Respirology & Internal Medicine & Family Medicine
Pleuritis and pleurisy (pleural effusion)
The pleura is a bilaminar serous membrane surrounding each lung, composed of a visceral sheet (adhering to the pulmonary surface) and a parietal sheet (lining the inner surface of the rib cage, mediastinum and diaphragm), between which there is normally a virtual space containing a 5 to 15 mL liquid film facilitating the sliding of the two sheets during breathing. Pleuritis refers to inflammation of the pleura - most often of the parietal layer, which is richly innervated (unlike the visceral layer, which is not sensitive to pain) - producing the characteristic pleuritic chest pain: sharp, lateralized, aggravated by deep inspiration, coughing and certain movements, and relieved by immobility and compression of the thorax on the affected side. Pleurisy (or pleural effusion) refers to the abnormal accumulation of fluid in the pleural space, resulting either from increased fluid production (pleural inflammation, increased capillary pressure, hypoalbuminemia) or reduced fluid reabsorption (lymphatic obstruction). Pleural effusion is one of the most common respiratory conditions in medical practice - affecting around 1.5 million people a year in the USA - with an extremely diverse etiology ranging from heart failure (the most common outpatient cause) to infections (para-pneumonic effusion + empyema) to cancer (mesothelioma + pleural metastases), as well as pulmonary embolism, lupus, rheumatoid arthritis and many other systemic diseases. The fundamental distinction between transudate (protein-poor fluid resulting from an imbalance in hydrostatic or oncotic pressures) and exudate (protein-rich fluid resulting from inflammation or alteration of pleural capillaries or lymphatics) - established by Light's biochemical criteria on pleural fluid - is the essential first step in the investigation of a pleural effusion, as it points towards very different etiological groups.
Dry pleuritis (without effusion) vs pleurisy (with effusion)
- Pleuritis sicca (dry pleurisy - fibrinous pleuritis) : pleural inflammation without significant fluid accumulation → fibrinous deposits on pleural sheets → pleural rubbing on auscultation (rubbed leather sound + synchronous with breathing + heard on inspiration AND expiration - unlike pericardial rubbing related to heartbeat) + intense pleuritic chest pain + without dullness on percussion + without diminished vesicular murmur + causes : adjacent pneumonia (reactional pleuritis) + pulmonary embolism + viral pleuritis (Coxsackie - epidemic pleurodynia or Bornholm disease) + connectivites (SLE + RA) + uraemia
- Pleurisy (pleural effusion) : accumulation of fluid in the pleural space → lung backflow + dyspnoea if large volume (> 300-500 mL) + frank dullness on percussion (dullness) + obliteration of the vesicular murmur + abolished transmitted vocal vibrations + diminished tactile fremitus + absence of pleural friction (fluid separates the leaflets) + radiography: sloping homogeneous opacity with Damoiseau line (oblique + from bottom outwards to top inwards) if moderate to abundant effusion → meniscus sign
Light criteria - transudate vs. exudate
| Light criterion | Exudate (≥ 1 criterion) | Transudat (0 criteria) |
|---|---|---|
| Pleural protein/serum protein ratio | > 0,5 | ≤ 0,5 |
| Pleural LDH / serum LDH ratio | > 0,6 | ≤ 0,6 |
| Absolute pleural LDH | > 2/3 of normal upper limit of serum LDH | ≤ 2/3 of the LSN of serum LDH |
| Sensitivity / Specificity of Light criteria | Sensitivity 98 % for exudates + specificity 72 % + false positives: patients on diuretics (over-diureted heart failure → slightly elevated LDH → may be classified exudate whereas it is a transudate) → use serum albumin-pleural fluid gradient (> 12 g/L = transudate despite Light criteria) to correct | |
Aetiologies according to pleural fluid type
| Type | Main etiologies | Fluid characteristics and additional tests |
|---|---|---|
| Transudat | Congestive heart failure (most frequent cause - 35 % of all pleural effusions) + nephrotic syndrome + hepatic cirrhosis (hepatic hydrothorax - often right) + severe hypoalbuminemia + atelectasis + superior vena cava syndrome | Clear pale yellow fluid + protein < 30 g/L + low LDH + normal glucose + normal pH + no significant inflammatory cells + etiological treatment (diuretics if heart failure) without the need for systematic drainage |
| Exudate - infectious (parapneumonic + empyema) | Simple parapneumonic effusion: sterile pleural reaction adjacent to pneumonia → uncomplicated → resolution with antibiotics + Complicated parapneumonic effusion: bacterial infection of the effusion → pH < 7.20 + glucose 3× LSN + mandatory drainage + Empyema: frank pus in the pleural space → mandatory drainage + prolonged IV antibiotic therapy | Cloudy to purulent fluid + leukocytosis > 10,000/mm³ (PNN predominant) + pH < 7.20 + low glucose + very high LDH + bacteriological culture → chest drain drainage if pH < 7.20 + or glucose < 2.2 + or positive culture + or pus + intra-pleural fibrinolysis if septations (tPA + DNase) |
| Exudate - neoplastic | Pleural metastases (lung cancer +++ + breast cancer + lymphomas + ovarian cancer) + malignant pleural mesothelioma (asbestos) + rare primary pleural tumors | Serohemorrhagic or hemorrhagic fluid + positive pleural cytology in 60-70 % (malignant cells) + pleural needle biopsy or thoracoscopy if cytology negative + treatment: pleural talcage (chemical pleurodesis) or indwelling tunneled pleural catheter for recurrent pleurisy + systemic chemotherapy. |
| Exudate - pulmonary embolism | Present in 40 % of pulmonary embolisms + often small to moderate + serofibrinous or serohemorrhagic + pleuritic pain + possible hemoptysis + context of PE (tachycardia + dyspnea + risk factors) | Elevated D-dimer + thoracic CT angio = reference examination + anticoagulant treatment + effusion resolves spontaneously with anticoagulant treatment in most cases without the need for drainage. |
| Exudate - connective tissue and systemic diseases | SLE (systemic lupus erythematosus) → bilateral pleurisy often + ANA + positive anti-DNA + RA (rheumatoid arthritis) → very low glucose (characteristic) + very high LDH + medications (methotrexate + hydralazine + procainamide) + sarcoidosis + pleural tuberculosis | Tuberculosis: ADA (adenosine deaminase) > 40 IU/L + predominant lymphocytes + Koch culture + mycobacteria PCR + pleural biopsy (caseous granulomas) → 6-month anti-tuberculosis treatment + PR: glucose < 1.6 mmol/L + very high LDH |
| Hemothorax | Thoracic trauma + ruptured aortic aneurysm + spontaneous hemothorax (TVBP + anticoagulants + coagulopathy) + pleural fluid hematocrit / blood hematocrit > 50 % = true hemothorax → surgical drainage | Frankly hemorrhagic fluid + fluid/blood hematocrit > 50 % = hemothorax + mandatory chest drain (risk of fibrothorax if not evacuated) + surgery if active bleeding > 200 mL/h |
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Pleural adenosine deaminase (ADA) is a very useful marker for the diagnosis of pleural tuberculosis in countries with intermediate or high prevalence - ADA > 40 IU/L in lymphocytic exudative pleural fluid has a sensitivity of 93 % and a specificity of 90 % for pleural tuberculosis. In Quebec, the prevalence of TB is low but not zero (native populations + immigrants from endemic countries + homeless) - ADA should be routinely assayed in any unexplained lymphocytic exudate in a patient at risk.
Treatment
- Transudate - etiological treatment : diuretics if heart failure (furosemide + spironolactone) + IV albumin if severe nephrotic syndrome + sodium restriction + evacuating thoracocentesis is indicated only if dyspnea is severe (symptomatic drainage) → puncture not to exceed 1,500 mL in one go (risk of re-expansion pulmonary edema if drainage too rapid)
- Complicated parapneumonic exudate + empyema: chest drain (chest tube) + appropriate IV antibiotic therapy (amoxicillin-clavulanate + metronidazole + or piperacillin-tazobactam) × 2 to 4 weeks + intrapleural fibrinolysis if multiple septations (alteplase 10 mg + DNase 5 mg intrapleural 2×/day × 3 days) → improves drainage and reduces the need for surgery + surgery (VATS - video-assisted thoracic surgery) if medical drainage insufficient or empyema organized
- Recurrent neoplastic pleurisy: chemical pleurodesis (talcation) → instillation of talc (3-5 g in suspension) into the pleural space → aseptic inflammation → pleural symphysis → obliteration of the pleural space → success rate 70-90 % + or tunneled pleural catheter (Pleurx® - ambulatory long-term drain) → evacuation at home several times a week → alternative if pleurodesis impossible or lung not expandable (trapped lung)
- Inflammatory pleuritis (viral + lupus + pericarditis): NSAIDs (ibuprofen 600 mg × 3/day or indomethacin 50 mg × 3/day × 2 to 4 weeks) + colchicine 0.5 mg × 2/day × 3 months (reduces recurrences) + corticosteroids if SLE or NSAID resistance
Situations requiring urgent medical attention
Consult the emergency department or call 911 if pleuritic chest pain is accompanied by severe dyspnea at rest + oxygen saturation below 92 % + or cyanosis - a massive compressive or bilateral pleural effusion can compromise ventilation and requires urgent thoracocentesis. Consult rapidly (within 24 hours) if a known pleural effusion is accompanied by fever + chills + worsening dyspnea - these signs suggest an empyema requiring urgent drainage to avoid progression to irreversible fibrothorax.
For the evaluation of pleuritic chest pain or pleural effusion discovered on X-ray, diagnostic and therapeutic pleural puncture, and referral to pulmonology or thoracic surgery, Clinique Omicron offers medical consultations at its points of service in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's specialized physicians and nurse practitioners (NPs) assess pleuritic chest pain and pleural effusions discovered on X-ray or CT scan, prescribe full pleural fluid analysis (Light criteria + ADA + cytology + cultures), treat viral and inflammatory pleuritis with NSAIDs and colchicine, and refer to pulmonology or thoracic surgery for effusions requiring drainage, pleural biopsy or pleurodesis. Consultations are available at several points of service in Quebec, and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The contents of this page are provided for information purposes only and do not replace the advice of a physician or pulmonologist. Any unexplained pleural effusion should be punctured for fluid analysis - the only exception is a bilateral transudate in an obvious context of heart failure where the cause is certain and medical treatment alone is appropriate.
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