Residency · Residency · Internal Medicine

Perioperative Medicine: Risk Assessment Beyond the Heart

Introduction

Perioperative medicine encompasses the comprehensive evaluation and management of patients undergoing surgical procedures. While cardiac risk assessment has traditionally dominated preoperative evaluation, non-cardiac complications account for significant morbidity and mortality. A holistic approach to risk assessment improves outcomes and reduces preventable harm.

Preoperative Pulmonary Risk Assessment

Risk Factors for Postoperative Pulmonary Complications

• Patient-related factors: age > 60, COPD, current smoking, obesity (BMI > 40), obstructive sleep apnea, functional dependence
• Procedure-related factors: upper abdominal or thoracic surgery, duration > 3 hours, emergency surgery, general anesthesia
• The ARISCAT score stratifies patients into low, intermediate, and high risk for postoperative pulmonary complications
• Preoperative spirometry is not routinely recommended unless evaluating unexplained dyspnea

Risk Reduction Strategies

• Smoking cessation at least 4-8 weeks before surgery
• Preoperative inspiratory muscle training and incentive spirometry education
• Lung-protective ventilation strategies intraoperatively
• Early mobilization and aggressive pulmonary toilet postoperatively

Renal Risk Assessment

• Preoperative estimated GFR (eGFR) is a strong independent predictor of postoperative complications
• The KDIGO guidelines recommend identifying patients with CKD stage 3 or higher for enhanced monitoring
• Nephrotoxin avoidance: minimize contrast, NSAIDs, and aminoglycosides perioperatively
• Adequate volume status and avoidance of prolonged hypotension reduce acute kidney injury risk
• Patients on dialysis require coordination of dialysis timing relative to surgery

Hepatic Risk Assessment

Child-Turcotte-Pugh and MELD Scores

• Child-Pugh Class A: generally acceptable surgical risk
• Child-Pugh Class B: elevated risk; optimize before elective procedures
• Child-Pugh Class C: prohibitive risk for most elective surgeries
• MELD score > 15 is associated with significantly increased perioperative mortality
• Acute hepatitis is a contraindication to elective surgery

Hematologic Considerations

• Assess bleeding risk with a focused bleeding history rather than routine coagulation studies
• Manage anticoagulation bridging based on thromboembolic risk (CHA2DS2-VASc, mechanical valves)
• Thrombocytopenia: platelet count > 50,000/mcL is generally adequate for most procedures
• Develop a perioperative venous thromboembolism (VTE) prophylaxis plan using the Caprini score

Nutritional and Functional Assessment

• Malnutrition increases surgical site infections, delayed wound healing, and length of stay
• Screen with tools such as the Malnutrition Universal Screening Tool (MUST) or Subjective Global Assessment
• Preoperative albumin < 3.0 g/dL is a strong predictor of 30-day morbidity and mortality
• Consider prehabilitation programs combining exercise, nutrition optimization, and psychological support
• Frailty assessment using tools such as the Clinical Frailty Scale identifies patients at high risk for poor outcomes

Endocrine and Metabolic Optimization

• Perioperative glucose control: target glucose 140-180 mg/dL; avoid hypoglycemia
• Thyroid disease: severe hypothyroidism and thyroid storm must be addressed before elective surgery
• Adrenal insufficiency: stress-dose steroids for patients on chronic corticosteroids undergoing major surgery
• Manage diabetes medications perioperatively: hold metformin day of surgery, reduce insulin doses

Integrated Risk Calculators

• The ACS NSQIP Surgical Risk Calculator provides procedure-specific risk estimates for multiple outcomes
• Incorporates patient comorbidities, procedure type, and functional status
• Facilitates shared decision-making by presenting individualized risk information
• Does not replace clinical judgment but adds objective data to the preoperative discussion

Key Clinical Pearls

• Perioperative risk assessment must extend beyond cardiac evaluation to include pulmonary, renal, hepatic, hematologic, nutritional, and endocrine systems.
• Preoperative albumin and functional status are among the strongest predictors of postoperative outcomes across all surgical specialties.
• Frailty assessment and prehabilitation are emerging as essential components of preoperative optimization.
• Use validated risk calculators like ACS NSQIP to support shared decision-making with patients.
• A multidisciplinary perioperative medicine team improves care coordination and reduces complications.

References

1. Fleisher LA, Fleischmann KE, Auerbach AD, et al. 2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery. Journal of the American College of Cardiology. 2014;64(22):e77-e137.
2. Canet J, Gallart L, Gomar C, et al. Prediction of Postoperative Pulmonary Complications in a Population-based Surgical Cohort. Anesthesiology. 2010;113(6):1338-1350.
3. Bilimoria KY, Liu Y, Paruch JL, et al. Development and Evaluation of the Universal ACS NSQIP Surgical Risk Calculator. Journal of the American College of Surgeons. 2013;217(5):833-842.
4. Rockwood K, Song X, MacKnight C, et al. A Global Clinical Measure of Fitness and Frailty in Elderly People. CMAJ. 2005;173(5):489-495.

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