Thoracentesis

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W11 Thoracentesis

J. Terrill Huggins, Steven A. Sahn, Peter Doelken

Before Procedure

Indications

• Pleural effusion not explained by the clinical presentation

• Massive pleural effusion with impending respiratory failure

• Suspected pleural space infection

• Suspected complication of pneumonia (empyema)

• Suspected hemothorax

Anatomy

The pleura is a serous membrane that covers the lung parenchyma, mediastinum, diaphragm, and rib cage. The pleura is divided into the visceral and parietal pleura. The visceral pleura covers the lung parenchyma as well as the interlobar fissures. The parietal pleura lines the inside of the chest wall and the diaphragm. As pleural fluid forms, separation of the visceral and parietal pleural occurs, creating a space for a needle to be placed safely. Free-flowing pleural fluid will collect through gravitational effects in dependent areas, so if a patient is sitting upright, pleural fluid will collect along the diaphragm and the costophrenic and cardiophrenic angles. In contrast, in a supine patient, pleural fluid will collect along the posterior aspects of the lung.

The parietal pleural receives its blood supply from the systemic capillaries of intercostal arteries supplying the costal pleura, whereas the mediastinal pleura is supplied by the pericardiophrenic artery. The diaphragmatic pleura is supplied by the superior phrenic and musculophrenic arteries. The bronchial arteries probably supply the visceral pleura. The intercostal artery, vein, and nerve travel below the ribs. It is important to understand that the neurovascular bundle is not protected by the phalange of the rib within the first 8 to 10 cm from the origin of the vessels and nerves from the spine. Performing a thoracentesis in close proximity to the spine increases the risk for intercostal artery laceration and hemothorax.

Procedure

• Obtain informed consent.

• Place patient in a sitting position if hemodynamically stable, or move the patient to the edge of the bed, with the head of bed elevated to a 30- to 45-degree angle.

• Perform thoracic ultrasonography, and mark the puncture site.

• The upper margin of the rib immediately below the access area should be defined by palpation (may be impossible with obesity).

• The area should be disinfected with an iodophor- or chlorhexidine-containing antiseptic.

• Use 1% lidocaine without epinephrine for local anesthesia.

• Perform the procedure under sterile conditions at this point.

• Inject lidocaine subcutaneously into the periosteum of the rib and the parietal pleura, ensuring that the upper margin of the rib is identified and anesthetized.

• The upper margin of the rib should be identified with a 21-gauge needle prior to placing a thoracentesis catheter for a therapeutic procedure.

• Accessing the pleural space over the upper margin of the rib (should be identified) places the needle at a greater distance from the intercostal vessels and nerves.

• Always maintain the needle angle perpendicular to the patient.

• Once pleural fluid is aspirated, retract the needle outside the pleural space.

• Place a 30- to 60-mL syringe onto the needle, and advance into the pleural space to collect the specimen.

• If therapeutic thoracentesis is desired, withdraw the needle after pleural fluid is clearly aspirated.

• If fluid cannot be obtained with a small-gauge needle, no attempts at placing a thoracentesis catheter should be made.

• Insert the catheter-over-needle system under continuous application of suction until pleural fluid is aspirated.

• Once pleural fluid is obtained, advance the catheter system another 1 cm to place the catheter with its maximum diameter in the pleural space.

• Without advancing the needle, strip the catheter into the pleural space, and remove the needle.

• To prevent air entry into the pleural space, turn the thoracentesis stopcock off as related to the patient.

• Finally, connect the drainage tubing and collection bag to the thoracentesis catheter.

• To prevent development of excessively negative pleural pressures in ventilated patients, draining large amounts of pleural fluid is not recommended unless pleural manometry is performed.

After Procedure

Postprocedure Care

• Postprocedure chest radiograph should be performed on all ventilated patients.

• Monitor for signs of tension pneumothorax and hemothorax:

• Hypotension

• Worsening lung compliance in ventilated patients

• Tube thoracostomy is required in all patients who develop a pneumothorax on mechanical ventilation.

Outcomes and Evidence

• Feasibility and safety of ultrasound-guided thoracentesis in mechanically ventilated patients is strongly supported by the literature.

• Clinically directed thoracentesis should not be performed in mechanically ventilated patients.

• Bedside ultrasonography is the preferred modality for diagnosis of a pleural effusion in the critically ill patient.

Suggested Reading

Godwin JE, Sahn SA. Thoracentesis: a safe procedure in mechanically ventilated patients. Ann Intern Med. 1990;113:800-802.

Lomas DJ, Padley SG, Flower CDR. The sonographic appearance of pleural fluid. Br J Radiol. 1993;66:619-624.

Lichtenstein D, Hulot JS, Rabiller A, et al. Feasibility and safety of ultrasound-guided thoracentesis in mechanically ventilated patients. Intensive Care Med. 1999;25:955-958.

Mayo PH, Goltz HR, Tafreshi M, et al. Safety of ultrasound-guided thoracentesis in patients on mechanical ventilation. Chest. 2004;125:1059-1062.

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