© Springer International Publishing Switzerland 2017
Vincent Obias (ed.)Robotic Colon and Rectal Surgery10.1007/978-3-319-43256-4_1818. Anesthesia in Robotic Colon and Rectal Surgery
(1)
Department of Anesthesiology and Critical Care Medicine, The George Washington University Hospital, Washington, DC, USA
Background
Laparoscopic, minimally invasive surgery has been performed since the early 1900s when Dr. Georg Kelling, a German surgeon, used a technique he called “koelioskopie ” on dogs to utilize the pneumoperitoneum to stop intra-abdominal bleeding [1]. Then in 1910 a Swedish surgeon, Dr. Hans Christian Jacobaeus, was the first to use the technique on humans, which he called laparothorakoskopie [1]. Since that time, the technology of laparoscopy progressed, especially with gynecological surgeries, when in the 1960s and 1970s a German gynecologist, Dr. Kurt Semm, developed the automatic insufflator and hundreds of laparoscopic instruments [2]. However, it was not until 1982 that the solid-state video camera was utilized for laparoscopy and made the technique safe and practical for many surgical procedures [2]. Dr. Philippe Mouret, a French surgeon, performed the first laparoscopic cholecystectomy in 1987, and that same year scientists at Stanford began working on the “Telepresence Surgery System ,” the predecessor of today’s Da Vinci surgical robotic systems [3]. The robotic system was developed to help solve some of the limitations of traditional laparoscopy and to further expand the technique’s application in the world of surgery [3, 4]. As surgeries have evolved to incorporate this new technology, so have the anesthetic considerations.
A wide variety of laparoscopic procedures bring new proposed advantages of less postoperative pain, less opioid use, smaller incisions, decreased surgical stress, decreased wound complications, faster recovery times, shorter hospital stays, and reduced healthcare costs [5–8], but also bring about new challenges in delivering general anesthesia associated with CO2 insufflation and steep trendelenburg positioning, such as hemodynamic changes, decreased urine output, and decreased pulmonary function [9–17]. With the addition of the surgical robot to laparoscopic surgery, a new set of anesthetic considerations and challenges have arisen during the preoperative, intraoperative, and postoperative period. Since robotic surgery is an extension of a surgeon’s laparoscopic capabilities, it is crucial for the anesthesia provider and surgeon to first fully understand the physiologic changes and complications associated with laparoscopic surgery before tackling the additional concerns of the robot. We will briefly describe these issues before moving on to the specific robotic concerns for colorectal surgery.
Laparoscopic surgery and the pneumoperitoneum with CO2 insufflation provide specific physiologic challenges affecting the cardiovascular, pulmonary, renal, and neurologic systems. The mechanical stress due to the stretching of the abdomen and chemical stress of the highly absorbable carbon dioxide lead to sympathetic stimulation and neuroendocrine response of increased catecholamines, renin, angiotensin, vasopressin, and cortisol [9–12], which greatly affects the cardiovascular system. The heart is met with a host of physiologic changes including an increase in systemic vascular resistance, an increase in mean arterial pressure, an increase in cardiac filling pressure, an increase in afterload, an increase in dysrhythmias, a decrease in cardiac index, and a decrease in venous return. Similar to the heart, the lungs have to also work against the mechanical stress of CO2 insufflation. There is decreased lung volume, decreased lung compliance, increased airway resistance, as well as a displacement of the diaphragm cephalad, which can result in an endobronchial intubation [10, 11]. The mechanical and neuroendocrine stress of CO2 insufflation also impacts the kidneys, resulting in decreased renal blood flow, decreased glomerular filtration rate, and low urine output [18]. Urine output, fortunately, returns to normal ~2 h after the resolution of insufflation, and as long as insufflation pressures are less than 15 mmHg, laparoscopy is safe in patients with renal disease [19]. Therefore, we are unable to reliably use urine as an indicator of volume status and end-organ perfusion interoperatively [20]. While the brain may be relatively far from the peritoneum, it is still unable to escape the effects of CO2 insufflation. There is an increase in cerebral blood flow and an increase in intracranial pressure, making a laparoscopic procedure a concern for any patient with an intracranial mass or ventricular shunt [21]. Like intracranial pressure , intraocular pressure also increases with pneumoperitoneum, which raises concern for optic nerve ischemia, especially in the setting of high fluid administration and steep trendelenburg positioning [22]. While these physiologic changes are expected, there are several important complications associated with CO2 insufflation that the surgeon and anesthesiologist must be well aware of and ready to handle.
Complications during robotic surgery are specifically related to the pneumoperitoneum with intraperitoneal CO2 insufflation, extreme patient positioning, and surgical instrumentation. The complications from CO2 insufflation include cardiopulmonary compromise, renal dysfunction, and hypothermia. Potential surgical complications involve CO2 tracking to different spaces including subcutaneous tissue, thorax, mediastinum, pericardium, and gas embolism, as well as acute hemorrhage and bowel or bladder perforation [23]. Upper abdominal procedures, such as fundoplication and urologic procedures, have been found to have a higher rate of complications, especially when patients have multiple comorbidities [24–28]. Therefore, appropriate patient selection is crucial to minimizing risk associated with robotic surgery. We will first discuss preoperative anesthetic concerns regarding appropriate patient selection and interoperative monitoring before moving on to the special anesthetic concerns and considerations surrounding the interoperative and then postoperative period of robotic colorectal surgery.
Preoperative Concerns
Robotic surgery has some unique considerations and challenges such as longer operative times, large robotic systems with limited access to the patient, and the physiologic stress of pneumoperitoneum and extreme trendelenburg positioning [29], so selecting the appropriate patient is very important. As with any laparoscopic procedure with CO2 insufflation, there are several physiologic stresses the patient must be able to tolerate; however, the extreme trendelenburg and longer procedure times make these stresses more of a concern.
Patient Selection
As mentioned earlier there are several physiologic stresses on the heart that make the preoperative cardiovascular evaluation important, especially if a patient gets shortness of breath or chest pain with exercise less than 4 mets. From a pulmonary perspective the insufflation pressures and the steep trendelenburg can make it difficult to generate adequate tidal volumes, especially in very obese patients. Therefore, ventilator settings must be adjusted to minimize the high peak airway pressures as much as possible. As we stated before there is a drop in urine output interoperatively for a variety of reasons related to the pneumoperitoneum, but this returns to normal ~2 h after insulation and appears safe in renal patients as long as insufflation is less than 15 mmHg [19]. Robotic surgery would not be appropriate for patients with any concern for increased intracranial pressure such as intracranial masses or ventricular shuts, due to the pressure from insufflation and steep trendelenburg, which reduces venous return [21]. For similar physiologic reasons, patients with concern for high intraocular pressures are poor candidates for robotic surgery [22].
Monitoring and Vascular Access
Planning for monitoring the patient intraoperatively during a robotic surgery has a few unique considerations beyond the typical comorbidities of the patient. Since urine output may be low, or may not be indicative of volume status in robotic surgery, one may want to consider an arterial line in addition to standard ASA monitors. This would allow continuous blood pressure monitoring as well as volume status by way of respiratory variation or more specifically with stroke volume variation, using a Flotrac arterial transducer [30–32]. Volume status may also be measured with a central line and monitoring central venous pressure; however, it has been shown that using a Flotrac arterial transducer to measure stroke volume variation is just as accurate and may eliminate the need for placing a central line [31]. Volume status and fluid management is very important in robotic surgery as the steep trendelenburg positioning makes patients prone to facial, pharyngeal, and laryngeal edema, which could compromise the patient’s airway in the immediate postsurgical period [29]. Furthermore, a few studies have shown that fluid restriction may improve outcome after major elective gastrointestinal surgery [33]. Careful planning of the necessary monitors is important because the patient is carefully positioned for the robot with both arms tucked and secured with a beanbag; therefore, access to the patient intraoperatively is very limited and would require stopping the surgical procedure and carefully undocking the robot and deflating the beanbag, before being able to place an invasive monitor.
For the same reasons, adequate vascular access for potential emergent large volume resuscitation and medication administration needs to be established prior to final positioning of the patient. Central access is not necessarily needed for robotic surgery unless patient is a difficult peripheral IV placement, surgeon/anesthesiologist want CVP monitor for volume status, or patient’s comorbidities place patient at a higher risk for needing centrally administered medications. Two large bore peripheral intravenous lines should be sufficient, and if need for central access is determined emergently, the neck would be exposed and available for an external jugular peripheral IV or internal jugular central line during the case.
Intraoperative Concerns
Simply put, the goals of anesthesia are to optimize intraoperative conditions, provide rapid recovery, and minimize complications. General anesthesia with an endotracheal tube, muscle relaxation [34], and mechanical ventilation [35] provides the optimal working environment for the surgeon and safety for the patient [36, 37] undergoing robotic surgery. Faster recoveries and shorter hospital stays have been shown with minimally invasive and robotic surgery [5–8]; however, adequate pain control beginning in the perioperative period is crucial to continued pain control in the postoperative period. Pain control will be discussed in more detail in the postoperative section, as it is the major anesthetic concern during that time to help expedite recovery. Here we will focus on complications associated with robotic surgery due to pneumoperitoneum and extreme trendelenburg positioning, which the surgeon and anesthesiologist must recognize and deal with quickly.
Cardiopulmonary Complications
In addition to the physiologic cardiopulmonary changes with robotic surgery as described earlier, these patients are prone to cardiac dysrhythmias from increased vagal tone from peritoneal stretch and hypercarbia causing bradycardia and tachycardia, respectively [29]. In rare events they are also susceptible to complete cardiovascular collapse from profound vagal response, cardiac dysrhythmias, excessive intra-abdominal pressure, tension pneumothorax, cardiac tamponade, CO2 embolism, acute blood loss, myocardial infarction, and respiratory acidosis [29]. These patients are also vulnerable to hypoxemia from endobronchial intubation from the cephalad movement of the carina with insufflation and trendelenburg positioning [38, 39].
Subcutaneous Emphysema and Potential Sequela
Inadvertent extraperitoneal insufflation in the subcutaneous, preperitoneal, or retroperitoneal tissue can result in subcutaneous emphysema [40, 41], which is a risk of any laparoscopic procedure. Subcutaneous emphysema usually resolves on its own after deflation of abdomen; however, in some cases it has been shown to cause persistent hypercarbia in the recovery room [42], or extend to certain fascial compartments, such as the thorax and mediastinum, leading to hemodynamic instability from a tension capnothorax or cardiac tamponade, respectively [43]. CO2 can fill the fascial planes contiguous with the abdomen, chest, neck, and groin, and if subcutaneous emphysema extends to the chest and neck, it can then extend into the thorax and mediastinum [44]. Operative times of >200 min and use of six or more surgical ports increases the risk for subcutaneous emphysema [41], and subcutaneous emphysema can often be detected by crepitus or a sudden increase in end tidal CO2.
As previously mentioned, subcutaneous emphysema usually resolves on its own, but if persistent hypercarbia occurs despite hyperventilation, it may be necessary to deflate the abdomen and reinsufflate at a lower pressure. And if the CO2 tracks into the thorax, mediastinum, or pericardium, the cardiopulmonary repercussions [43, 44], such as tension capnothorax or cardiac tamponade, must be quickly recognized and treated with appropriate supportive care until the CO2 is evacuated from the thorax, mediastinum, or pericardium.
Capnothorax is a rare potentially life-threatening condition, which is most common with procedures near the diaphragm [23, 24, 45]. It may present as unexplained increased airway pressure, hypoxemia, hypercapnia, surgical emphysema, and if tension capnothorax occurs, it may present as severe cardiovascular collapse [43]. Treatment includes deflation of the abdomen with supportive care. If there is minimal physiologic compromise, conservative treatment with close observation may be sufficient as CO2 is rapidly absorbed [43, 46, 47]. However, if tension capnothroax with hemodynamic instability occurs, a chest tube may be necessary. Now capnomediastinum and capnopericardium are very rare, but if they occur, they can cause drastic hemodynamic compromise, requiring supportive care until the CO2 dissipates or is manually extracted.
CO2 Embolism
While CO2 can travel to several tissue spaces as mentioned earlier, it can also travel to the blood, and in a large enough quantity it can cause a CO2 gas embolism. CO2 embolisms have been well documented to have a high incidence in laparoscopic surgeries, but usually not having significant cardiopulmonary effects [48, 49]. Signs of CO2 embolism may include cardiac arrhythmia, hypoxemia, and hypotension, and an associated decrease in ETCO2 from a decrease in cardiac output, similar to any type of embolism. Because of the outflow obstruction caused by the embolism the EKG may show a right strain pattern and widening of the QRS complex. Or if the obstruction is preventing inflow back to the right heart from the head, one may see cyanosis of the head and neck. Furthermore, a patent foramen ovale or an atrial septal defect may result in paradoxical CO2 embolism to the brain. As with other CO2-related complications, if the patient is unstable, the abdomen should be deflated and patient should be hyperventilated to promote rapid CO2 washout while providing supportive care. However, the patient should also be turned to the left lateral decubitus with a head-down position to allow the gas to rise into the apex of the right ventricle and prevent pulmonary artery outflow obstruction. Hyperbaric oxygen has also been used to help treat CO2 embolisms [29].
Hypothermia
While little of the abdominal contents are directly exposed to the cold operating room environment in robotic surgery, patients are at the same risk of hypothermia as an open procedure. This is thought to be related to the convention loss of heat from the dry cool CO2 (21C), being continuously pumped into the peritoneum [50–52]. Appropriate warming of patient with convection-based warming blankets and fluid warmers may be necessary, especially for long procedures seen in robotics.
Positioning Complications
The long procedures also make patients susceptible to several complications related specifically to positioning. As we have alluded to several times in this chapter, the steep trendelenburg position and the increased intra-abdominal pressures can impact the airway by increasing peak airway pressure, increasing upper airway edema, and potentially cause a right mainstem or endobronchial intubation with diaphragm and mediastinum shifting cephalad. However, prolonged caudal displacement of the shoulder can lead to brachial plexus injury, so adequate padding of the shoulders prior to final positioning with the beanbag is essential [53]. Furthermore, the lithotomy positioning makes the patient susceptible to peroneal nerve injury resulting in foot droop, which again requires proper padding and inspection prior to final positioning. This positioning also further puts the patient at risk for a deep vein thrombosis from venous stasis [54], and sequential compression devices used during the procedure and early ambulation in the recovery period will help minimize this risk.
Surgical Injury
With any surgery there is the risk for inadvertent vascular or organ injury, and robotic surgery is no different. However, specific risks similar to laparoscopic surgery exist. These include GI, bladder, or vascular injury from a trocar or Veress needle. In order to minimize risk of perforating GI or bladder, the stomach and bladder should be decompressed with a gastric tube and foley catheter, respectively. Furthermore, if a vascular injury occurs acute blood loss may be difficult to see within the view of the camera port, so acute blood loss needs to be high on the differential for any unexplained hypotension, and if there is major bleeding the surgeon must convert to open [29]. Communication between the anesthesiologist and surgeon is key to ensuring patient safety during any surgery, but with the surgeon in a control station away from the patient in robotic surgery , it makes the need for good communication even more imperative.
Appropriate Surgical Environment
Good communication is not only for the just the surgeon and anesthesiologist, but for the entire operating room staff. There are more moving parts in a robotic surgery that require a well coordinated and flexible staff to ensure the case runs smoothly and safely. Operating room staff familiarity with equipment will help minimize operating time, minimize time to convert to open, and minimize time to expose patient in the event of a code. However, like with any emergency situation, preparedness and practice are what enable people to respond quickly and efficiently, and save those precious seconds that might save a patient’s life. With the initiation of any new robotic program, all staff should be taken through emergency scenario simulations, and these simulations should be repeated at least annually, if not biannually, to ensure staff familiarity. In addition to the staff needing to be familiar with all the bulky equipment of the robot, it is important that the operating room has the space to accommodate all of the equipment. Equipment should be strategically placed to facilitate patient access if needed [29].
Postoperative Concerns
Rapid recovery is a major goal and advantage of robotic surgery, and much of that is dependent on adequate pain control initiated from the beginning of the procedure and continued into the postoperative period. While laparoscopic procedures like robotic surgery have been shown to have less incisional pain [55], they do have a significant amount of visceral pain.
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