This course provides an overview of the approach for assessing preoperative risk in adults. It also reviews various screening and risk assessment tools and preoperative testing standards for healthy adults and those with identified risk factors.
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e evaluation should be conducted to identify risk factors and initiate management for correctable abnormalities. This evaluation can also help determine if additional perioperative monitoring or treatment will be required. A preoperative evaluation is conducted days to weeks before the surgical procedure and is typically done by an APRN or internist. Additional nonsurgical consults may be required, including cardiology, psychiatry, social work, and pulmonology. The preoperative evaluation aims to create an individualized surgical plan to minimize operative risk and potential complications. If modifiable factors are identified, the elective procedure may be delayed to optimally control underlying disorders (e.g., hematologic abnormalities, hypertension, or diabetes) or discontinue contraindicated medications. In addition, any patient who will undergo anesthesia must have a pre-anesthesia evaluation to assess the patient's current status and comorbidities, perioperative risk, and readiness for surgery. In the case of emergent surgical procedures, a formal preoperative evaluation may not be possible. HCPs should review the patient's history, particularly for allergies or other factors that may increase the risk of bleeding problems or adverse reactions to anesthesia (Mohabir & Coombs, 2022; Shaydakov & Tuma, 2022; Sweitzer, 2022).
Clinical Evaluation
The appropriate timing of a preoperative clinical evaluation depends on the patient's overall health status and the degree of risk and urgency associated with the planned procedure. Not all patients will need the same approach to preoperative screening. Healthy individuals can be screened much closer to the surgery date and will not likely need additional testing. However, patients with certain risk factors should be screened early to allow time to address modifiable risks. These patients may require further testing and planning well before the procedure. Preoperative assessment and testing clinics can provide coordinated medical and pre-anesthesia evaluations and laboratory testing services. Coordinating preoperative evaluations before the day of surgery can prevent unnecessary testing, surgical delays or cancellations, and complications (Smetana, 2022; Sweitzer, 2022).
A standardized preoperative screening evaluation form should be used to estimate perioperative risk and identify patients who need additional testing. Many screening tools are available, such as the American Association of Nurse Anesthesiology (AANA) pre-anesthesia questionnaire. This validated tool is frequently used because it is not too long and captures relevant information. A more complex option is the electronic Personal Assessment Questionnaire. The American College of Surgeons (ACS) National Survey Quality Improvement Program (NSQIP) developed a surgical risk calculator that combines procedure-specific risk with 20 patient factors. The tool calculates the risk for 15 different outcomes in graphic form, comparing each outcome risk with the average patient. This tool is also frequently used to help clinicians and patients make shared decisions regarding surgery (AANA, n.d.; ACS, 2021; Smetana, 2022; Sweitzer, 2022).
Numerous risk assessment tools are available for preoperative evaluation, with some evaluating general operative risk and others considering specific risk factors. HCPs conducting preoperative evaluations will use a general screening tool, such as the AANA pre-anesthesia questionnaire or the ACS NSQIP, for determining operative risk. Other, more specific screening tools may be required based on the type of surgery, patient status, and comorbidities. The American Society of Anesthesiologists (ASA) Physical Status Classification System is commonly used to assess a patient's medical comorbidities and predict perioperative risks. The classification system should be used for patients receiving anesthesia while also considering the type of procedure, frailty, and the patient's level of conditioning. The APA classification system is often built into general screening tools like the ACS NSQIP. See Table 1 for the ASA Physical Status Classification System (ASA, 2020).
Table 1
ASA Physical Status Classification System
ASA Physical Status Classification | Definition | Adult Examples (including, but not limited to:) |
ASA I | a normal healthy patient | - healthy, non-smoking, no or minimal alcohol use
|
ASA II | A patient with mild systemic disease | - mild diseases only, without substantive functional limitations
- current smoker or social alcohol drinker
- pregnancy, obesity (body mass index [BMI] 30-40 kg/m2), well-controlled DM or HTN, mild lung disease
|
ASA III | a patient with severe systemic disease | - substantive functional limitations from moderative to severe disease(s)
- poorly controlled DM or HTN, COPD, severe obesity (BMI ≥ 40 kg/m2), active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction (EF), end-stage renal disease (ESRD), regular dialysis, history (> 3 months) of myocardial infarction [MI], cerebral vascular accident [CVA], transient ischemic attack [TIA], CAD/stents
|
ASA IV | a patient with severe systemic disease that is a constant threat to life | - recent (< 3 months) MI, CVA, TIA, or CAD/stents, ongoing cardiac ischemia or severe valve dysfunction, severe reduction of EF, shock, sepsis, disseminated intravascular coagulation (DIC), acute renal disease or ESRD and not undergoing regular dialysis
|
ASA V | a moribund patient who is not expected to survive without the operation | - ruptured abdominal/thoracic aneurysm, massive trauma, intracranial bleed with mass effect, ischemic bowel with significant cardiac pathology, or multiple organ/system dysfunction
|
ASA VI | a declared brain-dead patient whose organs are being removed for donor purposes |
|
(ASA, 2020)
History
Regardless of the chosen preoperative screening tool, HCPs should ensure that they have completed a thorough and relevant history. Depending on the indication and nature of the surgery, additional, more focused questions may be assessed. General preoperative screening questions should include the following:
- risk factors for infection
- allergies
- alcohol, tobacco, and other illicit drugs
- cardiac risk factors
- active symptoms of cardiopulmonary disease (e.g., chest pain, dyspnea with exertion, cough, edema)
- risk factors for venous thromboembolism
- previous surgical and anesthesia history
- current prescription, over-the-counter (OTC), and herbal medications
- known disorders that increase the risk of complications, including OSA, HTN, CAD, kidney disease, liver disease, asthma, COPD, or diabetes
- risk for bleeding (i.e., history of bleeding with other surgeries, childbirth, or dental procedures; Mohabir & Coombs, 2022)
Risk Factors
Utilizing a validated screening tool can help HCPs identify factors that increase operative risk before surgery. Although risk factors can vary based on the type of surgical procedure, some elements are known to increase general operative risk (Smetana, 2022; Sweitzer, 2022).
Age
Age is considered a minor component of preoperative coronary risk, as recent research suggests that the impact of age on perioperative outcomes is small. Some studies have found an increased mortality risk related to elective surgeries with advanced age; however, other studies have found no relationship between age and mortality. Instead, the risk associated with older age is due to increased comorbidities, including functional impairment, frailty, malnutrition, and cognitive impairment. Older adults have a decreased physiologic reserve, which can cause greater morbidity if complications occur. HCPs should consider if an older adult may benefit from additional preoperative evaluations for these factors, but age alone should not be the sole criteria guiding preoperative testing. Although age has a minor influence on perioperative cardiac risk, there is a strong relationship between age and perioperative pulmonary complications (Mohabir & Coombs, 2022; Smetana, 2022; Sweitzer, 2022).
The ACS NSQIP can be used to assess perioperative risk for older adults. Frailty is of particular concern for morbidity and mortality in older adults. Frailty is defined as a decrease in physiologic reserve that exceeds what is expected based on age. Anyone over 65 should be screened for frailty because it is a strong predictor of complications, even for minor surgeries. Functional capacity refers to a patient's ability to perform basic, instrumental, and advanced activities of daily living. This can include toileting, grooming, eating, cooking, driving, and managing finances. If a patient loses the ability to perform these tasks, they are often described as experiencing a functional decline (Ward & Reuben, 2022). Physical frailty in older adults is typically defined as weight loss, malnutrition, slow gait, fatigue, weakness, and inactivity. Various rapid screening tools are available for assessing frailty, such as the Clinical Frailty Scale (CFS), commonly used to assess functional capacity in clinical practice due to its brevity. The scores ranged from 1 ("very fit, indicating a patient who is robust, active, energetic, motivated and fit") to 7 ("severely frail, completely dependent on others for ADLs or terminally ill") in the original scale (Dalhousie University, 2020, p. 1; Rockwood et al., 2005). The CFS was expanded in 2007, adding scores of 8 and 9 to characterize more severe cases of frailty and differentiate between severely frail, very severely frail, and terminally ill patients. Finally, in 2020 version 2.0 was released with minor edits to the categorical descriptions. A second option is the FRAIL scale, which can be completed quickly during a patient's history. It includes asking the patient about the following:
fatigue (have you felt fatigued most or all the time in the last month?)
resistance (do you have difficulty climbing a flight of stairs?)
ambulation (do you have difficulty walking a block?)
illnesses (do you have any chronic medical conditions, such as diabetes mellitus [DM], cancer, hypertension, chronic lung disease, heart disease or heart failure, angina, asthma, kidney disease, or a history of stroke or heart attack?)
loss of weight (more than 5% of your body weight in the last year without trying; Walston, 2021)
Each question is answered with yes or no, with 1 point assigned for each affirmative answer. A score of 0 represents a robust patient, 3-5 represents a frail patient, and some categorize a score of 1 or 2 as pre-frail (Walston, 2021).
Preoperative cognitive dysfunction or dementia strongly predicts postoperative delirium, cognitive decline, and neurocognitive disorders. The Mini-Cog is a screening tool to detect impaired cognition that can be used in preoperative evaluation. Other risk factors that should be considered in older adults include a history/risk of falls, dependence or partial dependence on others to complete activities of daily living (ADLs), and polypharmacy (Alzheimer's Association, n.d.; Barnett, 2019; Smetana, 2022; Sweitzer, 2022).
Cardiac Risk Factors
Patients with cardiac risk factors have a significantly higher risk of perioperative complications. Therefore, the ACC/AHA revised cardiac risk index should be used to assess perioperative cardiac risk. Based on this index, a history of CAD, CHF, cerebrovascular disease, insulin-dependent DM, and serum creatinine of 2.0 mg/dL or higher are independent predictors of cardiac risk. The risk of cardiac complications increases with each additional risk factor, with 0.4% for no risk factors, 1.0% for one factor, 2.4% for two factors, and 5.4% for three risk factors. Patients with active cardiac symptoms also have significant perioperative risk and require further evaluation, including stress echocardiography or angiography. For example, patients with unstable angina have a 28% risk of myocardial infarction. Coronary revascularization should be considered before surgery. For patients with stable angina, the perioperative risk is proportional to the exercise capacity (see below). HCPs should address active disorders using standard treatments (i.e., medication and dietary management) before surgery. Beta-blockers should be initiated for patients at risk for perioperative tachycardia, which can lead to heart failure and MI if left untreated (Mohabir & Coombs, 2022; Shaydakov, 2022).
Exercise Capacity
All patients should be assessed for exercise capacity, with good exercise tolerance associated with decreased perioperative risk. According to the American College of Cardiology/American Heart Association 2014 guideline on preoperative cardiac evaluation, patients with good exercise capacity (i.e., at least 4 metabolic equivalents [METs]) do not require preoperative testing. Subjective assessment of the patient's ability to expend 4 or more METS can be determined by self-reported ADLs (i.e., climbing a flight of stairs, walking up a hill, performing heavy work, or walking 4 miles per hour at ground level). However, a formal standardized assessment using the Duke Activity Status Index (DASI) is recommended over subjective reporting. In an extensive research study, investigators evaluated the functional capacity measured subjectively compared to DASI scores. The researchers found that subjectively reported functional capacity did not predict mortality after surgery; however, DASI scores were significantly associated with mortality. The DASI is a 12-item self-administered scale. Each DASI item (i.e., can you walk 1 to 2 blocks on level ground) is associated with weighted points. The DASI score is calculated by adding the points of all 12 performance items together, with a higher score indicating a higher functional status (Smetana, 2022; Sweitzer, 2022; Wijeysundera et al., 2018).
Medication Use
HCPs should obtain a history of medication use, including prescription, OTC, and herbal. Medication reconciliation is an essential component of the preoperative assessment to ensure an accurate, current list of medications. HCPs may need to consult family members or caregivers when patients cannot provide a precise account of their medication regime. The metabolism and elimination of medications can be altered during the perioperative periods. There is an increased risk of perioperative complications for patients taking numerous medications (i.e., three or more). For example, HCPs should identify antiplatelet or anticoagulant medications that can increase the risk of bleeding. ACE inhibitors or ARBs are often held for 24 hours before surgery due to the risk of intraoperative hypotension. Preoperative benzodiazepine use should be minimized due to the risk of perioperative delirium. Medications should be continued or tapered if they are associated with morbidity if withdrawn abruptly (Muluk et al., 2021; Smetana, 2022; Sweitzer, 2022).
Obesity
Numerous research studies have shown that for noncardiac surgery, obesity is not a risk factor for most adverse postoperative outcomes. However, severe obesity (BMI greater than 40 kg/m2) is associated with increased perioperative mortality due to preexisting cardiac and pulmonary disorders (e.g., HTN, CHF, CAD). Severe obesity is associated with an increased risk of wound complications (i.e., infections, dehiscence, fat necrosis), deep vein thrombosis (DVT), and pulmonary embolism (PE). For patients undergoing cardiac surgery, obesity has been found to increase the risk of prolonged mechanical ventilation (PMV), atrial arrhythmias, and length of stay (Mohabir & Coombs, 2022; Smetana, 2022; Sweitzer, 2022).
Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) increases the risk of perioperative morbidity and the potential for altered anesthetic management. In addition, patients with OSA have an increased risk of postoperative complications, including respiratory failure, hypoxemia, and unplanned reintubation. Since many patients have undiagnosed OSA, the ASA Task Force on Perioperative Management of patients with OSA recommends screening for OSA before surgery. Several validated screening tools exist for OSA, with the STOP-Bang questionnaire widely used. Sleep studies can be considered when further evaluation for OSA is deemed necessary (ASA, 2014; Smetana, 2022; Sweitzer, 2022).
Alcohol Misuse and Illicit Drug Use
HCPs should screen all patients before surgery for alcohol misuse due to the increased risk of postoperative complications. These patients should be referred for alcohol cessation programs as part of their primary care follow-up. Delaying an elective surgery for alcohol misuse management can be considered. The optimal period of alcohol cessation is unknown; however, at least 4 weeks of abstinence is required to reverse physiologic abnormalities. A validated screening tool should be used, such as the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) questionnaire. Studies have shown that patients with high AUDIT-C scores have longer hospital stays, more intensive care unit (ICU) days, higher unplanned reoperation rates, more surgical site infections, and cardiopulmonary complications. HCPs should also screen all patients for illicit drug use. The chronic use of opioids, amphetamines, or barbiturates increases the risk of withdrawal postoperatively. In addition, patients with opioid dependence often require higher amounts of medications for pain control intraoperatively and postoperatively due to tolerance (Smetana, 2022; Sweitzer, 2022).
Smoking
Smoking increases the risk of postoperative complications, including impaired wound healing, increased risk of infections, and pulmonary and neurological complications. HCPs should screen for smoking history and offer strategies to quit. Delaying elective surgeries should be considered to allow the patient time to quit smoking. The longer the cessation period, the greater reduction in risk for postoperative complications (Smetana, 2022; Sweitzer, 2022).
Infection
HCPs should screen patients for the risk of infection. Patients should be treated preoperatively with antibiotics if an incidental infection is found. In most cases, the surgery can be performed as planned unless prosthetic material is implanted; in this case, the surgery should be delayed until the infection is cleared. Viral respiratory infections, with or without fever, should be resolved before elective surgery (Mohabir & Coombs, 2022).
Nutritional Disorders and Fluid and Electrolyte Imbalances
Fluid and electrolyte imbalances can increase the risk of adverse perioperative outcomes. Dehydration can increase the risk of severe hypotension when general anesthesia is initiated. HCPs should correct dehydration with IV fluids before surgery. Electrolyte imbalances, including hyperkalemia, hypokalemia, hypomagnesemia, and hypocalcemia, should also be corrected before surgery due to the risk of lethal arrhythmias. Nutritional status should be assessed preoperatively due to the risk of complications, such as delayed wound healing and mortality. Severe nutritional risk factors include a low serum albumin level (less than 3 g/dL without evidence of hepatic or renal impairment), muscle wasting, a BMI less than 18.5 kg/m2, or unintentional weight loss of greater than 10% of body weight over 6 months. HCPs should consider delaying the surgical procedure to address nutritional deficiencies and decrease the risk of complications (Mohabir & Coombs, 2022).
Physical Examination
A head-to-toe assessment should be performed as part of the preoperative screening evaluation. HCPs should pay close attention to the cardiopulmonary system, cognitive function, and any signs of ongoing infection. A more detailed focused assessment may be warranted depending on the surgical procedure. Any identified abnormalities in the history or physical examination may require additional screening. Spinal abnormalities or scoliosis should be evaluated if spinal anesthesia is likely to be used (Mohabir & Coombs, 2022).
Laboratory Testing
The ACC/AHA practice guideline does not recommend routine preoperative laboratory testing for healthy adults (ASA score of 1 to 2) because the likelihood of silent disease is very low. However, HCPs sometimes perform this testing out of habit or concern for lawsuits. Routine laboratory testing in healthy adults would not likely influence perioperative management, and it is not cost-effective, can result in false positives, and delay surgery. It is recommended that HCPs determine the appropriateness of preoperative laboratory testing on a case-by-case basis. For example, if a patient has an underlying disease or risk factor that could affect operative management or it is a high-risk procedure, then testing may be indicated. Routine preoperative laboratory testing typically includes a complete blood count (CBC), basic metabolic profile (BMP), liver function tests, coagulation studies, and urinalysis. In cases where preoperative laboratory testing is necessary, HCPs can rely on normal test results within the past 4 months unless the patient's health status has changed. Preoperative beta-hCG (human chorionic gonadotropin) pregnancy testing should be done for all women of childbearing age (Bierle, 2020; Mohabir & Coombs, 2022; Smetana, 2022). Table 2 outlines specific laboratory tests and when they should be considered.
Table 2
Laboratory Tests and Preoperative Indications
Laboratory Test | Preoperative Indication |
CBC | - significant anticipated blood loss, particularly in patients over the age of 65
- known hemoglobinopathies
- hematologic or liver disease
|
Electrolytes | - medications that alter electrolytes (i.e., diuretics, angiotensin-converting enzyme [ACE] inhibitors, angiotensin-receptor blockers [ARBs])
- chronic kidney disease
|
Kidney function | - patients over 50 undergoing intermediate- or high-risk surgery
- nephrotoxic medications are expected to be used
- hypotension is likely
|
Fasting glucose or hemoglobin A1c | - diabetes
- vascular and orthopedic surgeries
|
Liver function tests | |
Coagulation studies | - personal or family history of bleeding diathesis or a bleeding disorder
|
Urinalysis | - urologic or gynecologic surgery
|
B-natriuretic peptide (BNP) | - borderline or unknown functional capacity
|
Albumin, pre-albumin, transferrin | |
(Bierle, 2020; Mohabir & Coombs, 2022; Smetana, 2022)
Other Preoperative Testing
A routine electrocardiogram (ECG) is not recommended for asymptomatic patients undergoing a low-risk surgical procedure. Without known cardiac disease, an ECG is unlikely to change perioperative management. The ACC/AHA guidelines recommend a preoperative ECG for patients with known CAD, peripheral artery disease (PAD), cerebrovascular disease, arrhythmias, or significant structural heart disease. An ECG is also recommended for severe obesity (BMI greater than 40 kg/m2) with at least one risk factor (i.e., HTN, hyperlipidemia, smoking, diabetes). Stress testing can be considered in patients with poor functional capacity (less than 4 METs) or symptomatic CAD. Chest radiography is not recommended as part of routine preoperative testing for healthy individuals because it does not significantly contribute to perioperative risk. Chest radiography is recommended for patients with known cardiopulmonary disease or those over 50 undergoing thoracic, abdominal, or abdominal aortic aneurysm surgery. The ACC/AHA guidelines also recommend chest radiography for patients with severe obesity to assess for undiagnosed heart failure, abnormal pulmonary vascularity, or cardiac chamber enlargement. Finally, pulmonary function tests (PFTs) are not indicated for healthy individuals. PFTs should be done for patients with dyspnea, poor exercise tolerance, or a cough that remains unexplained (Bierle, 2020; Fleisher et al., 2014; Mohabir & Coombs, 2022; Smetana, 2022).
References
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Alzheimer's Association. (n.d.). Mini-cog. Retrieved December 30, 2022, from https://www.alz.org/media/homeoffice/pdf%20test/minicog.pdf
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American College of Surgeons. (2021). Welcome to the ACS NSQIP surgical risk calculator. https://riskcalculator.facs.org/RiskCalculator
American Society of Anesthesiologists. (2020). ASA physical status classification system. https://www.asahq.org/standards-and-guidelines/asa-physical-status-classification-system
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