Liver and pancreatic surgery: Intraoperative management

Risk and outcome improvement

Components for the ACP to consider that influence postoperative morbidity include, but are not limited to, comorbid medical conditions, perioperative care to modify risk, and the ability to rescue should an adverse event occur. Identifying patients at increased risk of a poor outcome before surgery remains challenging, and what the anesthesiologist can do to improve perioperative outcome is not always obvious (see Chapter 27 ).

There are several scoring systems to assist clinical risk assessment. By entering data into a multivariable prediction model, an individualized patient risk score for certain morbidities and mortality can be included to guide surgical planning and informed consent. Surgical risk prediction models, such as the Physiological and Severity Score for the Enumeration of Mortality and Morbidity (POSSUM), are not always based solely on preoperative data, nor are they procedure specific, and they are complex to use. Anesthesiologists prefer a less complicated risk score, such as the American Society of Anesthesiologists’ Physical Status Score ( Table 25.1 ), which scores a patient on a scale that other patients may be compared, not the individualized risk prediction of an adverse outcome. However, even if the anesthesiologist knows the risk prediction or risk score, it may not be apparent which anesthesia management factors are independent risk factors for perioperative morbidity and amenable to preventive measures to improve outcome. Another option is to use a biomarker, such as plasma B-type natriuretic peptide concentrations, to predict complications; however, there is no biomarker specific to HPB surgery. No scoring system provides a clear identification of which elective surgery should proceed safely, and risk scores must be viewed in their clinical context.

Anesthetic management can be a Sophie’s choice: modifying one component to prevent a complication that leads to increasing risk by a different pathway. Anesthetic care, like all of life, has risk, and this risk is determined by the preoperative presence of one or more comorbidities that significantly augment the incidence of postoperative adverse events. A key component of complications after surgery is the failure to recognize the patients at risk so that appropriate assessments occur before surgery. Because anesthesia care is facilitative rather than therapeutic, the main outcome of anesthesia care has been traditionally measured in terms of absence of “complications.” Today it is rare for a patient to develop complications due directly to the act of anesthesia, yet anesthesia clinical decisions may impact the perioperative outcome. Given that anesthetic drugs are short-acting, it is not obvious that consequences of anesthetic management could last more than hours or days after surgery. There is arguably a shift toward avoiding anesthesia-related harm after surgery, such as the maintenance of normothermia, antibiotic dosing and glucose control (prevention of surgical site infection), thromboprophylaxis and β-blockade or prescribing target-controlled fluid management, opioid-sparing analgesia, or up-to-date intraoperative ventilation. The choices we make in the operating room may have an impact not only during the case, or in the immediate postoperative time, but long after the patient is discharged from the postanesthesia care unit (PACU).

The occurrence of a 30-day postoperative complication is more important than the preoperative patient risk and intraoperative factors in determining the survival after surgery. Postoperative morbidity has been shown to adversely affect long-term outcome after HPB surgery; therefore efforts aimed at reducing perioperative morbidity will not only reduce usage of resources but will likely further enhance the therapeutic benefit of resection. Given the impact of anesthesia intervention on long-term postoperative outcomes and costs, a natural evolution of the Michigan Surgical Quality Collaborative has been to expand the data collection and collaboration efforts to include the anesthesiology provider and process. The Multicenter Perioperative Outcomes Group (MPOG) has built a comprehensive perioperative patient registry based on electronic healthcare data. Preoperative and intraoperative data are collected and used to identify variations in anesthetic care and optimal care patterns. The data collected are used as a foundation of collaboration between surgeons and anesthesiologists to establish process of care and outcome measures to recommend best practice clinical standards where prospective effectiveness trials may be absent.

Although it is not possible to alter all risk factors, such as age, or avoid every potential consequence, such as pain, there are modifiable risk factors. Detailed evaluation and correction of all modifiable risk factors combined with best practice guidelines are our best choices to help avoid the most preventable complications. Before undergoing surgery, optimization of chronic medical conditions is of critical importance. Hyperglycemia should prompt evaluation of glycemic control including fasting glucose and HgbA1c levels. Uncontrolled diabetes has been associated with adverse postoperative outcomes including wound infections or organ space infection. Chronic cardiopulmonary comorbidities may require preoperative intervention and even modification of intraoperative approach. Functional status workup may identify correctable deficits that can be addressed preoperatively with physical conditioning, nutritional counseling, blood glucose control, and smoking cessation. To decrease patient anxiety, any complete preoperative evaluation of a patient undergoing HPB surgery should include extensive, preoperative education including education material and the opportunity to ask questions of the multidisciplinary team. Medical guidelines have rapid turnover, with medical reversal a reality, and staying current to apply evidence-based practice is recognizing that the correct “scientific answer” may shift over time. ^, Not only is the patient population becoming older with ever-expanding comorbidities, but improvements in the medical management of some chronic illnesses mean that the implications of such illnesses may be quite different today than years past. Select patients might be better served having HPB surgery at a major medical center where the multidisciplinary care team provides optimum preparation of patients as well as the ability and availability to minimize the impact on patients when adverse events occur. ^,

Cardiac evaluation

Although the perioperative event rate has declined because of better anesthetic and surgical techniques, perioperative cardiac complications remain a significant problem. The first step in preoperative care is an adequate identification of patients at risk for perioperative cardiac events. Clinical history, physical examination, and review of a baseline electrocardiogram usually provide enough data to estimate cardiac risk. Estimation of a stable patient’s cardiac risk can be derived from the Lee Revised Cardiac Risk Index (LRCRI), a simple index that identifies six independent risk factors to provide the risk of a cardiac complication in percentages. The risk of a perioperative major cardiac event (PMCE), defined as cardiac death, myocardial infarction (MI), or pulmonary edema within 30 days postoperatively, is the summation of an individual patient’s risk and functional capacity and the cardiac stress related to the surgery.

There are active cardiac conditions that may lead to cancellation of the procedure, unless the surgery is emergent, but most PMCE risk is silent, and the LRCRI has shown only moderate predictive performance. The absence of coronary computed tomographic angiography findings of coronary artery disease confers low PMCE risk regardless of clinical risk, and some have suggested adding this noninvasive test to the LRCRI. The 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery are an excellent framework for evaluating cardiac risk in the perioperative period for patients with clinical risk factors.

Cardiac functional status or capacity, as determined by doctors assessing patients with a brief set of questions, can be expressed in metabolic equivalents or simply the inability to perform various activities such as climbing two flights of stairs or walking four blocks. ^, A patient’s cardiac functional status has been thought to be positively associated with postoperative outcomes. ^, The Measurement of Exercise Tolerance before Surgery (METS) prospective cohort study concluded that subjectively assessed preoperative functional capacity did not accurately identify patients with poor cardiopulmonary fitness or predict morbidity or mortality. How this will affect the ACP’s choice for additional cardiac evaluation is unclear. Over the years, perioperative management has shifted from treating coronary obstruction with coronary revascularization toward medical therapy aiming at prevention of myocardial oxygen supply and demanding mismatch and coronary plaque stabilization. Today preoperative cardiac testing, cardiac stenting, and coronary revascularization are only performed for the same indications as the nonoperative setting. ^,

The risks and benefits of continuing perioperative medical management are complex. Perioperative β-blockade (PBB) has been shown to reduce the incidence of perioperative ischemic events and MI in patients with coronary artery disease but confers questionable benefit and possible harm in patients without coronary artery disease. ^, The PeriOperative Ischemic Study Evaluation (POISE) trial completely transformed the premise of PBB, finding PBB stroke morbidity outweighed any PMCE prevention. POISE confirmed what clinical anesthesiologists had experienced: increased intraoperative hypotension and bradycardia in low-risk patients with newly initiated PBB. PBB guideline revisions followed rapidly in 2009. The guidelines recommended continuation of β-blockers for patients who are already on them and the initiation of PBB for high-risk patients, but not to initiate PBB in low-risk patients in the perioperative period. β-Blockers should still be used to manage acute hypertension and tachycardia perioperatively in patients at risk for myocardial supply and demand imbalance. Similarly, balancing the risk-to-benefit ratio of dual antiplatelet therapy (APT) or aspirin interruption and the risk of stent thrombosis versus continuation and the risk of bleeding is challenging. The POISE-2 trial showed that perioperative aspirin did not reduce PCME at 30 days but did increase perioperative bleeding. Only a small number of patients in this trial had coronary stenting, and patients with a bare-metal stent (BMS) for less than 6 weeks or a drug-eluting stent (DES) for less than 1 year were excluded.

Contemporary data suggest that approximately one in five patients with coronary stent implantation will require noncardiac surgery within 2 years of their coronary intervention. Patients with freshly placed coronary stents presenting for liver surgery pose a significant challenge to anesthesiologists. It is no surprise that anesthesiologists must consistently stay current with rapidly evolving guidelines for the perioperative management of these patients. Some of the clinical questions that arise include the following: How soon can a stented patient undergo surgery? Should a patient continue APT during the perioperative period? What is the risk for surgical bleeding versus coronary thrombosis in this population? In 2016 the ACC/AHA guidelines recommended delaying noncardiac surgery 30 days after BMS implantation and 6 months after DES implantation. However, if the risk for delay for 6 months was greater that the risk for ischemia, elective surgery could be considered at 3 months.

Communication among the patient’s cardiologist, surgeon, and anesthesiologist is essential for the management of patients with active or quiescent coronary artery disease. At the authors’ institution, the medical consult takes into account both the ACC/AHA patient’s number of clinical factors (does the patient have an active cardiac condition; planned surgery, low or high risk; good functional capacity; further testing required) and the LRCRI (high-risk type of surgery; history of ischemic heart disease; history of congestive heart failure; history of cerebrovascular disease; diabetes mellitus [insulin dependent]; renal insufficiency [creatinine > 2]), to determine whether the patient is at acceptable risk to proceed to the planned surgery or if there is the need for further testing before surgery or pharmacologic intervention perioperatively.

In HPB patients with a history of alcohol abuse, cardiac assessment needs to stress the evaluation of myocontractile function. Two basic patterns of alcohol-induced cardiomyopathy have been shown: left ventricular dilation with impaired systolic function and left ventricular hypertrophy with diminished compliance and normal or increased contractile performance.

Geriatric evaluation

Elderly patients with impaired functional status have been shown to have increased morbidity and mortality when undergoing HPB surgery. ^, More than 80% of pancreatic cancers are diagnosed in patients older than 65 years old. Although age should not preclude surgery, at-risk elderly patients should have a comprehensive geriatric assessment and a multidimensional diagnostic tool used to test functional performance and mental status. Frailty has emerged as an important perioperative risk factor. Diagnosis of frailty is especially important in managing geriatric patients. It is a clinical syndrome in which three or more of the following criteria are met: unintentional weight loss of greater than 10 pounds within the previous year, self-reported exhaustion, weakness measured by grip strength, slow walking speed, and low levels of physical activity. Over 300 different types of frailty assessments have been created and used, but there is really no gold standard. Evidence of sarcopenia, which clinically manifests itself as a loss of skeletal mass, strength, and decreased physical performance, is often used to assess frailty. The most commonly used Fried phenotype looks at frailty as a syndrome, something with signs and symptoms that can be measured. In this case, 1 point is assigned to things like walking speed and weight loss, for a final score between 0 and 5. The frailty index is defined as the ratio of the number of deficits present in an individual to the total number of age-related health variables considered. The key here is that the deficits are measured across multiple domains. One compares the number of deficits with the total number measured and ends up with a score between 0 and 1. The clinical frailty score uses a scale of 1 to 9 where each number is associated with a short vignette and an image. The electronic rapid fitness assessment (eRFA) is a questionnaire developed at our institution and used by all the doctors of the geriatrics service to gauge and understand an older patent’s level of fitness. At the authors’ institution, all patients over 65 deemed at increased risk are referred to a geriatric specialist. This service also advises on medications to be used with caution and nonpharmacologic strategies to reduce delirium and analgesics while the patient is in the hospital.

Delirium (temporary inability to focus attention and think clearly) occurs in one of five older patients who undergo major surgery. Delirium is associated with a slower recovery and a poorer outcome, and a vicious circle may be initiated (delirium, physical restraint, and medication to treat delirium; postoperative complications; then more delirium). Korc-Grodzicki used comprehensive geriatric assessment components to predict the development of postoperative delirium and other comorbidities in patients undergoing varying abdominal surgeries. The study population included 416 patients, of which 20% of patients underwent HBP surgeries. Charleston comorbidity index score greater than 3, patients with a history of falls 6 months before surgery, instrumental activities of daily living scores of less than 8, and abnormal mini-cog test results were all predictive of postoperative delirium. In this study, patients who developed postoperative delirium had longer median length of hospital stays and greater likelihood of discharge to a skilled nursing facility. Randomized studies have shown that multicomponent interventions can reduce the incidence of delirium and/or related complications. We advocate a daily protection and intervention program based on early-start and supporting treatment, with increased monitoring, better pain relief, avoidance of polypharmacy, and good nutrition, but from a prevention or therapeutic point of view, there is no one target for decreasing the incidence after surgery. It has been suggested by some studies that the routine use of perioperative medications, such as dexmedetomidine or ketamine can prevent postoperative delirium; however, available evidence does not support this. Gabapentin may reduce postoperative delirium, perhaps by reducing pain and opioid administration.

Pulmonary evaluation

Despite steady advances in care, patients with respiratory disease are still at increased risk for postoperative pulmonary complications (PPCs). PPCs continue to rival cardiovascular complications in frequency and severity after hepatic surgery.

There are many limitations of studies that examine risk factors for PPCs, but there are some consistent patterns. Important risk factors for PPCs are the presence of pulmonary disease, cigarette smoking, low preoperative arterial oxygen saturation, acute respiratory infection during the previous month, age, preoperative anemia, site of surgery (with upper abdominal, especially near the diaphragm, or intrathoracic surgery being the highest risk), surgery duration of at least 2 hours, and emergency surgery. ^, Despite the increased risk of PPCs in patients with preexisting pulmonary disease, no prohibitive level of pulmonary function has been established for which surgery is contraindicated. Neither abnormal pulmonary function testing nor arterial blood gas analysis are useful in predicting risk. Thus these tests are only justified as part of an effort to optimize preoperative pulmonary status, either with an immediate perioperative course of systemic corticosteroids or antibiotics, or to advise if surgery should be delayed. Poor functional capacity and especially low anaerobic threshold have been associated with a high risk of postoperative complications and death. Submaximal cardiopulmonary exercise testing is a noninvasive objective test that measures a patient’s anaerobic threshold and patients with low subjective functional capacity or dyspnea may benefit from this test of cardiopulmonary reserve to determine complication risk. Although it seems reasonable to assume that fitter patients will have better outcome, a recent study suggested that cardiopulmonary exercise testing should not be used as a barrier to patients undergoing liver surgery. Potential interventions to reduce PPCs include smoking cessation, preoperative exercise training, early mobilization, postoperative parental nutrition, and optimal treatment of pain.

Although obesity presents the anesthesiologist with significant challenges, obesity per se is not a significant risk factor for PPCs and should not be used to deny a patient HPB surgery. There are two subsets of obese patients: one group is “the metabolically healthy but obese” and the other group is the “metabolically unhealthy but obese.” When an obese patient has three or more of the following criteria, abdominal obesity, increased triglycerides, decreased high-density lipoprotein, elevated cholesterol, hypertension, and glucose intolerance, the patient has a 2.5 increased incidence of PPCs. Obese patients are at risk of suffering from several respiratory derangements, including obstructive sleep apnea (OSA), obesity-hypoventilation syndrome, and restrictive impairment. The increase in body mass also results in increased oxygen consumption and carbon dioxide production. With these issues in mind, it is not surprising that acute PPCs are twice as likely in OSA patients. Many patients with OSA are undiagnosed, but there is a strong relationship between obesity and OSA. The American Society of Anesthesiologists (ASA) addressed this issue with practice guidelines, including assessment of patients for possible OSA before surgery and careful postoperative monitoring for those suspected to be at risk. It is unclear whether screening for OSA will affect surgical morbidity, but it is reasonable to question obese patients about symptoms that may suggest sleep apnea before HPB surgery. At Memorial Sloan Kettering Cancer Center (MSKCC), all obese patients are given the STOP (Snoring, Tiredness, Observed apnea, high blood Pressure)-Bang (Body mass index, Age, Neck circumference, and gender) questionnaire. Given the association of obesity and OSA with multiple medical conditions (increased risk of venous stasis, pulmonary embolism, hypertension, cerebral vascular accidents, cardiomyopathy, arrythmias, and ischemic heart disease) the anesthesiologist is in a position to have an informed discussion with the patient about the increased risk of morbidity and mortality and work with other members of the patient’s care team to determine whether any interventions should be initiated before surgery in an effort to minimize the risk of complications. Polysomnography is the gold standard for diagnosis of OSA, but it is expensive and a limited resource. The most reasonable approach is to check room air-pulse oximetry. If the patient has an oxygen saturation level less than 96%, further evaluation is warranted. A 2-week period of continuous positive airway pressure (CPAP) therapy has been shown to be effective in correcting abnormal ventilatory drive and improving cardiac function.

Hepatic evaluation

Risk factors and symptoms of liver disease are not as well defined as in other organ systems. There is no single biomarker for liver dysfunction; instead, the diagnosis of liver disease requires a high degree of suspicion, with a careful probing of the clinical history to identify specific risk factors for liver disease, such as previous blood transfusions, jaundice, travel, tattoos, high-risk sexual behavior, illicit drug use, excessive alcohol intake, or chemotherapy (see Chapter 4 ).

The goal of preoperative screening is to determine the presence of preexisting liver disease without the need for extensive or invasive monitoring. Liver function tests can measure different aspects of hepatic function, but as a group of tests, they lack specificity and are often affected by nonhepatic function. These biochemical markers cannot quantify hepatic cellular dysfunction. In contrast, anesthesiologists are often confronted with abnormal hepatic function tests in asymptomatic patients. In general, for asymptomatic patients with mildly elevated alanine and aspartate aminotransferase levels and a normal bilirubin concentration, cancellation of surgery is rarely indicated

Most hepatic resections are performed for metastatic cancer. In these patients the quantity of hepatocyte dysfunction, whether induced by preoperative alcohol, chemotherapy, or metabolic syndrome, is more elusive to identify. In patients with significant abnormalities, additional investigation is warranted, given the higher risk to patients having HPB surgery to evaluate whether there is underlying cirrhosis or steatosis. Serologic testing to exclude viral hepatitis and human immunodeficiency virus should always be performed.

The etiology of hyperbilirubinemia may have an obstructive or nonobstructive cause. No matter the root cause, jaundice adversely affects outcome. Unlike elevated bilirubin associated with hepatocyte disturbance, obstructive jaundice is typically seen in patients with bile duct obstruction and is not a contraindication for HPB surgery, if it is being performed to remove the cause of the obstruction. Biliary sepsis may contribute to the exacerbation of perioperative hemodynamic instability. In situations where there is clinical concern for the development of acute cholangitis, rapid biliary decompression and intravenous (IV) antibiotics should be administered preoperatively, and surgery should be delayed until the infection resolves. Patients with hyperbilirubinemia are a subset of patients with an increased risk of renal compromise after low central venous pressure (LCVP)-assisted hepatectomy. The surgeon and anesthesiologist must have a detailed discussion of risk versus benefit.

Alcohol use disorder

Patients with unhealthy alcohol use face increased perioperative risks from the medical consequences associated with alcohol consumption as well as from physiologic dependence and withdrawal. Up to 50% of patients presenting for gastrointestinal (GI) cancer surgery have alcohol use disorder. Studies have found that many surgical patients have not had been appropriately assessed for alcohol use in the preoperative evaluation. Abstinence from drinking, as imposed by a hospital admission, places patients at risk for alcohol withdrawal syndrome (AWS). The preoperative evaluation of patients with unhealthy alcohol use should include effective screening strategies to identify the presence of heavy alcohol use, detect end-organ damage secondary to alcohol consumption, and prompt intervention to address alcohol use before surgery. There are several screening tools to identify alcohol use disorder. The authors’ preference is to use the CAGE (cut down, annoyed, guilty, eye opener) questionnaire. AWS prophylaxis should begin on admission to the hospital. Evidence supports the use of benzodiazepines as first-line treatment. Two strategies are recommended: either a fixed-dosage or an as-needed regimen triggered by symptoms. These patients may have increased or decreased anesthesia requirements during induction and maintenance. The most common 90-day postoperative complications are infections, bleeding, and cardiopulmonary insufficiency; however, these complications are only increased if the patient has alcohol abuse at the time of surgery. For those patients with alcohol abuse at the time of surgery, the development of AWS is associated with a longer hospital stay and increased mortality.