Anatomy and Pathophysiology
The pleura is a serous membrane that covers the lungs, mediastinum, diaphragm, and thoracic cavity. The pleural space is a potential space between the lung and the thoracic cavity. A thin layer of fluid normally exists between the visceral pleura covering the organs and the parietal pleura covering the chest wall. This fluid acts as a lubricant.3 Pleural fluid originates from three sources: parietal capillaries, visceral capillaries, and the interstitium. Hydrostatic and oncotic forces govern the flow of fluid in the pleural space. These forces are summarized in Figure 40-1. In a healthy person, protein-free fluid enters the pleural space from the parietal pleura and is absorbed by the visceral pleura. Small amounts of protein then leak into the pleural space. Approximately 10% of the pleural fluid and large proteins are removed by the lymphatics at a rate of up to 20 mL/h for each hemithorax.2 Ventilation and muscular activity facilitate the action of the lymphatics.3
Schematic of pleural fluid homeostasis in a normal lung.
Alterations in pleural fluid homeostasis will lead to a pleural effusion: a pathologic collection of excess fluid, located between the visceral and parietal pleura. Hydrostatic changes result in protein-free effusions (transudates). Changes in oncotic pressure (abnormality in the lung or pleura) lead to effusions. The differential diagnosis of transudates and exudates is listed in Table 40-1.
Table 40-1 Differential Diagnosis of Fluid Exudates and Fluid Transudates in the Pleural Space ||Download (.pdf)
Table 40-1 Differential Diagnosis of Fluid Exudates and Fluid Transudates in the Pleural Space
|Collagen vascular disease||Cirrhosis of the liver with ascites|
|Drug-induced||Congestive heart failure|
|Esophageal rupture||Peritoneal dialysis|
|Systemic lupus erythematosus|
|Thoracic duct exposure|
A thoracentesis may be performed to remove pleural fluid for analysis to diagnose the etiology of the fluid (e.g., malignancy, infection). It may also be performed to relieve the patient's symptom of dyspnea when a large pleural effusion interferes with normal respiration or results in respiratory compromise.
The only absolute contraindications are an uncooperative patient or a patient who refuses to give informed consent for the procedure.16 Uncooperative patients or patients with altered levels of consciousness may require sedation for the procedure.
There are numerous relative contraindications to performing a thoracentesis. Patients receiving anticoagulants, with a bleeding diathesis (whether known or suspected), or thrombocytopenia have a significant risk of bleeding.2,16 Consider reversing the anticoagulant or the bleeding disorder prior to performing the thoracentesis. A small volume of pleural fluid may make the procedure difficult to perform and increase the risk of complications.16 Patients undergoing positive-pressure ventilation (i.e., mechanical ventilator, BiPAP, or CPAP) are at an increased risk of developing a pneumothorax and a tension pneumothorax.1 Although, one study has shown that a thoracentesis can be done as safely in a ventilator-dependent patient as in patients not being mechanically ventilated.17 Pleural adhesions may limit the amount of fluid obtained or require multiple thoracenteses to drain the fluid.1 Loculated pleural adhesions should be drained under ultrasound guidance. Areas of cellulitis or other infection on the chest wall should be avoided unless no alternate site can be identified for the procedure.1,3 Unsupervised physicians with little or no experience should not perform this procedure, as the risk of complications is increased.7 Patients with chronic obstructive pulmonary disease are at increased risk for complications.
Diagnostic Thoracentesis for Pleural Effusions
- Sterile gloves and gown
- Face mask with a face shield or goggles
- Local anesthetic solution, 1% to 2% lidocaine
- Heparin, 1000 U/mL
- Atropine, 1 mg
- Alcohol pads
- Povidone iodine or chlorhexidine solution
- Gauze 4 × 4 squares
- Sterile drapes
- Sterile towels
- Sterile gloves
- 25 or 27 gauge needle
- 21 and 22 gauge needles, 1.5 in. long
- 10 mL syringes
- 50 mL syringe
- 18 or 20 gauge needle
- Ultrasound machine
- 3.5 to 5.0 MHz phased-array ultrasound probe
- Sterile ultrasound gel
- Sterile ultrasound probe cover
Therapeutic Thoracentesis for Pleural Effusions
- The supplies listed above
- 16 to 18 gauge catheter-over-the-needle
- 14 to 18 gauge catheter-through-the-needle
- Three-way stopcock
- Connector tubing (connects to three-way stopcock and sterile container)
- Sterile container for pleural fluid
- 50 mL syringe
- Intravenous extension tubing
Commercial kits have been developed and are available to provide the equipment needed to perform a thoracentesis. The kits are disposable, intended for single-patient use, and contain the required equipment. They save time in that the equipment does not have to be found and set up. Disadvantages include potential increased cost and limited equipment in the kit.18 Common kits include the Pharmaseal, distributed by Baxter (Jacksonville, TX); the Arrow Clark Thoracentesis Kit, distributed by Arrow (Reading, PA); the Argyle Turkel Safety Thoracentesis Kit, distributed by Boston Scientific (Miami, FL), and the Turkel Thoracentesis Kit, distributed by Tyco Healthcare (Mansfield, MA).3
Explain the procedure, its risks, and benefits to the patient and/or their representative and obtain a signed consent form.1 The position of the patient can vary depending on their clinical condition. Patients who are ambulatory and cooperative should sit up at the edge of a bed with their feet on the floor or a stool (Figure 40-2). Place the patient's head and arms on an elevated bedside tray. The patient's back should be as vertical as possible so that the lowest part of the hemithorax is posterior. This will ensure that the free-flowing fluid remains posteriorly.1–3,16
Recommended positioning of an ambulatory patient for a diagnostic or therapeutic thoracentesis for the evacuation of fluid.2
In debilitated patients, one of three other positions is recommended. Place the patient in the lateral decubitus position, lying on the side of the pleural effusion. The patient's back should be along the edge of the bed. The procedure would then be performed in the midscapular line or the posterior axillary line. Place a ventilator-dependent patient into the lateral decubitus position, lying on the side with the pleural effusion.17 Second, place the patient supine and elevate the head of the bed as much as maximally possible. The patient would then be sitting with the assistance of the bed, and the procedure would be performed in midaxillary or posterior axillary line.3 Finally, the patient can be placed supine. The procedure would then be performed at the posterior or midaxillary line. With the patient supine, ultrasonography may be required to locate the pleural fluid. Sedation or paralysis may be needed for optimal positioning depending on the patients clinical condition.
After positioning the patient, clean any dirt or debris from the skin. Identify the anatomic landmarks required to perform the procedure. After viewing the chest radiograph and estimating the amount of pleural fluid, percuss from superior to inferior starting at the midscapular or posterior axillary line. The site chosen for aspiration should be a single interspace below the top of the dullness to percussion.
If the fluid thickness is less than 10 mm on radiographs, ultrasound may be used to locate the fluid.5,16 Alternatively, ultrasound can be routinely used to locate pleural fluid. Ultrasound has been shown to be comparable to CT for diagnosing and managing a pleural effusion.19
Although not required, some Emergency Physicians place the patient on the cardiac monitor, noninvasive blood pressure cuff, pulse oximetry, and supplemental oxygen to monitor them during and after the procedure. Apply povidone iodine or chlorhexidine solution to the skin surface and allow it to dry. Apply sterile drapes around the site of the procedure. If using an ultrasound-guided technique, be sure to fit the transducer with a sterile glove or probe cover before exposing the probe to the sterile skin. Use sterile ultrasound gel. Atropine should be at the bedside. It can be administered (1.0 mg subcutaneously or intramuscularly or 0.5 mg intravenously) to patients who develop symptomatic bradycardia during the procedure. The Emergency Physician should wear full personal protective equipment to protect themselves from contact with the patient's blood and body fluids as well as protect the patient from infection.
Place a skin wheal of local anesthetic solution over the thoracentesis site using a 25 or 27 gauge needle on a 10 mL syringe containing the local anesthetic solution. Remove the 25 or 27 gauge needle from the syringe. Apply a 21 or 22 gauge, 1.5 to 3.0 in needle to the syringe containing the local anesthetic solution. Anesthetize the subcutaneous tissues and the periosteum of the rib (Figure 40-3). Walk the needle up the rib while simultaneously injecting local anesthetic solution. Gently aspirate prior to injecting each time the needle is advanced to ensure that the needle is not within a blood vessel. When the superior border of the rib is located, slowly and carefully advance the needle over the rib while applying negative pressure on the syringe. Be sure not to insert the needle below the rib to avoid injury to the neurovascular bundle inferior to the rib. When the pleural space has been entered, fluid will flow into the syringe. Inject and aspirate small volumes (1 to 2 mL) while the needle is within the pleural cavity. This will distribute the local anesthetic solution into the pleural fluid and ensure anesthesia of the pleura. Withdraw the needle from the pleural cavity and out the skin.
Administration of local anesthesia. A skin wheal is made. The needle is inserted through the skin wheal while local anesthetic solution is injected to anesthetize the subcutaneous tissues and the periosteum of the rib. The needle is “walked” above the upper border of the rib (red jagged line) to avoid the neurovascular bundle inferior to the rib. The intercostal muscles, parietal pleura, and pleural space are then infiltrated with local anesthetic solution.
Diagnostic Thoracentesis Technique for Pleural Effusions
Attach an 18 gauge needle to a 50 mL syringe containing 1 mL of heparin. The heparin will ensure accurate pH and cell counts as it prevents the fluid from clotting. Introduce the needle through the anesthetized track and into the pleural cavity (Figure 40-4B). Aspirate up to 50 mL of fluid. Withdraw the needle and place the fluid into the appropriate sterile containers. Use proper techniques when transferring the fluid into containers or specimen tubes to prevent a needlestick injury.
Needle positioning for a diagnostic thoracentesis. A. The pleural space is entered above the effusion (too high). B. The pleural space is entered properly, over the rib and into the fluid. C. The needle is too low and enters the abdominal cavity below the diaphragm.
If pleural fluid cannot be aspirated, also known as a dry tap, four possibilities must be considered. The needle may be too short, positioned too high to reach the fluid (Figure 40-4A), positioned too low to reach the fluid (Figure 40-4C), or there may not actually be an effusion. Repeat the physical examination and review the chest radiograph to reconfirm the presence of a pleural effusion. Use ultrasound, if available, to assess the presence of a pleural effusion. Penetration of the lung with the needle is rarely catastrophic but can result in a pneumothorax.3
For debilitated patients, the principles are the same with the exception of the site for the procedure. If the patient is supine, use the midaxillary line or the posterior axillary line. Be cautious of the diaphragm, as it can be as high as the fifth interspace on expiration at the anterior axillary line. If the patient is in the lateral decubitus position, use the midscapular line or the posterior axillary line for the procedure.
Therapeutic Thoracentesis Techniques for Pleural Effusions
The same sterile preparation, location of fluid, positioning, and anesthesia considerations apply for therapeutic thoracentesis as with the diagnostic procedures. However, there is one difference between a diagnostic and a therapeutic thoracentesis—that is, the quantity of fluid removed. Up to 1.5 L is removed in a therapeutic thoracentesis. A diagnostic thoracentesis requires approximately 10 to 20 mL of pleural fluid.
Two types of catheters can be used to perform this procedure. They are the catheter-over-the-needle and the catheter-through-the-needle (Figures 40-5 & 40-6). The catheter-over-the-needle technique is most commonly used (Figure 40-5). Make a small “nick” in the skin with a #11 surgical blade at the needle insertion site. Attach a 14 to 18 gauge catheter-over-the-needle to a 10 mL syringe as a handle. Insert the catheter-over-the-needle into the nick and advance it, reproducing the original anesthetized tract (Figure 40-5A). Apply negative pressure to the syringe as the catheter-over-the-needle is advanced. Stop advancing the catheter-over-the-needle when fluid is aspirated. Angle the catheter-over-the-needle caudally. Securely hold the syringe and needle so they do not move. Advance the catheter until the hub is against the skin. Withdraw the needle and syringe as a unit while the catheter remains in the pleural cavity (Figure 40-5B). When the needle is removed, quickly cover the catheter with a gloved finger. This will prevent ambient air from entering the pleural cavity. Attach intravenous catheter extension tubing to the hub of the catheter. Place a three-way stopcock attached to a 50 mL syringe onto the extension tubing. Hold the catheter hub against the skin securely. Aspirate fluid into the syringe and then advance the fluid into the sterile container by adjusting the three-way stopcock.
The catheter-over-the-needle technique. A. The needle and catheter are inserted over the rib and aimed slightly caudally into the pleural cavity. B. The catheter is advanced into the pleural cavity and the needle is removed.
The catheter-through-the-needle technique. A. The needle is inserted over the rib and aimed slightly caudally into the pleural space. B. The catheter is inserted through the needle and into the pleural cavity. C. The needle is removed and the catheter remains within the pleural cavity.
An alternative option is to set up a siphon through the three-way stopcock. Prime the tubing with pleural fluid. Place the end of the tubing into a sterile container that is located below the site of the catheter. This allows the fluid to flow freely into the sterile container. Fluid can be removed in 50 mL aliquots up to 1.5 L. As a general rule, this is the limit, due to the risk of postevacuation pulmonary edema and excessive protein loss.1
The second option is to utilize the catheter-through-the-needle system (Figure 40-6), known as the Bardig Intracath system. It is not as popular as the catheter-over-the-needle systems. Place the needle on a tuberculin syringe. Insert the needle and advance it through the anesthetized tissues (Figure 40-6A). A small “nick” in the skin with a #11 surgical blade will facilitate needle entry. Apply negative pressure to the syringe as the needle is advanced along the anesthetized tract and into the pleural cavity (Figure 40-6A). Stop advancing the needle when fluid is aspirated. Securely hold the needle so it does not move. Remove the syringe and cover the needle hub with a gloved finger. This will prevent ambient air from entering the pleural cavity. Angle the needle slightly caudally and advance the catheter through the needle (Figure 40-6B). Withdraw the needle, leaving the catheter within the pleural cavity (Figure 40-6C). Once the needle is removed, do not readvance the needle, as the catheter may shear off and fall into the pleural cavity. Place a three-way stopcock or a large syringe onto the hub of the catheter. Place the needle guard on the needle. Secure the catheter by taping it to the skin. Withdraw fluid as previously described. Fluid can be removed in 50 mL aliquots up to 1.5 L. As a general rule, this is the limit, due to the risk of postevacuation pulmonary edema and excessive protein loss.1
An alternative approach is to use the Seldinger technique to insert a small bore catheter into the pleural cavity. The major disadvantages to this technique include the time it takes to insert the catheter, the cost of the catheter kit versus a catheter-over-the-needle, and catheter blockage (from cells, debris, and protein) requiring insertion of a second catheter. Another option is to use a central venous catheter kit.20,21 The larger catheter opening may not become obstructed as easily.
Ultrasound-Guided Technique for Pleural Effusions
Ultrasound can be used to map the location and the extent of pleural effusion, and to help identify the appropriate site of needle entry. Real-time guidance is usually not required. A 3.5 to 5.0 MHz phased-array probe is recommended for ultrasound-guided examination of the pleural space.22 In general, orientation of the probe follows the convention that the probe marker should correlate to the reference point in the left upper corner of the screen.
With the patient in an upright sitting position, percuss and auscultate the posterior thorax to estimate the location of pleural fluid. Apply sterile ultrasound gel onto the ultrasound probe cover. Place the probe at the intercostal space of the estimated level of pleural fluid in the posterior axillary line, usually at the level of ribs 9 to 11. Sweep the probe superiorly and inferiorly, as well as transversely, to assess the location and size of the fluid collection. Identify the liver on the right, the spleen on the left, and the diaphragm.
In a debilitated patient in the lateral decubitus position, place the ultrasound probe in the midscapular line or, if possible, the posterior axillary to locate the fluid. A ventilator-dependent patient should be placed in the lateral decubitus position. If the patient is supine, place the probe in the posterior or midaxillary line. The real-time movement of the diaphragm can be used as a key reference point when examining the pleural space.23 The liver may also be used as a echogenic reference point for the identification of adjacent hyperechoic or hypoechoic structures. Keep in mind that the best window to view the intrathoracic contents is through the intercostal space, as ultrasound penetration through the soft tissue is superior to that of bone.
The ultrasound waves will initially penetrate the skin, subcutaneous tissue, and muscle to produce multiple layers of varying echogenicity. The echogenic ribs cast an acoustic shadow (Figure 40-7). The parietal and visceral pleura are encountered posterior to the rib as two hyperechoic lines, each <2 mm thick.23,24 The diaphragm can be identified as a hyperechoic transverse structure at the base of the chest wall. The lung is visualized as a bright, hyperechoic structure just cephalad to the diaphragm. The lung should become more intensely hyperechoic, or brighter in the inspiration phase. A pleural effusion can be identified as an anechoic to a hypoechoic image above the diaphragm that decreases in size with inspiration.
Ultrasound image of a normal lung. Visualized from top to bottom are the subcutaneous tissues, muscle (M), rib shadow (arrowhead), and pleural line (arrows).
Two additional ultrasound findings should be identified on exam: “lung slide” and “comet tail” artifact. The movement of the lung in reference to the surrounding parietal pleura with inspiration and expiration produces an artifact referred to as “lung slide.” Normal inspiration should produce a “slide” with each breath, representing movement between the visceral and parietal pleural interface. The thin, hyperechoic sliding line is located approximately 0.5 cm below the surface of the rib, and should move back and forth with each inspiration.25 A “comet tail artifact” is another normal finding that can be readily identified in a healthy patient. The comet tail artifact is identified as a hyperechoic vertical artifact that slides transversely and is oriented perpendicular to the transverse “lung slide” previously mentioned.25
A pleural effusion is easily visualized using ultrasound (Figure 40-8). It appears black or anechoic. A distinct hyperechoic pleural line is not seen as the parietal and visceral pleura are separated by the effusion. Lung tissue appears hyperechogenic compared with the anechoic effusion (Figure 40-9). The pleural effusion can be seen moving during the respiratory cycle.
Ultrasound image of a pleural effusion. The pleural effusion appears black or anechoic (asterisk). The pleura is not brightly echogenic (arrows) due to the separation of the two layers. Note the rib shadow (arrowhead) in the upper part of the image.
Ultrasound image of a pleural effusion (asterisk) with the underlying hyperechoic lung tissue (L). Note the rib shadow (arrowhead) in the upper left of the image.
The posterior approach is the preferred choice in the stable, cooperative patient who is able to sit up and lean over a table (Figure 40-10). To survey the lung anatomy and map the effusion, scan the posterior hemithorax from the inferior border of the scapula to the upper lumbar region and from the paravertebral area to the posterior axillary line. Note the minimum depth of the effusion and the location of other vital structures (i.e., diaphragm, liver, spleen, and lung). Scan with the probe parallel to and perpendicular to the ribs, and observe the structures during the full respiratory phase. The diaphragm can go as low as the 12th rib posteriorly and as high as the 8th rib laterally. Determine the location of the skin entry site. Mark the site with a pen, surgical marker, or by indenting the skin with the cap of a needle. The ideal site should have a large area of pleural effusion and be free of any internal structures (i.e., liver, spleen, or diaphragm) along the needle path.
Posterior approach in the sitting patient. A linear ultrasound probe is seen here, although a phased-array probe is often preferred to visualize deeper structures.
The lateral approach is used for mechanically ventilated patients and for those who are unable to sit up for the procedure. Abduct the ipsilateral arm and place the hand behind the patient's head, as one would in preparation for the placement of a chest tube (Figure 40-11). Survey the anterior and lateral thorax from the midclavicular line to the posterior axillary line. Note the depth of the effusion and the location of any vital structures to be avoided. Determine and mark the skin entry site.
Lateral approach in the supine patient. A curvilinear probe is positioned in the midaxillary line. Note the coronal plane of the probe.
The lateral decubitus approach is an alternative for patients unable to sit upright. Place the patient on their side with the pleural effusion side down. Use ultrasound to map the effusion. Note the distance from the skin to the effusion, the depth of the effusion, as well as the presence of any important structures to be avoided. Determine and mark the skin entry site, usually at the posterior axillary line.
Regardless of the patient position or approach, do not allow the patient to move once they have been scanned and the skin entry site marked. Prep and drape the patient similar to that for the blind thoracentesis approach. Use local anesthetic to anesthetize the skin, rib, and pleura. The catheter-over-the-needle can be inserted blindly, as described previously, at the skin insertion site or using real-time ultrasound guidance.
The use of ultrasound guidance can be helpful. Place a sterile cover over the ultrasound probe. Apply sterile ultrasound gel over the cover. Rescan the patient in the area previously identified the skin entry site (Figure 40-12). Verify that no structures are along the needle path between the skin and the pleural effusion. Insert an 18 gauge catheter-over-the-needle into the pleural space using the technique already described while using ultrasound for real-time visualization of the needle entering the pleural cavity. The needle will appear as a thin, bright, hyperechoic structure moving through the skin, subcutaneous tissue, parietal pleura, visceral pleura, and finally reaching the hypoechoic pleural effusion (Figure 40-13). Aspirate to confirm that the catheter-over-the-needle is within the pleural effusion. Place the ultrasound probe aside. Continue the remainder of the procedure as described previously.
The pleural effusion (asterisk) is visible above the diaphragm (arrows). The liver (L) is seen below the diaphragm.
Long-axis view of a thoracentesis needle (arrows) being placed into a pleural effusion (asterisk) under ultrasound guidance. The rib shadow is denoted by an arrowhead.
Numerous analyses of the pleural effusion fluid are required to determine its etiology (Table 40-2). Large pleural effusions are more commonly associated with infections and malignancy.26 Fluid analysis criteria have been established to separate transudates and exudates.10,27 If the fluid fits one of the criteria in Table 40-3, it is an exudate. These parameters have been confirmed to have 98% sensitivity and 83% specificity in detecting exudates.28 Color and odor can be helpful. If the fluid has a putrid odor, consider an infection. White or yellow fluid suggests an empyema or chylothorax. The fluid's white blood cell count is of limited benefit. If it is >10,000, the fluid likely represents a parapneumonic effusion. A pleural fluid hemoglobin and hematocrit can be compared to that of the blood. Bloody pleural effusions are usually associated with malignancy, pneumonia, pulmonary embolism with a lung infarction, or trauma.29 If the fluid is grossly bloody, consider a hemothorax. If the pleural fluid's hematocrit is >50% of the serum hematocrit, a hemothorax is likely and chest tube placement should be considered. Other helpful tests include a fluid pH. If the pH is below 7.25 to 7.30, consider it the result of a parapneumonic process, rheumatologic process, esophageal rupture, or malignancy. An elevated amylase level suggests esophageal rupture, malignancy, or pancreatic disease.30 Elevated triglyceride levels suggest a chylothorax. Cytology is important to search for an underlying malignancy. Up to 50% of patients with a pulmonic malignancy will have neoplastic cells in the pleural fluid.3 Bacteriologic information such as Gram's stain, acid-fast, and fungal preparations are also important, although the yield can be below 30%.16 Fluid should always be sent for aerobic and anaerobic cultures to rule out an infectious etiology for the pleural effusion. The appearance of pleural fluid on ultrasound may help identify whether the pleural fluid is a transudate or an exudate. Transudates are consistently seen as anechoic, whereas exudates may range from an anechoic to a hyperechoic.31,32
Table 40-2 Laboratory Analysis of Pleural Effusions ||Download (.pdf)
Table 40-2 Laboratory Analysis of Pleural Effusions
Cell count and differential
Hemoglobin and hematocrit
Table 40-3 Laboratory Features of a Pleural Fluid Exudate ||Download (.pdf)
Table 40-3 Laboratory Features of a Pleural Fluid Exudate
Fluid/serum lactate dehydrogenase (LDH) > 0.6
Fluid/serum protein > 0.5
Pleural fluid LDH > 200 IU/mL
Pleural fluid LDH > 2/3 upper limit of normal for serum
When done aspiring fluid, remove the catheter and apply a bandage to the puncture site. Several authors have suggested that a postprocedure chest radiograph may not be necessary.33,34 These were small studies with methodologic errors. Omitting the postprocedure chest radiograph cannot be recommended at this time. Obtain a plain chest radiograph upon completion of the procedure to assess for a pneumothorax. An expiratory film is the best film to look for a pneumothorax, especially if it is small. Repeat a chest radiograph in 4 to 6 hours to look for a delayed pneumothorax. If no pneumothorax is present and if appropriate for the clinical condition, the patient may be discharged with good instructions and close follow-up.
The procedure site should be evaluated two to three times a day for signs of infection. These patients should be educated about the signs, symptoms, and significance of an infection. They should return to their primary physician or the Emergency Department immediately if they develop fever, chills, shortness of breath, redness or pus at the puncture site, or if any concerns arise.
The potential complications of a thoracentesis are listed in Table 40-4.1,3,16,28,35 Complication rates range from 20% to 50%. The major complications are a 5% to 19% incidence of pneumothorax and a 1% to 7% incidence of pneumothorax requiring a chest tube.11,36 One author recommends ultrasound-guided thoracentesis for all patients as the safest approach, although this is disputed by others.9,36 The majority of studies report lower rates of postprocedural pneumothoraces with ultrasound-guided thoracentesis performed by an experienced operator.9–11,15,37–41 However, others have not shown a significant difference in the incidence of postprocedural pneumothoraces with the use of ultrasound.42,43
Table 40-4 Potential Complications Associated with a Thoracentesis ||Download (.pdf)
Table 40-4 Potential Complications Associated with a Thoracentesis
Laceration of an intercostal nerve or vessel
Laceration of the liver or spleen
Pain at the procedure site
Reexpansion pulmonary edema
Shortness of breath
The use of the proper technique and the Emergency Physician's experience are important in reducing the rate of complications.44–46 Despite this, it is difficult to predict which patients may be at risk of developing a postprocedural pneumothorax.47 Drainage of large volumes of fluid, greater than 1.5 to 2 L, may increase the risk of developing a pneumothorax.48 Improper technique or tortuosity of the intercostal artery can result in intercostal artery injury.49 Qureshi compiled methods to reduce the incidence of pneumothorax.16 They are direct supervision of inexperienced operators, removal of small amounts of fluid, use of small-gauge needles, use of ultrasound for small effusions, and use of a needle-catheter system for a therapeutic procedure.