Pleural effusion — the Light's criteria and the management

The Light's criteria (the exudate if ANY) — effusion-to-serum protein ratio above 0.5, effusion-to-serum LDH ratio above 0.6, effusion LDH above two-thirds of the upper limit of normal serum LDH.^[1]

The management — the cause-based management:

• The transudate — treat the cause; thoracentesis not always needed if the clinical heart-failure picture.
• The large symptomatic — therapeutic aspiration or drain.
• The parapneumonic or the empyema — chest drain plus IV antibiotics; surgical referral for the loculated or refractory, intrapleural tPA plus DNase for the loculated.
• The malignant recurrent — indwelling pleural catheter or pleurodesis.
• The haemothorax — large-bore chest drain, surgical for the massive.

^[1]The empyema criteria for the drainage: pus, a pH below 7.2, a glucose below 3.3 mmol per litre, a positive culture or a high LDH.

The principles: Light's criteria classify exudates from transudates^[1]; treat-the-cause for the transudate; drain for empyema; aspiration for symptomatic; catheter or pleurodesis for recurrent malignant.