Tissue Plasminogen Activator Combined With Human Recombinant Deoxyribonuclease Is Effective Therapy for Empyema in a Rabbit Model

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.

DNase inhibits early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models

Anti-infection strategies against pleural empyema include the use of antibiotics and drainage treatments, but bacterial eradication rates remain low. A major challenge is the formation of biofilms in the pleural cavity. DNase has antibiofilm efficacy in vitro, and intrapleural therapy with DNase is recommended to treat pleural empyema, but the relevant mechanisms remain limited. Our aim was to investigate whether DNase I inhibit the early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models. We used various assays, such as crystal violet staining, confocal laser scanning microscopy (CLSM) analysis, peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), and scanning electron microscopy (SEM) analysis. Our results suggested that DNase I significantly inhibited early biofilm formation in a dose-dependent manner, without affecting the growth of P. aeruginosa or S. aureus in vitro. CLSM analysis confirmed that DNase I decreased the biomass and thickness of both bacterial biofilms. The PNA-FISH and SEM analyses also revealed that DNase I inhibited early (24h) biofilm formation in two empyema models. Thus, the results indicated that DNase inhibited early (24h) biofilm formation in P. aeruginosa- or S. aureus-induced rabbit empyema models and showed its therapeutic potential against empyema biofilms.

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.

Comparing the outcomes of intrapleural fibrinolytic and DNase therapy versus intrapleural fibrinolytic or DNase therapy: A systematic review and meta-analysis

BACKGROUND

Multiple studies describing the benefits of intrapleural fibrinolytic over placebo and DNase therapy have been published, but few have been published on intrapleural fibrinolytic and DNase therapy.

OBJECTIVE

Our meta-analysis aims to compare the outcomes of surgical intervention, mortality, and hospital length of stay between intrapleural fibrinolytic and DNase therapy with either intrapleural fibrinolytic or DNase therapy alone in patients with pleural space infections.

METHODS

We searched Pubmed, EMBASE, Web of Science, and Cochrane library databases for observational studies and randomized controlled trials (RCTs) containing comparative data for hospitalized adults and children with pleural infections receiving intrapleural therapy of fibrinolytic and DNase versus those receiving intrapleural fibrinolytic or DNase alone. Meta-analysis was performed using the Review Manager software, and heterogeneity was tested using I² statistics.

RESULTS

A total of 2 cohorts and 2 RCTs involving 362 adult and children was included. There was significant reduction in surgical intervention requirement among patients who received intrapleural fibrinolytic and DNase (OR 0.30; 95% CI 0.11-0.83; I² = 31%; P = 0.02) than those receiving either intrapleural fibrinolytic or DNase alone. No difference was observed for mortality (OR 0.72; 95% CI 0.31-1.71; I² = 0%; P = 0.46) and complication rates (OR 3.09; 95% CI 0.75-12,74; I² = 54%; P = 0.12). The hospital length of stay (mean 13.70 vs. 16.67 days; P = 0.19) and duration of chest tube drainage (mean 6.47 vs. 6.30 days; P = 0.58) was similar between the two groups.

CONCLUSION

Combination of intrapleural fibrinolytic and DNase, compared to single-agent intrapleural therapy alone, is associated with a lesser need for surgical interventions. However, no difference was found in mortality, hospital length of stay, and chest tube drainage duration.

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.

Recent Insights into the Management of Pleural Infection

Pleural infection in adults has considerable morbidity and continues to be a life-threatening condition. The term “pleural infection” encompasses complicated parapneumonic effusions and primary pleural infections, and includes but is not limited to empyema, which refers to collection of pus in the pleural cavity. The incidence of pleural infection in adults has been continuously increasing over the past two decades, particularly in older adults, and most of such patients have comorbidities. Management of pleural infection requires prolonged duration of hospitalization (average 14 days). There are recognized differences in microbial etiology of pleural infection depending on whether the infection was acquired in the community or in a health-care setting. Anaerobic bacteria are acknowledged as a major cause of pleural infection, and thus anaerobic coverage in antibiotic regimens for pleural infection is mandatory. The key components of managing pleural infection are appropriate antimicrobial therapy and chest-tube drainage. In patients who fail medical therapy by manifesting persistent sepsis despite standard measures, surgical intervention to clear the infected space or intrapleural fibrinolytic therapy (in poor surgical candidates) are recommended. Recent studies have explored the role of early intrapleural fibrinolytics or first-line surgery, but due to considerable costs of such interventions and the lack of convincing evidence of improved outcomes with early use, early intervention cannot be recommended, and further evidence is awaited from ongoing studies. Other areas of research include the role of routine molecular testing of infected pleural fluid in improving the rate of identification of causative organisms. Other research topics include the benefit of such interventions as medical thoracoscopy, high-volume pleural irrigation with saline/antiseptic solution, and repeated thoracentesis (as opposed to chest-tube drainage) in reducing morbidity and improving outcomes of pleural infection. This review summarizes current knowledge and practice in managing pleural infection and future research directions.

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.

A combined intrapleural administration of dornase alfa and tissue plasminogen activator is safe in children with empyema - A pilot study

OBJECTIVE

There is still no consensus regarding the treatment of empyema in children. Intrapleural combination of tissue plasminogen activator and dornase alfa is a promising treatment for empyema in adults. The aim of this pilot study was to determine whether this combination is safe and successful in pediatric empyema.

METHODS

Previous well children diagnosed with empyema as classified by the British Thoracic Society. After chest tube insertion, intrapleurally dornase alfa 2.5 mg for 2 days and tissue plasminogen activator 0.15 mg/kg for 3 days was given after which the chest tube was clamped for 4 h. Primary outcome was safety.

RESULTS

Ten consecutive children were included (4 boys, aged 3.2 (1.3-15.0) years old). No serious adverse events were seen. One child developed urticaria but additional intervention or cessation of the trial was not needed. There was no bleeding or mortality and no additional procedures were performed. The median hospital stay after intervention was 7.5 days.

CONCLUSIONS

The intrapleural treatment of dornase alfa and tissue plasminogen activator as treatment of empyema was safe in ten children with empyema. If confirmed in further studies, this combination of intrapleural therapy may improve the management of pediatric empyema.

Precision targeting of the plasminogen activator inhibitor-1 mechanism increases efficacy of fibrinolytic therapy in empyema

Plasminogen activator inhibitor‐1 (PAI‐1) is an endogenous irreversible inhibitor of tissue‐type (tPA) and urokinase (uPA) plasminogen activators. PAI‐1‐targeted fibrinolytic therapy (PAI‐1‐TFT) is designed to decrease the therapeutic dose of tPA and uPA, attenuating the risk of bleeding and other complications. Docking site peptide (DSP) mimics the part of the PAI‐1 reactive center loop that interacts with plasminogen activators, thereby affecting the PAI‐1 mechanism. We used DSP for PAI‐1‐TFT in two rabbit models: chemically induced pleural injury and Streptococcus pneumoniae induced empyema. These models feature different levels of inflammation and PAI‐1 expression. PAI‐1‐TFT with DSP (2.0 mg/kg) converted ineffective doses of single chain (sc) tPA (72.5 µg/kg) and scuPA (62.5 µg/kg) into effective ones in chemically induced pleural injury. DSP (2.0 mg/kg) was ineffective in S. pneumoniae empyema, where the level of PAI‐1 is an order of magnitude higher. DSP dose escalation to 8.0 mg/kg resulted in effective PAI‐1‐TFT with 0.25 mg/kg sctPA (1/8th of the effective dose of sctPA alone) in empyema. There was no increase in the efficacy of scuPA. PAI‐1‐TFT with DSP increases the efficacy of fibrinolytic therapy up to 8‐fold in chemically induced (sctPA and scuPA) and infectious (sctPA) pleural injury in rabbits. PAI‐1 is a valid molecular target in our model of S. pneumoniae empyema in rabbits, which closely recapitulates key characteristics of empyema in humans. Low‐dose PAI‐1‐TFT is a novel interventional strategy that offers the potential to improve fibrinolytic therapy for empyema in clinical practice.

Advances in pleural infection and malignancy

Pleural infection and malignancy are among the most common causes of pleural disease and form the mainstay of pleural practice. There has been significant research and increase in scientific understanding in these areas in the past decade. With regard to pleural infection, the rising incidence remains worrying. An increased awareness allowing earlier diagnosis, earlier escalation of therapy and the use of validated risk stratification measures may improve outcomes. In pleural malignancy, research has enabled clinicians to streamline patient pathways with focus on reducing time to diagnosis, definitive management of malignant pleural effusion and achieving these with the minimum number of pleural interventions. Trials comparing treatment modalities of malignant pleural effusion continue to highlight the importance of patient choice in clinical decision-making. This article aims to summarise some of the most recent literature informing current practice in these two areas.

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.

Bronchopleural communication following intrapleural doses of tPA/DNase for empyema

Intrapleural tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) therapy is a new treatment for pleural infection. Clinical experiences of tPA/DNase therapy, and its complications, are cumulating. We present a patient with multiloculated empyema but no initial evidence of a bronchopleural fistula. She was treated with antibiotics and chest tube drainage of the basal collection through which four doses of tPA/DNase were delivered with success. The lateral collection worsened necessitating separate tube drainage and tPA/DNase treatment. She reported chest "fullness" when instilled the second dose. The third instillation of tPA triggered immediate vigorous coughing and expectoration of salty-tasting fluid, likely the tPA/saline solution. The symptoms spontaneously settled after 15 min, with no evidence of air leak. The loculated fluid was successfully evacuated. The patient made a full recovery after an antibiotic course with no long-term consequences. Pulmonary migration of drugs via a bronchopleural communication, although rare, can occur with intrapleural tPA/DNase therapy.

The effect of Cyclic-di-GMP on biofilm formation by Pseudomonas aeruginosa in a novel empyema model

Background

Pseudomonas aeruginosa (P. aeruginosa) is a common pathogenic bacterium which causes pleural empyema, and infection of P. aeruginosa is often associated with biofilm. The aim of this study was to establish a model of rabbit empyema infected by P. aeruginosa to determine whether it causes the formation of biofilm in the pleural cavity. Furthermore, we investigated the effect of cyclic diguanosine monophosphate (c-di-GMP) on biofilm formation in this P. aeruginosa empyema model.

Methods

Twenty rabbits were used and randomly divided into five groups: PAO1, PAO1ΔwspF, and PAO1/p_lac-yhjH infection groups, and Luria-Bertani (LB) broth and turpentine control groups. A drainage catheter was implanted into the pleural cavity through thoracentesis. The three infection groups were respectively infected with PAO1, PAO1ΔwspF, and PAO1/p_lac-yhjH strains, which caused empyema. The two control groups were injected with LB or turpentine. After 4 days of infection, we sacrificed the rabbits. We evaluated the pathology of pleura through hematoxylin-eosin staining. Colony count and crystal violet assay were used to analyze the biofilm formation on the surface of catheters. Scanning electron was used to observe the biofilm on the surface of the pleura. Peptide nucleic acids-fluorescence in situ hybridization (PNA-FISH) was used to observe the biofilm in the fibrinous deposition.

Results

By the PNA-FISH assay, biofilms were observed in the fibrinous deposition of the three infection groups. The red fluorescence area of the PAO1ΔwspF infection group was larger than that of the PAO1 and PAO1/p_lac-yhjH infection groups. Through electron microscopy, we observed that PAO1 strains were embedded in an electron-dense extracellular matrix on the surface of pleural tissue, and appeared to be biofilm-like structures. For the crystal violet assay, the optical density values of different groups were significantly different: PAO1ΔwspF > PAO1 > PAO1/p_lac-yhjH > control groups (P<0.05).

Conclusions

To the best knowledge of the authors, this is the first study to report P. aeruginosa forming biofilm in a novel animal model of pleural empyema. In addition, c-di-GMP signaling molecules played an important role in biofilm formation in the pleural cavity.

Effectiveness of Intrapleural Tissue Plasminogen Activator and Dornase Alfa vs Tissue Plasminogen Activator Alone in Children with Pleural Empyema: A Randomized Clinical Trial

IMPORTANCE

Clinical guidelines recommend that children with pleural empyema be treated with chest tube insertion and intrapleural fibrinolytics. The addition of dornase alfa (DNase) has been reported to improve outcomes in adults but remains unproven in children.

OBJECTIVE

To determine if intrapleural tissue plasminogen activator (tPA) and DNase is more effective than tPA and placebo at reducing hospital length of stay in children with pleural empyema.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, parallel-group, placebo-controlled, superiority randomized clinical trial included children diagnosed as having pleural empyema requiring drainage aged 6 months to 18 years treated at 6 tertiary Canadian children's hospitals. A total of 379 children were assessed for eligibility; 281 were excluded and 98 were randomized. One child was excluded after randomization for not meeting the inclusion criteria. Data were collected from March 4, 2013, to December 13, 2017.

INTERVENTIONS

Participants underwent chest tube insertion and 3 daily administrations of intrapleural tPA, 4 mg, followed by DNase, 5 mg (intervention group), or 5 mL of normal saline (placebo; control group). Participants, families, clinical staff, and members of the study team were blinded to allocation.

MAIN OUTCOMES AND MEASURES

The primary outcome was hospital length of stay from chest tube insertion to discharge. Secondary outcomes included time to meeting discharge criteria, time to chest tube removal, mean fever duration, additional pleural drainage procedures, hospital readmissions, and total health care cost.

RESULTS

Of the 97 analyzed children with pleural empyema, 52 (54%) were male, and the mean (SD) age was 5.1 (3.6) years. A total of 49 children were randomized to tPA and DNase and 48 were randomized to tPA and placebo. Treatment with tPA and DNase was not associated with decreased hospital length of stay compared with tPA and placebo (mean [SD] length of stay, 9.0 [4.9] vs 9.1 [5.3] days; mean difference, -0.1 days; 95% CI, -2.0 to 2.1; P = .96). Similarly, no significant differences were observed for any of the secondary outcomes. Of the 14 adverse events in the tPA and DNase group, 6 (43%) were serious; of the 21 adverse events in the tPA and placebo group, 8 (38%) were serious. There were no deaths.

CONCLUSIONS AND RELEVANCE

The addition of DNase to intrapleural tPA for children with pleural empyema had no effect on hospital length of stay or other outcomes compared with tPA with placebo. Clinical practice guidelines should continue to support the use of chest tube insertion and intrapleural fibrinolytics alone as first-line treatment for pediatric empyema.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01717742.

Biological effect of tissue plasminogen activator (t-PA) and DNase intrapleural delivery in pleural infection patients

Background

Pleural infection (PI) is a major global disease with an increasing incidence, and pleural fluid (PF) drainage is essential for the successful treatment. The MIST2 study demonstrated that intrapleural administration of tissue plasminogen activator (t-PA) and DNase, or t-PA alone increased the volume of drained PF. Mouse model studies have suggested that the volume increase is due to the interaction of the pleura with the t-PA via the monocyte chemoattractant protein 1 (MCP-1) pathway. We designed a study to determine the time frame of drained PF volume induction on intrapleural delivery of t-PA±DNase in humans, and to test the hypothesis that the induction is mediated by the MCP-1 pathway.

Methods

Data and samples from the MIST2 study were used (210 PI patients randomised to receive for 3 days either: t-PA and DNase, t-PA and placebo, DNase and placebo or double placebo). PF MCP-1 levels were measured by ELISA. One-way and two-way analysis of variance (ANOVA) with Tukey's post hoc tests were used to estimate statistical significance. Pearson's correlation coefficient was used to assess linear correlation.

Results

Intrapleural administration of t-PA±DNase stimulated a statistically significant rise in the volume of drained PF during the treatment period (days 1-3). No significant difference was detected between any groups during the post-treatment period (days 5-7). Intrapleural administration of t-PA increased MCP-1 PF levels during treatment; however, no statistically significant difference was detected between patients who received t-PA and those who did not. PF MCP-1 expression was not correlated to the drug given nor the volume of drained PF.

Conclusions

We conclude that the PF volume drainage increment seen with the administration of t-PA does not appear to act solely via activation of the MCP-1 pathway.

Alteplase and DNase for the treatment of pleural empyema in rats

BACKGROUND AND OBJECTIVES

Adjunctive intrapleural fibrinolytic is an option to treat empyema at fibrinopurulent stage, but there is controversy about which should be use. Our objective is to evaluate the action of alteplase and/or desoxyribonuclease at physical and chemical properties in vitro pus derived from an experimental induced empyema in rats.

METHODS

Streptococcus pneumoniae was introduced into the pleural cavity by thoracentesis through pleural pressure monitor. Animals were euthanized after 24 h, with macroscopic thoracic evaluation and measurement of amount of intrapleural liquid that was posteriorly stored at -80 °C. Selected samples were randomly distributed into four groups, then thawed at room temperature before exposure to one of the following: G1 = alteplase (n = 12), G2 = DNase (n = 12), G3 = alteplase + DNase (n = 12), or G4 = saline (n = 6). The mean molecular size in the fluid portion of the empyema was evaluated using dynamic light scattering; viscosity of the empyema fluid was measured using the drip method.

RESULTS

Macroscopic showed purulent liquid, with fibrin and septation, with mean volume of 4.16 ml (0.5-8 ml). All samples were culture-positive for Streptococcus pneumoniae. Comparing with control, all experimental groups presented reduction of larger than 135 nm molecular size, but there was only significant difference with alteplase (p = 0,02). Viscosity reduced at all experimental groups, but increased at control. DNase group presented negative median (-5 mPa/s) of viscosity, and differed significantly from that observed in the control group (p = 0.04).

CONCLUSIONS

Alteplase, DNase and alteplase + DNase changed significantly physical and chemical properties of experimental empyema at fibrinopurulent phase: alteplase reduced molecular size larger than 135 nm and DNase reduced viscosity.

Rethinking the Doses of Tissue Plasminogen Activator and Deoxyribonuclease Administrated Concurrently for Intrapleural Therapy for Complicated Pleural Effusion and Empyema

Background

Complicated parapneumonic effusions empyema (CPEE) is fairly common and associated with increased morbidity and mortality. The Multicenter Intrapleural Sepsis Trial 2 (MIST 2) established the combination of intrapleural deoxyribonuclease (DNase) and tissue plasminogen activator (tPA) as an effective treatment for CPEE, thereby avoiding surgery and decreasing the length of hospitalization. MIST 2, however, used a labor-intensive protocol with some risk of bleeding. We hypothesize the simpler regimen of concurrent administration of intrapleural tPA and DNase (lower dose of tPA and a higher DNAse dose) to be equally effective with a decreased risk of bleeding.

Methods

Retrospective analysis of the concurrent administration of intrapleural tPA and DNase for CPEE during November 2014 to February 2016 was done at a tertiary care center. The inclusion criteria included 1) pleural fluid with any of the following: (a) exudative and loculated effusion in a patient with pneumonia, (b) gram stain/culture positive, (c) macroscopically purulent 2) chest tube placement during current hospitalization 3) concurrent administration of intrapleural tPA and DNase (4mg and 10mg per instillation respectively). The exclusion criteria was 1) chest tube placement prior to current hospitalization and 2) age < eighteen.

Results

Seventeen patients received concurrent tPA and DNase therapy for CPEE in the study period. Two had chest tubes placed prior to current hospitalization and were excluded. Twelve patients (80%) were successfully discharged with clinical resolution of CPEE with medical therapy. One (7%) patient required surgery. No mortality due to pleural sepsis was noted. The median number of concurrent tPA and DNase treatment was two. Median cumulative tPA dose was 8 mg (mean: 14.1±17 mg) and median cumulative DNase dose was 20mg (mean: 19.7 ± 12.2 mg). The median dwell time for the chest tubes was 8.5 days. Our regimen had similar success when compared to MIST 2 and allowed for lesser treatments and cumulative doses. No complication of intrapleural therapy with hemorrhagic conversion of CPEE, or worsening pain leading to discontinuation of therapy was noted.

Conclusion

The concurrent administration of intrapleural therapy at lower doses than the current standard MIST 2 protocol is practical, efficient and effective. We suggest a higher DNase dose with a lower tPA dose which may further decrease hemorrhagic complications. Further randomized trials are required to establish the optimal dose of intrapleural therapy for CPEE.

Management of community-acquired pneumonia in immunocompetent adults: updated Swedish guidelines 2017

Based on expert group work, Swedish recommendations for the management of community-acquired pneumonia in adults are here updated. The management of sepsis-induced hypotension is addressed in detail, including monitoring and parenteral therapy. The importance of respiratory support in cases of acute respiratory failure is emphasized. Treatment with high-flow oxygen and non-invasive ventilation is recommended. The use of statins or steroids in general therapy is not found to be fully supported by evidence. In the management of pleural infection, new data show favourable effects of tissue plasminogen activator and deoxyribonuclease installation. Detailed recommendations for the vaccination of risk groups are afforded.

Intrapleural Dornase and Tissue Plasminogen Activator in pediatric empyema (DTPA): a study protocol for a randomized controlled trial

BACKGROUND

A randomized controlled trial of adults with empyema recently demonstrated decreased length of stay in hospital in patients treated with intrapleurally administered dornase alfa and fibrinolytics compared to fibrinolytics alone. Whether this treatment strategy is safe and effective in children remains unknown.

METHODS/DESIGN

This study protocol is for a superiority, placebo-controlled, parallel-design, multicenter randomized controlled trial. The participants are previously well children admitted to a children's hospital with a diagnosis of empyema requiring chest tube insertion and fibrinolytics administered intrapleurally. Children will be randomized after the treating physician has decided that pleural drainage is required but prior to chest tube insertion. After chest tube insertion, participants in the treatment group will receive intrapleurally administered tissue plasminogen activator (tPA) 4 mg followed by dornase alfa 5 mg. Participants in the placebo group will receive tPA 4 mg followed by normal saline. Study treatments will be administered once daily for 3 days. All participants, parents or caregivers, clinicians, and research personnel will remain blinded. The primary outcome is length of stay from chest tube insertion to discharge from hospital. Secondary outcomes include time to meeting discharge criteria, chest tube duration, fever duration, need for additional procedures, adverse events, hospital readmission, cost of hospitalization, and mortality.

DISCUSSION

This multicenter randomized controlled trial will assess the safety, effectiveness, and cost-effectiveness of combined treatment with dornase alfa and fibrinolytics compared to fibrinolytics alone for the treatment of empyema in children.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01717742 . Registered on 8 October 2012.

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.

Repeated therapeutic thoracentesis to manage complicated parapneumonic effusions

PURPOSE OF REVIEW

In complicated parapneumonic effusion (CPPE), antibiotics and evacuation of the infected pleural fluid are mandatory. The first-line evacuation treatment is still controversial. The aim of this article is to highlight the usefulness of repeated therapeutic thoracentesis (RTT) as a first-line treatment.

RECENT FINDINGS

In the most recent study on RTT in CPPE, disposable pleural needles were used and the median number of thoracentesis was 3. The success rate was 81%, and only 4% of the patients were referred for thoracic surgery. The 1-year survival rate was 88%. On multivariate analysis, the observation of microorganisms in the pleural fluid after Gram staining and first thoracentesis volume at least 450 ml was associated with a higher risk of RTT failure. RTT is less invasive and can target different loculated pleural collections. Patients are less confined to beds between each procedure, and could even be ambulatory managed. The use of intrapleural fibrinolytics in association with DNase could most likely enhance the efficacy of RTT.

SUMMARY

RTT is efficient and well tolerated in the management of CPPE, including pleural empyema, and could be proposed as a first-line therapy for CPPE. This technique could be used in association with intrapleural fibrinolytics and DNase.

Management of Intrapleural Sepsis with Once Daily Use of Tissue Plasminogen Activator and Deoxyribonuclease

BACKGROUND

Pleural infection remains a significant cause of morbidity, mortality, prolonged hospital stay, and increased healthcare costs, despite advances in therapy. Twice daily intrapleural tissue plasminogen activator (tPA)/deoxyribonuclease (DNase) initiated at the time of diagnosis has been shown to significantly improve radiological outcomes and decrease the need for surgery.

OBJECTIVES

To analyze our experience with once daily tPA/DNase for intrapleural sepsis.

METHODS

Data derived from consecutive patients with empyema and complicated parapneumonic effusion who received once daily intrapleural tPA/DNase between January 2012 and August 2014 were reviewed. Measured outcomes included treatment success at 30 days, volume of pleural fluid drained, improvement in radiographic pleural opacity, length of hospital stay, need for surgery, and adverse events.

RESULTS

55 consecutive patients (33 male; mean age ± SD, 54.6 ± 16.1 years) were treated with once daily intrapleural tPA/DNase for 3 days. The majority of the patients (n = 51; 92.7%) were successfully managed without the need for surgical intervention. The mean change in pleural opacity measured on chest radiograph at day 7 was -28.8 ±17.6%. The median amount of fluid drained was 2,195 ml. No serious adverse events requiring discontinuation of intrapleural medications were observed. The most common complication was pain requiring escalating doses of analgesics (n = 8; 15%). Compliance with the protocol was excellent.

CONCLUSION

Early administration of once daily intrapleural tPA/DNase for 3 days is safe, effective, and represents a viable option for the management of empyema and complicated parapneumonic effusion.

Tissue plasminogen activator potently stimulates pleural effusion via a monocyte chemotactic protein-1-dependent mechanism

Pleural infection is common. Evacuation of infected pleural fluid is essential for successful treatment, but it is often difficult because of adhesions/loculations within the effusion and the viscosity of the fluid. Intrapleural delivery of tissue plasminogen activator (tPA) (to break the adhesions) and deoxyribonuclease (DNase) (to reduce fluid viscosity) has recently been shown to improve clinical outcomes in a large randomized study of pleural infection. Clinical studies of intrapleural fibrinolytic therapy have consistently shown subsequent production of large effusions, the mechanism(s) of which are unknown. We aimed to determine the mechanism by which tPA induces exudative fluid formation. Intrapleural tPA, with or without DNase, significantly induced pleural fluid accumulation in CD1 mice (tPA alone: median [interquartile range], 53.5 [30-355] μl) compared with DNase alone or vehicle controls (both, 0.0 [0.0-0.0] μl) after 6 hours. Fluid induction was reproduced after intrapleural delivery of streptokinase and urokinase, indicating a class effect. Pleural fluid monocyte chemotactic protein (MCP)-1 levels strongly correlated with effusion volume (r = 0.7302; P = 0.003), and were significantly higher than MCP-1 levels in corresponding sera. Mice treated with anti-MCP-1 antibody (P < 0.0001) or MCP-1 receptor antagonist (P = 0.0049) demonstrated a significant decrease in tPA-induced pleural fluid formation (by up to 85%). Our data implicate MCP-1 as the key molecule governing tPA-induced fluid accumulation. The role of MCP-1 in the development of other exudative effusions warrants examination.

The Use of Recombinant Tissue Plasminogen Activator (rTPA) in The Treatment of Fibrinous Pleuropneumonia in Horses: 25 Cases (2007-2012)

Background

Information about treatment protocols, adverse effects and outcomes with intrapleural recombinant tissue plasminogen activator (rTPA) use in horses with fibrinous pleuropneumonia is limited.

Hypothesis/Objectives

Describe factors that contribute to clinical response and survival of horses treated with rTPA intrapleurally.

Animals

Horses with bacterial pneumonia and fibrinous pleural effusion diagnosed by ultrasonography, that were treated with rTPA intrapleurally.

Methods

Retrospective multicenter case series from 2007–2012. Signalment, history, clinical and laboratory evaluation, treatment, and outcome obtained from medical records. Regression analysis used to identify associations between treatments and outcomes.

Results

Thirty three hemithoraces were treated in 25 horses, with 55 separate treatments. Recombinant tissue plasminogen activator (375–20,000 μg/hemithorax) was administered 1–4 times. Sonographically visible reduction in fibrin mat thickness, loculations, fluid depth, or some combination of these was seen in 32/49 (65%) treatments. Response to at least 1 treatment was seen in 17/20 (85%) horses with sonographic follow‐up evaluation after every treatment. Earlier onset of rTPA treatment associated with increased survival odds. No association was found between cumulative rTPA dose or number of rTPA doses and survival, development of complications, duration of hospitalization or total charges. Clinical evidence of hypocoagulability or bleeding was not observed. Eighteen horses (72%) survived to discharge.

Conclusions and clinical importance

Treatment with rTPA appeared safe and resulted in variable changes in fibrin quantity and organization within the pleural space. Recombinant tissue plasminogen activator could be a useful adjunct to standard treatment of fibrinous pleuropneumonia, but optimal case selection and dosing regimen remain to be elucidated.

Intrapleural tissue plasminogen activator and deoxyribonuclease for pleural infection. An effective and safe alternative to surgery

RATIONALE

Intrapleural tissue plasminogen activator (tPA)/deoxyribonuclease (DNase) therapy for pleural infection given at the time of diagnosis has been shown to significantly improve radiological outcomes. Published cases are limited to only a single randomized controlled trial and a few case reports.

OBJECTIVES

Multinational observation series to evaluate the pragmatic "real-life" application of tPA/DNase treatment for pleural infection in a large cohort of unselected patients.

METHODS

All patients from eight centers who received intrapleural tPA/DNase for pleural infection between January 2010 and September 2013 were included. Measured outcomes included treatment success at 30 days, volume of pleural fluid drained, improvement in radiographic pleural opacity and inflammatory markers, need for surgery, and adverse events.

MEASUREMENTS AND MAIN RESULTS

Of 107 patients treated, the majority (92.3%) were successfully managed without the need for surgical intervention. No patients died as a result of pleural infection. Most patients (84%) received tPA/DNase more than 24 hours after failing to respond to initial conservative management with antibiotics and thoracostomy. tPA/DNase increased fluid drained from a median of 250 ml (interquartile range [IQR], 100-654) in the 24 hours preceding commencement of intrapleural therapy to 2,475 ml (IQR 1,800-3,585) in the 72 hours following treatment initiation (P < 0.05). We observed a corresponding clearance of pleural opacity on chest radiographs from a median of 35% (IQR 25-31) to 14% (7-28) of the hemithorax (P < 0.001), as well as significant reduction in C-reactive protein (P < 0.05). Pain necessitating escalation of analgesia occurred in 19.6% patients, and nonfatal bleeding occurred in 1.8%.

CONCLUSIONS

This large series of patients who received intrapleural tPA/DNase therapy provides important evidence that the treatment is effective and safe, especially as a "rescue therapy" in patients who do not initially respond to antibiotics and thoracostomy drainage.

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.

A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats

OBJECTIVE

To review the current literature in reference to the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats.

ETIOLOGY

Pyothorax, also known as thoracic empyema, is characterized by the accumulation of septic purulent fluid within the pleural space. While the actual route of pleural infection often remains unknown, the oral cavity and upper respiratory tract appear to be the most common source of microorganisms causing pyothorax in dogs and cats. In human medicine, pyothorax is a common clinical entity associated with bacterial pneumonia and progressive parapneumonic effusion.

DIAGNOSIS

Thoracic imaging can be used to support a diagnosis of pleural effusion, but cytologic examination or bacterial culture of pleural fluid are necessary for a definitive diagnosis of pyothorax.

THERAPY

The approach to treatment for pyothorax varies greatly in both human and veterinary medicine and remains controversial. Treatment of pyothorax has classically been divided into medical or surgical therapy and may include administration of antimicrobials, intermittent or continuous thoracic drainage, thoracic lavage, intrapleural fibrinolytic therapy, video-assisted thoracic surgery, and traditional thoracostomy. Despite all of the available options, the optimal treatment to ensure successful short- and long-term outcome, including the avoidance of recurrence, remains unknown.

PROGNOSIS

The prognosis for canine and feline pyothorax is variable but can be good with appropriate treatment. A review of the current veterinary literature revealed an overall reported survival rate of 83% in dogs and 62% in cats. As the clinical presentation of pyothorax in small animals is often delayed and nonspecific, rapid diagnosis and treatment are required to ensure successful outcome.

Advances in the management of pleural disease

Pleural disease affects over 3000 people per million population annually. Consequently, it represents a significant proportion of the respiratory physician's workload and can present to clinicians of all backgrounds in primary and secondary care. Pleural effusions have been reported in association with over 50 different conditions; some related to specific pulmonary pathologies, but many being manifestations of multisystem disease. The burden that conditions such as pleural infection; malignant pleural disease; and pneumothorax impose on patients and health care systems is enormous and growing. As such, a clear understanding of these key conditions is crucial to any physician regardless of the specialty. This article addresses a number of areas relating to pleural disease, providing an overview of the diagnostic and therapeutic advances that have been made in our understanding of pleural pathology in recent years. The directions that future research in this important area of respiratory medicine might take will also be discussed.

Treatment of complicated pleural effusions in 2013

The incidence of pleural infection seems to be increasing worldwide. Despite continued advances in the management of this condition, morbidity and mortality have essentially remained static over the past decade. This article summarizes the current evidence and opinions on the epidemiology, etiology, and management of complicated pleural effusions caused by infection, including empyema. Although many parallels may be drawn between children and adults in such cases, most trials, guidelines, and series regard pediatric patient groups and those more than 18 years of age as separate entities. This review focuses mainly on the treatment of adult disease.

New therapy of pleural empyema by deoxyribonuclease

Empyema is a severe complication of different diseases and traumas. Management of this complication is difficult and should comprise general and local procedures. The general procedure is mainly based on administering wide-spectrum antibiotics. Local management depends on patient general condition, but in all cases the essential procedure is to insert a drain into the pleural cavity and to evacuate the pus. Sometimes pus is very thick and its evacuation and following re-expansion of the lung is rather impossible. In these patients surgical intervention is needed. The use of intrapleural enzymes to support the drainage was first described in 1949 by Tillett and Sherry using a mixture of streptokinase and streptococcal deoxyribonuclease. Nowadays, purified streptokinase has come into widespread use, but recent studies reported no streptokinase effect on pus viscosity. On the other side, deoxyribonuclease reduces pus viscosity and may be more useful in treatment. We report two cases of intrapleural administration of Pulmozyme (alfa dornase – deoxyribonuclease (HOFFMANN-LA ROCHE AG) in dosage 2 × 2.5 mg with a significant improvement caused by changes in pus viscosity.

The diagnosis and management of empyema in children: a comprehensive review from the APSA Outcomes and Clinical Trials Committee

The aim of this study is to review the current evidence on the diagnosis and management of empyema. The American Pediatric Surgical Association Outcomes and Clinical Trials Committee compiled 8 questions to address. A comprehensive review was performed on each topic. Topics included the distinction between parapneumonic effusion and empyema, the optimal imaging modality in evaluating pleural space disease, when and how pleural fluid should be managed, the first treatment option and optimal timing in the management of empyema, the optimal chemical debridement agent for empyema, therapeutic options if chemical debridement fails, therapy for parenchymal abscess or necrotizing pneumonia and duration of antibiotic therapy after an intervention. The evidence was graded for each topic to provide grade of recommendation where appropriate.

Effects of extracellular DNA on plasminogen activation and fibrinolysis

The increased levels of extracellular DNA found in a number of disorders involving dysregulation of the fibrinolytic system may affect interactions between fibrinolytic enzymes and inhibitors. Double-stranded (ds) DNA and oligonucleotides bind tissue-(tPA) and urokinase (uPA)-type plasminogen activators, plasmin, and plasminogen with submicromolar affinity. The binding of enzymes to DNA was detected by EMSA, steady-state, and stopped-flow fluorimetry. The interaction of dsDNA/oligonucleotides with tPA and uPA includes a fast bimolecular step, followed by two monomolecular steps, likely indicating slow conformational changes in the enzyme. DNA (0.1-5.0 μg/ml), but not RNA, potentiates the activation of Glu- and Lys-plasminogen by tPA and uPA by 480- and 70-fold and 10.7- and 17-fold, respectively, via a template mechanism similar to that known for fibrin. However, unlike fibrin, dsDNA/oligonucleotides moderately affect the reaction between plasmin and α(2)-antiplasmin and accelerate the inactivation of tPA and two chain uPA by plasminogen activator inhibitor-1 (PAI-1), which is potentiated by vitronectin. dsDNA (0.1-1.0 μg/ml) does not affect the rate of fibrinolysis by plasmin but increases by 4-5-fold the rate of fibrinolysis by Glu-plasminogen/plasminogen activator. The presence of α(2)-antiplasmin abolishes the potentiation of fibrinolysis by dsDNA. At higher concentrations (1.0-20 μg/ml), dsDNA competes for plasmin with fibrin and decreases the rate of fibrinolysis. dsDNA/oligonucleotides incorporated into a fibrin film also inhibit fibrinolysis. Thus, extracellular DNA at physiological concentrations may potentiate fibrinolysis by stimulating fibrin-independent plasminogen activation. Conversely, DNA could inhibit fibrinolysis by increasing the susceptibility of fibrinolytic enzymes to serpins.

Characterization of a new mouse model of empyema and the mechanisms of pleural invasion by Streptococcus pneumoniae

Although empyema affects more than 65,000 people each year in the United States and in the United Kingdom, there are limited data on the pathogenesis of pleural infection. We investigated the pathogenesis of empyema using animal and cell culture models of Streptococcus pneumoniae infection. The pathological processes during the development of empyema associated with murine pneumonia due to S. pneumoniae (strain D39) were investigated. Lungs were examined using histology, and pleural fluid and blood bacterial colony-forming units, cytokine levels, and cellular infiltrate were determined over time. Bacterial migration across mesothelial monolayers was investigated using cell culture techniques, flow cytometry, and confocal microscopy. After intranasal inoculation with 10(7) S. pneumoniae D39 strain, mice developed pneumonia associated with rapid bacterial invasion of the pleural space; raised intrapleural IL-8, VEGF, MCP-1, and TNF-α levels; and caused significant intrapleural neutrophilia followed by the development of fibrinous pleural adhesions. Bacterial clearance from the pleural space was poor, and in vitro assays demonstrated that S. pneumoniae crossed mesothelial layers by translocation through cells rather than by a paracellular route. This study describes key events during the development of S. pneumoniae empyema using a novel murine model of pneumonia-associated empyema that closely mimics human disease. The model allows for future assessment of molecular mechanisms involved in the development of empyema and evaluation of potential new therapies. The data suggest that transmigration of bacteria through mesothelial cells could be important in empyema development. Furthermore, upon entry the pleural cavity offers a protected compartment for the bacteria.

Intrapleural use of tissue plasminogen activator and DNase in pleural infection

BACKGROUND

More than 30% of patients with pleural infection either die or require surgery. Drainage of infected fluid is key to successful treatment, but intrapleural fibrinolytic therapy did not improve outcomes in an earlier, large, randomized trial.

METHODS

We conducted a blinded, 2-by-2 factorial trial in which 210 patients with pleural infection were randomly assigned to receive one of four study treatments for 3 days: double placebo, intrapleural tissue plasminogen activator (t-PA) and DNase, t-PA and placebo, or DNase and placebo. The primary outcome was the change in pleural opacity, measured as the percentage of the hemithorax occupied by effusion, on chest radiography on day 7 as compared with day 1. Secondary outcomes included referral for surgery, duration of hospital stay, and adverse events.

RESULTS

The mean (±SD) change in pleural opacity was greater in the t-PA-DNase group than in the placebo group (-29.5±23.3% vs. -17.2±19.6%; difference, -7.9%; 95% confidence interval [CI], -13.4 to -2.4; P=0.005); the change observed with t-PA alone and with DNase alone (-17.2±24.3 and -14.7±16.4%, respectively) was not significantly different from that observed with placebo. The frequency of surgical referral at 3 months was lower in the t-PA-DNase group than in the placebo group (2 of 48 patients [4%] vs. 8 of 51 patients [16%]; odds ratio for surgical referral, 0.17; 95% CI, 0.03 to 0.87; P=0.03) but was greater in the DNase group (18 of 46 patients [39%]) than in the placebo group (odds ratio, 3.56; 95% CI, 1.30 to 9.75; P=0.01). Combined t-PA-DNase therapy was associated with a reduction in the hospital stay, as compared with placebo (difference, -6.7 days; 95% CI, -12.0 to -1.9; P=0.006); the hospital stay with either agent alone was not significantly different from that with placebo. The frequency of adverse events did not differ significantly among the groups.

CONCLUSIONS

Intrapleural t-PA-DNase therapy improved fluid drainage in patients with pleural infection and reduced the frequency of surgical referral and the duration of the hospital stay. Treatment with DNase alone or t-PA alone was ineffective. (Funded by an unrestricted educational grant to the University of Oxford from Roche UK and by others; Current Controlled Trials number, ISRCTN57454527.).

Intrapleural therapy in management of complicated parapneumonic effusions and empyema

Empyema thoracis causes high mortality, and its incidence is increasing in both children and adults. Parapneumonic effusions (PPEs) develop in about one-half of patients hospitalized with pneumonia, and their presence increases mortality by about four-fold. PPEs can be divided into simple PPEs, complicated PPEs, and frank empyema. Two guideline statements on the management of PPEs in adults have been published by the British Thoracic Society (BTS) and the American College of Chest Physicians; a third guideline statement published by the BTS focused on management of PPEs in children. The two adult guideline statements recommend drainage of the pleural space in complicated PPEs and frank empyema. They also recommend the use of intrapleural fibrinolysis in those who do not show improvement. The pediatric guideline statement recommends adding intrapleural fibrinolysis to those treated by tube thoracostomy if they have loculated pleural space or thick pus. Published guideline statements on the management of complicated PPEs and empyema in adults and children recommend the use of intrapleural fibrinolysis in those who do not show improvement after pleural space drainage. However, published clinical trial reports on the use of intrapleural fibrinolysis for the treatment of pleural space sepsis suffer from major design and methodologic limitations. Nevertheless, published reports have shown that the use of intrapleural fibrinolysis does not reduce mortality in adults with parapneumonic effusions and empyema. However, intrapleural fibrinolysis enhances drainage of infected pleural fluid and may be used in patients with large collections of infected pleural fluid causing breathlessness or respiratory failure, but a proportion of these patients will ultimately need surgery for definite cure. Intrapleural streptokinase and urokinase seem to be equally efficacious in enhancing infected pleural fluid drainage in adults. In most of the published studies in adults, the use of intrapleural fibrinolysis was not associated with serious side effects. There is emerging evidence that the combination of intrapleural tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) is significantly superior to tPA or DNase alone or placebo in improving pleural fluid drainage in patients with pleural space infection. In children, intrapleural fibrinolysis has not been shown to reduce mortality, but has been shown to enhance drainage of the pleural space and was safe. In addition, two prospective, randomized trials have shown that intrapleural fibrinolysis is as effective as video-assisted thoracoscopic surgery for the treatment of childhood empyema and is a more cost-effective treatment and therefore should be the primary treatment of choice.

Update on pleural diseases--2007

BACKGROUND

New information is available on pleural diseases. The authors selected articles to make recommendations on diagnostic and treatment aspects of pleural diseases.

MATERIALS AND METHODS

Eleven articles published in the English language between 2004 and 2007 were chosen. The basis of selection of the articles was the impact on daily practice, change in prior thinking of a disease process or specific treatment modality, as well as proper design and execution of the study. 5-Amino-laevulinic acid with fluorescent light combined with white light may allow further diagnostic yield in undiagnosed pleural disease. FDG-PET may allow prognostication of patients with pleural tumors. Utilizing ultrasound by trained Emergency Department physicians is a rapid and effective technique to evaluate non-traumatic pleural effusions in symptomatic patients. Serum osteopontin levels may distinguish patients exposed to asbestos with benign disease from those with pleural mesothelioma. Administration of streptokinase in patients with empyema does not need for surgical drainage, length of hospital stay, or mortality as compared to conventional treatment with chest tube drainage and intravenous antibiotics. Silver nitrate may be an alternative agent to talc for producing pleurodesis. Routine use of graded talc (50% particles greater than 25 microns) is recommended to reduce the morbidity associated with talc pleurodesis. Study design does not permit us to conclude that aspiration of spontaneous pneumothorax is as effective as chest tube drainage. Pleural catheter may prove to be an important palliative modality in treating debilitated patients or patients with trapped lung who show symptomatic improvement with drainage; however, at the present time, these catheters cannot be considered a first line treatment option for patients with malignant pleural effusion. One of the studies reviewed showed no significant difference in tract metastasis in patients with malignant mesothelioma undergoing an invasive pleural procedure with or without irradiation to the procedure site. However, the design of the trial does not allow us to make this conclusion at the present time.

Empyema thoracis

Epmyema thoracis is associated with high mortality ranging between 6% to 24%. The incidence of empyema is increasing in both children and adults; the cause of this surge is unknown. Most cases of empyema complicate community- or hospital-acquired pneumonia but a proportion results from iatrogenic causes or develops without pneumonia. Parapneumonic effusions (PPE) develop in about one half of the patients hospitalized with pneumonia and their presence cause a four-fold increase in mortality. Three stages in the natural course of empyema have long been described: the exudative, fibrinopurulent, and organizing phases. Clinically, PPE are classified as simple PPE, complicated PPE, and frank empyema. Simple PPE are transudates with a pH > 7.20 whereas complicated PPE are exudates with glucose level <2.2 mmol/l and pH < 7.20. Two guidelines statements on the management of PPE in adults have been published by the American College of Chest Physicians (ACCP) and the British Thoracic Society (BTS). Although they differ in their approach on how to manage PPE, they agree on drainage of the pleural space in complicated PPE and frank empyema. They also recommend the use of intrapleural fibrinolysis and surgical intervention in those who do not show improvement, but the level of evidence for the use of intrapleural fibrinolysis is not high highlighting the need for more research in this area. A recently published large randomized trial has shown no survival advantage with the use of intrapleural streptokinase in patients with pleural infection. However, streptokinase enhances drainage of infected pleural fluid and may still be used in patients with large collection of infected pleural fluid causing breathlessness or ventilatory failure. There is emerging evidence that the combination of intrapleural tPA/DNase is significantly superior to tPA or DNase alone, or placebo in improving pleural fluid drainage in patients with pleural space infection. A guideline statement on the management of PPE in children has been published by the BTS. It recommends the use of antibiotics in all patients with PPE in addition to either video-assisted thoracoscopic surgery (VATS) or tube thoracostomy and intrapleural fibrinolysis. Prospective randomized trials have shown that intrapleural fibrinolysis is as effective as VATS for the treatment of childhood empyema and is a more economic treatment and therefore, should be the primary treatment of choice.