INTRODUCTION — All patients who undergo anesthesia must have a preanesthesia evaluation by an anesthesia clinician to assess the patient's medical conditions, perioperative risk, and readiness for the planned procedure, and to create an anesthetic plan. This topic will discuss the components of preanesthesia evaluation, including risk assessment and appropriate preoperative testing.
Preoperative medical evaluation and medication management are discussed separately. (See "Preoperative medical evaluation of the healthy adult patient" and "Perioperative medication management".)
Preoperative evaluation and management for specific medical conditions are also discussed separately. (See 'Conditions that increase perioperative risk' below.)
GOALS FOR PREANESTHESIA EVALUATION — Goals of preoperative evaluation are to assess the patient's medical status and ability to tolerate anesthesia for the planned procedure, reduce the risks of anesthesia and surgery, and to prepare the patient for the procedure. Adequate preoperative patient evaluation and preparation may improve patient satisfaction, as well as decrease complications, delays, cancellations, costs, and mortality [1-5].
COMPONENTS OF THE PROCESS — Components of the preanesthesia evaluation process may include the following:
●Clinical evaluation to identify comorbid conditions, allergies, and previous complications of anesthesia
●Management and optimization of medical diseases that affect perioperative risk
●Perioperative risk assessment to inform shared decisions on alternatives for care
●Creation of a plan for anesthesia and postoperative care
●Education of patients and families about expectations surrounding anesthesia care
●Obtaining informed consent (see 'Consent and decision making' below)
●Determination of appropriateness for care in ambulatory surgical facilities or remote locations (see "Office-based anesthesia", section on 'Patient selection')
●Motivating patients to stop smoking, lose weight, or commit to other preventive care
●Meeting regulatory requirements
TIMING OF PREANESTHESIA EVALUATION — The most appropriate timing for preanesthesia evaluation depends upon the general health status of the patient, his or her relationship with other care providers, the degree of risk associated with the planned procedure, and the urgency of the procedure. Other patient factors (eg, language barrier, intellectual disability) may also enter into the decision on timing, method, and location of the evaluation.
Not all patients will benefit from the same approach to preanesthesia evaluation, and resources need to be matched with expected benefits. Healthy patients having low-risk procedures can usually be seen on the day of the procedure immediately before anesthesia. (See 'Healthy patients' below.)
High-risk patients or patients having high-risk procedures may require further work-up, time for medical interventions, and intensive planning well in advance of the procedure. (See 'Conditions that increase perioperative risk' below.)
Many centers have created guidelines for screening in order to triage patients for the timing and method of preanesthesia evaluation. Such screening optimally occurs as soon as a procedure is considered. Screening information can be completed by the patient or family member/guardian in person (paper or electronic version), remotely via electronic health record tools, with web-based programs, or during a telephone interview. Suggested patient and procedure triage criteria are shown in tables (table 1 and table 2). The form we use to collect some of the necessary information and to start a medical history is shown in a table (table 3).
PREANESTHESIA CLINIC — Preoperative assessment and testing clinics can provide coordinated anesthesia, surgical, and nursing assessments, and laboratory services for patients who require assessment before the day of surgery. In effective preoperative medicine clinics, the anesthesiologist performs a comprehensive assessment, orders testing, intervenes to optimize comorbid conditions, arranges for necessary consultations for optimization, provides fasting and medication instructions, and communicates with the anesthesia clinicians who will care for the patient. High-risk patients and patients who undergo high-risk procedures may benefit from having informed consent for anesthesia obtained in a preanesthesia clinic, without the time constraints of discussions on the day of surgery. (See 'Consent and decision making' below.)
Evaluation of high-risk patients in a preoperative clinic may reduce unnecessary testing [5,6], case cancellations  and delays on the day of surgery , and mortality . In addition, perioperative medicine clinics provide opportunities for behavioral modification intervention (eg, smoking cessation) at a 'teachable moment' when patients may be more receptive to change due to an upcoming surgical procedure .
CLINICAL EVALUATION — We agree with the American Society of Anesthesiologists (ASA) Practice Advisory for Preanesthesia Evaluation  that the preanesthesia assessment should include, at a minimum, the following:
●A focused examination of the airway, lungs, and heart
●Review of pertinent medical records
●Indicated preoperative tests
●Consultations with specialists if necessary
Medical history and review of systems — The medical history includes the history of present illness, identification of the planned procedure, past and current medical conditions, medications and allergies, tobacco and substance abuse, past surgical history, and past experiences and problems with anesthesia in the patient or family members. The medical history should also include the severity and stability of the medical conditions, current or recent exacerbations, and prior treatments or planned interventions. A prior history of difficulty with airway management, severe postoperative nausea and vomiting, or a patient or family history of malignant hyperthermia or pseudocholinesterase deficiency is sought. (See "Susceptibility to malignant hyperthermia: Evaluation and management".)
A history of excessive sore throat after anesthesia, dental injury related to anesthesia, or 'requiring a small breathing tube' with previous anesthetics may indicate difficulty with airway management. Records from previous anesthetics should be reviewed when possible and may assist with planning for airway management (table 4).
A review of systems, including a general run-through of all organ systems, is especially useful to uncover symptoms that may lead to establishment of previously undiagnosed conditions. A review of records, including notes from primary care clinicians or specialists, and test results can reveal issues the patient may not recall.
The patient's functional capacity or cardiorespiratory fitness may be the single best predictor of perioperative risk. The patient is commonly asked to name the most strenuous activity he or she does regularly, or has done most recently, and whether such activity causes chest pain, dyspnea, or claudication. The inability to climb two flights of stairs or walk four blocks predicts an increased risk of postoperative cardiopulmonary complications after major noncardiac surgery [11,12]. Self-reported functional capacity may be inaccurate; observing the patient climbing stairs, or assessment with a six-minute walk test can provide additional information if inaccurate self-reporting is suspected. Use of an objective tool such as the Duke Activity Status Index (DASI)  or cardiopulmonary exercise testing (CPET) are more accurate measures of actual functional capacity and predictors of perioperative cardiac risk compared with subjective assessments . The DASI questionnaire consists of 12 items that measure the patient's functional capacity (table 5). Calculators that tally the score and convert the results to metabolic equivalents (METS) are available online. (See "Evaluation of cardiac risk prior to noncardiac surgery" and 'Functional status' below and "Preoperative medical evaluation of the healthy adult patient", section on 'Exercise capacity' and "Overview of pulmonary function testing in adults", section on 'Six-minute walk test'.)
Dyspnea is a common patient complaint that may be caused by a variety of disease states, including some that may confer increased perioperative risk and/or changes in management. In many cases, the etiology of dyspnea may be categorized as pulmonary or cardiovascular (figure 1 and table 6 and table 7). Clinical assessment and testing for patients with dyspnea are discussed separately. (See "Approach to the patient with dyspnea".)
Breastfeeding women — All women with children younger than two years of age should be asked whether they are breastfeeding. Breastfeeding women who will be separated from the infant for more than a few hours should be encouraged to express and store breast milk preoperatively for feeding the infant during that time. However, there is no need to discard expressed breast milk after anesthesia.
For almost all drugs used perioperatively, there is no evidence of adverse effects on the breastfed infant because the drugs are transferred to breast milk in only very small amounts. However, there is limited or no data on transfer of some anesthetic drugs to breast milk. Further guidance and general principles of perioperative care in breastfeeding women are shown in a table (table 8).
For information on specific medications, consult the LactMed database.
Anesthesia directed physical examination — At a minimum, the preanesthetic examination includes measurement of vital signs (blood pressure [BP], heart rate, respiratory rate, and oxygen saturation); height and weight measurements with body mass index calculation; auscultation of the heart and lungs (especially for irregular rhythms, murmurs, rales, or wheezing), basic neurologic examinations; and an airway assessment (table 4). (See "Airway management for induction of general anesthesia", section on 'Airway assessment' and "Management of the difficult airway for general anesthesia in adults", section on 'Recognition of the difficult airway'.)
The need to routinely measure BP in preoperative clinics has been questioned. Guidelines in the United Kingdom suggest that preoperative clinics do not need to measure BPs in patients being seen for elective procedures if they have documented BPs <160/100 mmHg in the referral letter from primary care . Patients often have anxiety-related elevated BPs during the preoperative visit even without a history of hypertension. In this setting, the BP should be repeated, medical records reviewed, or the patient asked about typical BP readings; if necessary, the patient can be asked to measure the BP at home and report the results. Ambulatory measurement of BP correlates with end-organ damage and predicts cerebrovascular and cardiovascular adverse events in the nonoperative setting significantly better than clinic measurements of BPs .
Patients should be assessed for loose, capped, damaged, missing, and artificial teeth, which are at increased risk for damage during airway management. Abnormalities should be documented and confirmed with the patient.
If regional anesthesia (ie, neuraxial anesthesia/analgesia, peripheral nerve block) is planned or possible, the regional anesthesia site is examined to assess for potential difficulty or infection, and any preexisting neuropathy or weakness should be documented.
RISK ASSESSMENT — Assessment of the patient's risks of anesthesia and the planned procedure is an important component of the preanesthesia evaluation. The overall perioperative risk reflects both the risks associated with the patient's medical conditions and the risk associated with the planned procedure.
●Risk assessment informs the plan for anesthesia, including the venue for the procedure, type of anesthesia, intraoperative monitoring, and resources required.
●An elevated risk may suggest the need for preoperative intervention, in-hospital or inpatient care rather than ambulatory surgery, and/or enhanced postoperative monitoring and care (eg, intensive care, postdischarge skilled nursing facility).
●Perioperative assessment of the risks of complications, mortality, and likelihood of return to independent living is part of informed consent, and may affect shared decisions regarding surgical and nonsurgical options for treatment.
Epidemiology of perioperative risk of complications — Perioperative complications are a major public health issue and a significant cause of avoidable morbidity and mortality . Mortality rates vary widely across hospitals and countries [18,19].
●Worldwide an estimated 300 million operations are performed each year, and approximately one out of four patients who undergo major surgery will develop complications [18,20]. Up to 2.5 million patients will die (1 percent risk) and 12.5 million will have costly adverse events each year [18,21,22].
●The incidence of complications varies across procedures  and patient populations. Patients at highest risk are those of advanced age with comorbid diseases having major surgery, with a hospital mortality rate as high as 12 percent .
●Long-term survival is significantly reduced for those patients who have perioperative complications, even if they survive to leave the hospital [17,24].
●The costs associated with complications after surgery are substantial. In one study mean hospital costs were $19, 626 (119 percent) higher for patients with complications ($36, 060) compared with those without complications ($16 ,434) .
Patient risk factors
ASA physical status — The American Society of Anesthesiologists physical status (ASA-PS) is a classification system that defines the overall health status of the patient and is used by anesthesiologists, surgeons, and other clinicians involved in perioperative care. An ASA-PS rating is assigned to every patient who undergoes anesthesia (table 9). The ASA-PS was not designed to evaluate patient risks, but it is widely used for this purpose.
ASA-PS designation is subjective, and assignments vary widely among clinicians, especially when determined by non-anesthesiologists [26,27]. Nonetheless, a higher ASA-PS is associated with complications, increased cost, unexpected hospital admission after ambulatory surgery, postoperative admission to the intensive care unit, hospital length of stay, and mortality (figure 2) [26,28-33].
The ASA-PS is a component of some more comprehensive tools for assigning perioperative risk. (See 'Risk assessment tools' below.)
Functional status — Several studies have shown that inability to perform average levels of exercise (4 to 5 metabolic equivalents [METs]) identifies patients at risk of perioperative complications [11,35]. Functional capacity reflects the integrated responses of the pulmonary, cardiovascular, circulatory, neuromuscular, and hematologic systems and muscle metabolism. The assessment can range from a self-reported ability to engage in activities of daily living, to six-minute walk tests [36-38], to objective testing of oxygen uptake with cardiopulmonary exercise testing (CPET) [39,40]. (See "Evaluation of cardiac risk prior to noncardiac surgery" and 'Medical history and review of systems' above.)
The self-reported Duke Activity Status Index (DASI), which includes 12 measures of functional capacity, may provide prognostic information about surgical risk (table 5). In a prospective cohort study of 1546 patients with high cardiac risk who underwent inpatient noncardiac surgery, a DASI score ≥34 was associated with reduced odds of myocardial injury, death within 30 days or one year, or new disability . DASI score <34 was associated with increased odds of 30 day death or myocardial infarction, and moderate to severe complications.
Biomarkers — Plasma biomarkers, such as beta natriuretic peptide, estimated glomerular filtration rate, and C-reactive protein (CRP) may have prognostication in predicting which patients will develop complications after major noncardiac surgery. Biomarkers are more highly predictive of major adverse cardiac events than for other complications . Elevated preoperative and postoperative plasma levels of CRP are associated with postoperative delirium, suggesting that a pre-inflammatory state and inflammatory response to surgery may be mechanisms of delirium .
Surgical risk — In general, intraperitoneal or intraabdominal, intrathoracic, and major vascular procedures, as well as longer procedures, those associated with greater blood loss and intraoperative fluid shifts, and emergency procedures are associated with higher perioperative risk. Laparoscopic, endovascular, orthopedic, peripheral procedures, and breast surgery usually carry lower risks.
However, there are broad variations of surgical risk within these categories. This concept was illustrated by a study that used data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database to determine the risk of perioperative adverse cardiac events (PACE), defined as cardiac arrest requiring cardiopulmonary resuscitation or acute myocardial infarction, for three million operations that occurred between 2010 and 2015 . There was a continuum of risk across over 1800 operations analyzed, and significant differences in risk among operations within traditionally designated low, intermediate, and high risk categories. As an example, there was a threefold difference in risk of PACE between laparoscopic total abdominal colectomy and Whipple procedure, both of which are considered high risk according to the RCRI. This risk stratification model requires external validation, and may require institution specific modification for application. Examples of the risk of PACE for selected common operations as determined by this model are shown in a table (table 11).
Surgical risk for specific postoperative outcomes (eg, cardiac complications versus pulmonary complications) are not equivalent. More accurate assessment of surgical risk is best accomplished by using computer- or web-based calculators of risk such as ACS NSQIP calculator to accurately define the procedural risk and to provide data-supported risk assessment .
For several guidelines and perioperative risk assessment tools, surgical risk has been defined according to risk of death or major adverse event, with high risk arbitrarily defined as having a greater than 5 percent risk of complications, intermediate risk as 1 to 5 percent risk, and low risk as less than 1 percent risk .
The only well-established very low-risk procedure is cataract extraction . If the patient is able to lie relatively flat, stay still, follow simple commands, and local anesthesia or monitored anesthesia care is planned, then there are few if any contraindications for cataract surgery. There is a probably small, irreducible risk of unfavorable outcomes after cataract surgery, given the population of older adult individuals who often have advanced diseases.
Risk assessment tools — A number of tools have been developed that combine patient and surgical factors to improve the accuracy of prediction of perioperative risk.
●The ACS NSQIP calculator is a free of charge online resource for overall risk assessment that combines procedure-specific surgical risk with 20 patient factors . The tool calculates risks of 15 separate outcomes, which are displayed in graphic form, with comparison to risk for an average patient. An example of a report generated by the ACS NSQIP calculator is shown in a figure (figure 3). Results can be easily understood by practitioners and patients and may help with shared decision-making, especially regarding specific risks that may be more meaningful to individual patients. For example, older patients are typically less concerned about death than about a degradation of quality of life or an inability to live independently . Use of the results of the NSQIP calculator as part of informed consent is discussed below. (See 'Consent and decision making' below.)
The ACS NSQIP calculator is based on data from hospitals participating in NSQIP and has not been validated externally. In addition, accuracy of risk estimates may be uneven across outcome measures, and the calculator may be less useful for some categories of procedures than others [48-51].
●Risk calculators specifically for cardiovascular complications include the Gupta Perioperative Risk for Myocardial Infarction or Cardiac Arrest (MICA) calculator, and the RCRI (table 10). These tools and their use in evaluating preoperative cardiac risk, and the use of the American College of Cardiology/American Heart Association guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery, are discussed separately. (See "Evaluation of cardiac risk prior to noncardiac surgery", section on 'Using risk assessment tools'.)
●A simple risk score has been developed for predicting 30-day mortality after noncardiac surgery using data from the ACS NSQIP database . Three elements, ASA PS status, surgery risk, and whether the procedure is performed on an emergency basis, are scored and assigned points. The scoring system and associated mortality are shown in a table (table 12).
●The Society of Neuroscience in Anesthesiology and Critical Care published consensus guidelines for risk assessment and reduction for perioperative stroke in noncardiac and non-neurological surgery . These guidelines address optimal timing of surgery after stroke, risk factors for postoperative stroke, appropriate use of antiplatelet agents, and bridging anticoagulation .
●Risk calculators have been developed to estimate the risk of postoperative respiratory failure or pneumonia. Some have used the ACS NSQIP data to create these [54,55]. Established risk factors for broader pulmonary complications include a history of cigarette use (current or exceeding 40 pack-years); ASA-PS ≥2; age ≥70 years; chronic obstructive pulmonary disease; neck, thoracic, upper abdominal, aortic, or neurologic surgery; procedures ≥2 hours; planned general anesthesia (especially with endotracheal intubation); albumin concentration <3g/dL; inability to walk two blocks or climb one flight of stairs; or a body mass index ≥30 [54,56-59]. (See "Evaluation of perioperative pulmonary risk", section on 'Estimating postoperative pulmonary risk'.)
HEALTHY PATIENTS — Patients who are <65 years of age, who are determined to be healthy or to have stable, adequately treated medical conditions on preoperative screening, and who are having low-risk surgery can usually be evaluated by the anesthesia clinician on the day of surgery. Exceptions to this rule are shown in a table (table 1). These patients generally do not require routine testing. (See 'Preoperative testing' below.)
Healthy patients who are scheduled to undergo high-risk surgery should be evaluated in advance of surgery to allow adequate time for testing and patient preparation.
CONDITIONS THAT INCREASE PERIOPERATIVE RISK — Some medical conditions are associated with increased perioperative risk. Patients with these conditions may require more extensive preanesthesia evaluation and/or testing.
Advanced age — Older adults have a higher risk for perioperative complications than younger patients, primarily as a result of comorbidities. After adjusting for comorbidities, the impact of age on perioperative outcomes is somewhat mitigated. A checklist for preoperative assessment of geriatric patients is shown in a table (table 13). Particular concerns that apply to the preoperative evaluation of older patients include the following:
●Frailty – Frailty is defined as a decrease in physiologic reserve that exceeds what might be expected from advanced age alone, and is associated with increased morbidity and mortality. All patients older than 65 years of age having major surgery should be screened for frailty (figure 4). Frailty is a stronger predictor than age of adverse outcomes. Nursing home residents are at particularly high risk of death and further functional decline even with minor surgeries . (See "Anesthesia for the older adult", section on 'Assessment for frailty'.)
●Treatment goals – The risks of surgery, likelihood of the patient returning to baseline functional status, and advance directives should be reviewed with all patients and are particularly important for older patients.
●Cognitive dysfunction – Impaired cognition and dementia are common and are often unrecognized in older adults. Preoperative cognitive dysfunction is the strongest predictor of postoperative delirium, neurocognitive disorders, and cognitive decline [61-66]. Other risk factors include advanced age and lower educational achievement. Using a basic cognitive screening tool such as the Mini-Cog (freely available through the Alzheimer's Association) to screen patients preoperatively can assist with decisions and planning. (See "Perioperative neurocognitive disorders in adults: Risk factors and mitigation strategies".)
●History of falls – Patients who have fallen three or more times in the six months preceding major surgery have a 100 percent chance of a perioperative complication .
●Activities of daily living – Patients who are dependent or partially dependent on others to assist with bathing, feeding, and dressing have higher risks of adverse events when having surgery .
●Medications – Medication reconciliation is an important aspect of preoperative assessment and may be difficult in older adults who are taking multiple medications. (See "Anesthesia for the older adult", section on 'Medication history'.)
●Preoperative testing – There is no consensus on the specifics of routine testing in older patients. We recommend measuring hemoglobin (Hg), creatinine, and albumin preoperatively for patients >65 years of age who undergo moderate or high-risk surgery because of the relatively high incidence of anemia, renal dysfunction, and malnutrition in these patients .
Criteria for other preoperative laboratory testing, electrocardiogram (ECG), and chest radiograph should be based on comorbidities, rather than on age alone . (See "Perioperative blood management: Strategies to minimize transfusions", section on 'Selective laboratory testing' and 'Preoperative testing' below.)
●Hypertension – Hypertension is associated with an increased risk of perioperative cardiovascular complications, but it is not clear that preoperative normalization of blood pressure (BP) reduces perioperative risk. Hypertension over time is associated with cardiovascular complications that may increase perioperative risk, including diastolic dysfunction, heart failure (HF), renal impairment, cerebrovascular disease, and coronary artery disease (CAD). (See "Perioperative management of hypertension", section on 'Perioperative risks associated with hypertension' and "Anesthesia for patients with hypertension".)
There is little evidence for an association between perioperative complications and preoperative BP <180 mmHg systolic or 110 mmHg diastolic .
The optimal BP level that should be achieved in anticipation of elective surgery is unclear. For most patients, we agree with the Joint Guidelines from the Association of Anaesthetists of Great Britain and Ireland and the British Hypertension Society on the preoperative measurement and management of hypertension, which state that primary care practices should aim to control BPs to <160/100 before referral for elective surgery, but that if BPs are not known then surgery can proceed in patients with measurements <180 mmHg systolic and 110 mmHg diastolic in the preoperative clinic or on the day of surgery . The decision to delay surgery for BP optimization or institute new antihypertensive treatment must be individualized, based on patient factors and the urgency of surgery. Regardless of BP on the day of surgery, if patients have taken their BP medications, are asymptomatic, and there is evidence that the patient's BPs before the day of surgery are usually <160/100, then proceeding with planned anesthesia is acceptable.
Most antihypertensive agents can be continued up to and including the day of surgery, with the likely exception of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs). ACE inhibitors and ARBs may increase the incidence of hypotension during anesthesia and morbidity and mortality during major surgery . (See "Perioperative medication management", section on 'ACE inhibitors and angiotensin II receptor blockers'.)
●Heart failure – Patients with HF have a significantly higher risk of postoperative death than patients with coronary artery disease. Whenever possible, surgery should be delayed in patients with decompensated HF. HF is an important risk factor in the risk stratification models for preoperative assessment. (See 'Risk assessment tools' above.)
Decisions on whether and when to proceed with surgery, preoperative assessment, and preoperative medical management should reflect the urgency of the surgery, the stability of the patient's HF, and the possible therapeutic alternatives. Strategies for preoperative assessment, decision making regarding the timing of surgery, and perioperative management of patients with HF are discussed separately, and are shown in algorithms (algorithm 1 and algorithm 2). (See "Perioperative management of heart failure in patients undergoing noncardiac surgery".)
Preoperative testing for patients with HF is based on the likelihood that testing will change perioperative management or the decision to proceed with surgery. Indications for electrocardiogram, transthoracic echocardiogram, chest radiograph, and natriuretic peptide levels, and exercise testing are discussed separately. Measurement of beta natriuretic peptide (BNP) or N-terminal proBNP (NT-proBNP) is useful in patients with suspected HF or to guide optimization. BNP or NT-proBNP levels can identify patients at increased risk for major adverse cardiac events . (See "Perioperative management of heart failure in patients undergoing noncardiac surgery", section on 'Preoperative tests'.)
●Undiagnosed murmurs – Systolic murmurs may be the most common incidental finding during a cardiac physical examination. The differential diagnoses include aortic stenosis or sclerosis, mitral or tricuspid regurgitation, hypertrophic cardiomyopathy and hyperdynamic states secondary to infection, fever, thyrotoxicosis, and pregnancy. Patients with undiagnosed murmurs require an ECG and a careful history. Any abnormality on an ECG in patients with murmurs, symptoms of dyspnea, chest pain, syncope or near-syncope in patients with murmurs, and murmurs in individuals >50 years of age warrant an echocardiogram. (See 'Cardiac testing' below.)
Diastolic murmurs are always pathologic and warrant further evaluation. Mitral stenosis (MS) and aortic insufficiency are the most common causes with the former posing a significant perioperative risk if more than mild.
●Valvular heart disease – Stenotic cardiac valvular diseases (ie, aortic stenosis [AS] and MS) are associated with an increased risk of perioperative complications. Risks of anesthesia and surgery can be minimized by an accurate diagnosis of type and severity of disease, planning the appropriate anesthetic, instituting a higher level of monitoring (such as an arterial line, transesophageal echocardiography [TEE], or pulmonary artery catheter), changing venue for the procedure (for example, not an ambulatory surgical center), and managing postoperatively in an intensive care unit . Patients with known or suspected moderate or severe valvular disease should undergo preoperative echocardiography if there has been no echocardiogram within one year, or if there has been a significant change in physical examination or clinical status since the last evaluation (table 14) .
•AS is a common valvular lesion that increases in frequency with age and is associated with coronary artery disease. The preoperative evaluation and risk assessment for patients with AS, and indications for intervention, are discussed separately (table 15). (See "Noncardiac surgery in adults with aortic stenosis".)
•Severe asymptomatic and untreated symptomatic MS are associated with high perioperative risk. Preoperative evaluation and indications for intervention are discussed separately (table 16). (See "Rheumatic mitral stenosis: Overview of management", section on 'Management of noncardiac surgery'.)
•Regurgitant valvular lesions (ie, aortic regurgitation [AR] or mitral regurgitation [MR]) are typically better tolerated perioperatively than stenotic lesions. Preoperative risk assessment and evaluation are discussed separately. (See "Noncardiac surgery in patients with mitral or aortic regurgitation".)
•Patients with mechanical heart valves are usually maintained on anticoagulants. For most procedures, other than cataract surgery, these drugs are stopped preoperatively based on the half-life of the drug to allow normalization of coagulation parameters. Interruption of anticoagulation is usually coordinated with the patient's cardiologist. Perioperative management of anticoagulants is discussed separately. (See "Perioperative management of patients receiving anticoagulants".)
●Arrhythmias – The perioperative risk associated with some arrhythmias (eg, supraventricular tachycardia, asymptomatic ventricular arrhythmias) is unclear . However, some arrhythmias, including symptomatic bradycardia, symptomatic ventricular arrhythmias, Mobitz II, and third-degree heart block all increase perioperative risk , and may be associated with underlying cardiac disease . Patients with Mobitz II and complete heart block need to have all except emergency surgery delayed for further evaluation and likely pacemaker insertion. (See "The preoperative ECG: Evaluation and implications for anesthetic management".)
Clinically stable patients with atrial fibrillation (AF) are at elevated risk of perioperative complications but generally do not require special evaluation or a change in medical management unless there is a rapid ventricular rate, but may require modification of anticoagulation. (See "Perioperative management of patients receiving anticoagulants", section on 'Atrial fibrillation'.)
If AF is newly identified on a preoperative electrocardiogram or by physical examination, nonemergency surgery is usually delayed for evaluation. If necessary, an urgent cardiology consultation can be requested with a multidisciplinary discussion of the risks and benefits of proceeding with surgery. It may be reasonable to proceed with minor procedures, such as cataract surgery or colonoscopy, especially under monitored anesthesia care in patients with newly discovered preoperative AF as long as the patient has a controlled rate (ie, less than 100 beats per minute) and adequate blood pressure. These patients require expedited referral for evaluation and management of their AF. (See "Atrial fibrillation in patients undergoing noncardiac surgery", section on 'Patients with newly discovered atrial fibrillation' and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)
●Coronary artery disease – Coronary artery disease (CAD) is a risk factor for perioperative myocardial ischemia and infarction and death. CAD varies from a mild, stable disease with little impact on perioperative outcome, to severe disease that accounts for serious complications during anesthesia. A goal for preoperative evaluation is to identify a small subset of patients who have unstable or severe enough CAD that the planned surgical procedure will pose a significant risk. Even patients with significant CAD have a low risk when having low-risk surgeries [73,76]. An algorithm for preoperative cardiac risk assessment for patients with risk factors for CAD is provided (algorithm 3).
Preoperative cardiac risk assessment, including evaluation for CAD, and management of cardiac risk, are discussed separately. (See "Evaluation of cardiac risk prior to noncardiac surgery" and "Management of cardiac risk for noncardiac surgery" and "Noncardiac surgery after percutaneous coronary intervention".)
Preoperative coronary revascularization (ie, coronary artery bypass grafting and/or percutaneous coronary intervention) is discussed separately. (See "Management of cardiac risk for noncardiac surgery", section on 'Revascularization before surgery'.)
●Cardiac implantable electronic devices – Patients with pacemakers and implantable cardioverter defibrillators (ICDs) are often older adults, and may have HF, ischemic or valvular disease, cardiomyopathies, or potentially lethal arrhythmias that increase perioperative risk. Pacemakers and ICDs can be affected by intraoperative interference; a systematic approach to the perioperative evaluation and management of these devices is required, and is discussed separately. (See "Perioperative management of patients with a pacemaker or implantable cardioverter-defibrillator".)
Cerebrovascular disease — Individuals with cerebrovascular disease are at increased risk of CV and cerebrovascular events in the perioperative period [73,77]. The presence of cerebrovascular disease is often a marker for coexisting cardiovascular disease , and a stroke or transient ischemic attack (TIA) is a risk factor equivalent to known chronic coronary syndrome, also referred to as stable ischemic heart disease, in the Revised Cardiac Risk Index (RCRI). (See 'Risk assessment tools' above.)
The timing of surgery should be considered and elective surgery should be deferred in patients with recent stroke. Timing of surgery for patients with a history of stroke, the risk of perioperative stroke, and management of asymptomatic carotid bruits are discussed separately. (See "Perioperative stroke following noncardiac, noncarotid, and nonneurologic surgery", section on 'Patient risk factors'.)
Neurologic disease — A number of neurologic diseases increase perioperative risk or require specific perioperative evaluation and management. These issues are discussed separately. (See "Perioperative care of the surgical patient with neurologic disease".)
Pulmonary disease — Postoperative pulmonary complications contribute significantly to overall perioperative morbidity and mortality. Estimation of pulmonary risk is a standard element of all preoperative medical evaluations. Preoperative evaluation of pulmonary risk, including pulmonary function testing, the risks associated with pulmonary hypertension, and strategies to prevent pulmonary complications, are discussed separately. (See "Evaluation of perioperative pulmonary risk" and "Strategies to reduce postoperative pulmonary complications in adults" and "Anesthesia for patients with chronic obstructive pulmonary disease", section on 'Preanesthesia consultation'.)
Specialized testing, including cardiopulmonary exercise test and the six-minute walk test, are discussed separately. (See "Evaluation of perioperative pulmonary risk", section on 'Exercise testing' and "Overview of pulmonary function testing in adults", section on 'Six-minute walk test'.)
Obstructive sleep apnea — Patients with obstructive sleep apnea (OSA) are at increased risk of perioperative complications. Surgical risk, preoperative evaluation, and anesthetic management of patients with OSA are discussed separately. (See "Surgical risk and the preoperative evaluation and management of adults with obstructive sleep apnea" and "Intraoperative management of adults with obstructive sleep apnea".)
Kidney disease — Chronic kidney disease is associated with cardiovascular disease, and increases the risk of postoperative morbidity and mortality [79,80]. Chronic kidney disease (CKD) is a factor in several risk scores, including the RCRI and the Myocardial Infarction or Cardiac Arrest (MICA) cardiac risk calculator. (See "Overview of the management of chronic kidney disease in adults", section on 'Association with cardiovascular disease, end-stage kidney disease, and mortality' and "Evaluation of cardiac risk prior to noncardiac surgery".)
The strongest predictor of postoperative kidney dysfunction is preoperative kidney disease . We measure creatinine preoperatively if CKD is known or suspected, the patient is >65 years of age planning intermediate to high risk surgery, or if the use of intravenous contrast dye is planned. Serum electrolytes should also be measured in patients with CKD.
Patients with end-stage kidney disease on dialysis have a high incidence of other comorbidities and are at increased risk of perioperative complications. Preanesthesia evaluation and anesthetic management of patients on dialysis are discussed separately. (See "Anesthesia for dialysis patients".)
Liver disease — Severe liver disease increases perioperative risk, especially with major surgery. Preoperative evaluation, including preoperative laboratory evaluation, and assessment of perioperative risk in patients with liver disease, are discussed separately. (See "Anesthesia for the patient with liver disease", section on 'Preoperative evaluation for patients with known liver disease' and "Assessing surgical risk in patients with liver disease".)
●Diabetes – Diabetes mellitus is associated with increased risk of perioperative infection and postoperative cardiovascular morbidity and mortality [73,82-84]. Diabetes mellitus is associated with multisystem complications that may also affect perioperative management. Preoperative assessment and perioperative management of blood glucose in these patients are discussed separately. (See "Perioperative management of blood glucose in adults with diabetes mellitus" and "Overview of general medical care in nonpregnant adults with diabetes mellitus" and "Anesthesia for patients with diabetes mellitus".)
Long-term diabetic control, reflected in hemoglobin (Hg) A1c levels is likely much more important than a random blood glucose performed on the day of surgery. HgA1c predicts perioperative blood glucose levels , and elevated A1C may predict a higher rate of postoperative adverse events, including infection, myocardial infarction, and mortality. (See "Perioperative management of blood glucose in adults with diabetes mellitus", section on 'Laboratory'.)
Poorly controlled diabetes is associated with increased surgical site infections. Optimal blood glucose targets have not been determined, but for some procedures (eg, joint replacement or major spine surgeries) surgeons have established absolute A1C cutoffs for performing elective surgery (eg, <8 percent). (See "Susceptibility to infections in persons with diabetes mellitus", section on 'Risk of infection'.)
●Thyroid disease – Significant hyper- or hypothyroidism may increase perioperative risk . Preoperative evaluation and anesthetic management for patients with thyroid disease are discussed separately. (See "Anesthesia for patients with thyroid disease and for patients who undergo thyroid or parathyroid surgery".)
●Adrenal disorders – Patients with Cushing's disease and adrenal insufficiency require management to lower perioperative risk. (See "Treatment of adrenal insufficiency in adults" and "Overview of the treatment of Cushing syndrome".)
Patients with pheochromocytoma are at high risk of hemodynamic instability and arrhythmias during surgery. Preoperative evaluation and preparation of these patients are discussed separately. (See "Anesthesia for the adult with pheochromocytoma" and "Anesthesia for the adult with pheochromocytoma", section on 'Preoperative evaluation'.)
Patients who have been taking glucocorticoid medication are at risk for adrenal insufficiency in the perioperative period. Perioperative management of these patients is discussed separately. (See "The management of the surgical patient taking glucocorticoids".)
●Pituitary abnormalities – Pituitary abnormalities can cause hormonal hyposecretion or hypersecretion that may increase perioperative risk. As examples, both acromegaly and Cushing's syndrome increase the risk of difficulty with airway management , and are associated with cardiovascular disease and obstructive sleep apnea. (See "Causes and clinical manifestations of acromegaly", section on 'Sleep apnea' and "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Cardiovascular' and "Causes and clinical manifestations of acromegaly", section on 'Cardiovascular disease'.)
Anemia — Anemia is present in 5 to 7 percent of elective surgical patients, depending on associated comorbidities and age . Preoperative anemia, even when mild, is associated with increased 30-day mortality after major noncardiac surgery [89-91], and also increases need for perioperative transfusions. When hemoglobin testing is indicated, it should be done early enough to allow time for diagnosis and treatment of the causes of anemia or hemostatic abnormalities. Elective surgery is best delayed to allow time to identify and potentially correct abnormalities (algorithm 4). (See "Perioperative blood management: Strategies to minimize transfusions", section on 'Preoperative strategies' and 'Preoperative testing' below and "Diagnostic approach to anemia in adults".)
Patients with sickle cell disease are at risk of perioperative complications, some of which may be ameliorated by modifications in management. Perioperative management of these patients, including preoperative transfusion and control of acute pain, are discussed separately. (See "Red blood cell transfusion in sickle cell disease: Indications and transfusion techniques", section on 'Prophylactic preoperative transfusion' and "Acute vaso-occlusive pain management in sickle cell disease", section on 'Overview of acute pain management'.)
Perioperative concerns for patients with thalassemia, including anemia, skeletal abnormalities, and possible cardiac or hepatic complications, are discussed separately. (See "Management of thalassemia", section on 'Surgery/anesthesia concerns'.)
Malnutrition — Malnutrition is a strong predictor of perioperative mortality and morbidity, longer length of stay postoperatively, higher readmission rates, and increased costs of care . It is estimated that 50 percent or more of older adult patients having major surgery are undernourished . We screen patients for malnutrition, and send the following categories of patients for evaluation in a nutrition clinic or dietician intervention prior to surgery:
●BMI <18 kg/m2 (<20 kg/m2 for patients >65 years of age)
●Unplanned weight loss >10 percent of body weight in past six months
●Patient has eaten <50 percent of his/her normal diet in the preceding week
Patients screened as nutritionally at risk before major surgery may benefit from preoperative oral nutritional supplements with a minimum of 18 g protein two to three times per day for 7 to 14 days .
Thromboembolic disorders — Venous thromboembolism (VTE; deep venous thrombosis and pulmonary embolism) is common among surgical inpatients in the postoperative setting, and pulmonary embolism is one of the most common preventable causes of in-hospital deaths following surgery. Traditionally ambulatory surgeries were thought to have a very low risk of VTE, but with the increasing complexity of procedures being done on an outpatient basis, some patients with multiple risk factors are at similar risk to lower risk inpatients . Assessment of the risk of VTE, including inherited and acquired hypercoagulable states, and strategies for prevention are discussed separately. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients" and "Prevention of venous thromboembolism in adults undergoing hip fracture repair or hip or knee replacement" and "Overview of the causes of venous thrombosis".)
Patients who are chronically at increased risk of thromboembolism (ie, atrial fibrillation [AF], prosthetic heart valves, and recent or previous thromboembolic events) may require interruption of anticoagulation or perioperative bridging strategies. Perioperative management of these patients is discussed separately. Patients with recent arterial or VTE should have all except emergency surgery delayed for a minimum of 30 days and ideally should complete a three month course of uninterrupted anticoagulant therapy. (See "Perioperative management of patients receiving anticoagulants".)
Obesity — With the exception of thromboembolism and peripheral nerve injuries, obesity itself is not associated with an increased risk of adverse outcomes after noncardiac surgery and is not a factor in preoperative risk screening tools. (See "Preanesthesia medical evaluation of the patient with obesity", section on 'Perioperative risks in patients with obesity' and "Preoperative medical evaluation of the healthy adult patient", section on 'Obesity'.)
However, obesity is associated with difficulty with airway management, and with a number of comorbidities that increase perioperative risk, including obstructive sleep apnea, heart disease, hypertension, and diabetes mellitus. (See "Preanesthesia medical evaluation of the patient with obesity", section on 'Preoperative evaluation'.)
Tobacco use — Exposure to tobacco, directly or through second-hand smoke, increases the risk of many perioperative complications [96-98]. The benefits and optimal duration of smoking cessation are discussed separately. Preoperative clinics play an important role in discussing the benefits of smoking cessation and offering patients both pharmacologic and non-pharmacologic interventions. (See "Strategies to reduce postoperative pulmonary complications in adults", section on 'Smoking cessation' and "Preoperative medical evaluation of the healthy adult patient", section on 'Smoking'.)
Alcohol misuse — Patients who misuse alcohol on a regular basis have an increased risk of postoperative complications. (See "Preoperative medical evaluation of the healthy adult patient", section on 'Alcohol misuse'.)
PREOPERATIVE TESTING — Preoperative testing should be performed selectively, based on the patient's medical status, the planned procedure, and the likelihood that test results will change management or help with risk assessment (table 17). We agree with a practice advisory from the American Society of Anesthesiologists (ASA) , the Choosing Wisely initiative , and a safety guideline from the Association of Anaesthetists of Great Britain and Ireland , which recommend against routine preoperative laboratory testing in the absence of clinical indication.
Selective testing — The rationale for selective testing and predictive value of preoperative laboratory testing are discussed separately. (See "Preoperative medical evaluation of the healthy adult patient", section on 'Laboratory evaluation'.)
●For most low-risk procedures, no testing is indicated unless the patient has a new, unstable, or worsening condition.
●For intermediate- to high-risk surgeries, testing is indicated based on patient comorbidities when the results will change management or risk assessment.
●Testing is also based on the type of surgery (eg, expected blood loss or the use of contrast dye).
Specific preoperative laboratory tests are discussed separately. (See "Preoperative medical evaluation of the healthy adult patient", section on 'Laboratory evaluation'.)
Our recommendations for basic testing, and for testing for patients with suspected conditions who will undergo intermediate- to high-risk procedures are shown in tables (table 18 and table 19). These tests may not have added value for patients undergoing low-risk procedures and do not benefit patients having cataract surgery .
Blood type and screen and cross match — A blood type and screen is ordered whenever there is an anticipated need for a blood transfusion . Patients with known red blood cell (RBC) antibodies or with an elevated risk due to a history of transfusions or pregnancy should have a type and screen performed ahead of the day of surgery if there is even a moderate risk of bleeding. Significant or multiple RBC antibodies can present difficulties with finding compatible blood. Type and screen must be performed within three days of transfusion for patients who have been pregnant in the previous three months (or are currently pregnant), who have received a transfusion in the past three months, or in whom the pregnancy status or transfusion history is unknown. Otherwise, a type and screen is good indefinitely per US Food and Drug Administration (FDA) rules, though most institutions arbitrarily set expiration dates. Patients who have been transfused or pregnant at any time are at risk of having red cell antibodies, which can pose challenges for availability of compatible cross-matched blood . Information from a type and screen before the day of surgery can allow the blood bank adequate time to obtain blood. (See "Pretransfusion testing for red blood cell transfusion", section on 'Specimen requirements'.)
Blood type and cross match should be based on the expectation of blood loss. Most crossmatching is now electronic (as long as no RBC antibodies are present) and can be done within a matter of minutes. Using a maximum surgical blood order schedule or surgeon/procedure-specific data can optimize efficient testing and preparation of available blood products [103-105]. A type and cross match always expires within three days.
Pregnancy testing — Pregnancy testing on the day of surgery should be offered to female patients capable of having children (table 19). Pregnancy is excluded before gynecologic surgery in women of reproductive age, either by the use of a screening checklist (table 20) or by pregnancy testing. Women should have the right to refuse testing after a discussion of the potential risks associated with anesthesia, surgery, and pregnancy.
Routine preoperative pregnancy testing is controversial. Guidelines in the United Kingdom [106,107] and from the ASA  recommend offering pregnancy testing to women in whom pregnancy is possible, but some institutions go further and require pregnancy testing for all reproductive age women before anesthesia. We offer pregnancy testing to women who could be pregnant, after a discussion of the potential risks associated with anesthesia, surgery, and pregnancy, but give them the option to refuse testing.
Patients who could be pregnant should understand that pregnancy may change perioperative management. The patient might elect to cancel elective surgery or choose an alternative treatment approach. In addition, anesthetic technique may be changed, and there may be risks to the fetus if a pregnancy is undetected before surgery and anesthesia. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Effects of anesthetics on the fetus and the pregnancy'.)
Testing ahead of the day of surgery should be performed if pregnancy is suspected. However, routine screening for pregnancy is best done on the day of the surgery. (See "Overview of preoperative evaluation and preparation for gynecologic surgery", section on 'Pregnancy test'.)
Cardiac testing — Stress testing is rarely useful solely because of surgery, without other indications. Although there is a clear relationship between the degree of myocardial ischemia found on testing and prognosis, there is no evidence that prophylactic revascularization only to prevent ischemia at the time of surgery improves outcomes. In addition, stress testing can lead to further invasive procedures with attendant risks (eg, cardiac catheterization, percutaneous intervention, revascularization, radiation exposure, and delay of surgery), without proven benefit.
However, some experts recommend preoperative stress imaging in patients who are scheduled for major vascular surgery. (See "Evaluation of cardiac risk prior to noncardiac surgery".)
Preoperative cardiac evaluation and testing may differ for patients being evaluated for liver or kidney transplant. (See "Liver transplantation in adults: Patient selection and pretransplantation evaluation", section on 'Cardiac stress testing' and "Kidney transplantation in adults: Evaluation of the potential kidney transplant recipient", section on 'Coronary artery disease'.)
Patients who present preoperatively with unevaluated symptoms consistent with ischemia may meet criteria for evaluation with stress testing . In this case, the urgency of surgery factors into the decision on the type of testing performed. (See "Selecting the optimal cardiac stress test".)
The details of a preoperative positive stress test are as important as simply the fact that it shows ischemia, especially for patients with an established diagnosis of coronary artery disease (CAD). Large areas of stress-induced wall motion abnormalities on dobutamine stress echocardiography or poor exercise capacity on cardiopulmonary exercise testing (CPET) predict elevated risk [108,109], whereas fixed defects do not predict increased risk .
A resting echocardiogram is warranted in patients with undiagnosed murmurs and symptoms of dyspnea, chest pain, syncope or near-syncope, those with undiagnosed murmurs and an abnormal electrocardiogram (ECG), and murmurs in individuals >50 years of age. (See 'Cardiovascular disease' above and "Evaluation of cardiac risk prior to noncardiac surgery", section on 'Resting echocardiography'.)
Preoperative ECGs, chest radiographs, and pulmonary function testing are discussed separately. (See "Preoperative medical evaluation of the healthy adult patient", section on 'Electrocardiogram' and "Evaluation of perioperative pulmonary risk", section on 'Pulmonary function testing' and "Evaluation of perioperative pulmonary risk", section on 'Chest radiographs'.)
MEDICATION MANAGEMENT — The principles of perioperative medication management, and the management of common medications known to interact with anesthetic agents are discussed in detail separately. (See "Perioperative medication management".)
POSTOPERATIVE PLANNING — High-risk patients are best managed in intensive care units immediately postoperatively, with protocol-based care with careful attention to management of pain, hemodynamics, pulmonary toilet, and early interventions [18,110]. Arrangements for postoperative intensive care are often initiated during the preoperative evaluation session.
The plan for postoperative care is discussed in the UpToDate topics on anesthesia for specific surgical procedures and for patients with specific comorbidities.
CONSENT AND DECISION MAKING — Informed consent is obtained for anesthetic care and is based on the principle of patient autonomy (ie, the patients' right to be involved in decisions that affect them). In our experience, discussing options for upcoming anesthesia can lower anxiety and improve patient satisfaction.
Most patients want to be made aware of findings from their preoperative evaluation, be informed of risks, and be involved in decisions about their care. The results of risk assessment tools can be used as part of shared decision making and informed consent. In a single center study that evaluated sharing the results of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) calculator with patients, patient perceptions of the experience were favorable; 93 percent of patients said the results improved their understanding of their risks and 81 percent stated that they would want to know the details of risk before consenting to surgery . Overall, patients tended to overestimate their risks of surgery, though high-risk patients tended to underestimate their risks. Knowledge of personal risk decreased preoperative anxiety in 70 percent of patients, and had no effect on anxiety in 20 percent. The majority of patients were willing to undergo prehabilitation if it would reduce their risks of complications.
The following table outlines important components of patient preparation for shared decisions regarding their anticipated anesthesia (table 21) [112,113]. Patients need to be informed of the more common risks and, when appropriate, of complications that rarely occur after certain procedures but would have major impact (eg, postoperative visual loss associated with prone positioning for spine surgery). Complex discussions ideally occur before the day of surgery, with adequate time to address all questions.
Informed consent for medical procedures is discussed in detail separately. (See "Informed procedural consent".)
Patients with do not resuscitate (DNR) orders should not be denied anesthesia and procedural care simply because of their DNR status . Whenever possible, the anesthesia clinician should involve the patient, family members, and surrogates, as appropriate, in detailed discussion of the patient's values and preferences with respect to resuscitation. Some aspects of anesthesia care necessarily involve procedures that in other circumstances would be considered resuscitation (eg, endotracheal intubation). The patient's acceptance of specific procedures and levels of resuscitation (eg, pharmacologic reversal of hypotension related to anesthetic medication) should be determined and documented. The plan for postoperative reinstatement of any existing directives is determined and documented.
The Association of Anaesthetists of Great Britain and Ireland has created guidelines for consent for anesthesia , whereas the American Society of Anesthesiologists (ASA) has not.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Preoperative medical evaluation and risk assessment".)
SUMMARY AND RECOMMENDATIONS
●Goals of preanesthesia evaluation – All patients who undergo anesthesia must have a preanesthesia evaluation by an anesthesia clinician to assess the patient's perioperative risk and readiness for the planned procedure, and to create an anesthetic plan. The goals of preoperative evaluation are to assess the patient's medical status and ability to tolerate anesthesia for the planned procedure, reduce the risks of anesthesia and surgery, and to prepare the patient for the procedure. (See 'Goals for preanesthesia evaluation' above.)
•Healthy patients having low-risk procedures can be evaluated on the day of the procedure immediately before anesthesia. High-risk patients or those planning high-risk procedures may require testing, time for medical interventions, intensive planning, and may therefore benefit from assessment well in advance of the procedure. (See 'Timing of preanesthesia evaluation' above.)
•Patients with conditions that increase perioperative risk may require more extensive preanesthesia evaluation and/or testing than healthy patients (table 1). (See 'Conditions that increase perioperative risk' above.)
●Components of evaluation – Components of the preanesthesia evaluation process include clinical evaluation, risk assessment, optimization of medical diseases that affect perioperative risk, patient education and informed consent, and creation of a plan for anesthesia and postoperative care. (See 'Components of the process' above.)
•History and physical examination – Patients should be assessed with a medical history and anesthesia-directed physical examination, including an airway assessment. (See 'Clinical evaluation' above.)
•Risk assessment – Assessment of the patient's risks of anesthesia and the planned procedure informs the plan for anesthesia, may suggest the need for preoperative intervention and perioperative care, and may affect shared decisions regarding surgical and alternative options for treatment. (See 'Risk assessment' above.)
-Patients are assigned an American Society of Anesthesiologists Physical Status (ASA-PS) class in anticipation of anesthesia (figure 2). Patient factors, including comorbidities and functional status, affect the patient's predicted risk. (See 'Patient risk factors' above.)
-Risk assessment tools that include patient and surgical risk factors may be used to predict perioperative risks of cardiac and pulmonary adverse events and perioperative mortality (figure 3 and algorithm 3). (See 'Risk assessment tools' above.)
•Preoperative testing – Preoperative testing should be performed selectively, based on the patient's medical status, the planned procedure, and the likelihood that test results will change management or help with risk assessment (table 17 and table 18 and table 19). (See 'Preoperative testing' above.)
•Informed consent – For informed consent for anesthesia, patients should be made aware of the findings from their preoperative evaluations and perioperative risks, to allow shared decisions about options for care (table 21).
For patients with do not resuscitate (DNR) orders, the patient's acceptance of specific procedures and levels of resuscitation should be determined and documented, including the procedures necessary for anesthesia that would be considered resuscitation in other circumstances. (See 'Consent and decision making' above.)
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