Thoracentesis (Assist)
PREREQUISITE NURSING KNOWLEDGE
• Thoracentesis is performed with insertion of a needle or a catheter into the pleural space, which allows for removal of pleural fluid.
• Pleural effusions are defined as the accumulation of fluid in the pleural space that exceeds 10 to 20 mL and results from the overproduction of fluid or disruption in fluid reabsorption.1
• Thoracentesis is not used to verify the presence of pleural effusion. Diagnosis of pleural effusion is made via clinical examination, patient symptoms, and diagnostic techniques. A number of techniques can demonstrate pleural effusion with varying levels of sensitivity. Percussion requires a minimum of 300 to 400 mL for identification of a pleural effusion, whereas standard chest radiography requires 200 to 300 mL. Lateral decubitus radiographs can recognize smaller fluid amounts and highlight whether present fluid is free flowing. Ultrasound scan, computed tomography (CT) scan, and magnetic resonance imaging (MRI) technology can detect 100 mL of fluid with 100% sensitivity.1 Therefore, initial diagnosis of pleural effusion should use imaging techniques such as chest radiographs, ultrasound scan, CT scan, or MRI, combined with patient symptoms and clinical examination findings.
• Diagnostic thoracentesis is indicated for differential diagnosis for patients with pleural effusion of unknown etiology. A diagnostic thoracentesis may be repeated if initial results fail to yield a diagnosis.
• Therapeutic thoracentesis is indicated to relieve the symptoms (e.g., dyspnea, cough, hypoxemia, or chest pain) caused by a pleural effusion.
• Exudative effusions indicate a local etiology (e.g., pulmonary embolus, infection), whereas transudative effusions usually are associated with systemic etiologies (e.g., heart failure).
• Samples of pleural fluid are analyzed and assist in distinguishing between exudative and transudative etiologies of effusion. Results of laboratory tests on pleural fluid alone do not establish a diagnosis; instead, the laboratory results must be correlated with the clinical findings and serum laboratory results.
• Exudative pleural effusions meet one of the following criteria1:
Pleural fluid lactate dehydrogenase (LDH)-to-serum LDH ratio is greater than 0.6 international units/mL.
Pleural fluid LDH is more than two thirds of the upper limit of normal for serum LDH.
Pleural fluid protein-to-serum protein ratio is greater than 0.5 g/dL.
• A transudative pleural effusion is considered when none of the exudative criteria are met.
• Transudative effusions usually are associated with systemic etiologies (e.g., heart failure), whereas exudative effusions indicate a local etiology (e.g., pulmonary embolus, infection, open heart surgery).
• Relative contraindications for thoracentesis include the following:
Patient anatomy that hinders the practitioner from clearly identifying the appropriate landmarks
Patients undergoing anticoagulant therapy or having an uncorrectable coagulation disorder
Patients receiving positive end-expiratory pressure therapy
Patients with splenomegaly, elevated left hemidiaphragm, and left-sided pleural effusion
Patients with only one lung as a result of a previous pneumonectomy
• Ultrasound scan–guided thoracentesis is thought to reduce complications, especially when used in the last four patient groups listed in the relative contraindications list.2,3
• Complications commonly associated with thoracentesis include:
EQUIPMENT
Diagnostic Thoracentesis
• Baseline diagnostic study results (i.e., lateral decubitus chest radiograph, ultrasound scan imaging, CT scan, or MRI)
• Completed patient informed consent form
• Functional intravenous access
• Adhesive bandage or adhesive strip
• Intervention medications (opioid, sedative, or hypnotic agents, local anesthetic 1% or 2% lidocaine)
• One small needle (25-gauge, ⅝-inch long)
• 5-mL syringe for local anesthetic
• Three large needles (20-gauge to 22-gauge, 1½ to 2 inches long)
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