Synopsis
Distinguish fluid overload from exudative pleural disease, investigate an unexplained effusion safely and recognise infection, malignancy and rapid-drainage hazards that change the pathway.
- Confirm pleural fluid with chest radiography and thoracic ultrasound; ultrasound must guide the site of any pleural aspiration or drain insertion.
- Bilateral, symmetric effusions with a classic heart, renal, liver or hypoalbuminaemic picture can often be treated for the systemic cause first; sample when features are atypical, unilateral/asymmetric, febrile, painful or non-responsive.
- An unexplained unilateral effusion usually needs ultrasound-guided aspiration plus blood tests and contrast CT selected around the malignancy/infection question.
Key red flags
Fever, pleuritic pain, pneumonia, sepsis, loculation or echogenic/septated fluid; frank pus or low pH moves from diagnosis to urgent antibiotics and drainage.
Investigation priorities
Confirm amount/distribution, identify loculation and select a safe aspiration site.
Management branches
Bilateral, relatively symmetric effusions with a convincing systemic cause and no pleural red flags.
- Assess heart, renal, liver and albumin status; obtain ECG, renal/liver tests, albumin and natriuretic peptide/echo as clinically indicated.
- Treat the systemic cause and monitor symptoms, weight, renal function and imaging response.
Key medicines
Lidocaine 1% for pleural procedureInfiltrate skin, tract and parietal pleura incrementally; keep the total lidocaine dose at or below 3 mg/kg without adrenaline (1% solution contains 10 mg/mL) unless a lower product/patient limit applies.
Furosemide for congestive fluid overloadA common starting dose in a diuretic-naive congested adult is 20–40 mg orally or IV; in acute heart failure already taking a loop diuretic, NICE advises an IV dose at least equivalent to the existing daily dose, then titrate to response.