Local Anesthetic Thoracoscopy for Undiagnosed Pleural Effusion

Summary

Local anesthetic thoracoscopy (LAT) is essential for diagnosing recurrent, undiagnosed pleural effusion when a guideline-based workup fails to provide a specific cause. LAT can be performed as a day-case procedure by chest physicians. Here, we present a step-by-step approach for a successful and safe procedure.

Abstract

Local anesthetic thoracoscopy (LAT) is a minimally invasive diagnostic procedure gaining recognition among chest physicians for managing undiagnosed pleural effusions. This single-port procedure is conducted with the patient under mild sedation and involves a contralateral decubitus position. It is performed in a sterile setting, typically a bronchoscopy suite or surgical theater, by a single operator with support from a procedure-focused nurse and a patient-focused nurse.

The procedure begins with a thoracic ultrasound to determine the optimal entry point, usually in the IV-V intercostal space along the midaxillary line. Lidocaine/mepivacaine, with or without adrenaline, is used to anesthetize the skin, thoracic wall layers, and parietal pleura. A designated trocar and cannula are inserted through a 10 mm incision, reaching the pleural cavity with gentle rotation. The thoracoscope is introduced through the cannula for systematic inspection of the pleural cavity from the apex to the diaphragm. Biopsies (typically six to ten) of suspicious parietal pleura lesions are obtained for histopathological evaluation and, when necessary, microbiological analysis. Biopsies of the visceral pleura are generally avoided due to the risk of bleeding or air leaks. Talc poudrage may be performed before inserting a chest tube or indwelling pleural catheter through the cannula. The skin incision is sutured, and intrapleural air is removed using a three-compartment or digital chest drainage system. The chest tube is removed once there is no airflow, and the lung has satisfactorily re-expanded. Patients are usually discharged after 2-4 h of observation and followed up on an outpatient basis. Successful LAT relies on careful patient selection, preparation, and management, as well as operator education, to ensure safety and a high diagnostic yield.

Introduction

The incidence and prevalence of pleural diseases are increasing worldwide, especially pleural effusions, which have more than 50 recognized causes^1,2. Pleural malignancy is the leading cause of recurrent pleural effusion, mostly due to metastases from extrapleural lung, breast, or lymphoma malignancies³. Existing guidelines recommend pleural biopsies if the medical history, physical examination, radiology, and pleural tap for cytology, culture, and biochemistry fail to provide a diagnosis⁴. Pleural biopsies can be obtained either image-guided or under direct vision. Ultrasound (US)- or CT-guided percutaneous core biopsies allow sampling from most lesions in the costal part of the parietal pleura, with a diagnostic yield of 84% and 93%, respectively, in a recent systematic review⁵. US-guided pleural biopsy is superior in terms of a lower complication rate (4% vs. 7%), no irradiation, and availability as a bedside procedure⁵. Case reports show that lesions in the mediastinal pleura can be sampled using echoendoscopes⁶.

Thoracoscopy allows direct visual inspection and sampling of lesions in both the mediastinal, diaphragmatic, or costal pleura, making it the gold standard in the diagnosis of recurrent pleural effusion of an unknown cause^4,7. Thoracoscopy is performed as either a local anesthetic thoracoscopy (LAT) or video-assisted thoracoscopic surgery (VATS)⁸. LAT (also known as medical thoracoscopy or pleuroscopy) is a single-port procedure, routinely performed by pulmonologists in the bronchoscopy suite, and it carries a diagnostic yield for malignancy of 93%^9,10. LAT can be performed with either a semirigid or rigid endoscope, usually connected to a video-imaging source. A few publications discuss the benefits and disadvantages of these approaches^8,11,12,13. Briefly, the semirigid thoracoscope resembles a bronchoscope, and biopsies are obtained using similar forceps. The rigid endoscope has a larger diameter, is cheaper, and allows for larger biopsies, although this does not readily translate into marked differences in diagnostic yield^10,14,15. The safety of LAT is high, with a mortality rate of less than 0.5%, with this strongly related to pre-existing medical conditions^3,4. Contraindications of LAT are fewer than for VATS and include complete obliteration of the pleural space due to adhesions, skin infection at the site of entry, respiratory failure, cardiac instability, and uncorrectable coagulopathy^7,8,12. VATS is an in-hospital, 2 or 3-port procedure performed by thoracic surgeons, which must take place in a surgical theatre, requiring general anesthesia, intubation, single-lung ventilation, and post-operative admission. VATS has a diagnostic yield and complication rate similar to that of LAT but allows for more complex procedures to be undertaken^10,16.

Guidelines recommend LAT as the first-choice thoracoscopy due to its high diagnostic yield, low risk, lower costs, and the possibility for daycase management, reserving VATS for selected cases⁴. The choice of a rigid or semirigid thoracoscope is usually determined by local preference. LAT is not a new procedure, as it was described as early as the mid-19th century, popularized by Jacobaeus in 1910, increasingly used to treat pleural tuberculosis until the 1950s, and "rediscovered" in the 1980s as an important tool to diagnose recurrent pleural effusions^8,17.

Protocol

The following protocol will describe how to perform LAT in a clinical setting. The protocol is in accordance with the clinical practice and guidelines of the authors' hospitals (Odense, Næstved, Lleida, Bristol, and Preston). Written informed consent is obtained from the patient prior to the procedure. The main inclusion criteria for the procedure is recurrent pleural effusion of unknown cause, despite guideline-based work-up. Exclusion criteria include complete obliteration of the pleural space due to adhesions, skin infection at the site of entry, respiratory failure, cardiac instability, and uncorrectable coagulopathy.

1. Preparing for the procedure

1. Examine the available image and perform thoracic ultrasound (US) to confirm the presence of pleural effusion and a safe distance (>2 cm) from the parietal to visceral pleura at the expected entry site, preferably in the middle of the intercostal spaces 4 or 5 in the midaxillary line¹².
2. Mark the expected entry site with a designated pen.
3. In case of small-volume effusions, induce an artificial pneumothorax by inserting a blunt needle (e.g., 'Boutin needle') or a small-bore chest tube under direct ultrasound guidance. After fluid removal, air is introduced via the needle or drain, and ultrasound confirms the disappearance of lung sliding^8,12.
   1. If in doubt, perform a lateral decubitus chest X-ray to confirm the presence and depth of the pneumothorax.
4. Place the patient in the lateral decubitus position on a pillow or roll, facing the operator, with the effusion side up. The pillow/roll spreads the contralateral ribs, making it easier to insert the trocar and cannula, and minimizing the patient's discomfort¹¹.
5. Prepare for the sterile procedure according to local standards:
   1. For operator and any assistant: surgical hand scrub, sterile gown and gloves, mask, cap.
   2. For patient: cleanse the skin with an alcohol-based sterilizing solution, use sterile draping for coverage while leaving the expected entry site accessible.
   3. For tools: sterile table with a knife, trocar, cannula, endoscope, forceps, suction, and skin suture tools¹¹(see Table of Materials).
6. Commence sedation with a benzodiazepine (e.g., midazolam 1 mg/mL) IV in incremental doses, combined with an opiate (e.g., fentanyl 25 microgram/mL) IV in incremental doses to control pain and cough. In select centers, LAT may be performed with thoracic nerve blocks or with remifentanil sedation¹².
7. Ensure sufficient additional sedation is available during the procedure in case of pain, cough, or agitation.

2. Patient preparation

1. Anesthetize all layers step by step with 20 mL of lidocaine 1% (or mepivacaine 2%) plus adrenaline: the skin, subcutaneous tissue, intercostal muscle, parietal pleura, intercostal nerve, and rib periosteum (the caudal rim of the upper and cranial rim of the lower rib)^7,11,18.
2. End the local anesthesia by checking the correctness of the entry site through the aspiration of pleural fluid (or air if an artificial pneumothorax is present), and note the distance from the skin to the pleural space^11,12.
3. Have additional doses of local anesthesia available during the procedure in case of pain or agitation.
4. Perform skin incision and insertion of trocar and cannula.
   1. Make an approximately 10 mm incision in the skin and subcutaneous tissue parallel to the intercostal space to allow for the trocar and cannula to pass easily.
      NOTE: A longer incision does not add maneuverability and needs to be closed with more stitches, which is associated with the risk of infections¹⁹.
   2. Ensure with the tip of the scalpel that adequate parietal pleural anesthesia has been achieved before trocar insertion.
5. Perform a careful blunt dissection of the various layers between the skin and the pleura with either a narrow-tip straight or curved forceps until the pleural cavity is entered, and a tract of sufficient width to allow the trocar and cannula to pass has been created.
   NOTE: The release of fluid or air (the latter often heard as a 'hiss') confirms the location. Optional: Blunt dissection might not be necessary for semirigid procedures given the smaller diameter of the working channel.
6. Consider inserting a closing ("mattress") suture (see Table of Materials), which is used later to seal the skin once the post-LAT chest drain is removed.
7. Guided by the distance from the skin to the pleural space, insert the trocar and cannula with a cork-screw movement until a sudden release of resistance is felt. Then, remove the trocar and push the cannula forward to lie 1-3 cm within the pleural cavity^11,12.

3. Inspection of the pleural cavity

1. Ensure that the thoracoscope image is optimized for focus and color correction, and that the lens has been warmed or has demisting liquid applied.
2. For semi-rigid LAT, insert the thoracoscope via the cannula and apply suction to remove the remaining fluid. For rigid LAT, insert a separate suction tube via the cannula to remove fluid before inserting the camera (Figure 1 and Figure 2).
3. Inspect the pleural cavity systematically: the apex, mediastinal surface, diaphragm, and costal pleura back to the apex. As with other endoscopic techniques, experts use deliberate and minimal movements to achieve full inspection^20,21.
   NOTE: If using a rigid setup, initial inspection is best carried out using a 50-degree lens before switching to a 0-degree lens for intervention.
4. Full visibility of the pleural space may be limited by fibrous pleuro-pulmonary adhesions¹². Gently swipe away fine adhesions with the thoracoscope, but avoid those with a vascular supply.

4. Tissue biopsy

1. Sample suspicious lesions on the parietal pleura with six to ten biopsies using appropriate forceps with a 'grip and strip' approach (Figure 3A,B). Ensure that there is sufficient penetration of the parietal pleural membrane, as the invasion of subpleural fat can affect mesothelioma T classification^8,12.
   1. Take care to avoid the visceral pleura due to the risk of lung injury and subsequent persistent air leak.
   2. Exercise caution to avoid the intercostal neurovascular bundle due to the risk of bleeding and neuralgia.
      NOTE: Safety tip: Feeling the rib with the forceps and obtaining biopsies from the parietal pleura 'on' the rib is believed to reduce the risk of bleeding and damage to underlying vessels.
   3. For semirigid thoracoscope procedures, introduce the forceps via the endoscope working channel. Switching to narrow-band imaging may improve the visualization of areas with abnormal vascular patterns^13,22.
   4. For rigid thoracoscope procedures, introduce over-scope forceps.
2. In the absence of clear malignant infiltration but with strong clinical suspicion of malignancy, perform random biopsies¹¹.
3. Send 1-2 biopsies for culture and tuberculosis analysis, especially in endemic areas, or in patients with risk factors²³.
4. If pleural infection is suspected during LAT, remove infectious debris (Figure 3C) and adhesions as far as possible^12,24. Note that LAT is not an optimal procedure for the clearance of complex or widespread pleural infection⁹.

5. Termination and insertion of chest tube

1. Remove the thoracoscope and cannula.
2. Insert the post-LAT chest tube (typically 16-24 F, see Table of Materials) into the pleural space via the port tract.
3. Close the incision with the "mattress" suture (as described in 2.6) or use another closing suture.
   ​NOTE: Talc pleurodesis and/or placement of an indwelling pleural catheter (IPC) can be optionally performed in combination with the LAT procedure and are now standard practice in many centers⁸. The description of talc pleurodesis or IPC procedures is beyond the scope of the current review.

6. Follow-up procedures

1. Remove the chest tube when air and fluid production ceases, typically within 1-2 h.
   NOTE: While a pre-removal chest X-ray or thoracic ultrasound is not mandatory, it may be helpful for assessing lung re-expansion.
2. Close the incision with appropriate sutures or adhesive glue (see Table of Materials).
3. Observe the patient for stability over 2-4 h.
   NOTE: Although a post-removal chest X-ray or thoracic ultrasound is not mandatory, it can be helpful in assessing lung re-expansion. Patients who are well and stable after observation are discharged with a written action plan in case of serious symptoms²⁵.
4. Admit frail patients to the ward for further observation and treatment.

Results

The described LAT technique using either the rigid or semirigid thoracoscopes (Figure 1 and Figure 2) enables the operator to perform conclusive biopsy sampling from the visceral pleural (Figure 3) with a diagnostic yield of 93% in a large systematic review on more than 5000 procedures (Table 1 and Supplementary File 1) (rigid: 93% [95% confidence interval 91%-95%]; semirigid: 93% [89%-97%])

Discussion

This article provides a practical approach for performing LAT.

A single randomized trial compared rigid with semirigid LAT and found no differences concerning diagnostic yield or safety¹⁵. Evidence on how to optimize the critical steps is sparse. A group of one of the authors suggested eight critical steps for semirigid LAT and presented a competence checklist for learning LAT in a phantom based on their own experiences, narrative reviews^8,<...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Chest tube			16-24F
Forceps			narrow tip, straight or curved
Indwelling pleural catheter	Rocket Medical plc.	R55400-16-MT	or PleurX (from Becton Dickinson) or similar
Local anaesthetics			20 mL of lidocaine 1% (or mepivacaine 2%) ± adrenaline
Non-absorbable suture			Eg. Dafilon 2/0
Rigid thoracoscope	Karl Storz GmbH	Hopkins-II	with forceps 26072A and cannula+trocar 30120 NOL (or similar from eg. Richard Wolf GmbH)
Scalpel			triangular
Semirigid thoracoscope	Olympus	LTF-160	with forceps FB-420K and cannula+trocar N1002130