Early Video-assisted Thoracoscopic Surgery or Intrapleural Enzyme Therapy in Pleural Infection: A Feasibility Randomized Controlled Trial. The Third Multicenter Intrapleural Sepsis Trial-MIST-3.

Rationale: Assessing the early use of video-assisted thoracoscopic surgery (VATS) or intrapleural enzyme therapy (IET) in pleural infection requires a phase III randomized controlled trial (RCT). Objectives: To establish the feasibility of randomization in a surgery-versus-nonsurgery trial as well as the key outcome measures that are important to identify relevant patient-centered outcomes in a subsequent RCT. Methods: The MIST-3 (third Multicenter Intrapleural Sepsis Trial) was a prospective multicenter RCT involving eight U.K. centers combining on-site and off-site surgical services. The study enrolled all patients with a confirmed diagnosis of pleural infection and randomized those with ongoing pleural sepsis after an initial period (as long as 24 h) of standard care to one of three treatment arms: continued standard care, early IET, or a surgical opinion with regard to early VATS. The primary outcome was feasibility based on >50% of eligible patients being successfully randomized, >95% of randomized participants retained to discharge, and >80% of randomized participants retained to 2 weeks of follow-up. The analysis was performed per intention to treat. Measurements and Main Results: Of 97 eligible patients, 60 (62%) were randomized, with 100% retained to discharge and 84% retained to 2 weeks. Baseline demographic, clinical, and microbiological characteristics of the patients were similar across groups. Median times to intervention were 1.0 and 3.5 days in the IET and surgery groups, respectively (P = 0.02). Despite the difference in time to intervention, length of stay (from randomization to discharge) was similar in both intervention arms (7 d) compared with standard care (10 d) (P = 0.70). There were no significant intergroup differences in 2-month readmission and further intervention, although the study was not adequately powered for this outcome. Compared with VATS, IET demonstrated a larger improvement in mean EuroQol five-dimension health utility index (five-level edition) from baseline (0.35) to 2 months (0.83) (P = 0.023). One serious adverse event was reported in the VATS arm. Conclusions: This is the first multicenter RCT of early IET versus early surgery in pleural infection. Despite the logistical challenges posed by the coronavirus disease (COVID-19) pandemic, the study met its predefined feasibility criteria, demonstrated potential shortening of length of stay with early surgery, and signals toward earlier resolution of pain and a shortened recovery with IET. The study findings suggest that a definitive phase III study is feasible but highlights important considerations and significant modifications to the design that would be required to adequately assess optimal initial management in pleural infection.The trial was registered on ISRCTN (number 18,192,121).

The Biological Role of Pleural Fluid PAI-1 and Sonographic Septations in Pleural Infection: Analysis of a Prospectively Collected Clinical Outcome Study.

Rationale: Sonographic septations are assumed to be important clinical predictors of outcome in pleural infection, but the evidence for this is sparse. The inflammatory and fibrinolysis-associated intrapleural pathway(s) leading to septation formation have not been studied in a large cohort of pleural fluid (PF) samples with confirmed pleural infection matched with ultrasound and clinical outcome data. Objectives: To assess the presence and severity of septations against baseline PF PAI-1 (Plasminogen-Activator Inhibitor-1) and other inflammatory and fibrinolysis-associated proteins as well as to correlate these with clinically important outcomes. Methods: We analyzed 214 pleural fluid samples from PILOT (Pleural Infection Longitudinal Outcome Study), a prospective observational pleural infection study, for inflammatory and fibrinolysis-associated proteins using the Luminex platform. Multivariate regression analyses were used to assess the association of pleural biological markers with septation presence and severity (on ultrasound) and clinical outcomes. Measurements and Main Results: PF PAI-1 was the only protein independently associated with septation presence (P < 0.001) and septation severity (P = 0.003). PF PAI-1 concentrations were associated with increased length of stay (P = 0.048) and increased 12-month mortality (P = 0.003). Sonographic septations alone had no relation to clinical outcomes. Conclusions: In a large and well-characterized cohort, this is the first study to associate pleural biological parameters with a validated sonographic septation outcome in pleural infection. PF PAI-1 is the first biomarker to demonstrate an independent association with mortality. Although PF PAI-1 plays an integral role in driving septation formation, septations themselves are not associated with clinically important outcomes. These novel findings now require prospective validation.

Parapneumonic Effusion and Empyema.

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