Summary
The preoperative evaluation is a review of a patient’s physical condition in preparation for surgery. The history and physical examination are the foundation of this assessment and focus on identifying predisposing factors for cardiac and pulmonary complications and on determining a patient’s functional capacity to define fitness for surgery. The history and physical examination findings determine the need for additional laboratory or diagnostic testing if such evaluation changes the course of action or improves patient health and outcomes. Presurgical medical optimization, including proper subspecialty consultation, improves surgical outcomes in patients with coexisting diseases. Preoperative preparation and optimization efforts focus on identifying and mitigating modifiable risk factors to improve surgical and longitudinal outcomes while reducing healthcare costs.
Preoperative Evaluation
The preoperative evaluation is a review of a patient’s physical condition in preparation for surgery. The history and physical examination are the foundation of this assessment and focus on identifying predisposing factors for cardiac and pulmonary complications and on determining a patient’s functional capacity to define fitness for surgery. The history and physical examination findings determine the need for additional laboratory or diagnostic testing if such evaluation changes the course of action or improves patient health and outcomes. Presurgical medical optimization, including proper subspecialty consultation, improves surgical outcomes in patients with coexisting diseases. Preoperative preparation and optimization efforts focus on identifying and mitigating modifiable risk factors to improve surgical and longitudinal outcomes while reducing healthcare costs.
Elements of Preoperative Evaluation
The essential component of the preoperative evaluation is the history, which details past and current medical and surgical status, family and genetic history, and documentation of tobacco, alcohol, and substance use. A detailed list of allergies and reactions, as well as previous anesthetic experiences, helps formulate the anesthetic plan. A complete 12-point review of systems identifies any undiagnosed or inadequately optimized disease. Cardiovascular and pulmonary diseases are the primary drivers of adverse perioperative outcomes and are the most relevant in determining fitness for anesthesia and surgery [Reference Gupta, Fernandes, Rao and Dhanpal1].
A focused preoperative physical examination includes, at a minimum, documentation of vital signs, including height and weight, with body mass index (BMI) calculation, and an assessment of the airway, lungs, and heart, and a basic neurologic examination. Unexpected abnormal findings on the physical examination, such as a new heart murmur or an unexplained decline in functional capacity, compel investigation before elective surgery.
Medication Reconciliation
A complete medication history, including current and new drug therapy and unusual reactions or responses to drugs, ensures safe perioperative care. Medications that provide physiologic homeostasis should be continued preoperatively. The decision to continue, discontinue, or modify chronic medication regimens requires thoughtful risk–benefit analysis. Polypharmacy is common in elderly patients, and the preoperative evaluation is an opportunity to identify and mitigate duplicated medications and those with cross-reactivity. This encounter is also an opportunity to ensure that appropriate stroke and cardiovascular risk reduction strategies, such as statin therapy, are in place.
Risk Stratification
Perioperative risk is determined by healthcare, patient, and socio-economic factors [Reference Aronson, Murray and Martin2]. Healthcare factors include elements specific to the type and magnitude of the surgical procedure and those encompassing anesthesia type and management techniques employed, such as goal-directed fluid therapy. Patient characteristics include fixed risk factors, such as age and genetics, and modifiable risk factors, such as smoking, nutrition status, and anemia. Perioperative outcomes are directly affected by social determinants of health, such as economic stability, physical environment, and level of education.
Deciding to have surgery is a complex consideration of risks, short- and long-term benefits, alternatives, and effects on longitudinal health. A primary goal of the preoperative evaluation is to make surgery safer by estimating the total risk relative to the benefits of proceeding with surgery and reducing modifiable risk. Communicating the risk to the patient, along with risk reduction strategies in the interest of shared decision-making, affects whether or not to proceed with surgery.
ASA Physical Status Classification
Originally intended to assess and communicate a patient’s preanesthesia medical comorbidities, the American Society of Anesthesiologists (ASA) physical status classification is a current standard of risk assessment and a mandated element of the preanesthetic evaluation by the Joint Commission. The ASA scoring system alone does not predict perioperative risks. When combined with other factors such as frailty and functional status, it demonstrates excellent risk prediction, and higher scores correlate with increased postoperative morbidity and mortality [Reference Knuf, Maani and Cummings3]. This scale is based solely on the presence of existing disease and does not consider the risk of the surgical procedure.
Cardiac
Cardiac functional status or capacity, expressed as metabolic equivalents (METs), is determined subjectively by assessment with a brief set of questions and has been thought to be positively associated with postoperative outcomes. Many risk models rely on this assessment. Achieving four METs of activity without symptoms is a good prognostic indicator of perioperative outcomes [Reference Fleisher, Fleischmann and Auerbach4]. A subjective assessment of functional status does not accurately identify patients with inadequate functional capacity or predict postoperative morbidity or mortality [Reference Wijeysundera, Pearse and Shulman5]. The Duke Activity Status Index (DASI) provides an objective assessment of functional capacity. Compared with cardiopulmonary exercise testing and subjective assessment of functional capacity, only DASI scores successfully predicted the primary outcomes of myocardial injury or death at 30 days. A DASI score of <34 is associated with an increased risk of 30-day death, myocardial infarction (MI), and moderate to severe complications [Reference Wijeysundera, Beattie and Hillis6].
All patients scheduled for noncardiac surgery should have an initial assessment of the percentage risk of a major adverse cardiac event (MACE) using validated models that include information from the history and physical examination, objective functional capacity score, electrocardiogram, laboratory studies, and planned procedure. The calculated risk aids the patient and perioperative specialists in weighing the risks and benefits and determining the optimal timing of surgery. The risk score guides decision-making as to whether the planned surgery should proceed without further preoperative cardiovascular testing or whether postponement for additional testing is indicated. Preoperative risk stratification is also instrumental in determining if a patient would benefit from preoperative coronary revascularization or consideration of a lesser-risk or nonsurgical alternative. The risk assessment occasionally uncovers undiagnosed problems or inadequately managed chronic conditions requiring optimization. The decision to pursue further cardiovascular testing considers both short- and long-term risk reductions.
The Revised Cardiac Risk Index (RCRI) or the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) risk prediction tool are two commonly used risk indices. The RCRI is simpler and has been widely used and validated for many years. The NSQIP calculator is more complex, requiring calculation through an online algorithm. A more straightforward tool derived from the NSQIP database is the Gupta myocardial infarction or cardiac arrest (MICA) calculator. The newer Cardiovascular Risk Index (CVRI) is a validated model with higher discriminatory power than the RCRI [Reference Dakik, Chehab and Eldirani7]. For patients at low MACE risk (<1%), no further testing is indicated. For patients with higher MACE risk (>1%) and inadequate functional capacity (<4 METs), the question becomes whether further cardiovascular testing will change management and improve the outcome.
Pulmonary
Postoperative pulmonary complications adversely influence a patient’s postoperative course. They are a significant source of postoperative morbidity and mortality, resulting in substantial increases in healthcare resource utilization. Table 1.1 details the patient and surgical risk factors associated with postoperative pulmonary complications. The ARISCAT Risk Index is a commonly used risk prediction tool to identify patients at risk of postoperative pulmonary complications and likely to benefit from presurgical risk reduction interventions, such as increased physical activity and preoperative incentive spirometry. All available risk indices provide a reliable estimation of postoperative pulmonary complication risk, but the ARISCAT Risk Index is the most practical for preoperative assessment. The strongest predictor for postoperative pulmonary complications is poor functional capacity. Any history suggesting unrecognized chronic lung disease or heart failure, such as reduced functional capacity, unexplained dyspnea, or cough, requires further evaluation. Pulmonary function tests and routine chest X-rays do not appreciably add to risk stratification.
Table 1.1 Predictive risk factors for postoperative pulmonary complications
| Patient risk factors | Surgical risk factors |
|---|---|
|
|
a Factors assessed by the ARISCAT Risk Index.
Preoperative Optimization and Prehabilitation
Safe and efficient surgical and anesthesia practice requires a fit and medically optimized patient. Numerous epidemiological studies indicate that inadequate preoperative preparation is a significant contributory factor to the primary causes of perioperative morbidity and mortality. Postoperative morbidity is a significant surgical outcome in terms of economic consequences to healthcare institutions. Preoperative comorbidities, coupled with surgical complexity, predict adverse outcomes and increased healthcare resource utilization. Given preoperative time and resource limitations, it is reasonable to focus these efforts on patients at high risk of postoperative morbidity and mortality. Preoperative optimization and prehabilitation represent prudent economic strategies for reducing short- and long-term healthcare expenses and improving longitudinal population health.
Preoperative optimization is a process of clinician-managed interventions not directly involving patient effort or behavior modification, such as medication adjustment, glucose management, or anemia correction, designed to prepare the patient psychologically and physiologically to handle the stress of surgery. Prehabilitation differs from optimization and is the active preoperative process of enhancing a patient’s functional capacity to allow better tolerance of the stressors of surgery and recovery. Prehabilitation efforts implemented to improve postoperative outcomes involve lifestyle interventions, such as nutritional supplementation, physical exercise, stress reduction, and smoking cessation.
Coexisting Disease
Cardiac
Ischemic Heart Disease
Patients with coronary stents undergoing noncardiac surgery are at high MACE risk even when receiving perioperative antiplatelet therapy, and withholding one or both antiplatelet medications increases the risk of thrombosis. They are also at high risk of significant bleeding when one or both medications are continued. MACEs, including stroke, are mainly related to previous medical conditions and perioperative blood loss, and not to the surgery itself. In patients undergoing noncardiac surgery after a percutaneous coronary intervention (PCI) with second-generation drug-eluting stents, the incidence of MACEs, including death, MI, stent thrombosis, and the need for repeat revascularization, was highest in the first 6 months after the PCI [Reference Smith, Warner and Warner8]. Elective procedures should be delayed for at least 6 months in patients with drug-eluting stents, at least 30 days for those with bare-metal stents, and 14 days following balloon angioplasty to allow for uninterrupted dual antiplatelet therapy.
Hypertension
Perioperative hypertension is primarily a manifestation of acute or acute-on-chronic hypertension. Perioperative hypertension occurs mainly for two reasons: (1) worsening of chronic hypertension; or (2) a response to transient factors, such as pain, anxiety, or withholding of blood pressure medications. Hypertension is not a significant factor for determining perioperative cardiac risk, but it does contribute to several conditions that are, such as chronic renal disease and diastolic dysfunction. In the absence of acute end-organ dysfunction, there is little justification for case cancellation for blood pressures below 180/110 mmHg.
Isolated systolic hypertension (ISH) is the most common type of hypertension in the elderly. It is associated with a two- to fourfold increase in the risk of MI, left ventricular hypertrophy (LVH), renal dysfunction, stroke, and cardiovascular mortality. Characteristics of ISH include a widened pulse pressure and a systolic blood pressure of ≥140 mmHg, with a diastolic blood pressure of <90 mmHg. Elderly patients benefit significantly from therapies to reduce systolic blood pressure. The preoperative treatment of ISH risks diastolic hypotension and compromise of perfusion to vascular beds, and requires careful consideration.
Bioprosthetic and Mechanical Heart Valves
Anticoagulation management in the patient with a bioprosthetic or mechanical valve undergoing surgery considers the type, location, and number of prosthetic heart valves, planned surgical procedure and bleeding risk, and other patient risk factors for thromboembolism, and the planned procedure. The primary concern with interrupting anticoagulation is thromboembolism, which carries a 20% mortality rate and a 40% rate of significant disability [Reference Tan, Wall and Rosengart9]. The decision to interrupt anticoagulation and whether or not to bridge with low-molecular-weight heparin requires stratification of a patient’s risk of thromboembolism versus significant bleeding. Thromboembolism risk stratification tools, such as the BleedMAP and HAS-BLED scores, are useful in clinical decision-making. Patients undergoing procedures with associated low bleeding risk should be continued on their regular anticoagulation regimen. The thromboembolic risk is highest within the first three months of bioprosthetic or mechanical mitral valve replacement or repair. Noncardiac surgery should be deferred to avoid interruption of anticoagulation.
Heart Failure
Heart failure represents a spectrum of disease, and perioperative risk varies depending on where the patient is along the continuum. Risk is lowest for those patients with asymptomatic diastolic dysfunction where ejection fraction is preserved, and highest for those at the end-stage with reduced ejection fraction. The postoperative mortality risk is higher in patients with heart failure than in those with coronary artery disease, and elderly patients with heart failure have substantially higher risks of postoperative mortality and hospital readmission. The preoperative assessment goals for heart failure patients before noncardiac surgery include: assessing functional status; identifying asymptomatic patients who are at risk of developing heart failure in the postoperative period; determining whether heart failure patients are stable and optimally managed or showing signs and symptoms of decompensation; recognizing high-risk heart failure syndromes, including new-onset heart failure; and identifying comorbidities that impact the stability of heart failure in the postoperative period. The inability to achieve 4 METs functional capacity by walking four average-length city blocks and climbing two flights of stairs without experiencing symptomatic limitation was 71% sensitive and 47% specific for predicting severe postoperative complications. Given the critical prognostic implications of functional capacity to surgical outcomes, the New York Heart Association (NYHA) functional classification (see Table 1.2) categorizes heart failure patients based on functional capacity limitations and symptom development. Postoperative mortality increases with severity of the preoperative functional impairment, from 4% in NYHA class 1 to 67% in class IV.
Table 1.2 New York Heart Association functional classification
| NYHA class | Symptoms |
|---|---|
| I | No limitations of physical activity. Ordinary activity does not cause dyspnea, palpitations, or fatigue |
| II | Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in dyspnea, palpitations, or fatigue |
| III | Pronounced limitation of physical activity. Comfortable at rest, but less-than-ordinary physical activity results in dyspnea, palpitations, or fatigue |
| IV | Unable to carry on any physical activity without discomfort. Symptoms of heart failure at rest. Discomfort increases with any physical activity |
Asymptomatic diastolic dysfunction is common in elderly and hypertensive patients and presents considerable perioperative challenges. Diastolic dysfunction is an underestimated disease and is independently associated with major adverse outcomes in patients undergoing both cardiac or noncardiac surgery. The most straightforward approach to recognizing asymptomatic left ventricular dysfunction is maintaining a high index of suspicion when a patient provides a history of risk factors or presents with particular physical signs, such as resting tachycardia or the presence of a fourth heart sound. Identification of suspicious signs and symptoms warrants prompt cardiology referral. A risk stratification model, such as the RCRI or NSQIP calculator, including heart failure as a procedural risk factor provides an accurate MACE risk assessment. Both models offer an estimation of MACEs, but the NSQIP calculator also provides estimates of several other adverse outcomes, such as postoperative pulmonary complications (PPCs) and expected length of stay.
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