Indications for Thoracentesis

Objectives Know when to consider a thoracentesis Know how to evaluate if safe to perform thoracentesis Know when to consult specialists Quick review of pathophysiology of effusions Know how to analyze the fluid obtained Know when pleural fluid results suggest a need for a chest tube Summary

Indications for thoracentesis Symptom relief Dyspnea Unstable pulmonary mechanics, gas exchange Diagnostic purposes When the cause of the effusion is unclear

Pre-procedure check list Normal hemostasis Effusions with thickness > 1 cm on lateral decubitus film Ultrasound evaluation of the pleural space Weigh risks and benefits of procedure 4 studies between 1983 and 1994 looking at complications of thoracentesis reported rates of pneumothorax between 11 to 19%. 2 studies in 2009 and 2010 specifically addressing use of ultrasound for fluid location show risk of pneumothorax declines to 0.6 to 1.1%. Good training and experience matter. Risks for complications: large volume thoracentesis, COPD

When to consult with specialists Consult Pulmonary Team when: If overall clinical situation warrants pulmonary specialty assist If pre-procedure evaluation indicates may be difficult thoracentesis to perform If medical team lacking a member who feels confident performing the procedure Pulmonary team strongly encourages consults with them prior to requesting Intervention Radiology to perform the procedure

Etiology of a Pleural Effusion Pleural fluid accumulates when formation exceeds absorption Normally: Fluid enters pleural space from parietal pleura capillaries and is drained via the lymphatics in parietal pleura. Fluid can also come from: interstitial spaces of lung via visceral pleura peritoneal cavity via small holes in diaphragm. Lymphatics have capacity absorb 20 times more fluid than is normally formed.

Diagnostic Approach to Pleural Effusions Transudative effusions occur with either increased mean capillary pressure or decreased oncotic pressure Cirrhosis Left ventricular failure Nephrotic syndrome SVC obstruction Myxedema Peritoneal dialysis PE Exudative effusions occur with damage or disruption of the normal pleural membranes or vasculature occurs, leading to increased capillary permeability or decreased lymphatic drainage. Infectious diseases Malignancy Pulmonary embolism Collagen vascular diseases: RA, SLE, Wegener’s g.,Sjogren’s Drug-induced: nitrofurantoin, amiodarone, bromocriptine

Differentiation between exudative and transudative Exudative effusions meet at least one of the following criteria, transudative meet none: Light’s criteria: Pleural fluid protein/serum protein>0.5 Pleural fluid LDH/serum LDH>0.6 Pleural fluid LDH more than 2/3 normal upper limit for serum 2 Test Rule: Pleural fluid cholesterol > 45 mg/dL Pleural fluid LDH > .45 upper limit normal serum LDH 3 Test Rule: as above 2 Test, but add: Pleural fluid protein > 2.9 g/dL Note if fluid exudative, need description of fluid, pH, glucose level, differential cell count, microbiologic studies, and cytology If criteria met for exudative yet clinically suspect transudative, measure difference between serum and pleural fluid albumin levels. If difference > 1.2 g/L, effusion is transudative. If measure fluid protein, a difference > 3.1 g/dl indicates transudate.

Other diagnostic pleural fluid tests Glucose < 60 mg/dL Malignancy Bacterial infections Rheumatoid pleuritis Amylase Acute pancreatitis Esophageal rupture Lung carcinoma Triglycerides > 110 mg/dL, milky appearance Chylothorax , usually from trauma or mediastinal tumors Cell count predominantly neutrophils in febrile pt with normal pulmonary parenchyma Intraabdominal abscess

Other diagnostic pleural fluid tests Bloody pleural fluid Pleural hematocrit/serum hematocrit > 0.5 = hemothorax Usually result of trauma or tumor, or infarction Tuberculous effusions Exudative with predominantly small lymphocytes Adenosine deaminase > 40 IU/L Interferon gamma > 140 pg/mL, positive PCR for TB DNA Fluid culture, needle biopsy of pleura pH < 7.3 Empyema malignancy esophageal rupture Collagen vascular disease TB

Factors suggestive of need for chest tube (placed in increasing order of importance) Loculated pleural fluid Pleural fluid pH < 7.20 Pleural fluid glucose < 60 mg/dL Chylothorax Hemothorax Positive Gram stain or culture of pleural fluid Presence of gross pus in pleural space

Summary Indications: symptom relief, stabilization, and diagnostic Weigh risks and benefits Pre-procedure, double check safety: hemostasis, fluid quantity and location Call Pulmonary consult if: Need pulmonary input in the case Pre-procedure check indicates a difficult thoracentesis Team lacking a member with good experience and confidence in performing the thoracentesis Recommend calling Pulmonary prior Interventional Radiology

Resources Reducing iatrogenic risk in thoracentesis: establishing best practice via experiential training in a zero-risk environment. Duncan DR, Morgenthaler TI, Ryu JH, Daniels Chest. 2009;135(5): 1315 2. Pneumothorax following thoracentesis: a systematic review and meta-analysis. Gordon CE, Feller-Kopman D, Balk EM, Smetana GW Arch Intern Med. 2010;170(4):332 Complications associated with thoracentesis. Seneff MG, Corwin RW, Gold LH Chest 1986; 90:97-100 Thoracentesis: complicatons, patient experience and diagnostic value. Collins TR, Sahn SA. Am Review Respiratory Disease 1983; 127:A114 Harrison’s Principles of Internal Medicine, 17th edition. Fauci, Braunwald, Kasper, Hauser, Longo, Jameson, Loscalzo. 6. UpToDate online. www.uptodate.com.