Pleural Effusion in CVICU: Diagnosis and Management

Definition and Pathophysiology

Pleural effusion is defined as an abnormal accumulation of fluid in the pleural space exceeding the normal amount of 0.1 to 0.2 mL/kg body weight 2
Common mechanisms include increased pulmonary capillary pressure, increased pleural membrane permeability, decreased oncotic pressure, or lymphatic obstruction 2
Pleural effusions are categorized as transudative or exudative 2

The prevalence of pleural effusions following cardiac surgery is high, with 42-89% of patients showing radiographic evidence of pleural effusion in the early postoperative period 3
Approximately 6.6% of patients require intervention following coronary artery bypass grafting (CABG) or valve surgery 3

Early postoperative effusions typically have higher erythrocyte, LDH, and eosinophil counts, related to surgical trauma and bleeding 3
Late effusions are predominantly lymphocytic with lower LDH levels, suggesting an immune-mediated response 3
Surgical trauma is a common cause of pleural effusions in CVICU 3
Chylothorax can occur due to operative damage to the thoracic duct 3
Postoperative infection is a potential cause of pleural effusions in CVICU 3

Chest pain may be present, typically dull and aching rather than pleuritic 4
Tachypnea is a common symptom of pleural effusions in CVICU 3
Many patients may be asymptomatic, especially with small effusions 4
Clinically significant effusions are defined by increased respiratory support requirements, shortness of breath, cough, tachypnea, and pain 3

Chest radiographs can typically detect >75 mL on lateral view and >175 mL on frontal view 2
Thoracic ultrasound can detect >20 mL of pleural fluid and is recommended for guiding thoracentesis 2, 5
Chest CT can detect >10 mL of pleural fluid and is considered the reference standard for imaging 2
CT is helpful to evaluate underlying parenchymal disease, mediastinal lymph node involvement, and pleural lesions 6

Protocolized intervention for symptomatic effusions with estimated volume >480 mL can reduce length of stay by 3±1.5 days compared to diuresis alone 3
Ultrasound-guided thoracentesis is well-tolerated and preferred over surgical tube thoracostomy as initial intervention 3
Caution should be taken if removing more than 1.5 L on a single occasion to avoid re-expansion pulmonary edema 7, 5
Purulent or turbid fluid indicates pleural infection requiring prompt chest tube drainage 5
Positive Gram stain or culture requires chest tube drainage and appropriate antibiotics 5
pH < 7.2 indicates need for chest tube drainage 5
Consider chemical pleurodesis for recurrent malignant pleural effusions 5
Palliative drainage can provide symptomatic relief for malignant pleural effusions 5

Monitor for pleural effusions in all post-cardiac surgery patients, as they are extremely common 3
Consider dedicated follow-up and drainage protocols, which can enhance recovery rates by up to 15% 3
Small effusions can be observed if asymptomatic 5