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  1. Anesthetic technique. General anesthesia, in combination with epidural or regional anesthesia, is the preferred technique. If an epidural is used, it should be placed at the thoracic level (see Chapter 20).
    1. General anesthesia can be maintained with volatile anesthetic or total intravenous anesthesia (TIVA).
    2. Muscle relaxants are useful adjuncts to general anesthesia. Although surgical exposure does not require muscle relaxation, movement and coughing carry some risk.
    3. One-lung ventilation is typically necessary to isolate and collapse the operative lung to provide optimal surgical exposure. This can be achieved with DLT or bronchial blocker as described in the section that follows.
    4. Epidural analgesia is an effective method for postoperative pain relief after thoracotomy. The epidural may be used intraoperatively to augment the general anesthetic.
  2. Positioning. Operations for lung resection are most commonly performed in the lateral decubitus position with the bed sharply flexed and the hemithorax on the operative side parallel to the floor.
    1. The arms are usually extended in front of the patient and must be carefully padded to avoid compression of the radial and ulnar nerves or obstruction of arterial and venous cannulas. This can usually be avoided by placing cannulas in the dependent arm. The dependent brachial plexus must be checked for excessive tension. Various devices exist for supporting the upper arm securely above the lower, leaving the anesthetist with good access to the lower arm. Neither arm should be abducted more than 90°.
    2. The neck should remain in a neutral position, which requires constant support of the head during the movement of the bed into the flexed position. The dependent eye and ear should be carefully checked to ensure that they are not under any direct pressure.
    3. The lower extremities should be padded appropriately to avoid compression injuries. In male patients, the scrotum should be free of compressive forces.
    4. During the positioning process, the vital signs should be closely observed because pooling of blood in dependent extremities may cause hypotension.
    5. Changes in position can move the endobronchial tube or blocker and change V̇/Q̇ relationships.
    6. Lung compliance, lung isolation, and oxygenation should be reassessed after any change in position.
  3. Emergence and extubation. The goal of the anesthetic technique selected is to have an awake, comfortable, and extubated patient at the end of the procedure.
    1. Before closing the chest, the operative lung is inflated with 20 to 30 cm H2O pressure for 15 to 30 seconds to reinflate the atelectatic areas and check for significant air leaks.
    2. Chest tubes are inserted to drain the pleural cavity and promote lung expansion. Chest tubes usually are placed under water seal and up to 20 cm H2O suction, except after a pneumonectomy. After pneumonectomy, a chest tube, if used, should be placed under water seal only. Applying suction could shift the mediastinum to the draining side and reduce venous return, causing tension physiology.
    3. At the conclusion of the procedure with both lungs ventilated, nitrous oxide, in concentrations up to 70%, can provide a smooth emergence. It is essential that the chest tubes are functioning. Ensuring complete reversal on paralysis is also key in these patients.
    4. Prompt extubation avoids the potential disruptive effects of endotracheal intubation and positive-pressure ventilation on fresh suture lines. If postoperative mechanical ventilation is required, the DLT should be exchanged for a conventional ETT with a high-volume low-pressure cuff. Inspiratory pressures should be kept as low as possible.
  4. Surgical techniques
    1. Lateral or posterolateral thoracotomy is an approach for the resection of large pulmonary neoplasms or abscesses. Thoracotomy is often preceded by staging procedures such as bronchoscopy, mediastinoscopy, or thoracoscopy. If the staging procedures are performed at the same sitting, the anesthetic should be planned to accommodate the possibility of a shortened procedure if metastatic disease is discovered.
    2. Video-assisted thoracoscopic surgery (VATS) is a common approach for wedge resection, segmentectomy, and lobectomy. Thoracoscopic surgery may result in less postoperative pain and a shorter recovery time. Lung isolation is required for adequate visualization of the surgical field.
    3. Robot-assisted thoracoscopic surgery (RATS) is a growing technique that is theoretically superior to VATS in that the accuracy of the robotic arm facilitates lymph node resection with the conservation of nerves and improved cure rates.
      1. As with VATS, positioning is in lateral decubitus and complete collapse of the operative lung must be maintained. Low-pressure CO2 is often used to augment this collapse.
      2. Good pressure point padding must be ensured due to extremes of positioning with robotic surgery.
      3. It has been previously stated that once the robot is docked, the surgical bed must not be moved at all. However, newer robotic system allows the robot and the surgical bed to be moved as one unit, decreasing the risk for patient injury when the bed position is changed.
      4. It is important to ensure that adequate muscle relation during RATS as patient coughing or movement during surgery can be dangerous.
  5. Endobronchial tubes. Placement of a DLT is indicated for lung protection (for significant hemoptysis or unilateral infection), bronchoalveolar lavage, or surgical exposure.
    1. Choice of tube
      1. DLTs range in size from 26 to 41 French. In general, a 39- or 41-French tube is chosen for adult males and a 35- or 37-French is chosen for adult females. Selection is also based on the patient’s height. In general, for men, 70 inches is used for a cutoff height between the 39- or 41-French tubes. For women, 65 inches is a cutoff between 35 or 37 French.
      2. Right- and left-sided DLTs are available and are designed to conform to either the right or the left mainstem bronchus. Each tube has separate channels: one for ventilation of the bronchus and the other for the trachea and nonintubated bronchus. Right-sided tubes have a separate opening (Murphy eye) in the bronchial lumen to permit ventilation of the right upper lobe.
      3. The choice of a left- or right-sided tube depends on the type and side of operation. If a mainstem bronchus is absent, stenotic, disrupted, or obstructed, the DLT must be placed on the opposite side, preferably under direct fiberoptic guidance. In most cases, the choice of a left- versus right-sided tube is not so absolute. Most surgical procedures can be performed with a left-sided DLT. It is our practice, however, to selectively intubate the dependent (nonoperative) bronchus. This ensures that the endobronchial tube will not interfere with resection of the mainstem bronchus if this is necessary. Also, if the nondependent lung is intubated, ventilation of the dependent lung through the tracheal lumen may be compromised by mediastinal pressure pushing the tube against the tracheal wall and creating a “ball-valve” obstruction.
    2. Insertion
      1. The endobronchial tube, including both cuffs and all necessary connectors, should be carefully checked before placement. The tube may be lubricated, and a stylet should be placed in the bronchial lumen.
      2. After laryngoscopy, the endobronchial tube should be inserted initially with the distal curve facing anteriorly. Once in the trachea, the stylet should be removed and the tube rotated so that the bronchial lumen is toward the appropriate side. The tube is then advanced to an average depth of 29 cm at the incisors or gums (27 cm in females) or less if resistance is met.
      3. Alternatively, a fiberoptic bronchoscope can be passed down the bronchial lumen as soon as the tube is in the trachea and then used to guide the tube into the correct mainstem bronchus.
      4. Once the tube has been inserted and connected to the anesthesia circuit, the tracheal cuff is inflated, and manual ventilation is initiated. Endotracheal placement is confirmed by the presence of end-tidal CO2 and the auscultation of bilateral breath sounds. The tracheal side of the adapter is then clamped, and the distal tracheal lumen is opened to atmospheric pressure via the access port. The bronchial cuff is inflated to a point just sufficient to eliminate air leak from the tracheal lumen, and the chest is auscultated. Breath sounds should now be limited to the side that has been endobronchially intubated. Moving the clamp to the bronchial side of the adapter and closing the tracheal access port should cause only the nonintubated side to be ventilated.
      5. Fiberoptic bronchoscope should be used to confirm tube position. When passed down the tracheal lumen, the bronchoscope should reveal the carina with the proximal edge of the bronchial cuff just visible in the mainstem bronchus. Passing the bronchoscope down the bronchial lumen should reveal either the left mainstem bronchus or the bronchus intermedius, depending on whether a left- or right-sided tube has been placed. The orifice of the right upper lobe should be visible through the side lumen of a right-sided tube. A bronchoscope should be kept available throughout the case.
      6. Lung isolation can be monitored continuously if the anesthesia machine is able to measure inspiratory and expiratory volumes independently and display the leak.
    3. DLT tube malposition commonly has a few patterns.
      1. The tube is placed too far into the bronchus so that the distal lumen ventilates a single lobe.
      2. The tube is too shallow such that the bronchial balloon obstructs the entire tracheal lumen.
      3. A left-sided tube is misplaced into the right mainstem bronchus, with the right upper lobe mistakenly thought to be the entire right bronchus. This malposition can be corrected under bronchoscopic guidance via the bronchial lumen, withdrawing the tube to the trachea and directing toward the left mainstem bronchus.
    4. Prior to extubation or any significant manipulation of the endobronchial tube, the bronchial cuff should be deflated.
    5. The procedure for passing an endobronchial tube through an existing tracheostomy stoma is identical. Bronchoscopy will help to determine how far the tube should be advanced once it is in the trachea.
  6. Univent tubes are large-caliber ETTs encompassing a small integrated channel for a built-in bronchial blocker. Indications for a Univent tube include the need for post-op intubation, the desire to avoid changing from a DLT to a single-lumen tube, and situations in which placement of a DLT is difficult or contraindicated. A potential complication is inadvertent advancement and insufflation of the bronchial blocker into the trachea, causing complete obstruction to ventilation.
    1. Insertion. The Univent tube is inserted into the trachea in the usual fashion and is rotated toward the operative lung. After inflation of the tracheal cuff, the bronchial blocker is advanced into the operative mainstem bronchus under fiberoptic guidance. After appropriate positioning, the cuff of the bronchial blocker is inflated. Because the Univent tube is made of Silastic rather than polyvinyl chloride, thorough lubrication of the bronchoscope is required.
    2. Collapse of the operative lung occurs through both exhalation via the small distal opening in the blocker and progressive absorption of oxygen from the lung, which will produce alveolar collapse. This is a slow process but may be hastened by deflating the blocker and disconnecting the anesthesia circuit while observing the lung. Once collapse has occurred, the blocker can be reinflated and the circuit reconnected.
  7. Bronchial blockers may be used routinely, but especially in situations in which it is not possible to place an endobronchial tube, including in pediatric patients, in those with difficult airway anatomy, or where satisfactory lung isolation cannot be achieved by other means.
    1. Vascular occlusion catheters, such as the Fogarty, are an older source for bronchial blocker. An appropriately sized Fogarty catheter (8- to 14-French venous occlusion catheter with a 10-mL balloon) is selected and placed into the trachea before endotracheal intubation. After intubation, the balloon tip is positioned with a fiberoptic bronchoscope in the appropriate mainstem bronchus and inflated. Lung collapse occurs slowly, via absorption of gases. There is no ability to suction or perform maneuvers such as continuous positive airway pressure (CPAP) to the nonventilated lung.
    2. The Arndt blocker is a bronchial blocker especially designed for lung isolation. Placement is facilitated by a distal loop that can be snared with a bronchoscope. The airway connector is well designed, with separate access ports for the blocker, bronchoscope, and ventilation circuit. Like the Univent tube, the blocker has a small central lumen that can be used for lung collapse or CPAP.
    3. The Y-shaped EZ-blocker is designed to simplify positioning. Like the Arndt blocker, it includes an airway connector that allows simultaneous ventilation, bronchoscopic visualization, and blocker placement. This blocker terminates at a Y shape that mimics the carinal division into the mainstem bronchi, terminating with a cuff on each extension. The blocker is placed such that the Y sits at the carina with the extensions in each mainstem bronchus. Each cuff can be inflated by its corresponding balloon. Like the other blockers, each extension has a small central lumen.
  8. Complications of lung isolation techniques include collapse of obstructed segments of the lung, airway trauma including bronchial rupture, bleeding, and aspiration during prolonged efforts at intubation. Hypoxia and hypoventilation may occur both during placement efforts and as a result of malpositioning.
  9. One-lung ventilation. General anesthesia, the lateral position, an open chest, surgical manipulations, and one-lung ventilation all alter ventilation and perfusion.
    1. Oxygenation
      1. The amount of pulmonary blood flow passing through the unventilated lung (pulmonary shunt) is the most important factor determining arterial oxygenation during one-lung ventilation.
      2. Diseased lungs often have reduced perfusion secondary to vascular occlusion or vasoconstriction. This may limit shunting of blood through the nonventilated operative lung during one-lung ventilation.
      3. Perfusion of the unventilated lung is also reduced by hypoxic pulmonary vasoconstriction (HPV). HPV is the pulmonary vascular mechanism that diverts blood flow away from poorly ventilated areas of the lung, minimizing V̇/Q̇ mismatch.
      4. Positive end-expiratory pressure (PEEP) has variable effect on the PVR, and PEEP has not been definitively shown to improve oxygenation during one-lung ventilation, but it is used as part of lung-protective strategies.
      5. The lateral position (as opposed to supine) reduces pulmonary shunting, because gravity decreases blood flowing to the nondependent lung.
      6. Oxygenation should be continuously monitored by pulse oximetry.
    2. Ventilation
      1. Arterial carbon dioxide tension during one-lung ventilation is generally maintained at the same level as on two lungs. This should not be at the expense of hyperinflating or overdistending the ventilated lung.
      2. Controlled ventilation is mandatory during open-chest operations.
      3. Plateau (or end-inspiratory) airway pressure should generally be maintained below 25 cm H2O to avoid overdistention of the lung. The occurrence of high airway pressure should be investigated immediately, including with a fiberoptic bronchoscope and is usually due to malpositioning of the endobronchial tube or the presence of secretions.
      4. Tidal volume should be maintained in the 4 to 6 mL/kg range for protective one-lung ventilation.
      5. A moderate increase in partial pressure of carbon dioxide in arterial blood is usually well tolerated. Respiratory rate can be increased to maintain minute ventilation if necessary (as long as intrinsic PEEP and air trapping are minimal).
      6. When switching from two-lung to one-lung ventilation, manual ventilation allows instantaneous adaptation to the expected changes in compliance and facilitates assessment of lung isolation. Once tidal volume and compliance have been assessed by hand and lung collapse has been confirmed visually, mechanical ventilation can be reinstituted.
  10. Management of one-lung ventilation
    1. Anesthetic management. During one-lung ventilation, the use of nitrous oxide is limited or discontinued if there is any evidence of a significant decrease in partial pressure of oxygen in arterial blood (eg, a decrease in oxygen saturation).
    2. Difficulties with oxygenation during one-lung ventilation may be treated with a variety of maneuvers directed at decreasing blood flow to the nonventilated lung (decreasing shunt fraction), minimizing atelectasis in the ventilated lung, or providing additional oxygen to the operative lung.
      1. Tube position should be reassessed by fiberoptic bronchoscopy and repositioned if necessary. Additionally, the bronchial lumen should be suctioned to clear secretions and ensure patency.
      2. CPAP can be applied to the nonventilated lung with a separate circuit. Under direct visualization, the collapsed lung is inflated and then allowed to deflate to a volume that will not interfere with surgical exposure (usually 2-5 cm H2O CPAP).
      3. PEEP may be increased to the ventilated lung to treat atelectasis, but this may lower arterial oxygen saturation if a greater proportion of blood flow is forced into the unventilated lung as a result.
      4. Recruitment maneuvers to overcome atelectasis have been shown to be effective.
      5. Apneic oxygenation may be provided to the nonventilated lung by partially inflating it with 100% oxygen and then capping the exhalation port. In this way, a motionless partially collapsed lung is maintained. Reinstallation of oxygen will be necessary every 10 to 20 minutes.
      6. In the event of persistent hypoxemia that is uncorrectable by combinations of the aforementioned therapies or a sudden precipitous desaturation, the surgeon must be notified and the operative lung reinflated with 100% oxygen. Two-lung ventilation should be maintained until the situation has stabilized, after which the operative lung can be allowed to collapse again. Periodic reinflations or manual two-lung ventilation may be required to maintain an adequate arterial oxygen saturation throughout some procedures. Consideration should also be given to nonpulmonary etiology of the shunt (ie, PFO with right to left shunt) in the setting of elevated right-sided pressures on OLV.
      7. TIVA may be preferred to the administration of a volatile anesthetic, because it is easier to maintain a constant depth of anesthesia while performing maneuvers to improve oxygenation and ventilation. TIVA has not been shown to decrease hypoxia, and unlike inhalation agents, it does not attenuate the inflammatory response.
      8. If hypoxemia persists, the surgeon can minimize shunt by compressing or clamping the pulmonary artery of the surgical lung or any of its available lobes.
      9. CPB or ECMO can be instituted to provide oxygenation (see Chapter 29) in extreme situations.
    3. When switching from one-lung back to two-lung ventilation, a few manual breaths with a prolonged inspiratory hold will help to reexpand collapsed alveoli.
  11. Postoperative analgesia. Posterolateral thoracotomy is a painful incision, involving multiple muscle layers, rib resection, and continuous motion as the patient breathes. Therapy for postoperative pain should begin before the patient emerges from general anesthesia.
    1. Epidural analgesia has been long considered the preferred approach for postthoracotomy pain management (see Chapter 39). Ipsilateral shoulder pain that thoracotomy patients commonly note is referred pain from phrenic nerve irritation and is not covered by epidural analgesia but is well treated with adjuncts, such as nonsteroidal analgesics and acetaminophen.
    2. Paravertebral nerve blocks
      1. Recent studies have suggested that paravertebral nerve blocks are an effective alternative to epidural analgesia in thoracotomy patients.
      2. Preoperative blocks are usually performed to provide sensory block from approximately T4 to T9. These blocks can be placed intraoperatively in the surgical field or percutaneously using anatomic landmarks, or ultrasound for guidance. The block may be conducted with the patient in either the sitting or prone position. Ultrasound-guided paramedian sagittal or transverse intercostal techniques may be used. For both ultrasound percutaneous techniques, the end point of the block is visualization of depression of the pleura by the local anesthetic into the paravertebral space. If landmark technique is used, the endpoint of the block is loss of resistance. A single-shot block provides analgesia for 12 to 24 hours depending on choice of local anesthetic. Additionally, an infusion catheter may be placed in the paravertebral space for continuous postoperative analgesia.
      3. Intercostal nerve blocks can be placed under direct thoracoscopic guidance, or percutaneously by following landmarks. The neurovascular bundle travels in a groove inferior to each rib. These nerve blocks provide analgesia for 6 to 8 hours. Care to avoid intravascular injection is important.
    3. Parenteral opioids, if required, should be administered judiciously.
    4. Nonsteroidal anti-inflammatory agents, such as ketorolac, have proved effective as a supplemental analgesic but should be used with caution in the elderly, in patients with renal insufficiency, and in those with a history of gastric bleeding. Acetaminophen is also effective for the treatment of referred shoulder pain as described above.