Episode 52: Pleural effusions in the ICU with Emily Fridenmaker

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Discussing pleural effusions in the critically ill, including how and when to drain them, methods of drainage, interpreting laboratory studies, and managing complications, with Dr. Emily Fridenmaker (@emily_fri), pulmonologist and intensivist at Charleston Area Medical Center in West Virginia.

Continuing education for this episode

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Takeaway lessons

1. IMAGING
   1. CXR – underestimate
      1. Lateral – 75mL (5-15 mL is normal)
      2. AP – 175mL
         iii. 500mL for 100% sensitivity
   2. CT – overestimate
      1. Contrast can help delineate pleural surface
   3. Ultrasound – goldilocks
      1. Can see 5-50mL fluid
      2. > 1cm generally safe to sample
2. INITIAL WORKUP
   1. Thora – no absolute contraindications
      1. Should tap an effusion if you don’t know what’s causing it
         1. Diagnostic or therapeutic
         2. Does little to change hypoxia—can impact dyspnea though due to diaphragm length-tension relationships
         3. Complication rate = ??
      2. Differential
         1. Nucleated cells – greater than 50k usually paraPNA/empyema
         2. Lymphocytosis – TB, lymphoma, sarcoid, RA, yellow nail syndrome, chylothorax, cancer
         3. Eosinophilia – >10%; pneumo, hemo, infarction, asbestos, parasites, fungus, drugs, catamenial, malignancy, TB, CEP
         4. Mesothelial – normal in pleural fluid
      3. Light’s Criteria—protein and LDH (serum and pleural), albumin, cholesterol
         1. Aim was to have a high sensitivity, since shouldn’t miss an exudate
         2. The criteria—any one of them gives you an exudate
         3. Pleural protein/serum protein > 0.5—can be elevated by diuresis
         4. Serum albumin/pleural > 1.2
         5. Pleural LDH/serum LDH > 0.6
         6. Pleural fluid LDH > 2/3 ULN
         7. Cholesterol >45 can also help to indicate an exudate
         8. Glucose
            1. Low: complicated effusion/empyema, malignant, TB, lupus, rheumatoid pleurisy, esophageal rupture
         9. pH – normal is 7.6 due to bicarb gradient
            1. <7.3 – same conditions as low glucose ii. If low, higher yield on cytology for malignancy, less response to chemical pleurodesis
            2. Parapneumonic <7.15 – needs pleural space drainage
            3. Lidocaine will falsely drop the pH
         10. Amylase – pancreatic or esophageal etiologies
         11. ADA – TB; usually >40
         12. Cytology – malignant; sensitivity is 60%, 85% with second sample
3. TRANSUDATIVE VS EXUDATIVE
   1. Transudative
      1. Atelectasis, CHF, hepatic hydrothorax, low albumin, iatrogenic, nephrotic syndrome, PD, urinothorax
   2. Exudative
      1. Infectious, drug induced, trauma, malignancy (stage 4), CTD (RA, lupus, EGPA, GPA), hypothyroid/ovarian hyperstimulation syndrome, chylothorax, pancreatitis, sarcoid, post cardiac injury syndrome, radiation, PE, BAPE
4. PARAPNEUMONIC CLASSIFICATIONS
   1. Simple – resolve with abx (1-2 weeks), don’t require drainage or special abx considerations
      1. Free flowing, sterile
      2. Exudative – neutrophilic predominance, normal pH and glucose level
   2. Complicated – evidence of infection of the space
      1. Exudative, high white count, pH <7.2, glucose <40 (or 60?), LDH >1000, + gram stain
      2. Large, loculated, thickened pleura, air bubbles in effusion
   3. Empyema (subset of complicated)
      1. Pus in the pleural space
      2. Longer clinical course, possibly subacute
         D. Complex
         i. Internal loculations
5. MANAGEMENT OF COMPLICATED PARAPNEUMONIC EFFUSIONS
   1. Drainage usually required for source control—poorer prognosis without it
      1. Particularly if pH <7.15, low glucose, or LDH>1000
   2. Empyema
      1. Loculated
      2. + gram stain or culture
      3. Thickened parietal pleura
   3. Approach to drainage: Tube thoracostomy
      1. Small bore (10-14) similar efficacy to large
      2. MIST 1 – no difference in mortality or need for VATS between large, medium, or small bore tubes
         1. Retrospective—small bore noninferior
         2. Flush q6 to keep patent
      3. Suction is typical but not necessary
      4. Reimage after placement, when drainage slows
      5. Remove when less than 50-100mL for a couple of days, imaging is improved, clinically improving
      6. Reimage in about 2 weeks
   4. Failure of drainage – Repeat imaging 24hrs after completion of chosen intervention
      1. Lytics, multiple tubes preferred before VATS
         1. Probably best for early, multiloculated effusions
         2. DNAse breaks down DNA, reducing viscosity. tPA is fibrinolytics, busts up loculations
         3. MIST 2 – less need for VATS (30-80%) with tpa (10)/dornase (5) BID x 3 days
         4. New data shows simultaneous admin may be as efficacious
      2. VATS if significant organization, trapped lung (can be elective)
         1. No mortality benefit shown
         2. Pleural hemorrhage – 1-7%, indication for VATS
         3. Indicated when abx, tube, lytics have failed
         4. Also indicated up front if there is significant organization, fibrothorax, trap
         5. May need to be converted to open thoracotomy
         6. Maybe reduced LOS? MIST 3 looking at early VATS vs early lytics
      3. Window thoracostomy/eloesser flap
6. ANTIMICROBIAL THERAPY
   1. i. CAP – Rocephin + flagyl or unasyn
   2. Lots of clinda resistance now
   3. Atypicals rarely cause complicated effusions
   4. MDRO risk factors – MRSA, pseudomonas, and anaerobes
   5. Optimal duration unknown
      1. usually 2-3 weeks for complicated
      2. 4-6 weeks for empyema
      3. Can switch to PO when clinically improving
      4. Radiographic resolution can take weeks to months; this is not the goal
7. COMPLICATIONS OF PLEURAL SPACE INFECTIONS
   1. Fibrothorax, pleural fibrosis
   2. Restriction, unexpandable lung
   3. Decortication not considered unless restriction/limitation present 6 months later