolysis began in the early 1990s, with the execution of 3 multicenter trials designed to compare this potentially less invasive therapy to the then standard of care for acute limb ischemia, open surgical revascularization. Even with the development of several bioengineered lytic agents, the major risk of thrombolytic therapy continues to be bleeding complications. Nevertheless, data exist to suggest that thrombolysis should be considered as an adjunct to open surgery, percutaneous interventions, or, occasionally, as sole therapy for acute vascular occlusion. This review summarizes the developmental milestones in the history of thrombolysis and reviews data supporting its use in acute arterial occlusions.

The History of Primary Angioplasty and Stenting for Acute Myocardial Infarction

The evolution of the management of acute myocardial infarction (MI) has been one of the crowning achievements of modern medicine. At the turn of the twentieth century, MI was an often-fatal condition. Prolonged bed rest served as the principal treatment modality. Over the past century, insights into the pathophysiology of MI revolutionized approaches to management, with the sequential use of surgical coronary artery revascularization, thrombolytic therapy, and percutaneous coronary intervention (PCI) with primary coronary angioplasty, and placement of intracoronary stents. The benefits of prompt revascularization inspired systems of care to provide rapid access to PCI. This review provides a historical context for our current approach to primary PCI for acute MI.

Pericardial Infusion of Tissue Plasminogen Activator in Fibropurulent Pericarditis

A 61-year-old man developed a loculated fibropurulent pericarditis, a rare complication of bacteremia. This occurred as a complication of a Staphylococcal aureus bacteremia from a head and neck abscess following self-extraction of a tooth. Despite surgical intervention and placement of 2 pericardial drains, a refractory, inadequately drained infected pericardial effusion persisted. Although there is limited experience with thrombolytic therapy to dissolve a fibrin clot in the pericardium, break down loculated adhesions, and facilitate free drainage of infected material, lysis is well described in the management of exudative pleural effusions. After infusion of 30 mg of tissue plasminogen activator in 100 cc normal saline through the pericardial drain of the patient, a large amount of infected serosanginous material subsequently drained during the next 2 days. The patient became afebrile and culture negative, remained hemodynamically stable, and had resolution of his pericarditis and pericardial effusion on electrocardiogram and echocardiogram, respectively.

Thrombolytic Therapy: A Comprehensive Review of its Use in Clinical Medicine—Part I

In the first part of this comprehensive review of thrombolytic therapy in clinical medicine, we begin with a brief history of fibrinolysis, followed by a review of the components of die endogenous fibrinolytic system and the currently available plasminogen activators. An in-depth examination of thrombolysis in treatment of acute myocardial infarction follows, Including recommendations for management based on available clinical trial data. New developments in thrombolytic therapy are also discussed.

Dose dependency of outcomes of intrapleural fibrinolytic therapy in new rabbit empyema models

The incidence of empyema (EMP) is increasing worldwide; EMP generally occurs with pleural loculation and impaired drainage is often treated with intrapleural fibrinolytic therapy (IPFT) or surgery. A number of IPFT options are used clinically with empiric dosing and variable outcomes in adults. To evaluate mechanisms governing intrapleural fibrinolysis and disease outcomes, models of Pasteurella multocida and Streptococcus pneumoniae were generated in rabbits and the animals were treated with either human tissue (tPA) plasminogen activator or prourokinase (scuPA). Rabbit EMP was characterized by the development of pleural adhesions detectable by chest ultrasonography and fibrinous coating of the pleura. Similar to human EMP, rabbits with EMP accumulated sizable, 20- to 40-ml fibrinopurulent pleural effusions associated with extensive intrapleural organization, significantly increased pleural thickness, suppression of fibrinolytic and plasminogen-activating activities, and accumulation of high levels of plasminogen activator inhibitor 1, plasminogen, and extracellular DNA. IPFT with tPA (0.145 mg/kg) or scuPA (0.5 mg/kg) was ineffective in rabbit EMP (n = 9 and 3 for P. multocida and S. pneumoniae, respectively); 2 mg/kg tPA or scuPA IPFT (n = 5) effectively cleared S. pneumoniae-induced EMP collections in 24 h with no bleeding observed. Although intrapleural fibrinolytic activity for up to 40 min after IPFT was similar for effective and ineffective doses of fibrinolysin, it was lower for tPA than for scuPA treatments. These results demonstrate similarities between rabbit and human EMP, the importance of pleural fluid PAI-1 activity, and levels of plasminogen in the regulation of intrapleural fibrinolysis and illustrate the dose dependency of IPFT outcomes in EMP.

Trends in treatment of infectious parapneumonic effusions in U.S. children's hospitals, 2004-2014

PURPOSE

The purpose of this study was to examine trends in the treatment of patients with infectious parapneumonic effusions in U.S. children's hospitals over the past decade.

METHODS

The PHIS database was queried for patients younger than 18years old with pneumonia and pleural effusion in three yearlong periods over the past decade. Variables included age, gender, payer, race/ethnicity, hospital region, hospital type, markers of illness severity, and treatment group (antibiotics alone, chest tube thoracostomy±thrombolytics, video-assisted thoracoscopy (VATS), or thoracotomy).

RESULTS

5569 patients were included in the final analysis. The proportion of patients treated with antibiotics alone increased from 62% to 74% from 2004 to 2014 (p<0.001). Among patients requiring pleural space drainage, the frequency of VATS peaked in 2009 (50.8%), dropping to 36.4% in 2014 (p<0.001), while tube thoracostomy, usually with fibrinolytics, rose from 39.0% in 2009 to 53.2% in 2014 (p<0.001).

CONCLUSION

In a select cohort of free-standing, tertiary care U.S. children's hospitals, antibiotic administration alone remains the most common treatment approach to infectious parapneumonic effusions. VATS treatment for those patients requiring pleural space drainage is being gradually supplanted by thoracostomy tube placement with instillation of fibrinolytics.

Pleural infection: past, present, and future directions

Pleural space infections are increasing in incidence and continue to have high associated morbidity, mortality, and need for invasive treatments such as thoracic surgery. The mechanisms of progression from a non-infected, pneumonia-related effusion to a confirmed pleural infection have been well described in the scientific literature, but the route by which pathogenic organisms access the pleural space is poorly understood. Data suggests that not all pleural infections can be related to lung parenchymal infection. Studies examining the microbiological profile of pleural infection inform antibiotic choice and can help to delineate the source and pathogenesis of infection. The development of radiological methods and use of clinical indices to predict which patients with pleural infection will have a poor outcome, as well as inform patient selection for more invasive treatments, is particularly important. Randomised clinical trial and case series data have shown that the combination of an intrapleural tissue plasminogen activator and deoxyribonuclease therapy can potentially improve outcomes, but the use of this treatment as compared with surgical options has not been precisely defined, particularly in terms of when and in which patients it should be used.

Life-threatening pleural hemorrhage following intrapleural enzyme therapy and successful treatment with fibrin-thrombin sealant pleurodesis: a case report

INTRODUCTION

Intrapleural fibrinolytic enzyme therapy is a potentially surgery-sparing treatment for poorly resolving parapneumonic effusion and empyema. It is safe in the majority of patients, however the most significant risk associated with this treatment is severe bleeding secondary to pleural hemorrhage. Contraindications for intrapleural enzyme therapy are not widely agreed upon and little is known about how to treat this difficult and potentially lethal hemorrhagic complication.

CASE PRESENTATION

An independent 82-year-old Caucasian man presented to hospital with an empyema complicating community-acquired pneumonia and coincidental pulmonary embolus. He was initially commenced on intravenous antibiotics, pleural drainage and anticoagulation, however failed to improve significantly and was commenced on intrapleural fibrinolytic enzyme therapy. Shortly after, he suffered severe pleural hemorrhage that was uncontrollable despite emergency thoracotomy and washout. Subsequent hemostasis was achieved after re-exploration and application of topical fibrin-thrombin sealant spray. The patient survived and was discharged home.

CONCLUSIONS

Intrapleural enzyme therapy can be effective in loculated parapneumonic effusion and empyema, but massive pleural hemorrhage can complicate its use. Pleural hemorrhage appears to be associated with anticoagulation or coagulopathy, and can be difficult to manage. This case adds to the body of data on bleeding complications following intrapleural enzyme therapy, and to the best of our knowledge is the first report of fibrin-thrombin sealant use in this setting.

Intrapleural administration of DNase alone for pleural empyema

INTRODUCTION

Pleural empyema is a severe complication of various diseases. The essential is the inserting a drain into the pleural cavity and evacuation of the pus. Sometimes the pus is very thick and its evacuation and re-expansion of the lung is very difficult.

METHODS

We report a group of 10 patients with intrapleural administration of Pulmozyme (dornase alpha) in dosages of either 2.5 mg once or on two separate occasions. All of the patients had a chest tube inserted into the pleural cavity. Measurement of viscosity was done before and after the instillation of the dornase alpha.

RESULTS

In six patients dornase alfa was introduced into the pleural cavity once. Three of them received this on the 4th whilst the rest were treated with the agent on the 6th day. Four patients received the dornase alpha twice because of the small amount of drainage fluid after the previous instillation. Five patients were discharged from hospital with complete re-expansion of their lungs. Two patients were qualified for a surgical operation since the lung was trapped and did not re-expand. Three patients had to be discharged with a drain as a result of incomplete re-expansion of the lung. In all the patients the density of the pus after administering the dornase alpha decreased and the amount of the pus drainage increased.

CONCLUSIONS

Dornase alpha may be used in some patients with pleural empyema with good results.

Intrapleural tissue plasminogen activator and deoxyribonuclease therapy for pleural infection

Pleural infection remains a global health burden associated with significant morbidity. Drainage of the infected pleural fluid is important but can often be hindered by septations and loculations. Intrapleural fibrinolytic therapy alone, to break pleural adhesions, has shown no convincing advantages over placebo in improving clinical outcome. Deoxyribonucleoprotein from degradation of leukocytes contributes significantly to high viscosity of infected pleural fluid. Recombinant deoxyribonuclease (DNase) is effective in reducing pleural fluid viscosity in pre-clinical studies. The combination of tissue plasminogen activator (tPA) and DNase was effective in animal model experiments of empyema. The benefits were established in a randomized clinical trial: those (n=48) treated with tPA/DNase had significantly improved radiological outcomes and reduced need of surgery and duration of hospital stay. A longitudinal observational series of 107 patients further confirmed the effectiveness and safety of tPA/DNase therapy, including its use as 'rescue therapy' when patients failed to respond to antibiotics and chest tube drainage. Overall, a short course of intrapleural tPA (10 mg) and DNase (5 mg) therapy provides a cure in over 90% of patients without requiring surgery. The treatment stimulates pleural fluid formation, enhances radiographic clearance and resolution of systemic inflammation. Serious complications are uncommon; pleural bleeding requiring transfusion occurred in ~2% of cases. Pain can occur, especially with the first dose. Treatment is contraindicated in those with significant bleeding diathesis or a bronchopleural fistula. Future research is required to optimize dosing regimens and in refining patient selection.

[The management of complicated parapneumonic effusions in France]

INTRODUCTION

There are no French guidelines for the management of complicated parapneumonic effusions. A national observational study was carried out to assess the main features of current clinical practice for this condition.

MATERIAL AND METHODS

A questionnaire was sent by email to the 1500 members of the Société de Pneumologie de Langue Française (SPLF) between 15th November and 15th December 2012.

RESULTS

There were 92 responders, i.e. a response rate of 6%. Of these, 87 physicians mentioned that they were involved in the management of patients with complicated parapneumonic effusions with a median number of cases of 10 per year (IQR: 5-20). Chest tube drainage was the main approach used for pleural fluid aspiration (n=51/87), followed by repeated thoracentesis (n=29/87) and early surgery (1/87). Five physicians answered both chest tube drainage or repeated thoracentesis and one physician either chest tube drainage or early surgery. Pleural fibrinolytics were never used by 20% of physicians, only in case of loculations by 70% and by 10% of respondents in all cases. Only 3 physicians combined fibrinolytics with DNAse. A double antibiotic dose was used by one third of physicians. All the physicians used respiratory physiotherapy during hospitalization and to aid recovery. Follow-up practices were heterogeneous.

CONCLUSIONS

The management of complicated parapneumonic effusions varies significantly in France. National guidelines may be helpful to define best practice and aid in its implementation.

[Parapneumonic pleural effusions: Epidemiology, diagnosis, classification and management]

Parapneumonic pleural effusions represent the main cause of pleural infections. Their incidence is constantly increasing. Although by definition they are considered to be a "parapneumonic" phenomenon, the microbial epidemiology of these effusions differs from pneumonia with a higher prevalence of anaerobic bacteria. The first thoracentesis is the most important diagnostic stage because it allows for a distinction between complicated and non-complicated parapneumonic effusions. Only complicated parapneumonic effusions need to be drained. Therapeutic evacuation modalities include repeated therapeutic thoracentesis, chest tube drainage or thoracic surgery. The choice of the first-line evacuation treatment is still controversial and there are few prospective controlled studies. The effectiveness of fibrinolytic agents is not established except when they are combined with DNase. Antibiotics are mandatory; they should be initiated as quickly as possible and should be active against anaerobic bacteria except for in the context of pneumococcal infections. There are few data on the use of chest physiotherapy, which remains widely used. Mortality is still high and is influenced by underlying comorbidities.