Anesthetic Considerations for Laparoscopic and Robotic-Assisted Surgery




Laparoscopic and robotic-assisted laparoscopic procedures are widely used in urologic surgery, conferring significant benefit to patients and improving outcomes. Benefits include less postoperative pain, faster recovery, shorter hospital stay, less blood loss, and lower incidence of postoperative wound infection. Robotic-assisted surgery has increased dramatically worldwide and is now considered the standard of care in the United States for prostatectomies. Limited access to the patient, extreme Trendelenburg positioning, and an immoveable, docked robot present unique challenges for the anesthesia care team, particularly during crisis management.


The goal of anesthetic management is to provide optimal and safe surgical conditions while managing the pathophysiologic responses associated with laparoscopic surgery. This is a collaborative effort that requires effective and frequent communication with the surgical team and operating room staff. Protocols for rapid port removal and undocking the robot should be available and familiar to the team should a crisis situation arise.


There are few absolute contraindications to laparoscopic surgery, and case reports and retrospective reviews document its safety in high-risk patients. Laparoscopic surgery remains contraindicated in patients with increased intracranial pressure and nontreatable coagulopathy because of carbon dioxide (CO 2 ) insufflation and risk of uncontrolled bleeding. Ventriculoperitoneal shunt, congestive heart failure, and severe chronic obstructive pulmonary disease (COPD) are considered relative contraindications.


The ability of patients to tolerate prolonged, extreme positions, pneumoperitoneum, and CO 2 absorption must be weighed against the benefits of minimally invasive surgery for each patient.


Preanesthesia Assessment


Patients are ideally evaluated in a preoperative clinic to identify patient-specific and procedural risk factors, plan perioperative management, and optimize comorbid conditions. Routine, protocolized preoperative testing is expensive and has not resulted in improved patient outcomes. The evaluation should include a focused physical examination, documentation of coexisting disease, and patient education on risks and potential strategies to minimize them. Additional testing and consultation should be tailored to the patient’s comorbid conditions, functional capacity, and the surgical procedure. Further cardiac workup should follow current American College of Cardiology/American Heart Association (ACC/AHA) guidelines. Patients considered at high risk should be counseled regarding the rare event in which a planned laparoscopic procedure must be converted to an open procedure.




Physiologic Changes


The physiologic changes that accompany laparoscopic surgery are caused by pneumoperitoneum, steep Trendelenburg position, CO 2 absorption, surgical procedure, and the patient’s cardiovascular and pulmonary status.


Pneumoperitoneum


Pneumoperitoneum is established by insufflating the abdomen with CO 2 , targeting intra-abdominal pressure (IAP) between 12 and 15 mm Hg. The increase in IAP displaces the diaphragm cephalad, decreasing pulmonary compliance and total lung volume. The head-down position does not appear to exacerbate these changes, even in the morbidly obese. Atelectasis and increased airway pressures result from reduced functional residual capacity and total lung compliance. These changes are well tolerated in healthy patients. Atelectasis may be more prominent in the elderly owing to increased closing capacity with age. Decreases in oxygen saturation can be treated with the judicious application of positive end-expiratory pressure (PEEP). Recruitment maneuvers in addition to PEEP improve respiratory mechanics and oxygenation in healthy-weight and obese patients during pneumoperitoneum.


Pressure-controlled ventilation is frequently used to lower peak airway pressure after insufflation of the abdomen, although it offers no hemodynamic benefit over volume-controlled ventilation during robotic-assisted radical prostatectomy. Pulmonary barotrauma from increased plateau and airway pressures can lead to pneumothorax (PTX), pneumomediastinum (PMD), or pneumopericardium (PPM), particularly in patients with COPD.


Pneumoperitoneum increases systemic vascular resistance (SVR) and mean arterial pressure (MAP), with unpredictable effects on cardiac output (CO). Increases in SVR are the result of mechanical as well as neuroendocrine responses to pneumoperitoneum. IAPs above 12 mm Hg have been shown to decrease CO and increase SVR. In hypovolemic patients, impairment of venous return by pneumoperitoneum may cause sudden or large decreases in blood pressure. Mechanical compression of the renal arteries and increased secretion of antidiuretic hormone and vasopressin decrease renal blood flow, glomerular filtration rate, and urine output. Peritoneal stretching may cause severe bradycardia and even asystole owing to increased vagal tone ( Table 7-1 ).



TABLE 7-1

Cardiopulmonary Responses to Pneumoperitoneum Less Than 25 mm Hg

















































Measurement Response
Heart rate Increased or decreased
Stroke volume Decreased
Mean arterial pressure Increased
Systemic vascular resistance Increased
Cardiac output Decreased or unchanged
Central venous pressure Increased
Functional residual capacity Decreased
Respiratory compliance Decreased
Peak airway pressures Increased
Pa o 2 Decreased or unchanged
Pa co 2 Increased
Cerebral blood flow Increased
Intracranial pressure Increased
pH Decreased or unchanged

Pa o 2 , partial arterial oxygen tension; Pa co 2 , partial pressure of carbon dioxide in arterial blood.


Carbon Dioxide Absorption


Carbon dioxide is commonly used for abdominal insufflation because it is highly soluble, chemically inert, colorless, inexpensive, and less combustible than air. Because of its high solubility, it is less likely than air (nitrogen) to cause clinically significant gas embolus. CO 2 is systemically absorbed during laparoscopy, causing hypercarbia. The degree of hypercarbia depends on CO 2 insufflation pressure and perfusion of the insufflation site and is higher in retroperitoneal surgery. Hypercarbia can cause arrhythmias and contributes to increased SVR during laparoscopy. MAP, cerebral blood flow, and intracranial pressure are also increased. Mild hypercarbia can improve tissue perfusion through vasodilatation and by shifting the oxyhemoglobin dissociation curve to the right. In healthy patients, excess CO 2 is easily eliminated by increasing minute ventilation 20% to 30%. However, hypercarbia-induced vasoconstriction in the pulmonary circulation may be poorly tolerated in patients with pulmonary hypertension.


Patient Position


Steep Trendelenburg position (25- to 45-degree head down) is necessary for proper surgical exposure during many urologic procedures. Instituting this position after abdominal insufflation significantly increases central venous pressure (CVP), MAP, CO, and stroke volume, as well as mean pulmonary artery pressure and pulmonary artery wedge pressure. These changes are well tolerated in healthy patients, and CO is preserved.


Neurologic complications from cerebral edema after prolonged Trendelenburg position have been reported. Although cerebral perfusion pressure in steep Trendelenburg is maintained in most cases, Schramm and colleagues found impaired cerebral autoregulation in 23 patients undergoing robotic-assisted prostate surgery. Limiting the duration of steep Trendelenburg and keeping MAP within normal limits is a sensible strategy.


Intraocular pressure increases with time in steep Trendelenburg. However, no perioperative visual loss (POVL) has been attributed to steep Trendelenburg positioning alone in patients without preexisting ocular disease ( Table 7-2 ).



TABLE 7-2

Physiologic Changes in Steep Trendelenburg Position




























Measurement Response
Cardiac output Increased or unchanged
Mean arterial pressure Increased
Stroke volume Increased
Mean pulmonary artery pressure Increased
Pulmonary artery wedge pressure Increased
Central venous pressure Increased
Intraocular pressure Increased




Anesthetic Management


General endotracheal anesthesia with neuromuscular blockade is the preferred technique for most major laparoscopic urologic procedures. Extreme patient positioning, prolonged abdominal insufflation, and patient discomfort make neuraxial techniques alone impractical. Although supraglottic devices have been used successfully during laparoscopic cholecystectomies and shorter gynecologic laparoscopic procedures, their use in longer procedures requiring steep Trendelenburg positioning has not been sufficiently studied for them to be recommended.


Monitoring should include electrocardiography, noninvasive blood pressure, pulse oximetry, capnography, peripheral nerve stimulator, and temperature probe. Placing two blood pressure cuffs and two large-bore intravenous lines may be helpful when access to the patient is restricted. A central line is rarely indicated. Patients with significant cardiopulmonary disease may require invasive blood pressure monitoring for frequent arterial blood gas analysis.


Propofol is the most frequently used sedative-hypnotic for induction of general anesthesia, although other agents may be preferable in selected high-risk patients. Tracheal intubation and controlled mechanical ventilation are used to offset the effects of positioning, pneumoperitoneum, and CO 2 absorption. After the patient has been padded and positioned, all intravenous and monitoring lines should be tested and confirmed operational. Migration of the endotracheal tube (ETT) into the right mainstem bronchus has been reported in patients after abdominal insufflation in Trendelenburg position. The cause is cephalad displacement of the diaphragm and movement of the carina toward the relatively fixed ETT. Securing the ETT immediately after the cuff passes the vocal cords may minimize this risk. Rechecking the position of the ETT after abdominal insufflation and placing the patient in Trendelenburg position are recommended. An orogastric tube is placed to deflate the stomach after the ETT is secured. Eyes should be protected with lubricating ointment, taped, and padded. Manipulation of the heavy, metal robotic camera occurs just above the patient’s head, neck, and face. Protective preventative measures must be taken to pad or shield the patient’s head in case of a dropped camera, lens, or other instrument.


Maintenance of anesthesia is accomplished through the use of an inhalational agent, opioid, and muscle relaxant. Alternatively, total intravenous anesthesia (TIVA) with propofol can be used in lieu of an inhaled anesthetic and is associated with less postoperative nausea and vomiting. Although the choice of inhaled agent or TIVA is unimportant in most cases, the use of nitrous oxide is controversial. Concerns that it creates suboptimal operating conditions by causing bowel distention have led to infrequent use during laparoscopic procedures.


Insensible and third-space fluid losses are appreciably less for laparoscopic surgery compared with open procedures. Conservative intravenous fluid administration during robotic-assisted prostatectomy decreases the amount of urine obscuring the operative field and may also reduce the postoperative laryngeal edema resulting from prolonged steep Trendelenburg position.




Postoperative Management


Pain Management


Although pain is often less after robotic-assisted laparoscopic surgery compared with conventional laparoscopy and open procedures, opioids are often required in the postoperative period. Neuraxial opioids are frequently administered as part of an enhanced recovery protocol for major laparoscopic surgery. Opioid analgesics are associated with a number of undesirable side effects, including nausea, vomiting, pruritus, urinary retention, respiratory depression, and delayed return of bowel function. Although there are no procedure-specific recommendations for pain management after major laparoscopic urologic surgery, opioid-sparing multimodal analgesia is gaining popularity to mitigate these side effects and promote early recovery. Systemic steroids, pregabalin, nonsteroidal anti-inflammatory drugs, and cyclooxygenase-2–selective inhibitors have been used successfully before, during, and after surgery to decrease postoperative opioid requirements. Local infiltration of port sites has been shown to be more effective at reducing postoperative pain when administered preemptively ( Table 7-3 ).



TABLE 7-3

Commonly Used Analgesic Agents


































Drug Name Drug Class Mechanism of Action Side Effects
Morphine
Fentanyl Hydromorphone Oxycodone Hydrocodone
Opioid μ-Receptor agonist Nausea, vomiting, pruritus, urinary retention, respiratory depression, constipation
Pregabalin
Gabapentin
Anticonvulsant α 2 δ Protein binding Dizziness, somnolence, dry mouth, edema, blurred vision
Ketorolac
Naproxen
Ibuprofen
Aspirin
Nonselective nonsteroidal anti-inflammatory Cyclooxygenase antagonist Bleeding, cardiovascular thrombotic events, gastrointestinal irritation, ulceration, renal impairment
Acetaminophen Analgesic-antipyretic Inhibition of prostaglandin synthesis in central nervous system Hepatotoxicity, nausea, vomiting
Celecoxib Cyclooxygenase-2–selective nonsteroidal anti-inflammatory Cyclooxygenase-2 antagonist Cardiovascular thrombosis, peripheral edema, dizziness, headache, abdominal pain, nausea, vomiting, renal impairment

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Sep 11, 2018 | Posted by in ABDOMINAL MEDICINE | Comments Off on Anesthetic Considerations for Laparoscopic and Robotic-Assisted Surgery
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