Year : 2010 | Volume
: 13 | Issue : 2 | Page : 169--175
Anesthesia for robotic cardiac surgery: An amalgam of technology and skill
Sandeep Chauhan, Subin Sukesan
Department of Cardiac Anaesthesiology, 7th Floor, CNC, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 029, India
Department of Cardiac Anaesthesiology, 7th Floor, CNC, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 029
The surgical procedures performed with robtic assitance and the scope for its future assistance is endless. To keep pace with the developing technologies in this field it is imperative for the cardiac anesthesiologists to have aworking knowledge of these systems, recognize potential complications and formulate an anesthetic plan to provide safe patient care. Challenges posed by the use of robotic systems include, long surgical times, problems with one lung anesthesia in presence of coronary artery disease, minimally invasive percutaneous cardiopulmonary bypass management and expertise in Trans-Esophageal Echocardiography. A long list of cardiac surgeries are performed with the use of robotic assistance, and the list is continuously growing as surgical innovation crosses new boundaries. Current research in robotic cardiac surgery like beating heart off pump intracardic repair, prototype epicardial crawling device, robotic fetal techniques etc. are in the stage of animal experimentation, but holds a lot of promise in future
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Chauhan S, Sukesan S. Anesthesia for robotic cardiac surgery: An amalgam of technology and skill.Ann Card Anaesth 2010;13:169-175
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Chauhan S, Sukesan S. Anesthesia for robotic cardiac surgery: An amalgam of technology and skill. Ann Card Anaesth [serial online] 2010 [cited 2021 Oct 20 ];13:169-175
Available from: https://www.annals.in/text.asp?2010/13/2/169/62947
Robotic cardiac surgery is now performed by several centers all over the world, including at least three in India; and their numbers are likely to increase. Robotic cardiac surgery helps reduce the size of surgical incisions, decrease surgical stress, minimize blood loss, and in early patient recovery. In addition, patient satisfaction is improved because of far better cosmetic results. In order to keep pace with the developing technologies in this field it is imperative for cardiac anesthetists to have a working knowledge of these systems to formulate an anesthetic plan, recognize potential complications, provide safe patient care and adapt to the fast developing field.
Two surgical robotic systems are in use today: Zeus Surgical System (Computer Motion, California, USA) and da Vinci Surgical System (Intuitive Surgical, California, USA).
The da Vinci System consists of three parts:
The control console where the surgeon sits to view the operative field and operates the robotic arms performing the surgery. An instrument tower containing video equipment to display an image of the operative field for the whole team, and Carbon dioxide (CO 2 ) insufflating equipment. The robot with three arms (four arms in the new version).
The main difference between the da Vinci and the Zeus systems is that the Zeus System uses a voice activated camera which can move in or out, based on the surgeon's voice command, and the robotic arms are attached to the table itself. ,,
Practical Difficulties Of Robotic Assisted Cardiac Surgeries
The robotic component of the da Vinci System, which has robotic arms, is very large in size, and so its positioning beside the patient is very crucial to avoid collision amongst the arms, or with the camera assistants or the patient when the arms move (patient-robot conflict). The large size of the robotic arms invades the anesthetist's working space and may make access to the patient difficult. This can make detection and management of endotracheal tube dislodgement or cardiopulmonary resuscitation almost impossible after robotic arm insertion. All the staff must be trained to quickly detach and remove the robot from the patient in such an emergency. Repositioning of patients after robotic arm placement is a very tedious process, hence proper positioning in the first instance is essential. Any motion of the patient or operating table with the robotic arms in situ may cause serious harm to the patient. 
Surgical Procedures Performed with Robotic Assistance
A long list of cardiac surgeries which can be performed better with the use of robotic assistance is given in [Table 1]. This list is continuously growing as surgical innovation crosses new boundaries.
Perioperative Anesthesia Plan
The perioperative anesthetic plan should keep in view the primary cardiac disease of the patient, restrictions set by the use of the robot, implication of one lung physiology in the setting of cardiac disease, prolonged percutaneous cardiopulmonary bypass (CPB) with its problems, and management of any complications, which may arise.
Patient selection: Proper patient selection is crucial for optimal results. Adequate patient size to allow insertion of robotic instruments with adequate movement of robotic arms is important. Ability of the patient to tolerate one lung ventilation (OLV - with the lung on the side of the chest through which instruments are introduced being deflated to avoid lung injury) should be tested prior to actual commencement of surgery in view of cardiac disease such as coronary artery disease (CAD), preexisting lung disease such as chronic obstructive pulmonary disease (COPD), tuberculosis, chronic bronchitis, asthma, or presence of cyanosis such as Tetralogy of Fallot's or severe pulmonary hypertension in left to right shunts. Elective CPB using femoral cannulation may be needed in these cases prolonging CPB times if OLV is not tolerated. Conditions such as chronic renal, hepatic failure, coagulopathy or a previous neurological event such as stroke which may not allow prolonged CPB should be screened for. Other relative contraindications are shown in [Table 2].
A typical arrangement of the robotic equipment and the position of the team are shown in [Figure 1].
Important issues specific to management of robotic cardiac surgery include patient positioning, long duration of the procedure, patient hypothermia, respiratory and hemodynamic effects of OLV and concealed blood loss. Good anesthetic management requires skills of cardiac & thoracic anesthesia, transesophageal echocardiography (TEE) and nonsternotomy CPB management [Table 3],[Table 4]. Patient hypothermia is an important problem because of the long procedural time, requiring active measures to prevent hypothermia. Apart from the use of OLV, CO 2 is insufflated into the hemithorax through the side being operated upon, to prevent smoke formation and hazard of gas explosion in the hemithorax. Increased CO 2 pressure, above 5-10 mmHg, may reduce venous return to the heart or result in increased arterial CO2 tension. , An 18G venous cannula in the pleural space can be used to measure pleural pressure and also act as a vent for excess CO 2 , avoiding tension capnothorax. Gastric decompression with a nasogastric tube may prevent rise of airway or intrapleural pressures from gastric distention. The capnothorax may interfere with TEE monitoring.
Right radial or bilateral radial arterial pressure is used for monitoring. This is done to detect migration of the endovascular balloon cannula causing obstruction of the innominate artery, if the heart port cannula is used for endovascular CPB.
Patient position: Proper patient position may be the key to a comfortably performed robotic cardiac surgery. Proper position allows robotic arm movement without obstruction and allows easy initiation of percutaneous CPB if needed for the procedure. Access to the patient chest and airway is nearly impossible after docking of the robot inside the patient chest through the working ports. Precautions must be taken to confirm the position of the double lumen endotracheal tube (DLT) before final patient position using a fiberoptic bronchoscope. For most robotic cardiac surgeries, the patient is positioned supine. The arm on the side of the chest port placement is allowed to hang over the edge of the table in a sling to allow space for port placement. Pads may be placed below the chest to elevate this hemithorax by 25-30 to allow port placement in a triangular arrangement. External defibrillating patches and electrocardiogram (ECG) stickers should be away from the site of port placement. External defibrillation patch electrodes are essential because defibrillation using external or internal paddles is not possible. The patient should be painted and draped for emergency sternotomy if required. A change in the electrical axis of the heart after creation of a capnothorax may make ST segment analysis on ECG unreliable. ,,,,,, [Table 5] shows problems specific to robotic cardiac surgery.
Respiratory System: Need for OLV and creation of a capnothorax with CO 2 insufflation on the side of robotic port placement causes respiratory embarrassment. There is a ventilation perfusion (V/Q) mismatch, increase in shunt flow, large alveolar arterial oxygen gradient [P (A-a) O 2 ] and low arterial oxygen tension (PaO 2 ). Expiratory pressures don't return to zero and increase in closing volume during OLV. The airway is narrowed because of the use of DLT, prolonging alveolar emptying time. Some alveoli do not empty completely and compress adjacent ducts and alveoli. Other alveoli are over inflated and damaged because of the high inspiratory pressures during OLV resulting in alveolar edema. Creation of a capnothorax in this hemithorax, worsens the respiratory dysfunction and adds hemodynamic instability because of obstruction to systemic venous return. Exaggerated responses may be seen in chronic smokers, obese or those with congestive heart failure (CHF). ,,,
Cardiovascular system: CO 2 insufflation into the non-ventilated hemithorax with the deflated lung causes rise in intrathoracic pressure and decreases venous return. This causes reduced cardiac output, increased central venous pressures (CVP), mean pulmonary artery pressure (mPAP), and pulmonary capillary wedge pressure (PCWP). Mixed venous oxygen saturation (SvO 2 ) decreases during OLV regardless of CO 2 insufflation and recovers on resumption of two lung ventilation. Moderate rise in arterial CO 2 tension (PaCO 2 ) during OLV and a marked rise in PaCO 2 during CO 2 insufflation is a cause for concern as it can cause coronary vasoconstriction. Maintaining insufflation with CO 2 at two to three liters per minute, avoiding intrapleural pressures above 10 mmHg, reduces chances of cardiorespiratory compromise. ,,,
Hypothermia: There is a need to guard against progressive hypothermia, which occurs during the course of robotic cardiac surgery, because of exposure, prolonged surgery, use of cold intravenous fluids, respiratory gases and CO 2 insufflation.
Preparation and Monitoring
Cardiac medication, including beta blockers, calcium channel blockers, and nitrates should be continued on the day of surgery. Angiotensin converting enzyme inhibitors should be omitted to prevent unexpected hypotension on CPB. Antiplatelet drugs such as clopidogrel need to be stopped five to seven days earlier, especially if neuraxial blockade is planned. Smoking should be stopped and preoperative bronchodilators started. Serum electrolytes especially K + and Mg ++ should be normalized. Premedication may include an oral benzodiazepine such as Midazolam 0.1 mg/Kg. Monitoring before surgery includes ECG, end tidal CO 2 concentration, pulse oximeter, CVP, right and left radial intraarterial pressure, bispectral index (BIS), nasopharyngeal temperature and urine output. Specialized cardiac monitoring may include a pulmonary artery catheter (PAC) and TEE.
Induction and Maintenance Of General Anesthesia
The selected anesthetic should take into consideration the patient's history and co morbidities. Anesthetic techniques are primarily narcotic-based, induction being with a hemodynamically stable agent such as Etomidate with Rocuronium for muscle relaxation. Longer acting muscle relaxants may subsequently be added to ensure patient immobility after port placement. , Sudden patient movement with robotic arms in situ may be devastating. Intubation is done with an appropriate sized DLT. Either a left or a right sided DLT may be used but it may be advisable to intubate the bronchus on the side to be ventilated. 
Cardiopulmonary Bypass Management
Management of CPB for robotic surgeries follows the same principles as per conventional cardiac surgery with a few variations.
Placement of Cannulae
Arterial access: Fesoral arterial cannulation is the standard because of its ease of placesent and cossetic appearance. TEE assesssent of the descending aorta is essential to rule out severe atherosclerosis. Biosedicus (Medtronic. Minneapolis. MN, USA# 965530-015) arterial cannulae of sizes 15 Fr to 19 Fr can be introduced transfesorally using Seldinger technique with a side port for distal lisb perfusion for conventional fesorofesoral CBP. Endoclamp 10.5 Fr intra-arotic balloon clasp (Heartport Inc Redwood City, CA, USA) introduced transfesorally into the ascending aorta, has a balloon which on inflation, internally cross clasps the aorta and has a distal port for aortic root venting, antegrade delivery of cardioplegia and for active suctioning and deairing at the tersination of CPB.
Venous access: Venous cannulae is longer, but with a thinner wire reinforced wall to allow larger internal diameter for adequate drainage (Medtronic. Minneapolis. MN, USA# 96600-015). Despite this, transfemoral cannulae may not empty the ventricles completely requiring additional cannulation of superior vena cava (SVC) via internal jugular vein (IJV). Kinetic assisted venous drainage  using a centrifugal pump on the venous return line or vacuum assisted venous drainage using approximately -20mmHg wall suction on the hard shell reservoir may improve venous drainage by 20-40%. , TEE is helpful to guide cannulations, guide wire placement and final positioning of the SVC and inferior vena cava (IVC) cannulae. For percutaneous CPB, the anesthesiologist places a PAC for venting the pulmonary artery and a Coronary Sinus (CS) catheter for retrograde cardioplegia through the right IJV, with positioning of both catheters confirmed by TEE. On inflating the CS catheter balloon a previously right atrial trace changes to a right ventricular trace. A 100 units/kg dose of heparin is recommended before CS manipulation to avoid CS thrombosis. The PA vent catheter allows passive venting of the pulmonary artery at approximately 50ml/min [Figure 2].
Commencement of CPB and aortic cross clamp: Bypass is initiated with monitoring of right radial arterial pressure, aortic root pressure and with vacuum assisted or kinetic assisted venous drainage. The endoaortic balloon is inflated to 250 - 300 mmHg pressure after TEE guided position check, if the percutaneous Endoclamp system is used, to produce an internal crossclamp [Figure 3].
Decompression of the heart may be aided by the PA catheter vent. Cardioplegia can be administered antegrade, through a distal port in the endovascular aortic cannula and the aortic root can subsequently be vented, through this port. Cardioplegia can be given retrogradely through a CS catheter if required. Apart from the Endoclamp system, another system in use is the Estech (Estech, Danvillie, CA, USA) which is similar, except for a port distal to the balloon to allow antegrade aortic flow. Transthoracic aortic clamping can be performed by use of a Softclamp (Ethicon Systems Inc, Sommerville, NJ, USA), which can be placed transthoracically on the aorta or a long bladed aortic cross clamp, the CardioVasive™ Chitwood Transthoracic Aortic Cross Clamp (Scanlan International Inc., Minneapolis, MN).  Pump flows may need to be reduced during cross clamping for all the above clamps both transthoracic and endovascular, for proper placement and prevention of damage to the aorta. Dislodgement of the balloon of an endovascular catheter can lead to obstruction of the innominate artery, with cerebral hypoperfusion and neurological injury. BIS monitoring may be helpful in detecting balloon migration, apart from TEE and the radial artery pressure trace. Occasionally the balloon may migrate proximally obstructing the coronary arteries, causing myocardial dysfunction. Use of the endoaortic balloon catheter should be avoided in heavily atherosclerotic aorta for fear of dislodgement and embolization of plaque.
Deairing and weaning: Deairing of the heart is difficult after CPB, in robotic cardiac surgery. There is lack of direct access to the heart for the surgeon and with the use of the slight lateral tilted position, the intracardiac air tends to be retained along dorsal interventricular septum and right pulmonary veins. Use of CO 2 insufflation into the hemithorax tends to displace any air from the exposed areas of the heart and this is supplemented by hand ventilation to expel air from the pulmonary veins. Weaning off CPB is done under TEE guidance following standard practices as for the type of surgery with conventional CPB. At the end of the procedure, after reversal of heparin with protamine, the DLT is changed for a single lumen endotracheal tube using a tube changer, if difficulty is anticipated due to airway edema. If surgical trauma to the lung has resulted in intrabronchial bleeding, use of the DLT for lung separation may be continued into the intensive care unit, till bleeding is controlled. Air and CO 2 act as electrical insulators, increasing transthoracic electrical impedance and defibrillation thresholds. Reversal of the capnothorax and institution of two lung ventilation may help in successful defibrillation using the external defibrillation patch electrodes. 
Future Trends in Robotic Cardiac Surgery
The scope of future application of robotic assistance for robotic cardiac surgery is endless. [Table 6] shows procedures expected to be routinely performed using robotic assistance.
Most of the current research in robotic cardiac surgery is in the stage of animal experimentation, but holds a lot of promise.
Off Pump Cardiac Repair: (OPCARE) Beating heart off pump intracardiac repair was studied in bovine experiments using a robotic system with two ultrasound based intracardiac visualization systems (Clearview Ultra, Boston Scientific, La Grenne, France and Accunav, Mountain view, CA, USA), allowing for two different but simultaneous planes of the heart, and identification of both, intracardiac structures and the robotic instruments, within the heart chambers. It was possible to visualize both, the intracardiac structures and robotic instruments through flowing blood using the state of the art intracardiac ultrasound probe introduced through the bovine femoral vein. 
Prototype epicardial crawling device: An endoscopic robotic device for intrapericardial intervention on the beating heart is under development. The device adheres to the porcine epicardium and crawl like an inch worm at 8 cm / min under surgeon control to reach any site on the surface of the beating heart. The device has two modular suction pads and obviates the need for lung deflation, cardiac stabilization, and multiple port placement [Figure 4]. The first application being planned is for epicardial lead placement for cardiac resynchronization therapy and delivery of stem cell or myoblasts to areas of failing myocardium for regenerative therapy. 
Robotic fetal techniques: Fetal cardiac disease can now be diagnosed as early as 16 weeks of gestation. Using robotic telemanipulation, direct visualization of the choroidal vessels is possible, allowing access to fetal cardiac chambers with catheters and the opportunity for intracardiac manipulation. Ultrasound probes can be placed at the tips of these intracardiac catheters for proper visualization. High frequency transducers (40-50 mHz) can already visualize cardiac anatomy in mice fetus at 9.5 days gestation, with resolutions of 30 mm. With real time 3 dimensional imaging, prenatal cardiac intervention for human fetal aortic valve stenosis can reduce left ventricular hypoplasia, restoring ventricular growth and function ,, [Figure 5].
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