Image-guided drainage of intrathoracic air and fluid collections

General description of procedure, equipment, technique

In some patients with intrathoracic fluid collections, the use of sonography, computerized tomography (CT), or fluoroscopy to guide percutaneous placement of small-bore drainage catheters allows for a less invasive alternative to “blind” or “convention” large-bore chest tube placement or surgical management. Sonography is typically used to characterize pleural fluid collections and guide diagnostic thoracentesis, and aids in the proper placement of indwelling pleural catheters.

CT provides a more comprehensive assessment of extent of pleural disease and is used in managing loculated pleural fluid collections and in drainage of intrapulmonary abscesses or infected bullae.

Fluoroscopy is useful for guiding evacuation of pneumothorax and for catheter manipulation and exchange in patients with intrapleural devices placed to drain fluid collections.

Indications and patient selection

A variety of intrathoracic fluid collections can be managed with small-bore catheters placed percutaneously using imaging guidance. Examples include:

• Complicated parapneumonic effusion and empyema

• Hemothorax

• Pneumothorax

• Malignant pleural effusion

• Selected transudative pleural effusions, including those in patients with intractable effusion secondary to congestive heart failure or hepatic hydrothorax

• Postoperative fluid collections, including pleural effusions, chylous effusions following esophagectomy, and loculated pneumothorax

• Lung abscess, infected bullae, and infected bronchogenic cyst

In general, pleural effusions that are small and free-flowing usually require only simple drainage and routine studies for fluid characterization. In these cases, image guidance techniques may enhance diagnostic thoracentesis. Image-guided catheter drainage of pleural fluid collections is recommended for patients at moderate or high risk of developing a “complex parapneumonic effusion” should it remain undrained.

Moderate and high-risk effusions are characterized by large size, presence of septation or loculation on sonography or CT, pH less than 7.2, LDH greater than 1000 IU/ml, glucose less than 40 mg/ml, positive gram stain, positive pleural fluid culture or frank pus. Patients best suited for image-guided percutaneous drainage, as opposed to surgical drainage, are those with smaller, free-flowing effusions or unilocular collections.

Patients with larger collections who are poor surgical candidates or for whom small-bore catheter placement may function as a bridge to surgical drainage may also benefit from image-guided catheter drainage. Larger, multiloculated effusions are usually best managed surgically, as surgery is generally highly successful and cost-effective.

Hemothorax is best managed with a large-bore tube thoracostomy or thoracoscopy in an effort to prevent fibrothorax and trapped lung. The technique is similar to that used for drainage of parapneumonic effusions.

A pneumothorax can be drained using a small-bore catheter. Indications for small-bore catheter placement include the presence of large or progressive spontaneous pneumothorax, including those that complicate percutaneous or transbronchial lung biopsy, central venous catheterization, or thoracentesis; and development of a loculated pneumothorax requiring precise drainage catheter placement using CT guidance. Patients with large air leaks that are due to a bronchopleural fistula are best managed using large-bore tube thoracostomy, and they may require surgical management for definitive therapy.

Most patients with malignant pleural effusions that persist or recur despite medical management of the underlying malignancy may be managed using small-bore catheter drainage and pleurodesis using a variety of sclerosing agents, including talc (Figure 1, Figure 2, Figure 3, Figure 4. Figure 5) as an alternative to an indwelling tunneled pleural catheter.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Contraindications

There are no absolute contraindications to image-guided thoracic drainage. A platelet count of less than 50,000, an uncorrected coagulopathy should be corrected prior to catheter placement if possible.

Details of how the procedure is performed

The approach to drainage of pleural space collections varies according to the indication for the procedure.

Parapneumonic effusion drainage:

Image-guided drainage of a parapneumonic effusion is performed via sonography for small or free-flowing effusions. CT provides a more global evaluation of the chest. CT is particularly useful for multiloculated collections and for those that are apical or medial in location and difficult to visualize and access via a standard intercostal approach.

Drainage may be performed using moderate sedation and local anesthesia to enhance patient comfort and cooperation. Small, 8-10-French pigtail drainage catheters are sufficient for serous, free-flowing collections and for use in children, whereas larger catheters (12-16-French) (Figure 6, Figure 7, Figure 8, Figure 9, Figure 10) or large-bore chest tubes (e.g., 28-French) are used for bigger, more viscous collections. Either a Seldinger technique, with gradual dilatation of the tract to the desired diameter, or a single-puncture, trocar-based technique can be utilized for catheter or tube placement.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Multiloculated collections may require placement of multiple catheters into separate, noncontiguous locules that are unlikely to drain using a single catheter even with adjunctive use of intrapleural fibrinolytics. Once appropriate positioning of the catheter is documented (usually through repeat imaging), the catheter is affixed to the skin and attached to a collection device (e.g., a Pleur-Evac) for suction drainage.

Intrapleural fibrinolytics, usually in the form of tissue plasminogen activator (t-PA), may be instilled through the tube daily (6 mg in 50 ml sterile water or normal saline) to drain loculated collections, those with internal septations noted on sonographic imaging, or thick, purulent collections that do not drain adequately following initial catheter placement. The MIST2 trial evaluating the combined use of intrapleural t-PA with DNase in patients with parapneumonic effusions suggests that this combination is superior to intrapleural fibrinolysis or DNase alone or no intrapleural therapy in the need for surgical referral and length of hospital stay. Therefore, placement of one or more thoracostomy tubes into large pleural locules followed by twice daily instillation of t-PA (10 mg) with DNase (5 mg) for three days is the non-surgical procedure of choice.

Pneumothorax drainage:

Non-loculated pneumothorax is best drained using fluoroscopy or CT guidance. An anterior approach via the second intercostal space in the mid-clavicular line allows access to the pleural apex, where the drainage holes in the distal end of the catheter are optimally positioned. A lateral intercostal approach can be used to avoid the breast in female patients.

Once the catheter entry site has been marked and the skin prepared using sterile technique, lidocaine is administered superficially and deeply into the subcutaneous layers until air can be aspirated into the syringe. The needle is then withdrawn to the point at which air can no longer be freely aspirated. This position defines the level of the parietal pleura, which is heavily innervated so it must be optimally anesthetized to allow painless catheter placement. The Seldinger technique or use of a trocar-based catheter can be employed to insert a catheter into the pleural space apex or into a loculated pneumothorax. The catheter is then affixed to the skin and attached to a Pleur-Evac for suction drainage.

Malignant pleural effusion drainage:

Sonographic guidance is used for catheter placement for drainage of malignant pleural effusions and subsequent pleurodesis. The patient is placed in the seated position. Ultrasound is used to select a catheter placement site along the lower posterolateral chest wall in order to prevent the patient from lying on the catheter when supine. Such catheter positioning also helps avoid injury to intercostal vessels, which tend to have a more reliably subcostal course then exists posteriorly, as they extend laterally from the paravertebral region.

A trocar-based technique similar to that used for drainage of other pleural fluid collections is performed using a sterile technique and local anesthesia. In order to minimize the risk of re-expansion pulmonary edema, care is taken to monitor intra-pleural pressure swings with manometry or for surrogate symptoms such as chest discomfort during the procedure.

Interpretation of results

Not applicable to this procedure.

Performance characteristics of the procedure (applies only to diagnostic procedures)

Not applicable.

Outcomes (applies only to therapeutic procedures)

The success rate for image-guided drainage of parapneumonic effusions is reported at 67-83 percent, but the success rate is highly dependent on the nature of the fluid, the size and complexity of the collection, patient comorbidities as well as the skill of the individual placing the catheter and caring for the patient.

The literature suggests that in well-selected patients the sequential administration of t-PA and DNase twice daily as described above resulted in a 4% versus 16% referral rate for surgical intervention at 3 months in pleural space infections. In addition, there was a reduction in hospital length of stay of 6.7 days compared to placebo without increase in adverse events.

Small-bore catheters have successfully drained pneumothoraces in more than 80 percent of patients, with lower complication rates compared to large-bore thoracostomy tubes.

Several studies have shown partial or complete response rates (improvement of dyspnea associated with minimal fluid re-accumulation) higher than 70 percent in selected patients with malignant pleural effusions with tube thoracostomy and talc slurry. Several of these patients benefited from small-bore catheter drainage and pleurodesis. Patients who have a persistently high volume of pleural fluid drainage (e.g., > 100 ml/day) and those who have significant pleural tumor burden or underlying parenchymal involvement are least likely to respond. For these patients, a tunneled, indwelling catheter (e.g., PleurX catheter) may allow for better control of fluid re-accumulation on a palliative, outpatient basis.

Alternative and/or additional procedures to consider

Simple thoracentesis, when employed early in the course of a simple parapneumonic effusion, can be as effective as tube thoracostomy. Although repeated thoracentesis may allow for successful management of non-loculated collections, they may be uncomfortable and impractical for many patients.

Placement of a large-bore thoracostomy tube into the dependent aspect of a non-loculated parapneumonic effusion may be effective, but the procedure has a relatively high failure rate for complex, multiloculated collections. Surgical drainage of complex parapneumonic effusions using video-assisted thoracoscopic surgery (VATS) has become the procedure of choice for many patients who are operative candidates. VATS is associated with a high success rate and is a cost-effective means of management.

Small and asymptomatic pneumothorax can be managed by observation, administration of supplemental oxygen, and simple needle aspiration if indicated. Large tube drainage is reserved for large pneumothoraces in patients with air leaks. Patients with ongoing air leaks and those with recurrent spontaneous pneumothorax are best managed using VATS for bleb resection and abrasive pleurodesis.

Malignant pleural effusions that are likely to respond to treatment of the underlying malignancy do not generally require drainage. In patients who require evaluation in order to establish a diagnosis of pleural malignancy, thoracoscopic pleural biopsy and talc pleurodesis are the most efficient means of management. Patients with a limited life expectancy who fail or refuse tube thoracostomy and pleurodesis can be managed using a tunneled, indwelling device (e.g., a PleurX catheter) that allows intermittent external drainage and a high rate of spontaneous pleurodesis.

Complications and their management

Complications of image-guided catheter placement include bleeding, nerve injury, pneumothorax, and infection. Sonographic and CT guidance can help avoid injury to the intercostal neurovascular structures beneath the ribs.

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