Pleural Effusion in the CVICU: Diagnosis, Signs, Symptoms, and Treatment
Pleural effusion is defined as an excessive accumulation of fluid in the pleural space that requires prompt diagnosis and treatment, particularly in the CVICU setting where patients are critically ill and may have multiple contributing factors. 1
Definition and Pathophysiology
- Pleural effusion occurs when there is an imbalance between pleural fluid formation and absorption, leading to fluid accumulation in the pleural space 1
- The incidence of pleural effusions in intensive care units varies from 8% when detected by physical examination to over 60% when routine ultrasonography is used 2
- CVICU patients are particularly susceptible due to large volumes of intravenous fluids, heart failure, hypoalbuminemia, and post-cardiac surgical states 2
Classification
- Transudative effusions: Result from systemic factors altering Starling forces (e.g., heart failure, cirrhosis)
- Exudative effusions: Result from local factors affecting the pleura (e.g., inflammation, malignancy)
- Light's criteria should be used to differentiate between transudates and exudates 3:
- Pleural fluid protein/serum protein ratio > 0.5
- Pleural fluid LDH/serum LDH ratio > 0.6
- Pleural fluid LDH > 2/3 upper limit of normal serum LDH
Signs and Symptoms
- Dyspnea (initially on exertion, progressing to rest)
- Pleuritic chest pain
- Predominantly dry cough
- Decreased breath sounds on affected side
- Dullness to percussion over the effusion
- Decreased tactile fremitus
- Tachypnea and respiratory distress in large effusions 1
- In CVICU patients, symptoms may be masked by sedation or mechanical ventilation 2
Diagnostic Approach
- Ultrasound guidance should be used for all pleural interventions to improve success rates and reduce complications 4
- Chest radiography (posteroanterior and lateral views) should be performed to confirm presence of effusion 3
- Thoracentesis should be performed for new and unexplained pleural effusions 3
- Pleural fluid analysis should include 3:
- Appearance and odor (should always be recorded)
- Cell count and differential
- Protein and LDH (both pleural and serum)
- pH (especially for suspected parapneumonic effusions)
- Glucose
- Cytology
- Gram stain and culture
- CT scanning may help differentiate pleural empyema from lung abscess and identify loculations 3
Common Causes in CVICU
- Heart failure (most common cause in CVICU)
- Post-cardiac surgery
- Parapneumonic effusions/pneumonia
- Pulmonary embolism
- Malignancy
- Extravascular catheter migration
- Atelectasis
- Hypoalbuminemia 2
Treatment Algorithm
1. Transudative Effusions (e.g., heart failure)
- Primary treatment focuses on addressing the underlying medical condition 4
- Optimize cardiac function and diuresis in heart failure patients 4
- Therapeutic thoracentesis for symptomatic relief while treating the underlying condition 4
- Avoid removing more than 1.5L of fluid at once to prevent re-expansion pulmonary edema 4, 5
2. Exudative Effusions
A. Parapneumonic Effusion/Empyema
- All patients should receive appropriate antibiotics with coverage for common respiratory pathogens 3
- Chest tube drainage is indicated if 3:
- Frank pus (empyema)
- Positive Gram stain or culture
- pH < 7.2
- Glucose < 2.2 mmol/L
- LDH > 1000 IU/L
- Small-bore chest tubes (14F or smaller) are recommended initially 4
- Consider intrapleural fibrinolytics for loculated effusions 3
- Surgical intervention if no improvement after 5-7 days of appropriate therapy 3
B. Malignant Pleural Effusion
- Therapeutic thoracentesis to assess symptom relief and lung expandability 3, 4
- For recurrent effusions with expandable lung, options include 3:
- Indwelling pleural catheter (IPC)
- Chemical pleurodesis with talc (either slurry through chest tube or poudrage via thoracoscopy)
- For non-expandable lung or failed pleurodesis, IPC is preferred 3
- IPC-associated infections can usually be treated with antibiotics without removing the catheter 3
Special Considerations in CVICU
- Thoracentesis is safe in mechanically ventilated patients but requires experienced operators 2
- Post-cardiac surgery patients frequently develop pleural effusions that may require drainage if causing respiratory compromise 2
- In patients with coagulopathy (common in CVICU), correct coagulation parameters before invasive procedures 2
- Monitor for pneumothorax after thoracentesis, especially in mechanically ventilated patients 2
- Consider ultrasound-guided thoracentesis to minimize complications 4, 5
Pitfalls to Avoid
- Avoid large volume thoracentesis (>1.5L) in a single procedure to prevent re-expansion pulmonary edema 4, 5
- Do not attempt pleurodesis without confirming complete lung expansion 4
- Avoid intercostal tube drainage without pleurodesis for malignant effusions as it has a high recurrence rate 5
- Do not delay drainage of complicated parapneumonic effusions or empyema 3
- Avoid diagnostic bronchoscopy for undiagnosed effusions unless the patient has hemoptysis or features suggestive of bronchial obstruction 3