What anesthetic techniques can be utilized for VAT?
VAT is usually performed under general anesthesia. It is essential to provide excellent lung deflation and maintain oxygenation using one-lung ventilation. With a thoraco-tomy incision, the surgeon can manually retract the lung if necessary, and has greater access and exposure. Under VAT, if the lung is not fully deflated, it is difficult for the surgeon to operate on the lung using the thoracoscopic instruments and it may be difficult to locate the lung nodule. If the pneumothorax is inadequate, the surgeon will have too small a working space. Inadequate surgical exposure may then necessitate a thoracotomy incision, which is associ-ated with a higher incidence of morbidity and mortality.
One-lung ventilation can most reliably be achieved with a double-lumen endobronchial tube, which allows for lung deflation by egress of gas through the lumen of the tube. As soon as the patient is turned to the lateral decubitus posi-tion, and the position of the tube is rechecked, the lung to be operated on is deflated, and one-lung ventilation is instituted.
An alternative to the double-lumen tube is a single-lumen tube, with a bronchial blocker, or a Univent® tube, which is a single-lumen tube that incorporates a blocker and a channel for the blocker. Prior to inflating the blocker, the breathing circuit should be disconnected, and the tracheal tube suctioned to facilitate deflation of the lungs. If the lung is not allowed to deflate prior to inflation of the bronchial blocker, it will take a long time for lung deflation to occur. Next the blocker is inflated, and ventilation is resumed. If a Fogarty embolectomy catheter is used as the blocker, the pathway for gas egress from the operated lung is completely occluded.
An alternative to the Fogarty embolectomy catheter is the Arndt blocker, which is a blocker specifically designed for use in the bronchi. The Arndt blocker has a lumen, which passes through the balloon to the tip of the catheter. There is a wire through the lumen, which protrudes beyond the distal tip, and ends in a loop. A fiberscope is passed through the loop and positioned in the bronchus to be blocked. The blocker is then advanced. Once the wire is removed from the catheter, it cannot be reinserted.
A blocker that has been recently introduced into prac-tice is the Cohen blocker. This blocker contains a wheel at the proximal end that bends the tip of the blocker when it is turned. This blocker also contains a lumen. However, the lumens of the Arndt and the Cohen blockers are much smaller than the lumen of a double-lumen tube, resulting in a much slower lung deflation.
VAT may be performed to evaluate and/or treat pleural disease, such as in a patient with a pneumothorax or a pleural effusion. A pleural biopsy and pleurodesis may be planned. In these cases, it may be possible to perform the surgery under epidural anesthesia or intercostal blocks; a general anesthetic may not be necessary. If surgery is performed under a regional block in a spontaneously breathing patient, the lung will collapse when the chest (pleural cavity) is opened.