anesthesia for robotic surgery.you can run but you can't hide

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Anesthesia for Robotic Surgery…you can run but you can’t hide (it’s coming your way) Julie Ann Lowery, CRNA, MS Upon conclusion of the lecture, the learner/participant will be able to: 1. Have a basic understanding of robotic principles and mechanisms 2. Identify some of the surgical advantages of using the robot with laparoscopic procedures 3. Describe some of the anesthetic considerations for the patient having a robotic assisted laparoscopic surgical procedure Robotic surgery has transformed laparoscopic surgical procedures. More and more centers across the United States are investing in robotic devices. While the initial cost may be substantial, the end results and improved outcomes to the patient are worth the investment. Robotic devices offer the surgeon unprecedented control and precision of the surgical instruments employed during minimally invasive procedures. This results in less postoperative pain for the patient, shorter hospital stays, quicker recovery times, better cosmetic effects, and physiologic function. Generally speaking, one may initially think of a robotic device in a sci-fi or futuristic reference, being autonomous and replacing the human surgeon. This could not be farther from the truth. Robotics, while a sign of the times and the

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Page 1: Anesthesia for Robotic Surgery.you can run but you can't hide

Anesthesia for Robotic Surgery…you can run but you can’t hide (it’s coming your way)

Julie Ann Lowery, CRNA, MS

Upon conclusion of the lecture, the learner/participant will be able to:

1. Have a basic understanding of robotic principles and mechanisms

2. Identify some of the surgical advantages of using the robot with laparoscopic procedures

3. Describe some of the anesthetic considerations for the patient having a robotic assisted laparoscopic surgical procedure

Robotic surgery has transformed laparoscopic surgical procedures. More and more centers across the United States are investing in robotic devices. While the initial cost may be substantial, the end results and improved outcomes to the patient are worth the investment. Robotic devices offer the surgeon unprecedented control and precision of the surgical instruments employed during minimally invasive procedures. This results in less postoperative pain for the patient, shorter hospital stays, quicker recovery times, better cosmetic effects, and physiologic function. Generally speaking, one may initially think of a robotic device in a sci-fi or futuristic reference, being autonomous and replacing the human surgeon. This could not be farther from the truth. Robotics, while a sign of the times and the future, require human intervention to operate. They help surgeons – not replace them.

a historical perspective

Robots were initially designed by the National Aeronautics and Space Administration (NASA) for use in space travel. These robotic devices were employed in performing manual tasks aboard a spacecraft or out in space where a human could not go or, at least, movement would be limited. Known as “slave devices”, these were

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controlled from a remote master control on Earth or from another spacecraft and were used extensively aboard the Space Shuttle missions between 1983 and 1997. From that technology emerged “virtual reality” which allowed the interaction with three-dimensional virtual screens. Robotic engineering and virtual reality were then coupled together to develop a dexterous telemanipulator for the anastomoses of nerves and vessels in hand surgery.

The U.S. Department of Defense recognized the applications that robotics and virtual reality could provide in treating wartime casualties on the battlefield. Through the application of virtual reality, a wounded soldier could “be brought” to a surgeon. This became known as “telepresence.” Via this concept, a surgeon located on board an aircraft carrier could perform surgical interventions on a wounded soldier who remained in a remote location near the battlefield. As a result, the Department of Defense went on to fund much research utilizing telemanipulation combined with telepresence for use in mobile surgical units.

In order to incorporate this technology to its full potential, engineers realized that the distance between the patient and the surgeon had limitations. To ensure the best accuracy and dexterity of the robotic device, the transmission delay or lag time between the surgeon’s maneuvers and the robot’s reception of the commands and implementation required specific design. Delays exceeding 200 milliseconds would compromise the surgical accuracy and precision. Subsequently, the utilization of high-bandwidth fiberoptic underground cable over long distances was found to be the best solution at that time, allowing for a latency time of 155 milliseconds.

The first video-laparoscopic cholecystectomy was performed in 1987 in France. In 1988, the innovation of laparoscopic surgery was introduced to the Society of American Gastrointestinal Endoscopic Surgeons. From that point on, the implementation of laparoscopy exploded! The advantages were soon realized: less invasive with better patient outcomes. On the flipside, this was virtually a new surgical realm to master. Surgeons lost their three-dimensional vision and impaired touch sensation. Additionally, a surgeon had to learn how to manipulate long instruments within the patient’s body that were not directly being viewed. While advancements were made in regards to the logistics and the surgical instruments of laparoscopy, a better technique was on the horizon. Hence, the incentive for robotic development.

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The ultimate goal was to develop a master-slave manipulator device which would mimic the natural movements of a surgeon’s hand and wrist. Early designs contained 4 degrees of freedom and by 1992, an instrument was developed that allowed for 6 degrees of movement. In 1999, Intuitive Surgical acquired the rights for the existing technology, utilizing this to develop robotic instruments with 6 degrees of freedom which have evolved to what is being widely used today.

the da Vinci Robotic Surgical System

Briefly, we’ll just highlight one of the most modern surgical robotic systems approved by the FDA – the da Vinci. This is a telemanipulator robot which means that it is under constant control of the surgeon operator who sits in a remote console. It is comprised of 3 components: a console, an optical three-dimensional vision tower, and a surgical cart. The surgical cart (the robotic component) consists of 3 arms that are manipulated by the surgeon via “real time” computer assisted control. One arm holds the endoscopic camera and the other 2 hold surgical manipulators and instruments. The latter employs 6 degrees of freedom plus grasp, equilibrating it to the articulation of the surgeon’s hand and wrist. This is a very heavy piece of equipment and extreme care must be taken with moving it. After the patient is positioned for the surgical procedure, the cart must be rolled into the surgical area and is then locked into position. It is imperative that the patient’s position is not changed after the robotic side arm is “docked” to avoid injury to patient. The console allows for a three-dimensional image of the surgical field. The endoscope transmits two separate optical and digital images to the console’s visual monitor. The surgeon is visualizing two separate monitors, each eye seeing through an independent camera channel which creates a three-dimensional image of the surgical field. Within the console, there are 2 levers – “the masters”, which attach to the surgeon’s index fingers and thumbs. There are also 3 foot pedals which allow the surgeon to disengage the robotic motions, adjust the endoscopic camera, and control the cauterization. Lastly, the optical tower consists of computer equipment which coordinates the left and the right “eyes” of the surgeon providing stereotactic vision. The computer also translates the movement of the surgeon’s hands into a digital format that corresponds to the robot’s articulations.

Surgical applications

Robotic technology has been successfully implemented in many surgical procedures, including gastrointestinal laparoscopic surgery, cardiac surgery, thoracic surgery, neurosurgery, urologic surgery,

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orthopedic procedures, and gynecologic procedures. I am the most familiar with robotic assisted urologic and gynecologic procedures so that is what I am going to specifically highlight. If robotics is being utilized in other types of surgical procedures listed above where you practice, I highly encourage you to learn about the anesthetic implications and volunteer to provide these patients anesthesia!

Urologic surgeryAt the University of North Carolina at Chapel Hill, the urology

surgeons are excellent with the da Vinci. Some of the primary urologic surgical procedures that employ the da Vinci robot are: nephrectomy, pyeloplasty, cystectomy with ileal conduit, and radical prostatectomy. The latter is probably the most frequent procedure which utilizes the da Vinci robot.

Prostate cancer is the leading form of cancer in males. It is the second highest cause of death in males in the US, killing more than 40,000 men annually. Early detection carries the best prognosis and allows patients to have more treatment options, including surgical removal of the prostate. In a nutshell, the goals surrounding a radical prostatectomy are:

Remove the prostate and cancer Preserve urinary function Preserve erectile function (via a nerve-sparing procedure or

approach) Analyze the prostate after surgery to assess the risk of

recurrence of cancerAs outlined above, performing a robotic assisted laparoscopic

radical prostatectomy offers the surgeon AND the patient many advantages. The da Vinci system allows the surgeon to have enhanced magnification, a 3-dimensional view of the operative field, and preserve the nerves responsible for erections. The patient benefits greatly as well:

Decreased blood loss Shortened length of hospital stay Decreased postoperative pain Less scarring Shorter urinary catheter time Faster return to regular activities Anticipation of improved potency and continence

Gynecologic surgeryRobotic assist is also being widely used in gynecologic procedures

for various underlying disorders: fibroids, pelvic masses, abnormal bleeding, endometriosis, pelvic floor disorders, and

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precancerous/cancerous disease processes. Depending upon the problem, treatment options may not necessarily include surgery. On the flipside, hysterectomy is the most common surgical procedure performed in women and roughly numbers about 650,000 cases annually in the US. The primary reason is that it is the definitive solution for many types of common gynecologic conditions. If surgery is indicated, minimally invasive surgical (MIS) procedures have numerous advantages which are quite similar to those outlined earlier:

Minimal blood loss Preservation of fertility for fibroid removal/myomectomy Reduction in hospital stay Less postoperative pain Absence of a midline abdominal incision Quicker recovery time

Anesthetic considerations

Several of the anesthetic implications specific to robotic procedures mimic those for any laparoscopic surgery. However, there are some considerations unique to these procedures that anesthesia providers need to appreciate and understand. Some of these are surgeon preferences but nonetheless, have good rationale behind them as they lead to optimal surgical conditions and in the long run, better outcomes for the patient. So, let’s highlight a few of the main considerations…

Anesthetic technique and agents…No mystery or surprises here. For any of the robotic procedures

mentioned above specific to urology and gynecology (my experience), these patients always receive a general anesthetic. A regional block – i.e. epidural catheter placement, either for anesthesia supplementation and/or postoperative analgesia is just not indicated or even necessary. So, for those of us who really enjoy (and prefer) doing general anesthesia, this makes us happy.

Each of us has our favorite anesthetic drugs, inhaled anesthetics, and techniques that we like to employ. Not a problem. As with any patient having any surgical procedure, the selected anesthetics should be catered around the patient, the patient’s history, and their accompanying co-morbidities.

I personally avoid the use of nitrous oxide with laparoscopic procedures for several reasons. But especially with the gynecologic procedures, postoperative nausea and vomiting has a higher incidence. So, why make a potentially bad problem worse? Additionally, high narcotic loads are not generally required as postoperative pain is much less a problem.

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Placement of IVs and additional invasive lines…For robotic assisted laparoscopic procedures, the patient’s arms

will be tucked in/secured at the sides. Additionally, you will not be able to access the patient’s arms or check the patency of the IV or fiddle with the noninvasive blood pressure cuff once the robot is “docked” into position. There are several reasons for the latter. Not only is the robot a huge piece of equipment but it will be literally in the way of accessing the patient. Also, the entire area above the patient is considered sterile.

So, here is the message – place anything in the patient (additional IVs, an arterial line) PRIOR to the robot being positioned and locked into place above the patient. It is a great idea to place a second large bore peripheral IV after induction. The patient usually will have had a bowel prep, probably will be dehydrated, and the surgeons are working in close proximity to large blood vessels. In the event you need to give volume and/or blood products quickly, you can do so without trouble if a second large IV is in place. And use a fluid warmer with the second IV set up. An anesthesia colleague once told me that he never had to dc an IV STAT. Makes sense…the second IV can always be removed easily when the patient reaches the PACU. Once again, you will not be able to crawl up under the drapes and start a second IV very easily in an emergent situation.

Just a word about an arterial line...placing one or not placing one should be determined by the patient and the patient’s presenting history. As with other clinical scenarios and patients, often times we place an arterial line for “our convenience.” Because the patient’s arms are tucked, having an arterial line for the sampling of ABG’s, a hemoglobin level, or even a blood sugar can be invaluable. If the patient does not warrant an arterial line postoperatively, it is easy enough for the PACU nurse to remove it then.

Lastly, make sure the IVs run well after the arms have been tucked in and the arterial line has an acceptable waveform.

Positioning the patient…The patient is under general anesthesia, the needed lines are in

place, and now the surgeons are ready to go! It is very important that all personnel in the operating room take an active role in properly positioning ANY patient for the surgical procedure. However, with robotic assisted procedures, there are a few nuances. Also, a surgeon may have a particular positioning technique or strategy which is fine as long as it’s safe for the patient. Since my primary experience is with urology and gynecology procedures, that is what I am going to discuss. For the most part, both require similar positioning of the patient.

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Robot assisted laparoscopic prostatectomy Arms padded and tucked at sides and well secured. We place a beanbag high on the OR table with the U shaped

tops wrapping around the patient’s shoulders for stabilization. Blue foam donuts are also placed between the shoulder AC joints and bean bag for padding. Padded shoulder blocks are then placed behind the bean bag for extra stabilization to prevent the patient sliding in the cephalad direction when placed into steep Trendelenburg.

Towels are placed across the patients chest and then wide adhesive tape is crossed across the patient’s chest and shoulders in an X formation to secure the patient to the OR table.

Our surgeons use a special OR table which splits the legs for surgical positioning. This minimizes the risk of peroneal nerve injury.

Once all of that is done, a “testing” of the Trendelenburg position is performed to ascertain that the patient is secure on the OR table and does not slide down in the cephalad direction. This is very important as the patient will be in steep Trendelenburg for quite some time.

Robot assisted pyeloplasty Lateral position – kind of a tilt, with the operative site on the

body (i.e. left or right) being up and the patient can remain relatively flat.

A beanbag is used to secure the patient. Don’t forget the axillary roll. Proper padding must be present between the arms and the legs,

especially between bony prominences. Ensure that the “up arm” is well secured so it does not fall and

stretch any nerves. Make sure the male genitalia are not getting squished between

the bean bag and body.

Robot assisted gynecologic procedures Arms padded and tucked at sides and well secured. While supine, padded shoulder blocks are placed superior to the

AC joints and fit snug on the OR table. The patient’s legs are placed into padded leg holders and gently

bent at the knee. Steep Trendelenburg is also required for this patient.

Nerve injuries remain one of the most common adverse outcomes in surgical patients and reported closed claims event. And while a patient may sustain a nerve injury even with the most meticulous

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surgical positioning and precautions placed, most nerve injuries are preventable. That means that we need to be knowledgeable about proper surgical positioning techniques, have the proper surgical padding and positioning equipment to utilize, and know the nerves which are at greatest risk for injury for this patient and for this procedure.

The ulnar nerve is the most common nerve injured during surgical procedures and anesthesia. One reason for its vulnerability is its superficial lie to the skin surface. It also can easily be trapped between the bony prominences surrounding it. Ulnar nerve injury is slightly less prevalent when the arms are tucked at the side. However, it remains important to wrap gel pads or foam around the ulnar area. The hands and fingers also need to be properly padded and secured. With gynecological surgery, the foot of the bed will be lowered. Ensure the fingers are not wedged in-between the OR table and the moveable end of the table foot piece. If they are, it is a great way to crunch fingers. Additionally, cut off the clamps on the IV tubing that will be next to the patient’s skin. Also, place a 4x4 between any IV connections and/or stopcocks so that these do not place pressure or leave an indentation in the skin. Once the arms are secured, double check that the arms are really secured. With draping and positioning, it becomes more difficult to detect if the arms “slipped” and are now dangling along side of the OR table.

When the legs are placed into padded leg holders, check that the legs are symmetrical – one should not be higher than the other. Also, excessive flexion and extension should be avoided as this can stretch the sciatic nerve. Ideally, the leg should be in a relaxed mid-position and both sides of the knees padded. The peroneal nerve runs lateral to the knee and the sapphenous nerve runs medial to the knee. If there is excessive pressure to either of these areas, these nerves are at jeopardy for injury.

If padded shoulder blocks are used (as mentioned above), astute and frequent checks for excessive pressure over the AC joint are mandated, especially when the patient is placed into the steep Trendelenburg position. Excessive pressure on this part of the shoulder can cause brachial plexus injury. Keep in mind that when the blocks are placed superior to the shoulder while the patient is in the supine position, they may not feel “tight” above the shoulder. But when the patient’s head is lowered and gravity forces the body weight downward, the latter force will be exerted against the shoulder blocks. Therefore, it is prudent to check the positioning of the blocks after they are put into place and make sure they fit very loosely around the shoulder – 2 fingers can easily be wedged between the shoulder and the block. This is somewhat of an insurance policy so that when the patient goes head down, at least the blocks were not too tight to begin with.

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Positive pressure ventilation – the challenges and the solutionsAll of us have administered anesthesia for patients undergoing

various laparoscopic procedures and are aware of the potential pulmonary dynamic changes that occur secondary to the CO2 insufflation. While this holds true for robotic assisted laparoscopy, it is worth mentioning a few words about the steep head-down position which is required.

The combination of the positioning and CO2 insufflation can make ventilating these patients challenging. If the patient is obese, it becomes even more challenging. Utilizing pressure ventilation can nicely circumvent this problem and allow us to achieve adequate tidal volumes. Keep in mind that you need to be watchful of the peak aspiratory pressures and not allow them to become excessive. The placement of an oral gastric tube is warranted.

IV fluids…minimize!Because patients have been NPO and especially if they have

undergone a bowel prep, we are inclined to want to give our patients a ton of IV fluids, especially at the beginning of the case. When you are providing anesthesia for a robotic assisted urologic or gynecologic procedure, forget about that concept! The exception is for pyeloplasties.

Our surgeons request that fluids intentionally be minimized before and during the surgical procedure. The primary reason for this is that excessive IV fluids potentiate the formation of edema in the face and in the airway mucosa quite possible preventing extubation of the patient. When these cases were taking longer to perform, this was a very real encountered problem. In robotic prostatectomies, minimizing the IV fluids can also keep excessive urine out of the pelvis which could obscure the surgeons’ view while sewing the anastomses. At the end of the case once the patient is flattened out, the surgeons then approve for us to give the patient IV fluids as needed. In robotic prostatectomies, our surgeons actually ask us to start loading the patient with IV fluids at this time point. Preoperatively, I like to inform the patient and any family members that it is not unusual for there to be visible swelling in the patient’s face and eyes postoperatively due to the steep head down position. While this will normalize within the first few hours after the procedure is complete, it may be a bit alarming to see and experience, especially if it were not discussed ahead of time.

One could possibly say that robotic assisted laparoscopic surgery is still in its infantile stages. With that stated, there is somewhat a lack of information in the literature discussing the specific anesthetic considerations for it. Therefore, consider this

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information a starting point and build upon it as you are able. From all indicators, it appears that the robot in surgical procedures is here to stay. Good luck!

References

Nishanian E, Mets B. Anesthesia for robotic surgery. In R. Miller (ed) Miller’s Anesthesia (6th ed). Elsevier Churchill Livingstone. Philadelphia. 2005

Many thanks to Les Meadowcroft, clinical sales rep with Intuitive Surgical, for his help and provision of data and slides pertaining to the da Vinci system.

Also I am very grateful to the advice and information from 2 of the best robotic surgeons I have the pleasure to work with at UNC: Dr. Eric Wallen (Urology) and Dr. John Boggess (GYN oncology).