Thoracoscopic Wedge Resection

Thoracoscopic wedge resection (TWR) is a minimally invasive (non–rib spreading), nonanatomic limited resection of a lung portion. The technique involves a video thoracoscope for access. The only difference between TWR and open resection in terms of technique is that the former involves minimal invasiveness. Video-assisted thoracoscopic surgery (VATS) is a safe procedure, even in high-risk patients such as elderly individuals and those with limited cardiopulmonary reserve.[1, 2, 3, 4] It is a parenchymal-sparing procedure that results in earlier recovery than conventional thoracotomy and that is associated with fewer postoperative complications (wound healing, dehiscence, intercostal nerve damage and pain).

Precise resection presents unique challenges and localization of the pathology site is arduous in some patients. For example, when the tumor is in the deep parenchyma, tumor identification is very difficult. Prior CT-guided localization is helpful. Margin distance in TWR affects local recurrence and securing a sufficient surgical margin is very important. Use of TWR is more limited when the tumor location is deep to the visceral pleura because it is difficult to secure an adequate surgical margin.[5] Overall, TWR is safe and reliable and very useful for lesions at the lung periphery or small lesions at the outer one third of the lung.

 

TWR is indicated as both a diagnostic and therapeutic intervention in several thoracic diseases. Lesions at the periphery or outer one third of the lung represent the most suitable indications. Common indications are listed below.[6, 7, 8]

Malignant indications are as follows:

• Early-stage non–small cell lung cancer (NSCLC; T1N0M0) and early-stage small-cell lung cancer in patients with limited cardiopulmonary reserve (although lobectomy is preferred)
• Metastasectomy of pulmonary metastases due to other cancers (renal, breast, colon, melanoma, sarcoma)
• Ground-glass opacification lesions on chest CT scan in patients with past or present cancer ^[5]
• Localization and excisional biopsy of ill-defined or small pulmonary lesions ^[9]

A study by Chiang et al in 1002 consecutive patients with cT1N0 lung adenocarcinoma concluded that wedge resection may be safe and feasible for sublobar resection in patients with a tumor diameter of 2 cm or smaller or a consolidation-to-tumor (C/T) ratio of 50% or lower. For patients who have cT1N0 lung adenocarcinoma with tumor diameter greater than 2 cm and a C/T ratio higher than 50%, these authors recommend segmentectomy as the appropriate surgical method for sublobar resection.[10]

Infectious indications for TWR include tubercular granulomas, aspergilloma, and focal organizing pneumonia. Other indications include the following:

• Excision of solitary pulmonary nodules
• Diagnosis of interstitial lung disease (ILD)
• Resection of hamartomas
• Resection of blebs
• Resection of pulmonary sclerosing hemangioma
• Resection of intralobar sequestrated lung
• Resection of localized bronchiectasis
• Lung volume reduction surgery in end-stage emphysema
• Resection of pulmonary arteriovenous malformations (PAVMs) ^{[11, 12]}

Contraindications to TWR are similar to those associated with VATS, including the following:

• Hemodynamic instabilit
• Inability to tolerate single-lung ventilation
• Coagulopathy
• Severe cardiopulmonary failure
• Prior talc pleurodesis
• Pleural adhesions
• Refractory or uncontrollable cough
• Lung lesion larger than 4 cm
• N2 lung cancer

Procedure Planning

Depending on pathological condition and comorbidities, outcomes of TWR vary. VATS resection is currently used for most thoracic surgeries, even in patients with limited cardiopulmonary reserve. Preoperative testing and patient selection are crucial to limit complications. Preoperative testing should include the following:

• Complete history and physical examination
• Routine blood tests
• Cardiac evaluation if the patient is symptomatic of or has risk factors for coronary artery disease (CAD) 
• Typed and cross-matched blood arranged for perioperative use
• Pulmonary function testing (discussed below)
• Imaging studies (discussed below)

Pulmonary function testing

Since TWR involves limited resection, it may be performed in patients with forced expiratory volume in 1 second (FEV1) and diffusing capacity of lung for carbon monoxide (DLCO) of less than 80% predicted. However, this necessitates further testing, such as cardiopulmonary exercise testing, split lung function, and predicted postoperative FEV1 and DLCO.

The European Respiratory Society (ERS) guidelines recommend limited resection if the predicted postoperative FEV1 and DLCO exceed 30% or the predicted postoperative peak oxygen consumption (VO2) exceeds 35% or 10 mL/kg/min.[13]

Imaging studies

Chest radiography is used to determine the location, size, and extent of the lesion(s). Most lesions listed above are incidental findings.

Chest CT scanning yields a higher sensitivity and specificity than chest radiography in identifying solitary pulmonary nodules and suspicious lesions. It is also helpful in assessing mediastinal lymph node involvement. It is the best modality for locating lesions in relation to fissures and lung edges, guiding the surgeon in localizing the resection site. Coronal view offers better delineation of lesions to surrounding structures. High-resolution CT (HRCT) scanning is more sensitive than conventional CT scanning. HRCT scanning is used to confirm the presence of emphysema, to quantify the amount of lung involved, and to locate bullous lesions.

Flexible bronchoscopy is essential in patients with lung cancer prior to surgery to exclude visible evidence of endobronchial disease.

Mediastinoscopy and lymph node sampling are required for accurate staging in lung cancer and involvement of nodes. N2 disease mandates open surgery for complete mediastinal lymphadenectomy or neoadjuvant chemotherapy.

The reported benefits of VATS compared with open thoracotomy includes smaller incisions, less pain, less blood loss, less respiratory compromise, less complications, and faster recovery times, all translating into shorter length of stay and similar survival.These findings have been reported in systematic reviews of randomized and nonrandomized clinical trials, and in comparative studies.[14]

Studies have compared lobectomy with wedge resection in NSCLC and have shown that the 5-year survival rate associated with wedge resection was lower than with lobectomy (58% vs 70%). However, rates of non–cancer-related deaths were higher in the wedge resection group than in the lobectomy group.[15, 16, 17, 18, 19, 20] In addition, patients undergoing wedge resection were in generally poorer health and had more comorbidities, thus making them ineligible for major lung surgery.

The mean mortality rate is 0%-2%.[21]  The mean operative time for VATS is less for simple resections.

A chest tube is left in postoperatively an average of 2-7 days. However, in some cases, a chest tube in not used or is removed early after VATS in selected patients, as it has shown reduced pain and increased lung function.[18, 19, 20]

The in-hospital length of stay and total cost of the procedure were significantly lower for VATS than for thoracotomy.[15, 16]

Informed consent should be obtained from all patients. A possible conversion to thoracotomy should be emphasized.

Equipment involved in thoracoscopic wedge resection (TWR) includes the following:

• Thoracoscope (5-mm or 10-mm scope with 0° or 30° lens)
• Television monitor
• Endoscope instruments
• Endostapling/transection devices
• Diathermy pen
• Thoracotomy tray (on standby)
• Suction source and tubing
• Chest tube (30F)
• Water seal drainage
• Sutures

Anesthesia

TWR requires general anesthesia provided through a double-lumen (preferable) or single-lumen tube with a bronchial blocker, in addition to single-lung ventilation. For some solitary pulmonary nodules, resection is performed with a local thoracic epidural, although this is not universal.

Positioning

The patient is placed in the full lateral decubitus position with the nonoperative lung in the dependent position and operated side of the lung unventilated. The operating table is flexed at midthorax to expand the intercostal space.[22] The patient’s shoulder and arm are extended and secured to a side rest.

Close intraoperative monitoring should include continuous pulse oximetry, capnography, mean arterial pressure, and heart rate.

Postoperatively, most patients are extubated in the operating room to prevent longer positive-pressure ventilation. Postoperative pain management consists of narcotics and narcoticlike agents. Chest tube is removed when the pleural effusion is lower than 400 mL/day and air leak flow < 40 mL/min for more than 8 h (and without spikes of airflow greater than this value).[22] Early ambulation is recommended.

A potential anesthesia-related complication is hoarseness of voice.

Potential cardiac complications include arrhythmias and angina.

Potential pulmonary complications include the following:

• Hemothorax
• Persistent air leak
• Subcutaneous emphysema
• Wound infection
• Ischemic necrotizing pneumonia
• Nonobstructive atelectasis
• Bronchopleural fistula
• Local and port-site recurrence of malignancy ^[23] (more common with wedge resection than with lobectomy)

The operative technique of thoracoscopic wedge resection (TWR) follows the same basic principles as those of thoracotomy except for minimal invasiveness and use of a thoracoscope. The operating surgeon should never hesitate to convert to open thoracotomy when complete resection of the lesion is in doubt. Conversion to thoracotomy is imperative in following conditions:[24]

• Massive bleeding
• Inability to locate the lesion
• Hilar or mediastinal lymphadenopathy
• The patient’s inability to tolerate single-lung ventilation

The steps of TWR are summarized below.[21, 25, 26, 27, 28, 29, 30, 31, 32, 33]

After anesthesia and positioning, the hemithorax is cleaned with antiseptics and sterile drapes placed. Considering the location of the pathology, the thoracoscope and instruments are positioned strategically to provide the best ergonomics for the surgeon in order to optimize the results.

Conventionally, wedge resections are performed with 3 small incision sites to accommodate the ports (5-10 mm)—one camera port and two ports for instruments. However, single-port VATS with the use of flexible instruments are becoming popular.[21, 28] A comparison study by Mizukami et al suggested that for pulmonary wedge resection, single-port VATS offers better pain control and cost-effectiveness than three-port VATS.[34]

The incision site depends on location of pathology. Incisions are placed at the upper end of ribs to avoid injury to the neurovascular bundle.

The primary incision site (generally for the thoracoscope [camera port]) is at the seventh or eighth intercostal space at the anterior to midaxillary line, which gives a panoramic view of entire lung. A trocar is introduced into the thoracic cavity, followed by insertion of the thoracoscope (see images below).

The second incision site is the anterior fourth and fifth intercostal space at the midclavicular or anterior axillary line. The third incision is posterior, at the fifth and sixth intercostal space adjacent to the scapula. These triangulated incisions are similar to a baseball-diamond concept. Ports are placed far enough from each other to avoid crowding of instruments. If conversion to open or minithoracotomy is required, connecting the anterior and posterior port sites provides incision access, and the inferior port is used for chest tube insertion.

Localization of the pathologic site is crucial, although this is arduous in some patients, especially those with small and deep lesions. The limited ability to digitally palpate the lung increases the risk of missing satellite lesions or other related pathology. Target lesions are identified based on visceral pleural changes such as puckering, dimpling, raised lesions over a deflated lung, increased vascularity, or overlying pleural adhesions. Expert surgeons seldom miss target lesions. For localizing lesions, preoperative CT-guided needle placement, hook-wire localization, or placement of radio-opaque marker (eg, methylene blue) can be used for guidance and lesion detection intraoperatively with fluoroscopy.[25, 26, 27]

Once the lesion is localized, several techniques may be used to resect the lung. The criterion standard method is resection with mechanical endoscopic staplers (see image below).

This is used to staple and resect the lung simultaneously (see images below).

Small lesions may be excised with single staple run, while larger lesions require 3-dimensional planning with numerous staple runs. The deflated lung tissue can be rotated from apex or base to lie over hilum to allow straight staple cuts. Other techniques include scalpel or diathermy resection with endoscopic suturing or a neodymium:yttrium-aluminum-garnet (ND:YAG) laser alone or in conjunction with mechanical staplers.

Endoscopic saline-enhanced thermal sealing is a new technology using a floating pen device or a grasper to resect the lung. Hemostasis is achieved with thermal sealing and does not require suturing or stapling. Unlike conventional cautery, this technique does not char the tissue.

The resected specimen is removed through the anterior port using wound protectors. Larger specimens are removed using endoscopic bags to prevent tumor implantation. After resection, the lung is examined for air leaks, and a chest tube is placed through the inferior port and connected to a water seal.

As an alternative to chest tube placement in selected patients, chest drainage may be provided by a 7-Fr double-lumen central venous catheter along with a prophylactic air-extraction strategy. A prospective randomized controlled trial by Wei et al found that acute pain after lung wedge resection through VATS was significantly lower with central venous catheter drainage than with conventional chest tube drainage.[35]