Surgical Technique Median Sternotomy 1012

Before the operation, while the patient is still awake, a thoracic epidural catheter is inserted for intraoperative and postoperative analgesia. Initially, a 6-8 cm3 bolus of a mixture of bupivacaine (0.25%) and fentanyl (75-100 mcg) is injected in the epidural catheter followed by a continuous infusion of a solution of bupivacaine (0.075% ) and fentanyl (5 mcg/cm3) at a rate of 8-10 cm3/h. A double-lumen tube is used for selective ventilation. The vertical skin incision is made shorter than the sternotomy itself to minimize the risk of postoperative sternal infection in the event that a tracheostomy is required during the postoperative period (see Fig. 1). A small sponge is placed on a ring forcep and inserted double lumen tube double lumen tube

Median Sternotomy Patient Positioning
Fig. 1. Median sternotomy incision (broken line) starts 2 cm below the edge of the manubrium and ends at the level of the xiphoid process. Note patient is intubated with a double-lumen tube.

under the xiphoid process and is used to gently sweep the pleura laterally on each side. Ventilation is temporarily halted during the actual sternotomy. These maneuvers decrease the odds of penetration of the pleural space when the sternum is divided with the saw. The sternum is handled delicately and hemostasis is achieved with electrocautery. Pads are placed on the sternal edges to minimize potential damage by the retractor, which can be standard or internal mammary retractor (Delacroix Chevalier, France) (see Fig. 2).

The procedure is initiated on the more severely diseased lung, which is disconnected from the ventilator and allowed to deflate. Ventilation is continued on the contralateral lung. After 5-10 min, the areas of the lung with the most perfusion will be deflated, whereas the areas most affected by emphysema will remain inflated. The pleura is opened carefully to avoid damage to the lung parenchyma. At the beginning of our experience, we routinely attempted to mobilize a portion of the apical parietal pleura to create a pleural tent, hoping to decrease the postresection residual pleural space. More often than not, the fragility of the tissue resulted in a fenestrated pleural tent. As this defeats the purpose of the pleural tent, we have since abandoned this fruitless exercise. The pleural space is inspected and the lung is palpated

Chevalier Sternal Retractor
Fig. 2. (A) The broken line shows the intended incision of the mediastinal pleura. (B) An internal mammary retractor is used to elevate the sternum to favor exposure of the operative side.

delicately and thoroughly in search of unexpected pathology. When present, adhesions are meticulously divided with the electrocautery as far from the lung as possible to avoid tears in the pulmonary parenchyma. Manipulations and electrocautery are avoided in the neighborhood of the phrenic nerve. Next, the inferior pulmonary ligament is divided under direct vision with the electrocautery to favor optimal reexpansion following the procedure. Although this maneuver can cause hypotension, it is usually transient and well-tolerated. The pleural cavity is then half-filled with saline solution, elevating the lung into the wound. This minimizes manipulation of the fragile emphysematous lung and decrease the chances of prolonged air leak or pulmonary contusions.

The areas of intended resection are usually identified prior to operation, by review of computed tomography (CT) and perfusion scans. Frequently, the disease is most advanced in the apices. The lung to be resected is grasped with several Duvall clamps (see Fig. 3) and the resection is effected by three to five applications of a linear 90-mm GIA device with 4.8-mm staples, resulting in the removal of approx 50% of the upper lobe. Whereas the goal of LVRS is to remove 20%-30% of each lung (10), it is unclear exactly how this number was adopted. Even if one accepts this number on faith, it is difficult if not impossible to measure the resected lung volume during surgery. The resected lung tissue is sometimes weighed, but at the time of surgery there is no way of knowing the specific density of the lung removed relative to that of the lung left behind. The resection follows an inverted "U" shape pattern, in order to avoid significant mismatch between the contour of the new lung apex and the chest wall (see Fig. 4). The staple line is buttressed with bovine pericardial strips (Peri-strips Dry™, Bio-Vascular, St. Paul, MN) to minimize postoperative air leaks. Staple lines may also be reinforced by other commercially available materials, such as polytetrafluoroethylene (PTFE). If pleural adhesions are too dense in the area of intended resection, extrapleural dissection is recommended and the parietal pleura adherent to the lung is included in the resected specimen. When the disease is most severe in the lower lobes, as in | -1 antitrypsin deficiency (13), the resection follows the contour of the underlying diaphragm.

The volume-reduced lung is then gently reexpanded under saline solution to check for air leaks. Although minimal leaks are tolerated, every effort is made to address significant leaks with either reapplication of the stapling device, careful suturing of the parenchyma with nonabsorbable sutures or—ideally—application of one of the recently FDA-approved lung sealant products (e.g., FocalSeal™, Focal, Inc, Lexington, MA). The saline solution is suctioned, hemostasis is verified, and the pleural space is drained with a single 32-Fr. chest tube, inserted laterally with the tip positioned at the apex. No specific effort is made to close the pleura because it is rarely possible to achieve a hermetic seal. The contralateral lung is then deflated and the procedure is repeated in a similar fashion. The sternum is closed with at least seven stainless steel wires and the rectus abdominis aponeurosis is reapproximated with interrupted sutures. Each of the chest tubes is connected to its own collection system and is left on water seal postoperatively.

Chest Tube Collection Device
Fig. 3. Several Duvall clamps are gently applied along the area to be resected. The stapling device is oriented in such a manner to effect an inverted "U" shape excision of the parenchyma.
Sternotomy
Fig. 4. Typical specimen from LVRS of the upper lobe.

Throughout the operation, optimal communication with the anesthesiologist is of the utmost importance. The timing of the lung reexpansion, the maximum airway pressure (< 25 cm H2O), and the timing of extubation (usually in the operating room at the conclusion of skin closure) are key points where coordination between the surgical team and the anesthesiologist is vital.

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