Chapter 31. Thoracentesis

Introduction

Thoracentesis is a procedure by which fluid is removed from either hemithorax through a needle or small catheter inserted for that purpose, and may be a diagnostic or therapeutic procedure.

Definitions and Terms

• ▪  Pleural tap: Typically used to describe a diagnostic thoracentesis
• ▪  Transudate: Pleural fluid where pathologic analysis of the fluid shows little protein and few cells—consistent with several primary etiologies
  • —Congestive heart failure
  • —Hypoalbuminemia
  • —Nephritic syndrome
  • —Cirrhosis
  • —Atelectasis or trapped lung
• ▪  Exudate: Pleural fluid with protein and or cells
  • —Pleural or pulmonary malignancy
  • —Hemorrhage
  • —Connective tissue disease
  • —Pulmonary embolism
  • —Lymphatic disease

Techniques

• ▪  There are many indications for thoracentesis that can generally be categorized under one of two headings:
  • —Diagnostic: Evaluation of pleural fluid to diagnose primary disease process
  • —Therapeutic: Done to drain fluid to improve respiratory status of the patient
• ▪  Contraindications.
  • —Bleeding diathesis (ie, low platelets, abnormal coagulation parameters)
  • —Small effusion with significant risk of injury to the lung during performance of the procedure
  • —Bullous disease on the side of the effusion
  • —Positive pressure ventilation (relative)
• ▪  The location of the effusion should be identified radiographically (ie, chest x-ray, CT scan, or ultrasound).
• ▪  Prior to procedure, the patient should be consented, prepped, and the universal protocol should be performed as per Section I.
• ▪  The patient is typically positioned in an upright position allowing fluid to settle at the bottom of the hemithorax, and percussion may be used to identify the interface between lung and fluid (Figure 31-1).
• ▪  The site is marked and local anesthetic infiltrated down to the rib (Figure 31-2).
• ▪  A needle is introduced into the pleural space and fluid withdrawal confirmed (Figure 31-3).
• ▪  A catheter is then inserted into the effusion using one of a variety of techniques, including catheter-through-needle, catheter-over-needle, and Seldinger exchange (Figure 31-4).
• ▪  The fluid is then drained into a vacuum bottle (Figure 31-5) or drainage bag.
• ▪  The fluid is then sent off for appropriate diagnostic studies.

Clinical Pearls and Pitfalls

• ▪  The drainage catheter may stop draining if the tip sucks up against lung or pleura, in which case the patient can be repositioned to move the effusion around in ...