Thoracentesis

Pleural effusions are a frequent problem encountered in pulmonary medicine. Some common causes of pleural effusion include chest infection, heart failure, liver failure, malignancy, and autoimmune diseases such as rheumatoid arthritis, to name a few. Often drainage of this fluid is required for both diagnostic and therapeutic purposes, which is called thoracentesis. For this procedure, we use a Safe-T-Centesis kit to place a temporary catheter in the pleural space and manually drain the fluid, which can then be sent to the lab for further testing, including cell counts, glucose, pH, protein levels, cytology, and bacterial cultures. Based on these results, we can determine if the effusion is exudative or transudative, which helps guide further management. In this case, our patient has a recurrent left-sided exudative effusion of unknown cause with underlying history of colon cancer, and malignant effusion is a concern, and we performed both diagnostic and therapeutic ultrasound-guided thoracentesis.

Pleural effusion; thoracentesis; Safe-T-Centesis; exudative; transudative.

Pleural effusion, which is the accumulation of fluid in the pleural space, is a very common problem we manage in pulmonary medicine with a broad range of etiologies. It is reported that there are up to 1.5 million cases of pleural effusion each year in the United States.¹ It is often necessary to drain this fluid for diagnostic purposes, but also for therapeutic benefit as well. 

Thoracentesis is a very common bedside procedure that is utilized to drain pleural fluid. In simplest terms, a catheter over a needle is inserted through the chest wall into the pleural space. With the assistance of ultrasound, we can safely identify the pleural effusion as well as surrounding structures, including the lung, diaphragm, and pleura. Thus, the safety of thoracentesis has been improved, and the risk of complications including bleeding and pneumothorax are reduced significantly. 

Prior to performing a thoracentesis, it is important to take a thorough history as well review of laboratory values and extensive review of the patient’s medication list, most importantly looking for any blood thinners a patient may be on. When taking a patient’s history, it is important to try and figure out what could potentially be causing the pleural effusion. For example, you want to explore for heart, kidney, or liver issues, prior or active cancer history, signs/symptoms of infection, and/or autoimmune symptoms. It is imperative to have an accurate and thorough history as this will help guide what testing you will perform on the pleural fluid. When reviewing the patient’s medication list, you want to look particularly for anticoagulants or antiplatelet medications, as being on these medications will increase the patient’s risk of bleeding. While it is not an absolute contraindication to performing thoracentesis if the patient is on anticoagulants/antiplatelet medications, the risks and benefits of interrupting medication and/or the need for bridging therapy before the procedure should be discussed with the patient. For those with a high thrombotic risk (eg, cardiac stents), the discussion may need to include other relevant specialty teams. However, a meta-analysis published in Chest 2021 showed that overall bleeding risk and mortality was not shown to be increased in patients with uncorrected coagulopathy, either due to underlying disease or medications.² When reviewing a patient’s laboratory data, it is important to look at patient’s total platelet count and INR. Ideally you would like platelets >50,000 and INR within normal range. However, as stated above, bleeding risk with uncorrected coagulopathy is not significantly increased, and if the procedure is emergent, it should not be delayed and be performed after discussion with the patient about the possibility of increased bleeding, albeit low.

On the physical exam, it is important to first make sure the patient has stable hemodynamics, including blood pressure, oxygen saturation, heart rate, and respiratory rate. You want to make sure the patient has a stable blood pressure prior to performing a thoracentesis, as the removal of a significant amount of fluid can temporarily cause the blood pressure to drop. You will then want to examine the patient’s back and make sure there are no open wounds or other skin abnormalities that might interfere with where you plan to perform the procedure. An important portion of your physical exam will include performing a bedside ultrasound of the lung and pleural space to get a better look at the fluid collection and decide where to safely perform the thoracentesis. We will review the other relevant imaging in the next section. 

To evaluate for a pleural effusion, generally a chest radiograph and ultrasound are a good place to start. While a chest radiograph will generally tell you if an effusion is present, the ultrasound will better identify both the size and echogenicity of the effusion, such as if it is a simple or complex appearing fluid collection. It has been shown that ultrasound is not only the safest way to identify pleural effusion (reduces exposure to radiation), but also a study done in 2011 showed 100% sensitivity, specificity, and diagnostic accuracy for thoracic ultrasound identifying a pleural effusion.³ CT imaging of the chest is not required prior to a thoracentesis, although it is very likely you will have this to review as well prior to the procedure.

None.

Before offering the thoracentesis procedure, safety, indication, contraindication and preparation need to be evaluated. 

Common indications for thoracentesis are to diagnose new or of uncertain etiology equal or more than 1 cm in size or unclear unilateral effusion as well as relief of symptoms with large pleural effusions. There is no absolute contraindication for thoracentesis. Common relative contraindications include bleeding disorders, uncorrected anticoagulation, cellulitis or wound at the thoracentesis puncture site, inability to cooperate or inexperienced operator. If concern for empyema and hemothorax, other pleural procedures such as chest tube is preferred than thoracentesis.³ 

Once confirmed thoracentesis is an appropriate procedure, informed consent must be taken and clearly documented including risk and benefits. There are no large studies to define bleeding risk related to thoracentesis. General rule is that holding the anticoagulants and antiplatelets in an elective procedure will likely reduce the bleeding risk. 

In the video the procedure is performed “at the bedside” but ideally, when feasible the procedure should be undertaken in a clean, dedicated procedure room.

The procedure will begin with proper positioning of the patient. There are 2 positions a patient can be in for this procedure. The ideal position will be to have the patient sit with legs hanging over the side of the bed, with arm rest on the table and feet on the floor/chair. If the patient is unable to sit, lateral decubitus position with extended arm position is also acceptable.  

Once the patient is in the proper position, the procedure site is confirmed using ultrasound probe with either abdominal probe or cardiac probe. The usual site is the posterolateral back at least 6–8 cm away from the spine, one to two intercostal spaces below the fluid but above the diaphragm. The needle entry site should be just above the rib to avoid injury to intercostal neurovascular structures. While there is no defined optimal size of a fluid collection, generally it is recommended that collection be at least 1 cm in size to ensure avoidance of surrounding structures.⁴ 

Once the site is marked and after time-out, sterilize the skin using chlorhexidine or other sterile solution and drape the skin under sterile condition. Safe-T-Centesis kit includes 10 cc of 1% lidocaine solution in a glass container with various needle sizes. To prevent glass shards from entering your syringe, recommend to use a filtered needle to draw the lidocaine. Switch to a 25-guage needle to make a subcutaneous wheel. It is important to make sure your patient is properly locally anesthetized prior to draining the pleural fluid as it will be quite painful for your patient if they are not. Once the top layer of skin is numb, switch to a 22-gauge needle perpendicular to the skin and inject lidocaine along the track with applying suction when you advance and give 1–2 cc of lidocaine every 3–5 mm depth. Once you reach the pleural space, you should get fluid drawn back into your syringe, and that is how you will know you are in the pleural space. As you remove the needle, it is important to not instill more lidocaine as you withdraw as this could introduce air and possibly infection (if the pleural fluid is infected) into the skin which could lead to complications. In certain patient populations such as large body habitus, it is sometimes needed to use the longer needle such as spinal needle or using the thoracentesis catheter itself depending on the experience level of the operator. 

Once the skin is properly numbed, make a small 3–5-mm skin nick with the scalpel. The catheter is slowly advanced through the skin nick, just above the rib while aspirating. Once the fluid return is observed, it is recommended to advance another 3–5 mm. Then, without moving the introducer needle, advance the catheter over the needle until hubbed. Attach the catheter to the drainage bag for fluid removal. Prior to fluid removal, it is important to educate patients on what to expect during the procedure. Coughing is an expected symptom with thoracentesis because as the lung re-expands this induces coughing. You should tell them if they develop chest pain or tightness to alert you right away as this could be a sign of lung entrapment or re-expansion pulmonary edema. Generally, we start by using our 50-cc syringe to draw up samples to be sent off for testing. You will continue to drain the fluid until 1) patient develops significant chest pain, tightness, or shortness of breath (as this could indicate re-expansion pulmonary edema), 2) drainage slows down indicating all the fluid has been removed, or 3) generally up to 1.5–2 L depend on patient’s tolerance.

If a patient develops persistent cough, dyspnea or chest pressure, stop drainage and evaluate for pulmonary edema. If the air bubbles were aspirated with symptoms of hypotension, hypoxia, or chest pain, stop drainage and evaluate for pneumothorax. If the patient develops hypotension especially in the older population, likely due to vasovagal syncope, stop the procedure immediately and call for help to stabilize vital signs. Upon completion of aspiration, ask the patient to hum or breathe out while removing the catheter and apply bandage.  

Complications of thoracentesis procedure includes pneumothorax, hemothorax, post procedure pain, re-expansion pulmonary edema, vasovagal syncope, injury to nearby structures including diaphragm, liver, spleen, heart, and major blood vessels. Generally recommend to obtain a postprocedure CXR to rule out the complications. Any anticoagulants held for the procedure can be safely re-started the following day. 

All pleural fluid needs to be sent for cell count/differential, LDH, total protein, gram stain, culture (aerobic and anaerobic), cytology, glucose, pH. Same day serum total protein and LDH is needed to calculate Light’s criteria. Additional labs can be sent upon clinical questionnaires. 

1. Sterile tray, sterile drape, skin antiseptic solution (e.g. chlorhexidine), lidocaine, sterile dressing, sterile gloves, catheter for drainage, introducer needle, scalpel, drainage tubing, collection bag.
2. Local anesthetic, usually lidocaine 1–2% solution (should be included in the kit but make sure to double check).
3. Several different gauge needles (18 gauge for drawing up lidocaine, 22 or 25 for administration).
4. Several syringes ranging from 5 mL to 60 mL (smaller for lidocaine, larger for fluid removal).
5. Aerobic and anaerobic blood culture bottles, clear specimen cup.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.