#28 Pleural Disease Part 2: Empyema & Hemothorax
On this episode of Critical Care Time, Nick & Cyrus revisit the pleural space! We had SO much great content we opted to split the episode into two parts. We also figured it would be nice to get an interventionalists take on this and we thus recruited Dr. Mike Sobieszczyk to help navigate this complex topic! Here we discuss things like hepatic hydrothorax, indwelling pleural catheters and all things parapneumonic effusion. Check it out and leave us a review! If you missed our first episode on pleural disease, head on back to episode 10 and get caught up. If you like what you heard here, make sure to come back in 2 weeks for the second part!
Quick Take Home Points:
Differentiate exudate from transudate using Light’s Criteria or PFO3. Remember than these rules can misclassify transudates as exudates.
Empyema can evolve rapidly from free flowing to loculated to thickened/organized. Early detection and intervention can prevent morbidity.
Indwelling pleural catheters (IPCs) can be used to drain recurrent pleural effusions. Pleurodesis can also prevent fluid reaccumulation. These therapies can be combined together.
Show Notes:
Exudate vs transudate: Light’s Criteria & beyond
Lights criteria is a tool utilizing biochemical data from the patient’s blood and pleural fluid to categorize pleural fluid into two broad categories:
Transudate is an accumulation of fluid (often due to a systemic process) where pulmonary hydrostatic pressure is increased or oncotic pressure is decreased (or both.)
Exudate is a more proteinacious fluid caused when the pleural surface or the adjacent lung show increased vascular permeability, typical caused by an inflammatory process.
Three labs are required to differentiate using Light’s Criteria: pleural fluid LDH, pleural fluid protein, and serum to pleural protein ratio.
A fluid is exudative if any of the following criteria are met:
pleural:serum protein ratio > 0.5
pleural:serum LDH ratio > 0.6
pleural LDH > 2/3 of the upper limit of normal for the serum (depends on your specific lab)
Light’s criteria tends to mischaracterize some transudates as exudates (up to 25% of transudates in some studies). This is particularly common with a “diuresed transudate”
Nick’s tip: If the pleural protein to serum protein difference is >3.1 g/dl its most likely a transudate. (e.g. if the pleural fluid has a protein much lower than the serum protein).
The History of Light’s criteria is also an interesting tangent…
The pleural fluid only three test combination (PFO3) uses only pleural fluid labs to characterize an effusion as exudate vs transudate. An effusion is exudative if any of the following criteria are met:
pleural fluid protein >3.0 g/dL
pleural fluid cholesterol >55mg/dL
pleural fluid LDH >0.67 times the upper limit of normal of serum LDH.
The appeal of the PFO3 is that it obviates the need to check additional serum labs. PFO3 has been validated in multiple large trials and shown to have equal diagnostic accuracy as the Lights criteria.
Other labs that are useful and should be routinely checked
Pleural fluid pH
Pleural fluid glucose
Pleural fluid cell count & differential
Pleural fluid smear and culture - ideally when you obtain pleural fluid cultures and if your institution allows for this, you should add samples into culture bottles. This has shown to increase your culture yield by 30%.
An empyema is typically defined by pH < 7.2, gluc <40, LDH >1000, elevated WBC in fluid. Frank pus = empyema.
Empyema is often seen due to PNA, but can occur in any case where bacteria inoculates the pleural space (trauma, post-op, liver/spine abscesses).
Empyema necessitans - empyema that spreads into the chest wall
Empyema evolve through stages:
STAGE 1: Simple parapneumonic - free flowing, sterile, inflammatory. Resolves on its own often once PNA resolves.
Usually uniform dark (hypoechoic) fluid
STAGE 2: Fibrinopurulent stage. Bacteria invade from the disease lung tissue into the effusion. Fibrin deposition and loculations = hallmark on imaging. “Complicated parapneumonic pleural Effusion.
Fluid becomes heterogeneous. Plankton sign & septations may be present on POCUS.
STAGE 3: Chronic organization: thickened pleura, possibly trapped lung, if left untreated.
Fluid is white (hyperechoic) and organied
Indwelling Pleural Catheters (IPCs)
Indwelling pleural catheters (IPCs) were designed for palliative treatment of recurrent malignant pleural effusions. The procedure is typically done in the ambulatory setting and under local anesthetic, and under sterile conditions. The catheter is tunneled under the skin, approximately 5 cm track, before inserting into the pleural space.
The goal is for the patient to be able to go home and give them the autonomy to manage their effusion with minimal healthcare interactions. Often times they can drain the catheter themselves, sometime with help of a family member or visiting nurse. It requires patient education up front and thorough screening, making sure the patient has the support network and adequate resources to accomplish this task (family, clean living environment, etc).
The original and most favorable data for IPC was in benefit of symptoms relief and improvement in quality of life, specifically in patient with mean cancer survival of 6 months.
The disadvantage of IPCs is that it is a nidus for infection. The device can also be a constant reminder for patient that they have cancer, likely end stage. Insurance coverage can be another challenge, often patient are allotted a ceratin amount of drainage kits which may not be enough for their needs. Additionally, travel can be limited as well, there are several companies that make IPC’s, each one has a proprietary drainage device and connection adaptor, and depending on what hospital the patient ends up in, the facility may not carry the same system, so emergent access can become a challenge.
Pleurodesis
Pleurodesis, in the simplest form, is causing of pleural injury in order to cause inflammation, thus initiating fibrosis and adherence between the parietal and visceral pleural. This can resolve several different pleural pathologies such as accumulation of air (pneumothorax) or fluid (effusion).
Pleurodesis can be accomplished many different ways - e.g a surgeon doing it with a scrubbing brush, a pulmonologist doing it with talc or another agent like bleomycin through a chest tube.
Currently the most effective sclerotic agent is medical graded talc. This can be applied through a chest tube or, in case of a malignant pleural effusion, through an IPC as a slurry or via a pleuroscopy as a poudrage.
In malignant pleural effusions, the data comparing the type of talc application, poudrage vs slurry, shows that there is no difference in outcomes.
The appeal of this strategy was demonstrated by the 2018 IPC-PLUS trial.
This was a prospective randomized controlled study comparing IPC with talc slurry vs IPC and placebo. 154 patient were randomized into these two groups. Both had IPC placed and day of procedure were instilled either talc or placebo, then were discharged home from clinic, drained twice per week. The IPC+talc group had higher rates of pleurodesis and 35 days (43% compared to 23% in placebo group).
Although the talc group had higher reports of chest pain and dyspnea, overall quality of life favored the intervention. This is an attractive option for the patient as it takes advantage of the benefits both of these interventions offer.
Managing empyema with small bore chest tubes and intrapleural lytic therapy
Historically, large bore chest tubes were used for empyema and hemothorax. Increasingly small bore tubes are used with signficantly less pain and complications.
The advantage of a smaller 14 fr pig tail is that it tend to be quicker to place, a less painful procedure and less painful for the patient to have. Pigtails are easier to direct into the diaphragmatic gutter, which can result in better drainage of fluid. Additional benefit is that most pigtails come with a stopcock which makes instilling flushes or medications easier.
Intrapleural lytic therapies can be delivered by chest tube and are associated with improved outcomes. The most common therapies delivered vie chest tube are tPA and DNase as demonstrated by the MIST 2 trial. This was a prospective double-blinded randomized trial that looked at 240 patients stratified into 4 treatment groups.
4 arm trial: tPa+placebo (n=52) vs DNase+placebo (n=51) vs tPA+DNase (n=52) vs Double placebo (n=55)
The tPA+DNase group (given at a dose of 10mg and 5mg respectively, twice daily over 3 days) resulted in significant radiographic improvement at 7 days, and a predetermined secondary outcome difference in lower rates of surgical referrals and shorter hospital stays favoring the treatment arm.
Pleural irrigation involves irrigation the pleural space via a chest tube with sterile saline, It’s effectiveness was demonstrated by the PIT trial, which was a smaller prospective study that randomized patients into a saline irrigation arm, 250cc of sterile saline twice daily for 3 days vs standard care, chest tube drainage.
The study showed that saline irrigation group had significantly greater reduction in pleural volume on follow up CT and significantly lower rates of surgical referrals.
There was no difference in length of stay, CRP or white count or complication rates.
Medical thoracoscopy (pleuroscopy) - is a good option and has shown to equivalent to enzymatic therapy with significant shorter hospital stay, an well designed smaller trial in the Blue Journal showed that quite nicely in 2020. Th procedure involves a semi-rigid or rigid pleuroscope, with usually a single port access via a trocar, and a blunt dissection of adhesions (like a adhesiolysis), you can suction pretty effectively with the pleuroscope and then place a chest tube to allow residual to drain,. The caveat is that it has to be done prior to any enzymatic therapy to reduce any risk of bleeding - you don’t want to face a pleural hemorrhage with a single port view, as this procedure is not equipped to deal with significant bleeding. The most feared complication of this is violating the visceral pleural and causing a persistent air leak. It can be done under conscious sedation and we have also done it under regional anesthesia with the patients being completely awake.
Multidisciplinary management
Managing pleural space infections required collaboration between specialties (pulmonary, thoracic surgery, and potentially others such as IR)
Ideally CT surgery should be consulted in the beginning. Reasonable to involve as your considering intrapleural therapy.
Patients that have a high RAPID score (BUN, age, presence of purulent drainage, infection source (CAP vs hospital), serum albumin) should initiate an early multidisciplinary discussion.
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