Pleural Effusion

Find it on exam - fullness of the intercostal spaces and dullness to percussion on that side, decreased breath sounds, decreased tactile and vocal fremitus, and egophony most pronounced at the superior aspect of the effusion. Symptoms track thoracic excursion, so a patient may be asymptomatic or breathless only on exertion.

Imaging thresholds - an upright PA film needs about 200 mL to obliterate the costophrenic angle (the meniscus sign); a lateral view picks it up at 50 mL. Chest ultrasound is more sensitive than either and is what you use to plan the tap.

Tap unilateral effusions - every unilateral effusion in an adult needs thoracentesis to determine the cause, and draining it improves symptoms and speeds recovery.

Stop at 1500 mL - removing more than 1.5 L in one sitting risks re-expansion pulmonary edema as the collapsed lung snaps open. Pleural manometry helps: stop when pleural pressure falls below -20 cmH2O, or when the patient develops chest pain.

Film after every tap - a chest x-ray is mandatory post-thoracentesis to look for residual fluid and pneumothorax.

The fluid names the disease - send pH, protein, albumin, LDH, glucose, triglycerides, cell count and differential, Gram stain and culture, and cytology. Exudates show elevated protein and LDH with low glucose. LDH over 1000 U/L suggests TB, lymphoma, or empyema. Triglycerides over 110 mg/dL means chylothorax, and milky fluid should make you look. Pleural fluid hematocrit over half the serum value means hemothorax. Amylase means esophageal rupture. Elevated adenosine deaminase points to TB in endemic areas.

Low pH means a tube - pH under 7.2 in a parapneumonic effusion, or organisms on Gram stain or culture, almost always requires chest tube drainage plus antibiotics. Small-bore drains work as well as large-bore for this. Failure to respond goes to thoracoscopic decortication, or intrapleural fibrinolytics and DNase in poor surgical candidates.

Light's criteria aren't perfect - they misclassify about 20% of transudates as exudates, classically the heart failure patient who has been diuresed for weeks. Read them against the clinical picture.

Chase what's underneath - jugular venous distension, an S3, and pedal edema point to heart failure; ascites and stigmata of liver disease to hepatic hydrothorax. The underlying disease is usually what threatens the anesthetic, not the fluid.

When the lung won't come back up - a trapped lung is a fibrinous restrictive pleural peel that prevents visceral and parietal apposition, and it presents as a chronic stable effusion that never resolves with drainage.

Malignant effusions - asymptomatic ones don't need drainage unless infection is suspected. Recurrent ones go to pleurodesis or a tunneled pleural catheter rather than repeat taps.

Own the chest tube pain - chest tubes hurt significantly, and anesthesia gets called for a pain pump or a thoracic epidural. Plan it before the tube goes in, not after.

A pleural effusion is fluid accumulating between the parietal and visceral pleura. Normally only 0.1 to 0.3 mL/kg sits there as lubricant, produced from the vasculature of the parietal pleura and reabsorbed by lymphatics in the dependent diaphragmatic and mediastinal parietal surfaces; an effusion means production has outrun absorption, or drainage has failed, or both.

Raised hydrostatic or fallen oncotic pressure gives a transudate — congestive heart failure, cirrhosis, nephrotic syndrome, hypoalbuminemia. Increased capillary and mesothelial permeability or impaired lymphatic drainage gives an exudate — pneumonia, tuberculosis (TB), malignancy, pancreatitis, lupus, rheumatoid arthritis, chylothorax, hemothorax.

What matters perioperatively is mechanics: fluid restricts thoracic excursion, compresses dependent lung, and creates shunt. A large effusion shifts the mediastinum toward the contralateral side. Roughly 1.5 million patients a year are affected in the United States, so it turns up constantly as a comorbidity.