Anaesthesia for Robotic Surgery
Content
Anaesthesia for robot-assisted laparoscopic surgery
Michael Irvine BSc (Hons) MB BS MRCP(UK) FRCA Vishal Patil MD FFARCS(I)
Over the last 20 yr, the applications of laparoscopic or minimally invasive surgery have increased exponentially, finding utility across virtually every branch of surgical practice. The potential advantages for patients include reduced pain, quicker recovery, shorter hospital stay, and smaller surgical incision. However, these benefits must be balanced against the difficulties of operating in a three-dimensional space while viewing a two-dimensional image, and using long instruments that magnify natural tremor and have limited mobility. In addition, complications of surgery may be increased as a result of limited view or access. Recently, robotic devices have been introduced to help overcome some of these limitations. These devices are not designed to be autonomous or to replace the surgeon. Rather, they are telemanipulators, that is, machines that allow the surgeon to control their instruments from a distance with a higher degree of precision and control than is normally possible, in theory allowing more technically difficult procedures to be performed. This article will discuss the history and utilization of the da Vinci robotic manipulator as this is by far the most common system in use today. The anaesthetic implications of its use for robotassisted prostatectomy will then be considered.
History
The term ‘robot’ was coined by the playwright Capek and colleagues1 in his satirical drama Rossum’s Universal Robots which premiered in 1921. The term was derived from the Czech robota, meaning serf labour. In the play, machines called robots are created to do mundane work freeing the people to enjoy other interests. Ultimately, the robots become stronger than their creators and start to exterminate the population. In reality, the first ‘robots’ began to appear in the 1940s with the introduction of industrial manipulators designed to
autonomously, repeatedly, and accurately perform a single task. Over time, the technology has developed, allowing these machines to perform increasingly complex tasks. Telemanipulators were developed by the National Aeronautics and Space Administration (NASA) in the 1980s, allowing slave devices in space to be controlled by remote master devices on earth. In the late 1980s, with the arrival of minimally invasive surgery, scientists at Stanford Research Institute began looking for ways to overcome the shortcomings of existing endoscopic instruments. They developed a prototype system in 1990 that allowed remote instrument manipulation and stereoscopic vision for use in endoscopic surgery. This development attracted the attention of the United States Department of Defence, which perceived that the technology could be used to treat wartime casualties on the battlefield.2 They hoped that the military’s best trauma surgeons could use the technology to treat wounded soldiers via satellite from hundreds of miles away, without being exposed to the risks of the battlefield. However, this application was not practically possible because of the problems of delay between input and response during signal transmission. However, this funding enabled the development of the da Vinci system, which was introduced into medical practice in 1999 by the Intuitive Surgical Corporation. There are currently more than 900 such systems in use throughout the world.
Key points The use of robot-assisted surgery is increasing in most surgical specialities. It is important that the anaesthetist understands the effects that the presence of a robot will have on their anaesthetic technique. Robot-assisted prostatectomy is currently the most common procedure, and successful anaesthesia requires meticulous attention to detail, especially during patient positioning. Surgical pneumoperitoneum combined with a steep Trendelenburg position may cause haemodynamic instability and hypoxaemia. Airway oedema may occur after surgery; this may be related to overadministration of fluids.
Michael Irvine BSc (Hons) MB BS MRCP(UK) FRCA Specialist Registrar in Anaesthesia Addenbrookes University Hospital NHS Trust Hills Road Cambridge CB2 0QQ UK Vishal Patil MD FFARCS(I) Consultant Anaesthetist Department of Anaesthesia Addenbrookes University Hospital NHS Trust Hills Road Cambridge CB2 0QQ UK Tel: þ 44 1223 217 434 Fax: þ44 1223 217 223 E-mail: [email protected] (for correspondence)
da Vinci surgical robot
The da Vinci system comprises three components: a master console; a robotic surgical manipulator; and a computer/visualization tower. The surgeon sits at the master console and controls the robotic surgical manipulator (Fig. 1). The console consists of a stereoscopic eyepiece that allows the surgeon to view a
doi:10.1093/bjaceaccp/mkp020 Advance Access publication 25 June, 2009 Continuing Education in Anaesthesia, Critical Care & Pain | Volume 9 Number 4 2009 & The Author [2009]. Published by Oxford University Press on behalf of The Board of Directors of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: [email protected]
125
Anaesthesia for robot-assisted laparoscopic surgery
Fig 2 The robot at work demonstrating the computer/visualization tower and the laparoscopic instruments.
Fig 1 Surgeon at work, using the da Vinci console.
three-dimensional image of the surgical field, two actuators that allow control of the robot’s arms, and a number of foot pedals that allow the surgeon to select between control of the camera and instruments, and vary diathermy power. The computer/visualization tower contains the computer that integrates the image from the camera and a monitor that allows the other theatre staff to observe the surgeon’s view (Fig. 2). The robotic surgical manipulator is a large cart that has three arms; one holds a camera and the other two hold interchangeable surgical instruments that are inserted into the patient through endoscopic ports. The arms are capable of accurately applying forces from a tiny amount for precision work up to several pounds for moving bulky tissues out of the way. Although the surgeon is physically remote, a scrubbed assistant is still required to insert the instruments through the endoscopic ports and to change the various instruments (Fig. 3). The robotic system has many advantages. The endoscopic camera is actually two cameras side by side that produce a threedimensional image which the surgeon views through a binocular eye piece. This provides the surgeon with true depth perception in the operative field. The system automatically filters and removes the natural hand tremor of the surgeon and can scale movements for fine precision work (i.e. 5 cm moved by the surgeons hand can be scaled to 1 cm by the surgical instrument). Finally, the surgical
Fig 3 The patient undergoing robotic surgery, in steep Trendelenburg tilt. The assistant is scrubbed, changing the instruments, while the surgeon is at the far side of the operating theatre, operating the console.
instruments incorporate a joint at the distal end, allowing them to approximate the articulation of the normal human wrist. This is described as having 6 degrees of freedom (DOF) rather than the 4 DOF that conventional laparoscopic instruments allow. It allows the surgeon to reach around, beyond, and behind tissue. The disadvantages of the system are that there is limited tactile feedback to the surgeon, who instead relies on visual clues such as tissue deformation to give a sense of force applied. The robotic cart itself is very heavy and bulky, and takes time to wheel into and out of position. Once the cart is locked and the robotic arms are inserted in the body cavity, any patient movement could be disastrous. In addition, the cost of the da Vinci system is approximately £0.5 M, and of course, there is a significant learning curve associated with its introduction that can lead to an increase in operative times. However, there is increasing evidence that once a surgeon has become skilled, the operative times are no longer than for a non-robotic procedure.3 The da Vinci system appears to be reliable, despite its technological complexity. A recent study of 700 consecutive
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Continuing Education in Anaesthesia, Critical Care & Pain j Volume 9 Number 4 2009
Anaesthesia for robot-assisted laparoscopic surgery
procedures demonstrated a system failure rate leading to abandonment of the procedure of 0.5%.4 Surgeons have introduced the da Vinci system across a broad range of specialities.5 Within general surgery, it is currently used for anti-reflux surgery, bariatric surgery, cholecystectomy, splenectomy, colonic resection, and adrenalectomy. It has been used in cardiothoracic surgery for coronary revascularization, mitral valve surgery, oesophageal resection, and pulmonary lobectomy. More recently, the system has been used for gynaecological oncology surgery and skull base surgery, where scaling of the surgeons movements allows extremely precise instrument manipulation. The development of smaller instruments and ports has allowed the technology to advance into paediatric surgery, including procedures on small infants. At present, the most common use by far is in urological surgery.
Anaesthesia for robot-assisted laparoscopic prostatectomy
The most common procedure utilizing the da Vinci system is robot-assisted prostatectomy. Perceived advantages are an improvement in continence and erectile function, along with a reduction in intraoperative blood loss, analgesic requirements, and length of stay. Proponents of the technique advocate discharge from hospital within 24 h of surgery. Many of the anaesthetic considerations considered here are equally applicable to other operations incorporating robot assistance.
Preoperative assessment
Alongside a standard assessment, it is important to recognize that these patients are relatively elderly and it is necessary to specifically enquire about cardiovascular and pulmonary co-morbidities. The procedure itself requires a prolonged period of steep Trendelenburg position, together with pneumoperitoneum; this can produce dramatic physiological derangement. Any patient with significant cardiovascular/respiratory disease should be considered for a standard open procedure or alternative non-surgical mode of therapy. It is also worth noting any history of glaucoma or central nervous system pathology as the patient position is associated with increased intraocular pressure and cerebral blood volume. Low-molecular-weight heparin, oral ranitidine, and laxative suppositories may be administered the night before surgery.
Conduct of anaesthesia
A standard induction and airway control with a tracheal tube is appropriate. Full routine monitoring including core temperature measurement should be applied. Unless co-morbidities exist, an arterial line or central access is not mandatory as the procedure itself carries no further risk than a standard laparoscopic one. A large bore cannula is usual as establishing further i.v. access once the procedure has started is difficult.
As the procedure may be prolonged, it is sensible to use a volatile agent for maintenance with a favourable recovery profile, for example, desflurane. Many institutions choose to run a background infusion of remifentanil. The patient must remain paralysed until the robot is undocked at the end of the procedure—usually with a continuous infusion of a non-depolarizing neuromuscular blocking agent. Intraoperative fluid should be given sparingly to reduce facial oedema (see later) and urine production, which impairs the surgical field before urethral anastomosis. The patient is placed in the lithotomy position with a steep Trendelenburg of 30 –458 for many hours. The arms are tucked by the side and a warming over-blanket should be applied to the upper torso as the procedure may be associated with hypothermia due to the prolonged pneumoperitoneum with dry, cold gases. To reduce the risk of deep vein thrombosis, our practice is to apply sequential compression stockings to the calves. After the urethra is catheterized, the patient is carefully positioned and the robot wheeled into position between the patient’s legs (Fig. 1). The assistant places the trocar for the camera via an umbilical incision and induces the pneumoperitoneum. It is important that the anaesthetist is especially rigorous in ensuring that there is no pressure in vulnerable areas, especially the elbows, axilla, back, and shoulders. There is at least one documented case of upper limb neuropraxia in this patient group, suspected to be due to the use of a poorly positioned shoulder brace to stop the patient slipping down the table.6 The position of the tracheal tube should be checked regularly. There are reports of airway obstruction during insufflation of the pneumoperitoneum, secondary to tracheal tube migration resulting from physical movement of the diaphragm and mediastinum by the pneumoperitoneum.7 The pulse oximetry probe should not be positioned on the ear because of the potential for erroneous readings.8 These may result from the high venous pressures in the ear lobe induced by the Trendelenburg position. Severe oral ulceration and conjunctival burns may be caused by reflux of stomach acid onto the face during the procedure; therefore, attempts should be made to ensure that the patients’ face is visible at all times during surgery.9 In addition, oral ranitidine premedication may reduce the risk of gastric reflux; it should be considered in all patients. There have also been reports of stridor after extubation of the trachea, presumed to be due to laryngeal oedema resulting from prolonged steep Trendelenburg and over judicious fluid administration.6 This was noted to be associated with peri-orbital oedema which should alert the anaesthetist to the possibility of airway oedema.
Pneumoperitoneum
The physiological effects of pneumoperitoneum in the Trendelenburg position are numerous and can be severe (Table 1).6 It is not uncommon for the patient to experience cardiovascular instability and hypoxaemia on carbon dioxide insufflation of the
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 9 Number 4 2009
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Anaesthesia for robot-assisted laparoscopic surgery
Table 1 Physiological effects and complications of pneumoperitoneum in the Trendelenburg position Cardiovascular system " systemic vascular resistance " mean arterial pressure " myocardial oxygen consumption # renal, portal, and sphlanchnic flow " ventilation –perfusion mismatch # functional residual capacity # vital capacity # compliance " peak airway pressure Pulmonary congestion and oedema Hypercarbia, respiratory acidosis " intracranial pressure " cerebral blood flow " intraocular pressure Catecholamine release Activation of renin –angiotensin system Gastro-oesophageal regurgitation Venous air embolism Neuropraxia, especially brachial Tracheal tube displacement Facial and airway oedema
within 30 s. It is possible to deliver a DC shock with the robot docked in position if required.
Communication
The successful use of the robot to assist in surgery depends upon excellent communication between all members of the theatre team. The surgeon sits behind a console, away from the site of operation, but must communicate effectively with both anaesthetic staff and his operative assistant at the patients’ bedside. The loss of eye contact can have a dramatic effect on the quality of communication and special care must be taken to ensure that transfer of information is precise and clear. This is aided by the addition of audio speakers to the video tower that transmit the operating surgeon’s voice.
Respiratory system
Central nervous system
Endocrine Others
Emergence from anaesthesia
When the robot’s arms have been removed from the patient, neuromuscular block may be reversed. Although some concern has been expressed in the past regarding slow wake up secondary to cerebral oedema after prolonged Trendelenburg, in our experience using desflurane as the inhalation agent, patients wake up quickly and appropriately at the end of the procedure.
peritoneum and it is important to exclude other causes such as tracheal tube migration. If the patient remains haemodynamically unstable or hypoxaemia is resistant to application of PEEP, the operation may have to be abandoned or converted to an open procedure. End-tidal carbon dioxide should be maintained at normal levels to reduce the risk of further potentially catastrophic increases in cerebral blood volume and intracranial pressure.9
Postoperative considerations
The postoperative course is usually uneventful. The incidence of complications is low; the most common is ileus secondary to pelvic haematoma and anastomotic leakage. Blood transfusion is not normally required as intraoperative blood loss is very low, but significant haemorrhage may be insidious and the patient should be carefully monitored in the immediate postoperative period. Multimodal analgesic agents including acetaminophen and nonsteroidal anti-inflammatory drugs (if there are no contraindications) should be administered. A small percentage of patients require opioids. Although some centres have used epidural analgesia,10 there is sparse evidence of any benefit, especially as early discharge is favoured. If an epidural is sited, it should not be used intraoperatively as the steep Trendelenburg position can cause a high block and increased cardiovascular instability. There are anecdotal reports of compartment syndrome in the calves after prolonged lithotomy, and patients should be routinely checked for calf tightness and tenderness until discharge. Before discharge from hospital, the surgical drains must be removed and the patient should be afebrile, comfortable on oral analgesics, be mobilizing, and have opened their bowels.
The robot
The robot itself introduces complexities which must be considered. It is an extremely heavy and bulky piece of equipment. The theatre can become very cramped with the addition of the surgical console, video tower, and robot cart. The arrangement of the equipment should be established and practiced in advance at institutions using a robot for the first time. When the robot is docked in position and the instrument and camera inserted through the laparoscopic ports, the robotic arms have little natural elasticity. It is critical therefore that the patient remains absolutely still otherwise tearing could occur at the laparoscopic port sites. The table position must not be moved under any circumstances unless the surgical instruments are disengaged. In addition, patient coughing could cause serious injury and must be avoided with continuous muscle relaxation. Finally, the bulk of the robot is positioned over the abdomen and chest. Although the incidence of airway or serious cardiovascular events are no greater in robot-assisted surgery, if they do occur, the position of the robot will interfere with effective cardiopulmonary resuscitation and airway interventions. The theatre team should practise and be familiar with an emergency drill for the removal of the robotic cart. With practise, at our institution, this drill has enabled us to be able to consistently remove the robot
References
1. Capek K. In: Playfair N, Selver P, trans., Landes WA, ed. Rossum’s Universal Robots. New York: Doubleday, 1923 2. Camarillo DB, Krummel TM, Kenneth Salisbury J. Robotic technology in surgery: past, present, and future. Am J Surg 2008; 188: 2s –15s
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Anaesthesia for robot-assisted laparoscopic surgery
3. Badani KK, Kaul S, Menon M. Evolution of robotic radical prostatectomy: assessment after 2766 procedures. Cancer 2007; 110: 1951– 8 4. Zorn KC, Gofrit ON, Orvieto MA et al. Da Vinci robot error and failure rates: a single institution experience on a single three-arm robot unit of more than 700 consecutive robot assisted laparoscopic radical prostatectomies. J Endourol 2007; 21: 1341–4 5. Nishanian EV, Mets B. Anaesthesia for robotic surgery. Miller’s Anaesthesia, Chapter 66 6. Phong SV, Koh LK. Anaesthesia for robotic-assisted radical prostatectomy: considerations for laparoscopy in the Trendelenburg position. Anaesth Intensive Care 2007; 35: 281– 5
7. Pathan H, Gulati S. A case of airway occlusion in robotic surgery. J Robotic Surg 2007; 1: 169–70 8. Ludbrook G, Sutherland P. Letter—Erroneous pulse oximetry readings during robotic prostatectomy. Anaesth Intensive Care 2007; 35: 281– 5 9. Conacher ID, Soomro NA, Rix D. Anaesthesia for laparoscopic urological surgery. Br J Anaesth 2004; 93: 89– 64 10. Costello TG, Webb P. Anaesthesia for robot-assisted anatomic prostatectomy. Experience at a single institution. Anaesth Intensive Care 2006; 34: 787– 92
Please see multiple choice questions 17 –20
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 9 Number 4 2009
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Michael Irvine BSc (Hons) MB BS MRCP(UK) FRCA Vishal Patil MD FFARCS(I)
Over the last 20 yr, the applications of laparoscopic or minimally invasive surgery have increased exponentially, finding utility across virtually every branch of surgical practice. The potential advantages for patients include reduced pain, quicker recovery, shorter hospital stay, and smaller surgical incision. However, these benefits must be balanced against the difficulties of operating in a three-dimensional space while viewing a two-dimensional image, and using long instruments that magnify natural tremor and have limited mobility. In addition, complications of surgery may be increased as a result of limited view or access. Recently, robotic devices have been introduced to help overcome some of these limitations. These devices are not designed to be autonomous or to replace the surgeon. Rather, they are telemanipulators, that is, machines that allow the surgeon to control their instruments from a distance with a higher degree of precision and control than is normally possible, in theory allowing more technically difficult procedures to be performed. This article will discuss the history and utilization of the da Vinci robotic manipulator as this is by far the most common system in use today. The anaesthetic implications of its use for robotassisted prostatectomy will then be considered.
History
The term ‘robot’ was coined by the playwright Capek and colleagues1 in his satirical drama Rossum’s Universal Robots which premiered in 1921. The term was derived from the Czech robota, meaning serf labour. In the play, machines called robots are created to do mundane work freeing the people to enjoy other interests. Ultimately, the robots become stronger than their creators and start to exterminate the population. In reality, the first ‘robots’ began to appear in the 1940s with the introduction of industrial manipulators designed to
autonomously, repeatedly, and accurately perform a single task. Over time, the technology has developed, allowing these machines to perform increasingly complex tasks. Telemanipulators were developed by the National Aeronautics and Space Administration (NASA) in the 1980s, allowing slave devices in space to be controlled by remote master devices on earth. In the late 1980s, with the arrival of minimally invasive surgery, scientists at Stanford Research Institute began looking for ways to overcome the shortcomings of existing endoscopic instruments. They developed a prototype system in 1990 that allowed remote instrument manipulation and stereoscopic vision for use in endoscopic surgery. This development attracted the attention of the United States Department of Defence, which perceived that the technology could be used to treat wartime casualties on the battlefield.2 They hoped that the military’s best trauma surgeons could use the technology to treat wounded soldiers via satellite from hundreds of miles away, without being exposed to the risks of the battlefield. However, this application was not practically possible because of the problems of delay between input and response during signal transmission. However, this funding enabled the development of the da Vinci system, which was introduced into medical practice in 1999 by the Intuitive Surgical Corporation. There are currently more than 900 such systems in use throughout the world.
Key points The use of robot-assisted surgery is increasing in most surgical specialities. It is important that the anaesthetist understands the effects that the presence of a robot will have on their anaesthetic technique. Robot-assisted prostatectomy is currently the most common procedure, and successful anaesthesia requires meticulous attention to detail, especially during patient positioning. Surgical pneumoperitoneum combined with a steep Trendelenburg position may cause haemodynamic instability and hypoxaemia. Airway oedema may occur after surgery; this may be related to overadministration of fluids.
Michael Irvine BSc (Hons) MB BS MRCP(UK) FRCA Specialist Registrar in Anaesthesia Addenbrookes University Hospital NHS Trust Hills Road Cambridge CB2 0QQ UK Vishal Patil MD FFARCS(I) Consultant Anaesthetist Department of Anaesthesia Addenbrookes University Hospital NHS Trust Hills Road Cambridge CB2 0QQ UK Tel: þ 44 1223 217 434 Fax: þ44 1223 217 223 E-mail: [email protected] (for correspondence)
da Vinci surgical robot
The da Vinci system comprises three components: a master console; a robotic surgical manipulator; and a computer/visualization tower. The surgeon sits at the master console and controls the robotic surgical manipulator (Fig. 1). The console consists of a stereoscopic eyepiece that allows the surgeon to view a
doi:10.1093/bjaceaccp/mkp020 Advance Access publication 25 June, 2009 Continuing Education in Anaesthesia, Critical Care & Pain | Volume 9 Number 4 2009 & The Author [2009]. Published by Oxford University Press on behalf of The Board of Directors of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: [email protected]
125
Anaesthesia for robot-assisted laparoscopic surgery
Fig 2 The robot at work demonstrating the computer/visualization tower and the laparoscopic instruments.
Fig 1 Surgeon at work, using the da Vinci console.
three-dimensional image of the surgical field, two actuators that allow control of the robot’s arms, and a number of foot pedals that allow the surgeon to select between control of the camera and instruments, and vary diathermy power. The computer/visualization tower contains the computer that integrates the image from the camera and a monitor that allows the other theatre staff to observe the surgeon’s view (Fig. 2). The robotic surgical manipulator is a large cart that has three arms; one holds a camera and the other two hold interchangeable surgical instruments that are inserted into the patient through endoscopic ports. The arms are capable of accurately applying forces from a tiny amount for precision work up to several pounds for moving bulky tissues out of the way. Although the surgeon is physically remote, a scrubbed assistant is still required to insert the instruments through the endoscopic ports and to change the various instruments (Fig. 3). The robotic system has many advantages. The endoscopic camera is actually two cameras side by side that produce a threedimensional image which the surgeon views through a binocular eye piece. This provides the surgeon with true depth perception in the operative field. The system automatically filters and removes the natural hand tremor of the surgeon and can scale movements for fine precision work (i.e. 5 cm moved by the surgeons hand can be scaled to 1 cm by the surgical instrument). Finally, the surgical
Fig 3 The patient undergoing robotic surgery, in steep Trendelenburg tilt. The assistant is scrubbed, changing the instruments, while the surgeon is at the far side of the operating theatre, operating the console.
instruments incorporate a joint at the distal end, allowing them to approximate the articulation of the normal human wrist. This is described as having 6 degrees of freedom (DOF) rather than the 4 DOF that conventional laparoscopic instruments allow. It allows the surgeon to reach around, beyond, and behind tissue. The disadvantages of the system are that there is limited tactile feedback to the surgeon, who instead relies on visual clues such as tissue deformation to give a sense of force applied. The robotic cart itself is very heavy and bulky, and takes time to wheel into and out of position. Once the cart is locked and the robotic arms are inserted in the body cavity, any patient movement could be disastrous. In addition, the cost of the da Vinci system is approximately £0.5 M, and of course, there is a significant learning curve associated with its introduction that can lead to an increase in operative times. However, there is increasing evidence that once a surgeon has become skilled, the operative times are no longer than for a non-robotic procedure.3 The da Vinci system appears to be reliable, despite its technological complexity. A recent study of 700 consecutive
126
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 9 Number 4 2009
Anaesthesia for robot-assisted laparoscopic surgery
procedures demonstrated a system failure rate leading to abandonment of the procedure of 0.5%.4 Surgeons have introduced the da Vinci system across a broad range of specialities.5 Within general surgery, it is currently used for anti-reflux surgery, bariatric surgery, cholecystectomy, splenectomy, colonic resection, and adrenalectomy. It has been used in cardiothoracic surgery for coronary revascularization, mitral valve surgery, oesophageal resection, and pulmonary lobectomy. More recently, the system has been used for gynaecological oncology surgery and skull base surgery, where scaling of the surgeons movements allows extremely precise instrument manipulation. The development of smaller instruments and ports has allowed the technology to advance into paediatric surgery, including procedures on small infants. At present, the most common use by far is in urological surgery.
Anaesthesia for robot-assisted laparoscopic prostatectomy
The most common procedure utilizing the da Vinci system is robot-assisted prostatectomy. Perceived advantages are an improvement in continence and erectile function, along with a reduction in intraoperative blood loss, analgesic requirements, and length of stay. Proponents of the technique advocate discharge from hospital within 24 h of surgery. Many of the anaesthetic considerations considered here are equally applicable to other operations incorporating robot assistance.
Preoperative assessment
Alongside a standard assessment, it is important to recognize that these patients are relatively elderly and it is necessary to specifically enquire about cardiovascular and pulmonary co-morbidities. The procedure itself requires a prolonged period of steep Trendelenburg position, together with pneumoperitoneum; this can produce dramatic physiological derangement. Any patient with significant cardiovascular/respiratory disease should be considered for a standard open procedure or alternative non-surgical mode of therapy. It is also worth noting any history of glaucoma or central nervous system pathology as the patient position is associated with increased intraocular pressure and cerebral blood volume. Low-molecular-weight heparin, oral ranitidine, and laxative suppositories may be administered the night before surgery.
Conduct of anaesthesia
A standard induction and airway control with a tracheal tube is appropriate. Full routine monitoring including core temperature measurement should be applied. Unless co-morbidities exist, an arterial line or central access is not mandatory as the procedure itself carries no further risk than a standard laparoscopic one. A large bore cannula is usual as establishing further i.v. access once the procedure has started is difficult.
As the procedure may be prolonged, it is sensible to use a volatile agent for maintenance with a favourable recovery profile, for example, desflurane. Many institutions choose to run a background infusion of remifentanil. The patient must remain paralysed until the robot is undocked at the end of the procedure—usually with a continuous infusion of a non-depolarizing neuromuscular blocking agent. Intraoperative fluid should be given sparingly to reduce facial oedema (see later) and urine production, which impairs the surgical field before urethral anastomosis. The patient is placed in the lithotomy position with a steep Trendelenburg of 30 –458 for many hours. The arms are tucked by the side and a warming over-blanket should be applied to the upper torso as the procedure may be associated with hypothermia due to the prolonged pneumoperitoneum with dry, cold gases. To reduce the risk of deep vein thrombosis, our practice is to apply sequential compression stockings to the calves. After the urethra is catheterized, the patient is carefully positioned and the robot wheeled into position between the patient’s legs (Fig. 1). The assistant places the trocar for the camera via an umbilical incision and induces the pneumoperitoneum. It is important that the anaesthetist is especially rigorous in ensuring that there is no pressure in vulnerable areas, especially the elbows, axilla, back, and shoulders. There is at least one documented case of upper limb neuropraxia in this patient group, suspected to be due to the use of a poorly positioned shoulder brace to stop the patient slipping down the table.6 The position of the tracheal tube should be checked regularly. There are reports of airway obstruction during insufflation of the pneumoperitoneum, secondary to tracheal tube migration resulting from physical movement of the diaphragm and mediastinum by the pneumoperitoneum.7 The pulse oximetry probe should not be positioned on the ear because of the potential for erroneous readings.8 These may result from the high venous pressures in the ear lobe induced by the Trendelenburg position. Severe oral ulceration and conjunctival burns may be caused by reflux of stomach acid onto the face during the procedure; therefore, attempts should be made to ensure that the patients’ face is visible at all times during surgery.9 In addition, oral ranitidine premedication may reduce the risk of gastric reflux; it should be considered in all patients. There have also been reports of stridor after extubation of the trachea, presumed to be due to laryngeal oedema resulting from prolonged steep Trendelenburg and over judicious fluid administration.6 This was noted to be associated with peri-orbital oedema which should alert the anaesthetist to the possibility of airway oedema.
Pneumoperitoneum
The physiological effects of pneumoperitoneum in the Trendelenburg position are numerous and can be severe (Table 1).6 It is not uncommon for the patient to experience cardiovascular instability and hypoxaemia on carbon dioxide insufflation of the
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 9 Number 4 2009
127
Anaesthesia for robot-assisted laparoscopic surgery
Table 1 Physiological effects and complications of pneumoperitoneum in the Trendelenburg position Cardiovascular system " systemic vascular resistance " mean arterial pressure " myocardial oxygen consumption # renal, portal, and sphlanchnic flow " ventilation –perfusion mismatch # functional residual capacity # vital capacity # compliance " peak airway pressure Pulmonary congestion and oedema Hypercarbia, respiratory acidosis " intracranial pressure " cerebral blood flow " intraocular pressure Catecholamine release Activation of renin –angiotensin system Gastro-oesophageal regurgitation Venous air embolism Neuropraxia, especially brachial Tracheal tube displacement Facial and airway oedema
within 30 s. It is possible to deliver a DC shock with the robot docked in position if required.
Communication
The successful use of the robot to assist in surgery depends upon excellent communication between all members of the theatre team. The surgeon sits behind a console, away from the site of operation, but must communicate effectively with both anaesthetic staff and his operative assistant at the patients’ bedside. The loss of eye contact can have a dramatic effect on the quality of communication and special care must be taken to ensure that transfer of information is precise and clear. This is aided by the addition of audio speakers to the video tower that transmit the operating surgeon’s voice.
Respiratory system
Central nervous system
Endocrine Others
Emergence from anaesthesia
When the robot’s arms have been removed from the patient, neuromuscular block may be reversed. Although some concern has been expressed in the past regarding slow wake up secondary to cerebral oedema after prolonged Trendelenburg, in our experience using desflurane as the inhalation agent, patients wake up quickly and appropriately at the end of the procedure.
peritoneum and it is important to exclude other causes such as tracheal tube migration. If the patient remains haemodynamically unstable or hypoxaemia is resistant to application of PEEP, the operation may have to be abandoned or converted to an open procedure. End-tidal carbon dioxide should be maintained at normal levels to reduce the risk of further potentially catastrophic increases in cerebral blood volume and intracranial pressure.9
Postoperative considerations
The postoperative course is usually uneventful. The incidence of complications is low; the most common is ileus secondary to pelvic haematoma and anastomotic leakage. Blood transfusion is not normally required as intraoperative blood loss is very low, but significant haemorrhage may be insidious and the patient should be carefully monitored in the immediate postoperative period. Multimodal analgesic agents including acetaminophen and nonsteroidal anti-inflammatory drugs (if there are no contraindications) should be administered. A small percentage of patients require opioids. Although some centres have used epidural analgesia,10 there is sparse evidence of any benefit, especially as early discharge is favoured. If an epidural is sited, it should not be used intraoperatively as the steep Trendelenburg position can cause a high block and increased cardiovascular instability. There are anecdotal reports of compartment syndrome in the calves after prolonged lithotomy, and patients should be routinely checked for calf tightness and tenderness until discharge. Before discharge from hospital, the surgical drains must be removed and the patient should be afebrile, comfortable on oral analgesics, be mobilizing, and have opened their bowels.
The robot
The robot itself introduces complexities which must be considered. It is an extremely heavy and bulky piece of equipment. The theatre can become very cramped with the addition of the surgical console, video tower, and robot cart. The arrangement of the equipment should be established and practiced in advance at institutions using a robot for the first time. When the robot is docked in position and the instrument and camera inserted through the laparoscopic ports, the robotic arms have little natural elasticity. It is critical therefore that the patient remains absolutely still otherwise tearing could occur at the laparoscopic port sites. The table position must not be moved under any circumstances unless the surgical instruments are disengaged. In addition, patient coughing could cause serious injury and must be avoided with continuous muscle relaxation. Finally, the bulk of the robot is positioned over the abdomen and chest. Although the incidence of airway or serious cardiovascular events are no greater in robot-assisted surgery, if they do occur, the position of the robot will interfere with effective cardiopulmonary resuscitation and airway interventions. The theatre team should practise and be familiar with an emergency drill for the removal of the robotic cart. With practise, at our institution, this drill has enabled us to be able to consistently remove the robot
References
1. Capek K. In: Playfair N, Selver P, trans., Landes WA, ed. Rossum’s Universal Robots. New York: Doubleday, 1923 2. Camarillo DB, Krummel TM, Kenneth Salisbury J. Robotic technology in surgery: past, present, and future. Am J Surg 2008; 188: 2s –15s
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3. Badani KK, Kaul S, Menon M. Evolution of robotic radical prostatectomy: assessment after 2766 procedures. Cancer 2007; 110: 1951– 8 4. Zorn KC, Gofrit ON, Orvieto MA et al. Da Vinci robot error and failure rates: a single institution experience on a single three-arm robot unit of more than 700 consecutive robot assisted laparoscopic radical prostatectomies. J Endourol 2007; 21: 1341–4 5. Nishanian EV, Mets B. Anaesthesia for robotic surgery. Miller’s Anaesthesia, Chapter 66 6. Phong SV, Koh LK. Anaesthesia for robotic-assisted radical prostatectomy: considerations for laparoscopy in the Trendelenburg position. Anaesth Intensive Care 2007; 35: 281– 5
7. Pathan H, Gulati S. A case of airway occlusion in robotic surgery. J Robotic Surg 2007; 1: 169–70 8. Ludbrook G, Sutherland P. Letter—Erroneous pulse oximetry readings during robotic prostatectomy. Anaesth Intensive Care 2007; 35: 281– 5 9. Conacher ID, Soomro NA, Rix D. Anaesthesia for laparoscopic urological surgery. Br J Anaesth 2004; 93: 89– 64 10. Costello TG, Webb P. Anaesthesia for robot-assisted anatomic prostatectomy. Experience at a single institution. Anaesth Intensive Care 2006; 34: 787– 92
Please see multiple choice questions 17 –20
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