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
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.