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Medical Evaluation of the Patient Undergoing Noncardiac Surgery

Chapter 492 | Part 19: Consultative Medicine · Parts 19-20 – Consultative & Emerging Topics · Chapter 492

Key Clinical Points

  1. The Revised Cardiac Risk Index (RCRI) identifies six predictive factors; risk of major cardiac events is 0.4%, 0.9%, 7%, and 11% for 0, 1, 2, and ≥3 factors respectively.
  2. Beta-blockers should be continued in patients chronically on therapy; initiation should not occur on the day of surgery; withdrawal is contraindicated.
  3. SGLT-2 inhibitors should be interrupted for at least 3–4 days prior to scheduled noncardiac surgery to prevent euglycemic diabetic ketoacidosis.
  4. DAPT: Aspirin should be continued perioperatively when the risk of increased cardiac events outweighs the risk of increased bleeding, except in neurosurgical or spinal procedures.
  5. Endocarditis prophylaxis is indicated for prosthetic cardiac valves, prosthetic material used in valve repair, previous infective endocarditis, cardiac transplant recipients with valvular regurgitation, and unrepaired cyanotic congenital heart disease.
  6. Severe aortic stenosis is associated with adverse outcomes; symptomatic patients should generally undergo valve intervention if noncardiac surgery can be deferred.
  7. Functional capacity <4 METs (inability to walk four blocks or climb two flights of stairs) warrants further noninvasive cardiac testing if results would change management.
  8. VTE prophylaxis for moderate risk includes low-dose unfractionated heparin (≤5000 units SC bid), low-molecular-weight heparin (e.g., enoxaparin 30 mg bid), or fondaparinux (2.5 mg qd).

1. DEFINITION & OVERVIEW

• Clinical Goal: Perform an individualized evaluation of the surgical patient to provide accurate preoperative risk assessment and stratification to guide perioperative risk-reduction strategies. • Risk Categorization: Clinical risk is categorized into low (<1%) and elevated risk for major adverse cardiovascular events (MACEs). • MACE Definition: Includes myocardial infarction (MI), pulmonary edema, ventricular fibrillation, primary cardiac arrest, and complete heart block. • Standardized Screening: Simple questionnaires are used to identify patients at intermediate or high risk who may benefit from detailed clinical evaluation. • Initial Evaluation: Must include a thorough history, physical examination, and a 12-lead resting electrocardiogram (ECG). • Procedure Urgency: Emergency procedures are associated with higher morbidity and mortality; assessment should be tailored to the urgency of the surgery.

1.1 Risk Stratification Tools

• Risk Assessment Tools: ◦ RCRI (Revised Cardiac Risk Index): Favored for accuracy and simplicity. ◦ NSQIP: American College of Surgeons’ National Surgical Quality Improvement Program risk calculator. ◦ SORT: Surgical Outcome Risk Tool. ◦ AUB-HAS2: American University of Beirut (AUB)-HAS2 Cardiovascular Risk Index (predicts 30-day death, MI, or stroke). • RCRI Predictors (1 point each): ◦ High-risk surgery (Vascular surgery except carotid endarterectomy; major intraperitoneal/intrathoracic procedures). ◦ Ischemic heart disease (MI history, current angina, requirement for sublingual nitroglycerin, positive exercise test, pathological Q waves, or history of PCI/CABG with current angina). ◦ Congestive heart failure (LV failure by physical exam, paroxysmal nocturnal dyspnea, pulmonary edema, S gallop, bilateral rales, or pulmonary edema on CXR). ◦ Cerebrovascular disease (History of TIA or stroke). ◦ Diabetes mellitus (Treatment with insulin). ◦ Chronic renal insufficiency (Serum creatinine >2.0 mg/dL). • RCRI Risk Outcomes: ◦ 0 points → 0.4% risk ◦ 1 point → 0.9% risk ◦ 2 points → 7% risk ◦ ≥3 points → 11% risk • Table 492-1 (Standardized Preoperative Questionnaire): Includes items for age, weight, height; gender/age thresholds; anticoagulant use; heart conditions (MI, angina, HF); other diseases (RA, kidney, liver, diabetes); respiratory status (SOB, oxygen, cough); and anesthesia history.

2. EPIDEMIOLOGY

• General Risk: Mortality risk is low with modern anesthesia for low-risk patients undergoing low-risk surgery. • Table 492-4 (Mortality Risk by Procedure Type): ◦ Higher Risk: Emergent major operations (especially in elderly); Aortic and other noncarotid major vascular surgery; prolonged surgery with large fluid shift/blood loss. ◦ Intermediate Risk: Major thoracic surgery; Major abdominal surgery; Carotid endarterectomy; Head/neck surgery; Orthopedic surgery; Prostate surgery. ◦ Lower Risk: Eye, skin, and superficial surgery; Endoscopic procedures.

2.1 Mortality Risk by Procedure Type

• Higher Risk: ◦ Emergent major operations (elderly). ◦ Aortic/noncarotid major vascular surgery. ◦ Prolonged surgery with large fluid shift or blood loss. • Intermediate Risk: ◦ Major thoracic/abdominal surgery. ◦ Carotid endarterectomy. ◦ Head/neck, Orthopedic, and Prostate surgery. • Lower Risk: ◦ Eye, skin, and superficial surgery. ◦ Endoscopic procedures.

3. ETIOLOGY & PATHOPHYYSICOLOGY

• Therapeutic Goals: Reduce perioperative adrenergic stimulation, ischemia, and inflammation. • Beta-blockers: Reduce risk for MI; however, the POISE trial showed increased death/stroke with excessive dosing. • Coronary Revascularization: Not recommended solely to reduce perioperative events; only considered if it would specifically reduce those risks in a specific patient. • Anesthetic Effects: ◦ Inhaled anesthetics → decrease arterial pressure (dose-dependent) via reduced sympathetic tone, vasodilation, and myocardial depression. ◦ Respiratory effects → dose-dependent respiratory depression with diminished response to hypercapnia/hypoxemia. • Neuromuscular Blockade: Prolonged blockade → increased risk of pulmonary complications due to loss of diaphragm/intercostal function, atelectasis, and V/Q mismatch.

4. CLINICAL FEATURES

• Functional Capacity (METs): ◦ Poor capacity: <4 METs (e.g., inability to walk 4 blocks or climb 2 flights of stairs at a normal pace). ◦ Management: Patients with poor/unknown capacity should undergo pharmacologic stress testing if it would change management. • Aortic Stenosis: ◦ Symptomatic → Intervention recommended if noncardiac surgery can be deferred. ◦ Asymptomatic (preserved EF) → Generally safe for low- to intermediate-risk surgery. • Table 492-3 (Assessment of Cardiac Risk by Functional Status): ◦ Higher Risk: Difficulty with ADLs; cannot walk 4 blocks/climb 2 flights; <4 METs; inactive but no limitations; active but easy tasks. ◦ Lower Risk: Performs regular vigorous exercises.

5. DIFFERENTIAL DIAGNOSIS

• ACS vs. Stable CAD: Critical distinction for management decisions. • Management of ACS: Must be evaluated and treated with goal-directed medical therapy.

5.1 ACS vs Stable CAD

• Acute coronary syndrome (step 2) → Evaluate and treat according to goal-directed medical therapy.

6. INVESTIGATIONS & DIAGNOSIS

• Initial Assessment: History, physical exam, and 12-lead ECG. • Noninvasive Testing: Not recommended for all patients; indicated only for those with poor/unknown functional capacity if it would alter management. • Pharmacologic Stress Options: Dobutamine stress echocardiography or myocardial perfusion imaging (dipyridamole, adenosine, or regadenoson) with thallium-201 and/or technetium-99m. • CCTA: May improve prediction of MACEs compared to RCRI, but evidence for improved outcomes is limited.

6.1 RCRI Markers

• High-Risk Surgery: Vascular surgery (except carotid endarterectomy); Major intraperitoneal or intrathoracic procedures. • Ischemic Heart Disease: History of MI; Current angina; Requirement for sublingual nitroglycerin; Positive exercise test; Pathological Q waves on ECG; History of PCI/CABG with current angina. • Congestive Heart Failure: LV failure by physical exam; Paroxysmal nocturnal dyspnea; Pulmonary edema history; S gallop; Bilateral rales; Pulmonary edema on CXR. • Cerebrovascular Disease: History of TIA or stroke. • Diabetes Mellitus: Treatment with insulin. • Chronic Renal Insufficiency: Serum creatinine >2 mg/dL.

6.2 Pulmonary Risk Factors

• Risk Factors (Table 492-5): ◦ Upper respiratory tract infection; Age >60; COPD; Cigarette use; ASA ≥2; Functional dependence; Congestive heart failure; Serum albumin <3.5 g/dL; Obstructive sleep apnea; Impaired sensorium; Abnormal chest exam; Alcohol use; Weight loss. • Spirometry Thresholds (before lung resection): ◦ FEV <2 L ◦ MVV <50% of predicted ◦ PEF <100 L or 50% predicted value ◦ PCO ≥45 mmHg ◦ PO ≤50 mmHg.

7. MANAGEMENT & TREATMENT

  1. Beta-Blocker Management: ◦ Chronic use → Continue therapy. ◦ Initiation → Do not initiate on day of surgery; only for high-risk patients if started well in advance. ◦ Withdrawal → Contraindicated.
  2. SGLT-2 Inhibitor Management: ◦ Stop 3–4 days before surgery to prevent euglycemic DKA.
  3. VTE Prophylaxis (Moderate Risk): ◦ Options: Low-dose unfuractionated heparin (≤5000 units SC bid), LMWH (e.g., enoxaparin 30 mg bid), or fondaparinux (2.5 mg qd).
  4. Endocarditis Prophylaxis: ◦ Indications: Prosthetic valves; prosthetic material in repair; prior IE; cardiac transplant with regurgitation; unrepaired cyanotic congenital heart disease.
  5. Aspirin Management: ◦ Continue perioperatively if risk of cardiac events outweighs bleeding risk (except neuro/spinal).
  6. Pulmonary Risk Modification (Table 492-6): ◦ Preoperatively: Smoking cessation; lung expansion training; bronchodilators/steroids; weight reduction. ◦ Intraoperatively: Limited anesthesia duration; avoid long-acting muscle blockers; maintain bronchodilation. ◦ Postoperatively: Mobilization of secretions; early ambulation; coughing; pain control without excessive narcotics.

8. PROGNOSIS & COMPLICATIONS

• RCRI Outcomes: Predicts MACE (MI, pulmonary edema, VF, asystole, heart block) based on score (0, 1, 2, ≥3). • Aortic Stenosis Outcomes: Symptomatic patients have poor outcomes; asymptomatic with preserved EF can undergo low/intermediate risk surgery.

9. SPECIAL CONSIDERATIONS

• Pulmonary Risk Factors (Table 492-5): ◦ Includes: Infection, Age >60, COPD, Smoking, ASA ≥2, Functional dependence, HF, Albumin <3.5 g/dL, OSA, Impaired sensorium, Abnormal chest exam, Alcohol use, Weight loss. • Risk Modification (Table 492-6): ◦ Preoperatively: Smoking cessation, lung expansion training, bronchodilators/steroids, weight reduction. ◦ Intraoperatively: Limited anesthesia duration, avoid long-acting muscle blockers, maintain bronchodilation. ◦ Postoperatively: Mobilization of secretions, early ambulation, coughing, pain control without excessive narcotics.

10. KEY PEARLS & CLINICAL TRAPS

• RCRI Score ≥3 is the threshold for high risk (11% MACE). • SGLT-2 inhibitors must be stopped 3–4 days prior. • Beta-blockers should never be started or stopped on the day of surgery. • Aspirin is continued unless there is a high risk of catastrophic bleeding (e.g., neuro/spinal). • Functional Capacity <4 METs requires further testing if it would change management.

DIAGNOSTIC APPROACH

  1. Initial Assessment: Perform thorough history, physical exam, and 12-lead ECG.
  2. Determine Urgency: Identify if procedure is emergency (higher risk) or elective.
  3. Identify ACS: If evidence of ACS → proceed to goal-directed medical therapy.
  4. Assess MACE Risk (RCRI): ◦ Risk <1% → Proceed to surgery. ◦ Risk >1% → Evaluate Functional Capacity (FC).
  5. Evaluate Functional Capacity (for Risk >1%): ◦ FC Good or Excellent → Proceed to surgery. ◦ FC Poor or Unknown → Consider noninvasive testing if it would change management.
  6. Pulmonary Assessment: Identify risk factors (Table 492-5) and implement modifications (Table 492-6).

FLOWCHARTS & ALGORITHMS

  1. Cardiac Risk Assessment Pathway: ◦ Patient → Need emergency noncardiac surgery? ◦ Yes → Evidence of ACS? ◦ → Yes: Proceed to ACS evaluation. ◦ → No: Proceed to surgery. ◦ No (Need elective noncardiac surgery) → Evidence of ongoing ACS? ◦ → Yes: Proceed to ACS evaluation. ◦ → No: Periprocedural risk for MACE <1%? ◦ → Yes: Proceed to surgery. ◦ → No (Risk >1%): Evaluate Functional Capacity (FC). ◦ → FC Good or Excellent: Proceed to surgery. ◦ → FC Poor or Unknown: Consider noninvasive testing if it would change management.

Reference Tables

TABLE 492-1 Standardized Preoperative Questionnaire a 1. Age, weight, height 2. Are you:

Harrison's 22e, p.3905

1. Age, weight, height
2. Are you:
Female and 55 years of age or older or male and 45 years of age or older?
If yes, are you 70 years of age or older?
3. Do you take anticoagulant medications (“blood thinners”)?
4. Do you have or have you had any of the following heart-related conditions?
Heart disease
Heart attack within the last 6 months
Angina (chest pain)
Irregular heartbeat
Heart failure
5. Do you have or have you ever had any of the following?
Rheumatoid arthritis
Kidney disease
Liver disease
Diabetes
6. Do you get short of breath when you lie flat?
7. Are you currently on oxygen treatment?
8. Do you have a chronic cough that produces any discharge or fluid?
9. Do you have lung problems or diseases?
10. Have you or any blood member of your family ever had a problem other than
nausea with any anesthesia?
If yes, describe:
11. If female, is it possible that you are pregnant?
Pregnancy test:
Please list date of last menstrual period:
492 Medical Evaluation of
the Patient Undergoing
Noncardiac Surgery
Prashant Vaishnava, David I. Sahar, Kim A. Eagle

TABLE 492-2 Clinical Markers Included in the Revised Cardiac Risk Index High-Risk Surgical Procedures Vascular surgery…

Harrison's 22e, p.3907

  • High-Risk Surgical Procedures
  • Vascular surgery (except carotid endarterectomy)
  • Major intraperitoneal or intrathoracic procedures
  • Ischemic Heart Disease
  • History of myocardial infarction
  • Current angina considered to be ischemic
  • Requirement for sublingual nitroglycerin
  • Positive exercise test
  • Pathological Q waves on ECG
  • History of PCI and/or CABG with current angina considered to be ischemic
  • Congestive Heart Failure
  • Left ventricular failure by physical examination
  • History of paroxysmal nocturnal dyspnea
  • History of pulmonary edema
  • S gallop on cardiac auscultation
    3
  • Bilateral rales on pulmonary auscultation
  • Pulmonary edema on chest x-ray
  • Cerebrovascular Disease
  • History of transient ischemic attack
  • History of cerebrovascular accident
  • Diabetes Mellitus
  • Treatment with insulin
  • Chronic Renal Insufficiency
  • Serum creatinine >2 mg/dL

TABLE 492-3 Assessment of Cardiac Risk by Functional Status

Risk Higher • Has difficulty with adult activities of daily living
• Cannot walk four blocks or up two flights of stairs or does
not meet a MET level of 4
• Is inactive but has no limitations
• Is active: easily does vigorous tasks
Lower • Performs regular vigorous exercises

TABLE 492-4 Gradation of Mortality Risk of Common Noncardiac Surgical Procedures Higher

Harrison's 22e, p.3908

Higher • Emergent major operations, especially in the elderly
• Aortic and other noncarotid major vascular surgery
(endovascular and nonendovascular)
• Prolonged surgery associated with large fluid shift and/or
blood loss
Lower • Eye, skin, and superficial surgery
• Endoscopic procedures

TABLE 492-5 Predisposing Risk Factors for Pulmonary Complications 1. Upper respiratory tract infection: cough, dyspnea…

Harrison's 22e, p.3909

    1. Upper respiratory tract infection: cough, dyspnea
      2. Age >60 years
      3. Chronic obstructive pulmonary disease
      4. Cigarette use
      5. American Society of Anesthesiologists Class ≥2
      6. Functional dependence
      7. Congestive heart failure
      8. Serum albumin <3.5 g/dL
      9. Obstructive sleep apnea
      10. Impaired sensorium (confusion, delirium, or mental status changes)
      11. Abnormal findings on chest examination
      12. Alcohol use
      13. Weight loss
      14. Spirometry threshold before lung resection
      a. FEV <2 L
      1
      b. MVV <50% of predicted
      c. PEF <100 L or 50% predicted value
      d. PCO ≥45 mmHg
      2
      e. PO ≤50 mmHg
      2

TABLE 492-6 Risk Modification to Reduce Perioperative Pulmonary Complications

  • Preoperatively
  • • Smoking cessation
    • Training in proper lung expansion techniques
    • Inhalation bronchodilator and/or steroid therapy, when indicated
    • Control of infection and secretion, when indicated
    • Weight reduction, when appropriate
  • Intraoperatively
  • • Limited duration of anesthesia
    • Avoidance of long-acting neuromuscular blocking drugs, when indicated
    • Prevention of aspiration and maintenance of optimal bronchodilation
  • Postoperatively
  • • Optimization of inspiratory capacity maneuvers, with attention to:
    • Mobilization of secretions
    • Early ambulation
    • Encouragement of coughing
    • Selective use of a nasogastric tube
    • Adequate pain control without excessive narcotics