Intrapleural Fibrinolytic Therapy for Empyema and Pleural Loculation: Knowns and Unknowns

Reduction in the need for surgery and mortality after early administration of fibrinolytics following empyema drainage

OBJECTIVES

Although intrapleural administration of fibrinolytics is an important treatment option for the management of empyema, the addition of fibrinolytics failed to reduce the need for surgery and mortality in previous randomized controlled trials. This study aimed to investigate the effects of administrating fibrinolytics in the early phase (within 3 days of chest tube insertion) of empyema compared with late administration or no administration.

METHODS

We used the Japanese Diagnosis Procedure Combination Inpatient Database to identify patients aged ≥16 years who were hospitalized and underwent chest tube drainage for empyema. A 1:2 propensity score matching and stabilized inverse probability of treatment weighting were conducted.

RESULTS

Among the 16 265 eligible patients, 3082 and 13 183 patients were categorized into the early and control group, respectively. The proportion of patients who underwent surgery was significantly lower in the early fibrinolytics group than in the control group; the odds ratio (95% confidence interval) was 0.69 (0.54-0.88) in the propensity score matching (P = 0.003) and 0.64 (0.50-0.80) in the stabilized inverse probability of treatment weighting analysis (P < 0.001). All-cause 30-day in-hospital mortality, length of hospital stay, duration of chest tube drainage, and total hospitalization costs were also more favourable in the early fibrinolytics group.

CONCLUSIONS

The early administration of fibrinolytics may reduce the need for surgery and death in adult patients with empyema.

A Novel Rabbit Model of Retained Hemothorax with Pleural Organization

Retained hemothorax (RH) is a commonly encountered and potentially severe complication of intrapleural bleeding that can organize with lung restriction. Early surgical intervention and intrapleural fibrinolytic therapy have been advocated. However, the lack of a reliable, cost-effective model amenable to interventional testing has hampered our understanding of the role of pharmacological interventions in RH management. Here, we report the development of a new RH model in rabbits. RH was induced by sequential administration of up to three doses of recalcified citrated homologous rabbit donor blood plus thrombin via a chest tube. RH at 4, 7, and 10 days post-induction (RH4, RH7, and RH10, respectively) was characterized by clot retention, intrapleural organization, and increased pleural rind, similar to that of clinical RH. Clinical imaging techniques such as ultrasonography and computed tomography (CT) revealed the dynamic formation and resorption of intrapleural clots over time and the resulting lung restriction. RH7 and RH10 were evaluated in young (3 mo) animals of both sexes. The RH7 recapitulated the most clinically relevant RH attributes; therefore, we used this model further to evaluate the effect of age on RH development. Sanguineous pleural fluids (PFs) in the model were generally small and variably detected among different models. The rabbit model PFs exhibited a proinflammatory response reminiscent of human hemothorax PFs. Overall, RH7 results in the consistent formation of durable intrapleural clots, pleural adhesions, pleural thickening, and lung restriction. Protracted chest tube placement over 7 d was achieved, enabling direct intrapleural access for sampling and treatment. The model, particularly RH7, is amenable to testing new intrapleural pharmacologic interventions, including iterations of currently used empirically dosed agents or new candidates designed to safely and more effectively clear RH.

Intrapleural tissue plasminogen activator and deoxyribonuclease administered concurrently and once daily for complex parapneumonic pleural effusion and empyema

BACKGROUND

Pleural infection is life-threatening and increasingly prevalent. In addition to usual care, twice-daily, separate administration of tissue plasminogen activator and deoxyribonuclease (tPA-DNase) reduces radiological pleural opacity with lower surgical referral rates.

AIMS

This retrospective cohort study examines the use of once-daily, concurrent administration of tPA-DNase for complex parapneumonic pleural effusion and empyema.

METHODS

Patients with pleural infection who received intrapleural tPA-DNase between October 2014 and July 2020 at Logan Hospital, where it is given concurrently and once-daily as salvage therapy, were retrospectively identified. Radiographic opacification, inflammatory markers, clinical response and complications were examined.

RESULTS

Thirty-one patients were identified. Mean age was 48.8 years (standard deviation [SD], 17.2). Median tPA-DNase administration was 3 (interquartile range [IQR], 2-3). Chest x-ray pleural opacity decreased significantly (P = 0.047) from a median of 39.6% (IQR, 28.8-65.7%) to 9.7% (IQR, 2.5-23.2%), a median relative reduction of 75.5% (IQR, 47.7-93.9%). White cell count and C-reactive protein improved significantly (P = 0.002 and P = 0.032, respectively) from a median of 16.3 × 109 /L (IQR, 11.8-20.6 × 109 /L) to 9.9 × 109 /L (IQR, 8.0-12.3 × 109 /L) and 311.0 mg/L (IQR, 218.8-374.0 mg/L) to 69.0 mg/L (IQR, 36.0-118.0 mg/L), respectively. No patients experienced significant bleeding or died. Five patients (16.1%) were referred for surgery.

CONCLUSION

This is pilot evidence that a practical regimen of concurrent, once-daily intrapleural tPA-DNase improved pleural opacification and inflammatory markers without bleeding or mortality. The surgical referral rate was higher than in studies assessing twice-daily administration, though the validity of this outcome as a measure of treatment success is limited, and further studies are needed to assess the optimal dose and frequency of intrapleural therapy and indications for surgical referral.

Pleural penetration of amoxicillin and metronidazole during pleural infection: An ambispective cohort study

OBJECTIVES

The pharmacokinetics of antibiotics in pleural fluid during pleural infections has been poorly described. This study aimed to explore amoxicillin and metronidazole diffusion into the pleural space.

METHODS

This was an ambispective, single-centre study that included patients with complicated parapneumonic effusion or pleural empyema managed with repeated therapeutic thoracentesis as first-line treatment between 2014 and 2022. Pleural steady-state or trough concentrations of amoxicillin and metronidazole were measured, with a lower limit of quantification of 5 mg/L.

RESULTS

Seventy paired blood and pleural samples were analysed from 40 patients. The median (interquartile range) patient age was 55 years (45-67 years) and 88% were male. The median patient weight was 65.8 kg (57.3-82 kg) and median plasma albumin concentration was 29.7 g/L (23.7-33.9 g/L). Median creatinine clearance was 106 mL/min (95-117 mL/min). Median amoxicillin pleural concentrations in patients treated with oral, bolus and continuous intravenous administrations (6 g/day) were, respectively, 5.2 (<5-6.4), 9.4 (8-13.1) and 10.8 (7.1-13.1) mg/L. Pleural concentrations were <5 mg/L in 5/11 samples (45%) with oral treatment and 6/59 (10%) with intravenous treatment. Median metronidazole pleural concentrations were 18.4 (15.7-22.8) mg/L, with all patients being treated orally (1.5 g/day).

CONCLUSIONS

Oral metronidazole (1.5 g/day) and intravenous amoxicillin (6 g/day) achieved therapeutic targets in pleural fluid in most cases, but oral amoxicillin did not.

Targeting the PAI-1 Mechanism with a Small Peptide Increases the Efficacy of Alteplase in a Rabbit Model of Chronic Empyema

The incidence of empyema is increasing and associated with a mortality rate of 20% in patients older than 65 years. Since 30% of patients with advanced empyema have contraindications to surgical treatment, novel, low-dose, pharmacological treatments are needed. A Streptococcus pneumoniae-induced rabbit model of chronic empyema recapitulates the progression, loculation, fibrotic repair, and pleural thickening of human disease. Treatment with single chain (sc) urokinase (scuPA) or tissue type (sctPA) plasminogen activators in doses 1.0-4.0 mg/kg were only partially effective in this model. Docking Site Peptide (DSP; 8.0 mg/kg), which decreased the dose of sctPA for successful fibrinolytic therapy in acute empyema model did not improve efficacy in combination with 2.0 mg/kg scuPA or sctPA. However, a two-fold increase in either sctPA or DSP (4.0 and 8.0 mg/kg or 2.0 and 16.0 mg/kg sctPA and DSP, respectively) resulted in 100% effective outcome. Thus, DSP-based Plasminogen Activator Inhibitor 1-Targeted Fibrinolytic Therapy (PAI-1-TFT) of chronic infectious pleural injury in rabbits increases the efficacy of alteplase rendering ineffective doses of sctPA effective. PAI-1-TFT represents a novel, well-tolerated treatment of empyema that is amenable to clinical introduction. The chronic empyema model recapitulates increased resistance of advanced human empyema to fibrinolytic therapy, thus allowing for studies of muti-injection treatments.

Management of complicated parapneumonic effusions

PURPOSE OF REVIEW

Approximately 36-57% of cases of pneumonia are associated with a parapneumonic effusion (PPE). It begins as sterile effusion, which can quickly evolve to a fibrinopurulent stage with evidence of infection called complicated parapneumonic effusions (CPPE). Marked fibrinous organization then follows. This study focuses on literature synthesis on management of CPPE.

RECENT FINDINGS

Ultrasound has become an indispensable tool in the identification and treatment of CPPE. Prompt antibiotic administration remains the universal standard of care. Decision to drain the fluid is based on fluid staging, characterization and assessment of risk of poor outcomes vs. risk of complications. There is growing evidence to support use of intrapleural fibrinolytic therapy (IPFT) in case of loculated effusions. Newer areas of research include antibodies against plasminogen activator inhibitors and stratification scores that can identify patients at an increased risk. Lastly, timing of surgical referral is an important area under study.

SUMMARY

Evolution of medical therapy over recent years has increased treatment success rates. Use of IPFT in conjunction to thoracostomy is now the standard of care for loculated effusions. Understanding available therapeutic options, both medical and interventional, can ensure evidence-based practice and improve patient-centred outcomes.

Management of Empyema Thoracis in Low-Resource Settings

Most cases of empyema thoracis are sequelae of severe pneumonia, but chest trauma and complications of chest tube insertion as cause are not uncommon in low-resource settings. Diagnosis is usually delayed due to delayed presentation to health care facilities, low index of suspicion among health care professionals, and inability to properly stage the disease with the available diagnostic tools. Early use of antibiotics and appropriate-sized and well-placed chest tube drainage is associated with good outcomes at a decreased cost. Surgical management of empyema thoracis is indicated when chest tube drainage and antibiotic treatment fail to achieve complete resolution.

Update on Novel Targeted Therapy for Pleural Organization and Fibrosis

Pleural injury and subsequent loculation is characterized by acute injury, sustained inflammation and, when severe, pathologic tissue reorganization. While fibrin deposition is a normal part of the injury response, disordered fibrin turnover can promote pleural loculation and, when unresolved, fibrosis of the affected area. Within this review, we present a brief discussion of the current IPFT therapies, including scuPA, for the treatment of pathologic fibrin deposition and empyema. We also discuss endogenously expressed PAI-1 and how it may affect the efficacy of IPFT therapies. We further delineate the role of pleural mesothelial cells in the progression of pleural injury and subsequent pleural remodeling resulting from matrix deposition. We also describe how pleural mesothelial cells promote pleural fibrosis as myofibroblasts via mesomesenchymal transition. Finally, we discuss novel therapeutic targets which focus on blocking and/or reversing the myofibroblast differentiation of pleural mesothelial cells for the treatment of pleural fibrosis.

From Bedside to the Bench—A Call for Novel Approaches to Prognostic Evaluation and Treatment of Empyema

Empyema, a severe complication of pneumonia, trauma, and surgery is characterized by fibrinopurulent effusions and loculations that can result in lung restriction and resistance to drainage. For decades, efforts have been focused on finding a universal treatment that could be applied to all patients with practice recommendations varying between intrapleural fibrinolytic therapy (IPFT) and surgical drainage. However, despite medical advances, the incidence of empyema has increased, suggesting a gap in our understanding of the pathophysiology of this disease and insufficient crosstalk between clinical practice and preclinical research, which slows the development of innovative, personalized therapies. The recent trend towards less invasive treatments in advanced stage empyema opens new opportunities for pharmacological interventions. Its remarkable efficacy in pediatric empyema makes IPFT the first line treatment. Unfortunately, treatment approaches used in pediatrics cannot be extrapolated to empyema in adults, where there is a high level of failure in IPFT when treating advanced stage disease. The risk of bleeding complications and lack of effective low dose IPFT for patients with contraindications to surgery (up to 30%) promote a debate regarding the choice of fibrinolysin, its dosage and schedule. These challenges, which together with a lack of point of care diagnostics to personalize treatment of empyema, contribute to high (up to 20%) mortality in empyema in adults and should be addressed preclinically using validated animal models. Modern preclinical studies are delivering innovative solutions for evaluation and treatment of empyema in clinical practice: low dose, targeted treatments, novel biomarkers to predict IPFT success or failure, novel delivery methods such as encapsulating fibrinolysin in echogenic liposomal carriers to increase the half-life of plasminogen activator. Translational research focused on understanding the pathophysiological mechanisms that control 1) the transition from acute to advanced-stage, chronic empyema, and 2) differences in outcomes of IPFT between pediatric and adult patients, will identify new molecular targets in empyema. We believe that seamless bidirectional communication between those working at the bedside and the bench would result in novel personalized approaches to improve pharmacological treatment outcomes, thus widening the window for use of IPFT in adult patients with advanced stage empyema.

Optimizing the management of complicated pleural effusion: From intrapleural agents to surgery

Pleural effusion is a frequent complication of acute pulmonary infection and can affect its morbidity and mortality. The possible evolution of a parapneumonic pleural effusion includes 3 stages: exudative (simple accumulation of pleural fluid), fibropurulent (bacterial invasion of the pleural cavity), and organized stage (scar tissue formation). Such a progression is favored by inadequate treatment or imbalance between microbial virulence and immune defenses. Biochemical features of a fibrinopurulent collection include a low pH (<7.20), low glucose level (<60 mg/dl), and high lactate dehydrogenase (LDH). A parapneumonic effusion in the fibropurulent stage is usually defined "complicated" since antibiotic therapy alone is not enough for its resolution and an invasive procedure (pleural drainage or surgery) is required. Chest ultrasound is one of the most useful imaging tests to assess the presence of a complicated pleural effusion. Simple parapneumonic effusions are usually anechoic, whereas complicated effusions often have a complex appearance (non-anechoic, loculated, or septated). When simple chest tube placement fails and/or patients are not suitable for more invasive techniques (i.e. surgery), intra-pleural instillation of fibrinolytic/enzymatic therapy (IPET) might represent a valuable treatment option to obtain the lysis of fibrin septa. IPET can be used as either initial or subsequent therapy. Further studies are ongoing or are required to help fill some gaps on the optimal management of parapneumonic pleural effusion. These include the duration of antibiotic therapy, the risk/benefit ratio of medical thoracoscopy and surgery, and new intrapleural treatments such as antibiotic-eluting chest tubes and pleural irrigation with antiseptic agents.

Intrapleural use of urokinase and DNase in pleural infections managed with repeated thoracentesis: A comparative cohort study

Introduction

Evacuation of infected fluid in pleural infections is essential. To date, the use of an intrapleural fibrinolytic agent such as urokinase and DNase has not yet been assessed in infections managed by repeated therapeutic thoracentesis (RTT).

Methods

We performed a retrospective comparative study of two successive cohorts of consecutive patients with pleural infections from 2001 to 2018. Between 2001 and 2010, patients had RTT with intrapleural urokinase (RTT-U). After 2011, patients received intrapleural urokinase and DNase with RTT (RTT-UD). Data were collected through a standardized questionnaire.

Results

One hundred and thirty-three patients were included: 93 were men and the mean age was 59 years (standard deviation 17.2). Eighty-one patients were treated with a combination of intrapleural urokinase and DNase, and 52 were treated with intrapleural urokinase only. In the RTT-UD, RTT failure occurred in 14 patients (17%) compared to 10 (19%) in the RTT-U group (P = 0.82). There was no difference between the two groups in intensive care unit admission, surgical referrals or in-hospital mortality. RTT-UD was associated with faster time to apyrexia (aOR = 0.51, 95%CI [0.37–0.72]), a reduced length of hospital stay (aOR = 0.61, 95%CI [0.52–0.73]) and a higher volume of total pleural fluid retrieved (aOR = 1.38, 95%CI [1.02–1.88]). Complications were rare with only one hemothorax in the RTT-UD group and no pneumothorax requiring drainage in either group.

Conclusion

Compared to urokinase only, intrapleural use of urokinase and DNase in RTT was associated with quicker defervescence, shorter hospital stay and increased volumes of pleural fluid drained. Randomized controlled trials evaluating urokinase and DNase with RTT technique would be required to confirm these results.

The Contribution of the Urokinase Plasminogen Activator and the Urokinase Receptor to Pleural and Parenchymal Lung Injury and Repair: A Narrative Review

Pleural and parenchymal lung injury have long been characterized by acute inflammation and pathologic tissue reorganization, when severe. Although transitional matrix deposition is a normal part of the injury response, unresolved fibrin deposition can lead to pleural loculation and scarification of affected areas. Within this review, we present a brief discussion of the fibrinolytic pathway, its components, and their contribution to injury progression. We review how local derangements of fibrinolysis, resulting from increased coagulation and reduced plasminogen activator activity, promote extravascular fibrin deposition. Further, we describe how pleural mesothelial cells contribute to lung scarring via the acquisition of a profibrotic phenotype. We also discuss soluble uPAR, a recently identified biomarker of pleural injury, and its diagnostic value in the grading of pleural effusions. Finally, we provide an in-depth discussion on the clinical importance of single-chain urokinase plasminogen activator (uPA) for the treatment of loculated pleural collections.

Small-bore catheter is more than an alternative to the ordinary chest tube for pleural drainage

Background:

Pleural collection is a common medical problem. For decades, the chest tube of different designs was the commonly used toll for pleural drainage. Over the past few years, small-bore catheter (SBC) has gained more popularity. We present our experience of using SBCs for the drainage of pleural collection of different etiologies.

Patients and Methods:

A total of 398 small-bore pleural catheters were inserted in 369 patients with pleural collection during the period from January 2013 to October 2019. Data were collected regarding the efficacy of drainage, experienced chest pain, duration of drainage, and the occurrence of complications.

Results:

Malignant associated (59.24%) and parapneumonic (19.57%) effusions constituted the most common causes. The drainage was successful in 382/398 (95.98%) occasions; six cases had incomplete fluid evacuation that required decortications; five cases (1.26%) had nonexpendable lung. Catheter reinsertion was needed due to dislodgment in 2 (0.50%) cases and obstruction in 3 (0.75%) cases. Sixty-two cases (15.58%) experienced chest pain. No patient developed empyema or cellulites at the site of catheter insertion. The duration of drainage ranged from 2 to 7 days, with an average of 3.5 days.

Conclusions:

SBC is equivalent to conventional chest tube for the drainage of pleural collection. Moreover, it has the advantages of less associated pain, versatility of insertion site, and relative safety of the technique in some risky and difficult situations.

Hemothorax: A Review of the Literature

Hemothorax is a collection of blood in the pleural cavity usually from traumatic injury. Chest X-ray has historically been the imaging modality of choice upon arrival to the hospital. The sensitivity and specificity of point-of-care ultrasound, specifically through the Extended Focal Assessment with Sonography in Trauma (eFAST) protocol has been significant enough to warrant inclusion in most Level 1 trauma centers as an adjunct to radiographs.^1,2 If the size or severity of a hemothorax warrants intervention, tube thoracostomy has been and still remains the treatment of choice. Most cases of hemothorax will resolve with tube thoracostomy. If residual blood remains within the pleural cavity after tube thoracostomy, it is then considered to be a retained hemothorax, with significant risks for developing late complications such as empyema and fibrothorax. Once late complications occur, morbidity and mortality increase dramatically and the only definitive treatment is surgery. In order to avoid surgery, research has been focused on removing a retained hemothorax before it progresses pathologically. The most promising therapy consists of fibrinolytics which are infused into the pleural space, disrupting the hemothorax, allowing for further drainage. While significant progress has been made, additional trials are needed to further define the dosing and pharmacokinetics of fibrinolytics in this setting. If medical therapy and early procedures fail to resolve the retained hemothorax, surgery is usually indicated. Surgery historically consisted solely of thoracotomy, but has been largely replaced in non-emergent situations by video-assisted thoracoscopy (VATS), a minimally invasive technique that shows considerable improvement in the patients' recovery and pain post-operatively. Should all prior attempts to resolve the hemothorax fail, then open thoracotomy may be indicated.

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.

Risk Stratification in Patients with Complicated Parapneumonic Effusions and Empyema Using the RAPID Score

PURPOSE

Complicated parapneumonic effusions and empyema are a leading cause of morbidity in the United States with over 1 million admissions annually and a mortality rate that remains high in spite of recent advances in diagnosis and treatment. The identification of high risk patients is crucial for improved management and the provision of cost-effective care. The RAPID score is a scoring system comprised of the following variables: renal function, age, purulence, infection source, and dietary factors and has been shown to predict outcomes in patients with pleural space infections.

METHODS

In a single center retrospective study, we evaluated 98 patients with complicated parapneumonic effusions and empyema who had tube thoracostomy (with or without Intrapleural fibrinolytic therapy) and assessed treatment success rates, mortality, length of hospital stay, and direct hospitalization costs stratified by three RAPID score categories: low-risk (0-2), medium risk (3-4), and high-risk (5-7) groups.

RESULTS

Treatment success rate was 71%, and the 90 day mortality rate was 12%. There was a positive-graded association between the low, medium and high RAPID score categories and mortality, (5.3%, 8.3% and 22.6%, respectively), length of hospital stay (10, 21, 19 days, respectively), and direct hospitalization costs ($19,909, $36,317 and $43,384, respectively).

CONCLUSION

Our findings suggest that the RAPID score is a robust tool which could be used to identify patients with complicated parapneumonic effusions and empyema who may be at an increased risk of mortality, prolonged hospitalization, and who may incur a higher cost of treatment. Randomized controlled trials identifying the most effective initial treatment modality for medium- and high-risk patients are needed.