Principles of anesthesia and physiology

Vascular access

Prior to procedure commencement, consideration needs to be made regarding bleeding risk. Adequate caliber and the site of intravascular access need to be established. Despite the lower rate of blood transfusion in robotic gynecological and urological surgery, ^, the placement of an arterial line is preferred because access to the patient during robotic surgery is compromised. Arterial catheterization enables constant evaluation of hemodynamics and intermittent testing of respiratory parameters, bleeding status, and biochemistry.

Robotic cardiac surgery necessitates the placement of cannulas in particular locations. Preparation for cardiopulmonary bypass may require the anesthesiologist to place a 15 to 17 Fr cannula in the right internal jugular vein to facilitate the drainage of the superior vena cava. Further placement of cannulas including a coronary sinus cannula may also be necessary, and the pulmonary artery cannula may need to be placed in an alternative position. Cannulas are placed using transesophageal echocardiography guidance and thus anesthesiologists need to be familiar with this approach. External defibrillation pads need to put in place, as internal defibrillation is not possible.

Patient protection

Extreme operating table positions encountered in robotic surgery require prevention of patient movement. This is achieved through use of antislip mats and patient restraints. Deep muscle relaxation prior to port placement and throughout surgery is required as patient movement may lead to injury. Neuromuscular monitoring sited prior to procedure commencement facilitates adequate relaxation.

Intravascular catheters must be protected from kinking and compression, as after the patient cart has been docked, the arms are not easily accessible. The position of the arterial line transducer should be placed at the same height as the head such that the measured blood pressure reflects cerebral perfusion. This is particularly important in robotic surgeries such as gastric surgery where the reverse Trendelenburg position may compromise cerebral blood flow if not adequately identified and treated.

Long duration and poor visualization of the patient throughout surgery means it is essential that adequate time be taken to ensure the patient is protected from pressure injury. While rare, the effects of peripheral nerve injury may be prolonged. Excessive stretching and direct pressure of nerves must be avoided.

Nerves at particular risk include the common peroneal nerve when the modified lithotomy position is used. The brachial plexus is at risk of injury if excessive pressure is placed over the acromioclavicular joint and with excessive abduction of the arm. Utilization of somatosensory evoked potentials to monitor brachial plexus neuropathy is advantageous in robotic transaxillary thyroid and parathyroid surgery.

When a lateral decubitus position is used in thoracic surgery patients, an axillary roll placed inferior to the axilla will protect the brachial plexus. In this position, adequate padding needs to be placed between the knees and ankles and in the dependent arm; hyperextension of the elbow needs to be avoided.

In all surgeries, a neutral position of the head and neck is sought after.

Pressure sores and gluteal injury are possible, particularly when the patient is placed in a lithotomy position.

There are a variety of ways to protect the eyes. Whichever approach is undertaken, it is mandatory to ensure eye lubrication, closure, and protection from pressure. Further eye protection from regurgitation of gastric contents is afforded by nasogastric tube insertion.

The prone position employed in robotic esophagectomy poses increased risk of pressure injury and regular checks need to occur.

In transoral robotic surgery (TORS), utilization of goggles and a mouthguard protect the eyes and teeth, respectively.

Protection of the patient’s head from the robotic arms can be achieved by clamping an anesthetic screen such that it rests immediately above the patient’s face.

Movement of the table once the patient cart is docked can only be achieved if the table-robot interface has been fitted with a specific upgrade that allows dynamic movement of the table while the robot is docked. If this upgrade is not present, movements of the table must be strictly avoided as rigid instruments may cause significant visceral injury.

The prolonged duration of many robotic procedures and the risk of venous stasis due to pneumoperitoneum dictate a plan for deep venous thrombosis (DVT) prophylaxis to be implemented. Use of stockings and pneumatic calf compressors decrease the risk of DVT.