PREOPERATIVE MEDICAL OPTIMIZATION
Risk Stratification | Cardiovascular Assessment | Medication Management | Functional Capacity
ASA Physical Status Classification
Critical Must-Knows
- Functional capacity under 4 METs predicts increased perioperative cardiac complications
- Beta-blockers should NOT be started perioperatively - increased stroke risk (POISE trial)
- Metformin cessation required on day of surgery to reduce lactic acidosis risk
- Aspirin continuation recommended for patients with coronary stents in past 12 months
- Delay elective surgery 4-6 weeks after acute MI or coronary intervention
Examiner's Pearls
- "RCRI score (Revised Cardiac Risk Index) stratifies cardiac risk - 6 predictors
- "Stop smoking minimum 4 weeks before surgery for wound healing benefit
- "HbA1c greater than 8.5% associated with increased infection and complications
- "Patients on oral anticoagulants need bridging plan individualized to thrombotic risk
Critical Preoperative Optimization Exam Points
Cardiac Risk Assessment
RCRI score is gold standard. Six predictors: high-risk surgery, ischemic heart disease, heart failure, stroke/TIA, diabetes on insulin, creatinine greater than 177. Score greater than 2 requires cardiology input.
Functional Capacity
Under 4 METs = high risk. Cannot climb 2 flights of stairs or walk 4 blocks = poor functional capacity. Requires further cardiac testing before major surgery.
Medication Management
STOP: warfarin 5 days, clopidogrel 5-7 days, DOACs 24-48h. CONTINUE: aspirin (unless neurosurgery), beta-blockers, statins, ACE inhibitors. START: nothing new perioperatively.
Diabetic Control
HbA1c greater than 8.5% = delay elective surgery. Day of surgery: hold metformin, reduce long-acting insulin by 20-25%, IV dextrose if NPO greater than 6 hours.
Principles of Risk Stratification
ASA Physical Status Classification
| ASA Class | Definition | Examples | Perioperative Management |
|---|---|---|---|
| ASA 1 | Healthy patient | No organic, physiologic, biochemical abnormality | Routine perioperative care |
| ASA 2 | Mild systemic disease | Well-controlled HTN, BMI 30-40, social smoker | Standard care with monitoring |
| ASA 3 | Severe systemic disease | Poorly controlled DM, COPD, BMI greater than 40, active smoker | Preoperative optimization, HDU consideration |
| ASA 4 | Life-threatening disease | Recent MI under 3 months, sepsis, ESRF | ICU planning, intensivist involvement |
Revised Cardiac Risk Index (RCRI)
RCRI Score Interpretation and Management
Management: Proceed with surgery. No further cardiac testing needed. Routine perioperative care.
Management: Consider cardiology consultation. Assess functional capacity - if greater than 4 METs, proceed. If under 4 METs or unknown, consider stress testing.
Management: Cardiology consultation mandatory. Functional capacity assessment. Stress testing or coronary imaging. May need coronary revascularization before surgery.
Functional Capacity Assessment
4 METs is the critical threshold. Activities requiring 4 METs: climb 2 flights of stairs, walk 4 blocks on level ground, do heavy housework. Patients unable to achieve 4 METs have significantly increased perioperative cardiac complications and require further evaluation before major surgery.
Cardiac Testing Indications
When to Order Stress Testing
- RCRI score greater than 2 AND functional capacity under 4 METs
- Recent MI (4-6 weeks ago) before elective surgery
- Unstable angina or decompensated heart failure
- High-risk surgery (vascular, prolonged)
Avoid Unnecessary Testing
- Good functional capacity (greater than 4 METs) regardless of RCRI
- Low-risk surgery (arthroscopy, minor procedures)
- Recent stress test (under 1 year) with no change in status
- Asymptomatic patient with ASA 1-2
Clinical Relevance - Respiratory Optimization
ARISCAT Score for Pulmonary Risk
ARISCAT Risk Factors
| Factor | Points | Clinical Significance |
|---|---|---|
| Age 50-80 years | 3 points | Decreased respiratory reserve |
| Age greater than 80 years | 16 points | High risk group |
| SpO2 under 96% | 8 points | Baseline hypoxemia |
| Respiratory infection in last month | 17 points | Active inflammation |
| Anemia (Hb under 100 g/L) | 11 points | Impaired oxygen delivery |
| Upper abdominal or thoracic surgery | 15 points | Direct pulmonary impact |
Smoking Cessation
Smoking Cessation Benefits
Reduced carbon monoxide levels. Improved oxygen-carrying capacity. Decreased sputum production begins.
Improved mucociliary function. Reduced postoperative pulmonary complications by 20%. Sputum volume normalized.
Significant reduction in wound complications. Improved immune function. Cardiovascular benefits established.
Timing Controversy
Cessation under 4 weeks may INCREASE pulmonary complications due to increased sputum production. Minimum 4 weeks required for benefit. If patient cannot stop 4+ weeks before, continue smoking up to surgery rather than stopping 1-2 weeks before.
Medication Management
Anticoagulation and Antiplatelet Agents
Warfarin Management Protocol
Perioperative Warfarin Protocol
Stop warfarin. Check INR. Assess thrombotic risk: mechanical heart valve, atrial fibrillation with CHADS2 greater than 4, VTE under 3 months = HIGH RISK (bridge with LMWH).
Confirm INR under 1.5. If still elevated, consider vitamin K 1-2 mg PO. Last LMWH dose 24h before surgery if bridging.
INR under 1.5 for neuraxial anesthesia. Proceed with surgery. Document hemostasis achieved.
Resume warfarin evening of surgery or next morning if good hemostasis. Restart LMWH bridging 24h post-op if high thrombotic risk.
Diabetic Medications
Day of Surgery - Type 1 Diabetes
- Basal insulin: reduce long-acting (glargine, detemir) by 20-25%
- Bolus insulin: hold short-acting
- IV dextrose: 5% dextrose with insulin sliding scale if NPO greater than 6h
- BGL monitoring: hourly intraoperatively, 2-hourly postop
- Target BGL: 6-10 mmol/L perioperatively
Day of Surgery - Type 2 Diabetes
- Metformin: HOLD on day of surgery (lactic acidosis risk)
- Sulfonylureas: HOLD on day of surgery (hypoglycemia risk)
- SGLT2 inhibitors: HOLD 3 days before (DKA risk)
- GLP-1 agonists: HOLD on day of surgery
- DPP-4 inhibitors: can continue
- Insulin: reduce basal by 20-25%, hold bolus
HbA1c Threshold for Elective Surgery
HbA1c greater than 8.5% (greater than 69 mmol/mol) associated with significantly increased perioperative complications: infection (2-3x risk), wound dehiscence, prolonged LOS, ICU admission. Consider delaying elective surgery to optimize control. Minimum 6-8 weeks needed to improve HbA1c. Discuss risk vs benefit with patient and anesthetist.
Cardiovascular Medications
Perioperative Management of Cardiac Medications
| Medication | Perioperative Action | Rationale |
|---|---|---|
| Beta-blockers (established use) | CONTINUE | Withdrawal causes rebound tachycardia and ischemia. Continue at same dose. |
| Beta-blockers (new start) | DO NOT START | POISE trial: increased stroke and mortality. Only continue if already established. |
| ACE inhibitors/ARBs | CONTINUE (controversial) | May cause intraoperative hypotension. Some hold on day of surgery. No consensus. |
| Statins | CONTINUE | Anti-inflammatory effect. Reduced perioperative MI. Give night before surgery. |
| Diuretics | HOLD on day of surgery | Risk of hypovolemia and electrolyte disturbance. |
Laboratory and Investigation Optimization
Preoperative Testing Guidelines
Age and ASA-Based Testing
| Test | ASA 1-2 Under 40 | ASA 1-2 Over 40 | ASA 3-4 Any Age |
|---|---|---|---|
| FBC | Not routine | If significant blood loss expected | Always |
| UEC | Not routine | If on ACE-I, diuretics, diabetes | Always |
| Glucose | Not routine | If diabetic or obese | Always |
| Coagulation | Only if bleeding history | If on anticoagulation | If liver disease or anticoagulated |
| ECG | Not routine | Over 45 or cardiac history | Always |
| CXR | Not routine | If cardiopulmonary symptoms | If moderate-severe lung/cardiac disease |
Avoid Unnecessary Testing
Routine preoperative testing in healthy patients (ASA 1-2) undergoing low-risk procedures does NOT improve outcomes and delays surgery. Test based on patient comorbidities and procedure risk, not age alone. Australian guidelines (ANZCA): no routine testing for ASA 1-2 patients under 40 years.
Summary: Targeted testing based on clinical assessment more valuable than blanket screening.
Evidence Base and Key Trials
POISE Trial - Beta-Blocker Initiation
- 8351 patients with atherosclerotic disease undergoing noncardiac surgery
- Randomized to metoprolol vs placebo started on day of surgery
- Reduced perioperative MI (OR 0.73) BUT increased stroke (OR 2.17) and mortality (OR 1.33)
- Bradycardia and hypotension more common with metoprolol
Smoking Cessation and Wound Complications
- Prospective study of 120 patients randomized to smoking cessation vs control
- 6-8 weeks cessation intervention before hip or knee arthroplasty
- Wound complications reduced from 31% to 5% with cessation
- Overall complications reduced from 52% to 18%
Revised Cardiac Risk Index Validation
- 4315 patients undergoing noncardiac surgery - derivation cohort
- 6 independent predictors identified: high-risk surgery, ischemic heart disease, CHF, CVA, DM on insulin, Cr greater than 2
- Risk of major cardiac events: 0 factors 0.4%, 1 factor 0.9%, 2 factors 6.6%, 3+ factors 11%
- Validated in separate cohort of 1422 patients
Preoperative HbA1c and Complications
- 504 patients undergoing elective total joint arthroplasty
- HbA1c greater than 7% associated with increased infection risk (OR 1.7)
- Each 1% increase in HbA1c increased infection risk by 30%
- HbA1c greater than 8.5% had 3-fold increased risk of any complication
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: High-Risk Cardiac Patient
"68-year-old male for elective THA. Previous MI 18 months ago (DES), diabetes on insulin, Cr 160. On aspirin, ticagrelor, metoprolol. Climbs 1 flight only. How to optimize?"
Scenario 2: Diabetic Control
"62-year-old female, HbA1c 9.8%, listed for revision TKA in 2 weeks. Previous wound infections. Patient keen to proceed. Your plan?"
MCQ Practice Points
RCRI Components
Q: Which of the following is NOT a component of the Revised Cardiac Risk Index? A: Hypertension. The six RCRI predictors are: high-risk surgery, ischemic heart disease, CHF, cerebrovascular disease, diabetes on insulin, and creatinine greater than 177.
Functional Capacity Threshold
Q: What functional capacity threshold predicts increased perioperative cardiac complications? A: Under 4 METs. Patients unable to climb 2 flights of stairs or walk 4 blocks have significantly increased cardiac risk.
POISE Trial Finding
Q: What did the POISE trial demonstrate about starting beta-blockers perioperatively? A: Increased stroke (OR 2.17) and mortality despite reducing MI. Only continue beta-blockers if patient already established on therapy.
Australian Context and Guidelines
ANZCA Guidelines: PS07 (pre-anesthesia consultation), PS18 (fasting), PS51 (smoking cessation), PS53 (blood management). No routine testing for ASA 1-2 patients.
Australian Resources: eTG (antibiotic prophylaxis), PBS (medication costs), Quitline 13 7848 (smoking cessation).
Medicolegal: Document ASA/RCRI scores, informed consent with patient-specific risks, medication plan. Common litigation: failure to identify high-risk patients, anticoagulation errors, proceeding despite modifiable risk factors.
PREOPERATIVE MEDICAL OPTIMIZATION
High-Yield Exam Summary
RCRI Score (6 Predictors)
- •HI DISC: High-risk surgery, Ischemic heart disease, Diabetes on insulin, Impaired renal (Cr greater than 177), Stroke/TIA, CHF
- •Score 0-1 = low risk (0.4-1%), proceed with surgery
- •Score 2 = intermediate (2.4%), assess functional capacity
- •Score 3+ = high risk (greater than 5%), cardiology consult
Functional Capacity
- •4 METs = critical threshold (climb 2 flights, walk 4 blocks)
- •Under 4 METs + RCRI greater than 1 = further cardiac testing
- •Good functional capacity (greater than 4 METs) = proceed regardless of RCRI
Medication Management
- •STOP: warfarin 5d, clopidogrel 5-7d, metformin day of, SGLT2i 3d before
- •CONTINUE: aspirin (if stent under 12mo), beta-blockers, statins
- •NEVER START: new beta-blockers perioperatively (POISE - increased stroke)
- •DOACs: stop 24-48h depending on renal function, no bridging needed
Diabetic Optimization
- •HbA1c greater than 8.5% = delay elective surgery 6-8 weeks to optimize
- •Day of surgery: hold metformin, reduce basal insulin 20-25%, hold bolus insulin
- •IV dextrose if NPO greater than 6h, target BGL 6-10 mmol/L
- •Poor control = 2-3x infection risk
Smoking and Anemia
- •Minimum 4 weeks cessation for benefit - under 4 weeks may worsen outcomes
- •Optimal cessation 8 weeks - reduces wound complications from 31% to 5%
- •Anemia: treat if Hb under 130 (M) or 120 (F), IV iron if time-critical
- •Expect Hb rise 10-20 g/L with 4 weeks treatment