The purpose of this study is to see if there is any benefit in adding saline irrigation through a chest tube to the standard course of treatment for people diagnosed or suspected of having a pleural space infection.

Pleural space infections portend considerable morbidity and require procedural and sometimes surgical intervention in the context of prolonged hospital stays (median length of stay has been reported as 14-19 days) for definitive management. Key aspects of management include pleural space evacuation and appropriate antimicrobial therapy. The antimicrobial regimen is initiated intravenously and is often transitioned to an oral regimen as guided by clinical improvement, radiographic improvement, and microbiologic studies though conventional bacterial cultures remain negative in as many as 40% of cases of pleural space infection. There is variability in antimicrobial duration though this is typically continued for at least 3 weeks. The MIST 2 trial investigated the role of intrapleural tissue plasminogen activator (t-PA) and dornase (DNase) in the management of pleural space infections, noting that disrupting septations and reducing pleural fluid viscosity were necessary steps to achieve successful drainage in in-vitro studies. MIST 2 demonstrated that a combination of intrapleural t-PA and DNase improved pleural space evacuation on serial chest x-ray and reduced the frequency of surgical referral and hospital length of stay.

Saline irrigation of the pleural space has been proposed to reduce stasis and dilute bacteria, cytokines, and coagulation factors, which induce pleural space organization. The Pleural Irrigation Trial was a pilot study evaluating the role of 250 cc 0.9% sodium chloride irrigation three times daily for 3 days in comparison to standard care, which included maintaining thoracostomy tubes on suction and flushing with 30 cc three times daily. Saline irrigation led to a 32.3% reduction in pleural fluid volume as assessed by computed tomography in comparison to 15.3% in the standard care arm. Fewer patients in the irrigation group were referred for surgery (OR 7.1).

To our knowledge, the efficacy of intrapleural saline irrigation in addition to fibrinolytic therapy has not been studied in comparison to fibrinolytic therapy alone. The Mayo Clinic Interventional Pulmonary practice in Rochester, MN intends to study this in the context of the inpatient pleural service, the team that is routinely consulted for patients with proven or suspected pleural space infections. This team routinely places and manages ultrasound-guided locking-loop thoracostomy tubes and additionally manages patients with thoracostomy tubes placed by intensivists, surgeons, and interventional radiologists when consulted. Our team intends to recruit hospitalized patients that meet the inclusion/exclusion criteria of the study. Those that provide informed consent to participate in the study will be randomized to usual care versus intrapleural saline irrigation + usual care.

Inclusion criteria:

• Purulent pleural fluid versus pleural fluid analysis demonstrating pH <7.2, glucose <60 mg/dL, positive Gram stain, or positive pleural fluid culture versus multiseptated pleural effusion with infection at top of differential diagnosis
• Patients initiating intrapleural lytic therapy under the care of the Interventional Pulmonary consult service at Mayo Clinic in Rochester, MN

Exclusion Criteria:

• Unwillingness to give informed consent
• Patients with known bleeding diathesis
• Platelet count <50,000 per μL
• INR >2.2 (of note, INR can be allowed to drift down or be reversed pharmacologically prior to initiation of intrapleural lytics/saline)
• Current use of systemic anticoagulation or antiplatelet therapy without the ability to hold therapy for the recommended amount of time prior to an invasive procedure (aspirin monotherapy is acceptable)
• Pregnant or nursing females, or females of child-bearing potential who decline a pregnancy test prior to enrollment
• Incarcerated patients
• Presence of ipsilateral bronchopleural fistula
• Current or recent (within past 30 days) presence of tunneled pleural catheter on the same side as the current proven/suspected pleural space infection