Anesthetic considerations for laparoscopic and robotic-assisted surgery





Introduction


Laparoscopic and robotic-assisted laparoscopic procedures are widely used in urologic surgery, conferring significant benefits to patients and improving outcomes. Benefits include reduced postoperative pain, faster recovery, shorter hospital stay, reduced blood loss, and lower incidence of postoperative wound infection. , Robotic-assisted surgery has increased dramatically worldwide and may be associated with fewer perioperative complications when compared to nonrobotic laparoscopic surgeries. Limited access to the patient, extreme Trendelenburg positioning, and an immovable 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, which 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 have demonstrated its safety in high-risk patients. Laparoscopic surgery remains contraindicated in patients with increased intracranial pressure (ICP) and untreatable 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.


Physiologic changes


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


Pneumoperitoneum


Pneumoperitoneum is established by insufflating the abdomen with CO 2 , targeting an intraabdominal 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 morbidly obese patients. Atelectasis and increased airway pressures result from reduced functional residual capacity and total lung compliance. These changes may be augmented with lateral positioning but are well tolerated in healthy patients. Atelectasis-induced shunting and hypoxemia may be poorly tolerated in elderly patients because of the relationship of increased closing capacity with age. Decreases in oxygen (O 2 ) 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.


Abdominal insufflation leads to biphasic changes in systemic vascular resistance (SVR), venous return (VR), and ultimately cardiac output (CO). The initial rise in IAP increases VR and CO as splanchnic, and portal blood volume is emptied into the central venous system. Additional increases in IAP cause inferior vena cava compression leading to decreased preload and CO. IAP above 12 mm Hg has been shown to decrease CO and increase SVR. Increases in SVR are the result of mechanical and neuroendocrine responses to pneumoperitoneum. Plasma concentrations of norepinephrine, epinephrine, renin, and aldosterone are significantly elevated during laparoscopic surgery, adversely affecting renal perfusion. Mechanical compression of the renal arteries and increased secretion of antidiuretic hormone and vasopressin decrease renal blood flow, glomerular filtration rate, and urine output. In hypovolemic patients, impairment of VR by pneumoperitoneum may cause sudden or large decreases in blood pressure. Peritoneal stretching may cause severe bradycardia and even asystole owing to increased vagal tone ( Table 7.1 ). The potential for cardiovascular and respiratory impairment due to pneumoperitoneum can be mitigated by using the lowest insufflation pressure necessary for adequate exposure of the operative field.



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
Pao 2 Decreased or unchanged
Paco 2 Increased
Cerebral blood flow Increased
Intracranial pressure Increased
pH Decreased or unchanged

Pao 2 , Partial arterial oxygen tension; Paco 2 , partial pressure of carbon dioxide in arterial blood.


Carbon dioxide absorption


CO 2 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 embolism. 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, myocardial depression, and pulmonary vasoconstriction and contributes to increased SVR during laparoscopy. Mean arterial pressure (MAP), cerebral blood flow, and ICP 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.


CO 2 levels may remain high even after abdominal desufflation. High minute ventilation should be maintained until excess CO 2 has been eliminated.


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 (SV), as well as mean pulmonary artery pressure and pulmonary artery wedge pressure. These changes are well tolerated in healthy patients and CO is preserved.


Prolonged Trendelenburg position can lead to facial and laryngeal edema with postoperative respiratory distress. The Trendelenburg position and high insufflation pressure can facilitate regurgitation of gastric contents onto the face and orbital area. Care should be taken to protect the eyes from potential injury.


ICP increases significantly during robotic-assisted laparoscopic prostatectomy (RALP), and 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. Intraoperative dexmedetomidine administration has been shown to attenuate increases in ICP during RALP as measured by optic nerve sheath diameter.


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


The kidney rest lateral decubitus position can lead to significant reductions in MAP, CO, and SV. These effects may be due to decreased VR and increased SVR.


Anesthetic management


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. Preoperative tests and consultations should be ordered on a selective basis to guide or optimize perioperative management. Routine protocolized preoperative testing is expensive and has not resulted in improved patient outcomes. The timing of the preoperative evaluation should be guided by the complexity and invasiveness of the surgical procedure and severity of disease. Patient assessment should include a focused examination of the airway, heart, and lungs; 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.


Preoperative fasting instructions should follow American Society of Anesthesiologists (ASA) guidelines and include clear carbohydrate rich fluids up to 2 hours prior to the procedure. , This approach avoids dehydration before surgery, reducing the risk of postoperative nausea and vomiting (PONV). A large carbohydrate load prior to surgery may decrease insulin resistance and catabolism and preserve muscle function as measured by grip strength.


With the development of the Enhanced Recovery After Surgery (ERAS) pathways, length of stay and postoperative complications have been significantly reduced. , Patients should be educated about the specific ERAS elements relevant to their surgical procedure during the preoperative assessment visit.


Preoperative management


The risks and benefits of general anesthesia and regional block, if utilized, are discussed in detail, and informed consent is obtained prior to surgery. Patients should be counseled about common postoperative side effects of anesthesia, including postintubation sore throat, facial edema from steep Trendelenburg positioning, PONV, shivering, pain and irritation from an indwelling urinary catheter, and possible confusion in elderly patients. In particular, discussing postoperative pain tolerances and setting expectations for pain management and early mobilization in the post-anesthesia care unit (PACU) are essential.


As a component of preventive multimodal analgesia, patients can receive oral nonopioid medications, including acetaminophen, nonsteroidal antiinflammatory drugs (NSAIDS), gabapentin/pregabalin, and cyclooxygenase (COX-2) inhibitors, in the perioperative setting. Routine administration of histamine-2 receptor blockers, proton pump inhibitors, or nonparticulate antacids is not recommended but should be used for patients who are at high risk for perioperative pulmonary aspiration. ,


Intraoperative management


General endotracheal anesthesia with neuromuscular blockade (NMB) 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 cholecystectomy 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. Invasive blood pressure monitoring may be required when significant blood loss is anticipated or in patients with significant cardiopulmonary disease.


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 the 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 the 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 preventive measures must be taken to pad or shield the patient’s head in case of a dropped camera, lens, or other instrument. Functionality and adequacy of all monitors and lines must be ensured after final positioning.


Maintenance of anesthesia is accomplished through the use of an inhalational agent, opioids, and muscle relaxant. Alternatively, total intravenous anesthesia (TIVA) with propofol can be used in lieu of an inhaled anesthetic and is associated with reduced PONV. Nitrous oxide is usually avoided due to concerns that it creates suboptimal operating conditions by causing bowel distension. Additionally, substituting nitrous oxide with air reduces the risk of PONV by 12%.


Increasingly, intraoperative anesthetic management is being informed by the adoption of ERAS pathways in minimally invasive urologic surgery. Although specific elements within these pathways may vary depending on procedure and evolving evidence, guidelines universally recommend minimizing intraoperative opioid administration. , Intravenous acetaminophen and ketorolac are frequently utilized along with neural blockade to decrease opioid requirements intraoperatively and postoperatively. Additionally, emerging evidence suggests that the use of opioid-free anesthesia for minimally invasive urologic surgery is feasible and may decrease postoperative opioid requirements and time to PACU discharge readiness. ,


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 RALP. Protective lung ventilation with low tidal volume (6–8 mL/kg ideal body weight) and PEEP (5–10 cm H 2 O) during pneumoperitoneum are utilized to mitigate postoperative pulmonary complications. Pulmonary barotrauma from increased plateau and airway pressures can lead to pneumothorax (PTX), pneumomediastinum (PMD), or pneumopericardium (PPM) particularly in patients with COPD.


Steep Trendelenburg position (more than 30–40 degrees) with modified lithotomy is necessary for proper surgical exposure during pelvic procedures. The legs are typically positioned in padded maneuverable supports concomitantly to avoid lumbar torsion and extreme hip extension. The ankle, knee, hip, and contralateral shoulder should be in alignment. Popliteal artery occlusion can be avoided by ensuring the weight of the leg rests on the heel rather than the back of the knee. Prior to prepping the patient, the table should be placed in steep Trendelenburg to ensure patient stability and acceptable airway pressures. An “egg crate” mattress or horseshoe shoulder brace will prevent cephalad migration during surgery. Modified or full lateral decubitus position is utilized for renal and adrenal procedures. An axillary roll under the dependent hemithorax supports the chest to prevent compression of the axilla and shoulder. Pillows should be placed between the knees and thighs and all pressure points padded. Greater degrees of table flexion and prolonged surgery can lead to neuromuscular complications.


Neuromuscular monitoring should be used whenever feasible to ensure adequate muscle relaxation in robot-assisted cases. Sudden movement can lead to major visceral injuries while the robot is docked and trocars are in place. Deep NMB can mitigate hemodynamic perturbations if high insufflation pressures are used during surgery.


Insensible and third-space fluid losses are appreciably lower for laparoscopic surgery than those for open procedures. Eliminating mechanical bowel preparation and encouraging clear fluid intake up to 2 hours preoperatively minimizes preoperative dehydration. Both hypervolemia and hypovolemia are associated with postoperative morbidity. Intravascular euvolemia should be maintained. Conservative intravenous fluid administration during RALP decreases the amount of urine obscuring the operative field and may also reduce postoperative laryngeal edema resulting from prolonged steep Trendelenburg position.


Emergence


Postoperative complications due to residual NMB can be avoided by administering sugammadex or neostigmine and glycopyrrolate during emergence from anesthesia and should always be administered. Ventilation/perfusion mismatch can be improved with recruitment maneuvers and raising the back of the operating table. CO 2 retention within the abdomen contributes to referred shoulder pain after laparoscopic surgery. Removal of residual CO 2 can be accomplished with recruitment maneuvers and normal saline irrigation. If laryngeal edema is suspected, a cuff leak test should be performed to ensure the patient can be extubated safely.


Postoperative management


Pain management


Although pain is often reduced after robotic-assisted laparoscopic surgery compared with conventional laparoscopy and open procedures, opioids are often required in the postoperative period. Incision sites, peritoneal stretching, and referred shoulder pain all contribute to postoperative discomfort after minimally invasive surgery. Utilizing low insufflation pressures and aspirating residual CO 2 after desufflation can significantly reduce postoperative pain.


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, respiratory depression, urinary retention, 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, acetaminophen, pregabalin/gabapentin, NSAIDS, and COX-2 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 antiinflammatory 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 antiinflammatory Cyclooxygenase-2 antagonist Cardiovascular thrombosis, peripheral edema, dizziness, headache, abdominal pain, nausea, vomiting, renal impairment


Transabdominal plane (TAP) block has also been used as part of a multimodal strategy to improve postoperative pain outcomes in laparoscopic patients with varying degrees of success. Differences in surgical procedure, timing of block administration, and dose and volume of local anesthetic may contribute to these conflicting results. Recently, robot-assisted TAP block administration was shown to be superior to local anesthetic port infiltration in reducing postoperative pain scores and opioid consumption in radical prostatectomy patients.


The quadratus lumborum (QL) block is distinct from the TAP block, affecting both visceral and abdominal wall pain. Local anesthesia is deposited into the thoracolumbar fascia, which extends posteriorly to the paravertebral region resulting in sensory inhibition from L1 to T7. The QL block has been shown to significantly reduce postoperative opioid consumption after laparoscopic nephrectomy , and laparoscopic pyeloplasty when compared to port site infiltration alone.


Paravertebral block has been shown to decrease postoperative opioid requirements after hand-assisted laparoscopic nephrectomy. It may be an attractive choice when bleeding and nephrotoxicity associated with NSAID administration are concerns.


Nausea and vomiting


Refractory PONV is upsetting to patients and can result in delayed PACU discharge, unplanned hospital admission, and increased health care costs. Laparoscopic surgery is strongly believed to be a risk factor for PONV. Other patient-specific risk factors include young age, nonsmoking status, female sex, and history of PONV or motion sickness. Anesthetic causes of PONV include the use of volatile anesthetics, nitrous oxide, and opioids . Modifying anesthetic technique, minimizing postoperative opioid consumption, and using effective antiemetic agents either alone or in combination can decrease risk. TIVA has been shown to decrease PONV risk by 25% in high-risk patients. Recommended pharmacologic antiemetic agents for PONV prophylaxis include 5-hydroxytryptamine (5-HT 3 ) receptor antagonists, neurokinin-1 (NK-1) receptor antagonists, antihistamines, corticosteroids, butyrophenones, and anticholinergics. The decision to use PONV prophylaxis should be based on patient risk factors, side effects of the antiemetics, and drug cost. Moderate- and high-risk patients may benefit from combination therapy using drugs that bind at different receptor sites. Drugs used for prophylaxis should not be repeated if rescue therapy becomes necessary ( Table 7.4 ).


Aug 8, 2022 | Posted by in UROLOGY | Comments Off on Anesthetic considerations for laparoscopic and robotic-assisted surgery
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