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
Clinical 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.
Memory Aids
HI DISCRCRI - 6 Predictors
| H | High-risk surgery Intraperitoneal, intrathoracic or suprainguinal vascular procedures |
| I | Ischaemic heart disease Prior MI, angina, positive stress test or pathological Q waves |
| D | Diabetes on insulin Insulin-requiring diabetes mellitus |
| I | Impaired renal function Creatinine over 177 micromol/L (2.0 mg/dL) |
| S | Stroke or TIA Cerebrovascular disease |
| C | Congestive heart failure History of heart failure |
| H | High-risk surgery Intraperitoneal, intrathoracic or suprainguinal vascular procedures | D | Diabetes on insulin Insulin-requiring diabetes mellitus | S | Stroke or TIA Cerebrovascular disease |
| I | Ischaemic heart disease Prior MI, angina, positive stress test or pathological Q waves | I | Impaired renal function Creatinine over 177 micromol/L (2.0 mg/dL) | C | Congestive heart failure History of heart failure |
Hook:Each predictor scores 1 point: 0-1 = low risk, 2 = intermediate, 3+ = high risk warranting cardiology input.
STOP-GO-NODay-of-Surgery Medications
| S | STOP these Metformin and sulfonylureas on the day, SGLT2 inhibitors 3 days before, diuretics on the day |
| G | GO (continue) Statins, established beta-blockers, and usually aspirin (especially with recent coronary stent) |
| N | NO new starts Never start a new beta-blocker perioperatively (POISE: excess stroke and death) |
| S | STOP these Metformin and sulfonylureas on the day, SGLT2 inhibitors 3 days before, diuretics on the day |
| G | GO (continue) Statins, established beta-blockers, and usually aspirin (especially with recent coronary stent) |
| N | NO new starts Never start a new beta-blocker perioperatively (POISE: excess stroke and death) |
Hook:STOP - GO - NO new starts: a quick framework for the common viva on which drugs to stop, continue or avoid initiating.
Overview
Preoperative medical optimization is the structured process of identifying, quantifying and modifying a patient's medical risk before elective or semi-elective surgery. The aim is not to clear every abnormality but to ensure the patient is in the best achievable physiological state, that risk is communicated for informed consent, and that the right level of perioperative monitoring is planned. For the orthopaedic candidate it is a high-yield non-operative topic that recurs across MCQ, viva and clinical components because the same principles apply to elective arthroplasty, fracture surgery and revision procedures.
The framework rests on three questions: How fit is the patient? (ASA grade, functional capacity in METs), What is the risk of this specific operation? (cardiac, pulmonary, bleeding and infection risk) and What is modifiable before surgery? (glycaemic control, anaemia, smoking, anticoagulation and cardiac medication management). The sections below work through cardiac, respiratory, metabolic, haematological and medication domains, then summarise the global evidence and exam essentials.
Quick Mental Model
Stratify
Combine ASA, RCRI and functional capacity (METs) to place the patient in a low, intermediate or high-risk band and decide who needs cardiology, CPET or biomarker input.
Optimize
Target the modifiable factors with the strongest evidence: smoking, glycaemic control, anaemia, and a clear medication interruption/resumption plan - then plan postoperative care level (ward vs HDU/ICU).
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. International guidance (NICE, ANZCA, ESA) converges on no routine testing for fit ASA 1-2 patients undergoing minor surgery.
Summary: Targeted testing based on clinical assessment more valuable than blanket screening.
Evidence Base and Key Trials
POISE Trial - Perioperative Beta-Blocker Initiation
- 8351 patients with, or at risk of, atherosclerotic disease undergoing noncardiac surgery across 190 hospitals in 23 countries
- Randomized to extended-release metoprolol succinate vs placebo started 2-4h before surgery, continued 30 days
- Fewer reached the cardiovascular composite endpoint (5.8% vs 6.9%, HR 0.84) and fewer had MI (4.2% vs 5.7%, HR 0.73)
- BUT excess deaths (3.1% vs 2.3%, HR 1.33) and stroke (1.0% vs 0.5%, HR 2.17), driven by hypotension and bradycardia
Preoperative Smoking Cessation Before Joint Replacement
- Randomized trial of 120 patients in 3 Danish hospitals undergoing elective hip or knee replacement
- Counselling plus nicotine replacement 6-8 weeks before surgery (cessation or at least 50% reduction)
- Overall complication rate 18% with intervention vs 52% in controls (p=0.0003)
- Wound-related complications 5% vs 31% (p=0.001); fewer cardiovascular events and reoperations
Revised Cardiac Risk Index (RCRI) - Derivation and Validation
- Prospective cohort of 4315 patients aged 50+ undergoing elective major noncardiac surgery
- Six independent predictors: high-risk surgery, ischaemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, creatinine over 2.0 mg/dL (177 micromol/L)
- Major cardiac complication rates with 0, 1, 2 and 3+ factors were 0.5%, 1.3%, 4% and 9% in derivation
- Validation cohort (n=1422) rates were 0.4%, 0.9%, 7% and 11%; outperformed prior indices on ROC analysis
Glycaemic Control and Arthroplasty Outcomes
- Nationwide Inpatient Sample analysis of over 1 million total hip and knee arthroplasties (1988-2005)
- Compared uncontrolled diabetes (n=3973), controlled diabetes (n=105485) and no diabetes (n=920555)
- Uncontrolled vs controlled diabetes: higher wound infection (adjusted OR 2.28), stroke (OR 3.42) and in-hospital death (OR 3.23)
- Uncontrolled diabetes increased length of stay by almost a full day
METS Study - Functional Capacity Assessment
- International prospective cohort of 1401 patients (Canada, UK, Australia, New Zealand) before major noncardiac surgery
- Compared subjective METs estimation with cardiopulmonary exercise testing, the Duke Activity Status Index (DASI) and NT-proBNP
- Subjective clinician estimation of functional capacity had only 19.2% sensitivity for detecting inability to reach 4 METs on CPET
- DASI score (not subjective assessment) independently predicted 30-day death or myocardial infarction
PAUSE Study - Perioperative DOAC Management
- Prospective cohort of 3007 patients with atrial fibrillation on apixaban, dabigatran or rivaroxaban undergoing elective surgery
- Standardized interruption: omit 1 day before low-bleeding-risk and 2 days before high-bleeding-risk procedures, with NO heparin bridging or routine coagulation testing
- 30-day major bleeding 0.9-1.85% and arterial thromboembolism 0.16-0.6% across the three DOAC cohorts
- Most patients had minimal residual anticoagulant (under 50 ng/mL) at the time of surgery
Preoperative Anaemia and Postoperative Mortality
- Systematic review and meta-analysis of 24 observational studies including 949445 patients
- 39.1% of patients were anaemic preoperatively
- Preoperative anaemia associated with higher 30-day/in-hospital mortality (OR 2.90), acute kidney injury (OR 3.75) and infection (OR 1.93)
- Anaemia strongly associated with red cell transfusion (OR 5.04)
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
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?"
Scenario 3: Anticoagulated Patient for Urgent Surgery
"74-year-old woman with atrial fibrillation (CHA2DS2-VASc 4) on rivaroxaban presents with a displaced intracapsular hip fracture. CrCl 55 mL/min. Last dose was this morning. How do you plan timing and anticoagulation?"
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.
Controversies & Areas of Uncertainty
ACE inhibitor / ARB on day of surgery
Holding versus continuing remains debated. Continuing risks refractory intraoperative hypotension; holding may risk rebound hypertension. Many centres now hold the morning dose for major surgery, but high-quality RCT evidence is limited and guidance is not uniform.
Optimal HbA1c threshold
Common practice uses 8.0-8.5% to defer elective arthroplasty, but the evidence base is observational and the ideal cut-off is contested. Chronic control matters more than a single value, and rigid thresholds risk inequity for patients who never reach target.
Metformin and lactic acidosis
The traditional teaching to stop metformin on the day of surgery rests on weak evidence; the absolute risk of lactic acidosis is very low in patients with normal renal function. Practice is shifting toward continuing metformin for minor surgery with preserved renal function.
Biomarker-guided assessment
Routine NT-proBNP/BNP and postoperative troponin surveillance (favoured by CCS/ESC) improve risk discrimination but generate downstream testing and uncertainty about how to act on isolated troponin rises. Adoption varies widely between countries.
Guidelines, Registries & Global Practice
Global Epidemiology
Worldwide, more than 300 million major surgical procedures are performed annually, and the proportion involving older patients with cardiovascular, respiratory and metabolic comorbidity continues to rise. Cardiac complications remain a leading cause of perioperative death after noncardiac surgery, and preoperative anaemia affects roughly one in three surgical patients (Fowler 2015). These figures make structured preoperative optimization a globally relevant, exam-favoured topic rather than a single-country concern.
Side-by-Side Society Guidance
Major Perioperative Guidelines Compared
| Body / Region | Cardiac Risk Tool | Perioperative Beta-Blocker | Distinctive Emphasis |
|---|---|---|---|
| ACC/AHA (US) | RCRI + stepwise algorithm, biomarkers (BNP/troponin) | Continue if established; do not start de novo | Functional capacity and METs central to the algorithm |
| ESC/ESA (Europe) | RCRI / NSQIP + NT-proBNP, troponin surveillance | May start only with careful titration days ahead | Strong push for biomarker-guided risk and PMCM clinics |
| NICE / BOA (UK) | Selective testing by ASA grade and surgical severity | Continue established therapy | Routine testing minimised; perioperative medicine pathways |
| CCS (Canada) | RCRI plus mandatory NT-proBNP/BNP screening | Avoid initiation; continue chronic therapy | Postoperative troponin surveillance strongly recommended |
Where Guidelines Genuinely Differ
The biggest international divergence is biomarker screening: Canadian (CCS) and European (ESC) guidance recommend routine preoperative NT-proBNP/BNP and postoperative troponin surveillance in higher-risk patients, whereas US (ACC/AHA) and UK (NICE) guidance are more selective. All major societies agree on NOT starting beta-blockers de novo (POISE) and on minimising routine testing in fit ASA 1-2 patients.
Registry and Outcome Evidence
Arthroplasty registries (NJR England and Wales, AOANJRR Australia, AJRR USA, Swedish SHAR, Norwegian and NZJR) consistently link uncontrolled diabetes, high BMI, current smoking and anaemia to higher revision and periprosthetic joint infection rates, reinforcing why modifiable comorbidities are optimised before elective joint replacement.
High- vs Limited-Resource Practice Variation
Well-Resourced Settings
Dedicated preoperative assessment clinics, CPET and biomarker testing, IV iron and erythropoietin pathways, anaesthetist-led optimisation and HDU/ICU step-down beds are routinely available.
Limited-Resource Settings
Optimization relies on robust clinical assessment (functional capacity, ASA, RCRI), targeted rather than routine investigations, oral iron and locally available antiplatelet/anticoagulant reversal, with judicious case selection where critical-care backup is scarce.
Medicolegal Principles (Universal)
Document ASA and RCRI scores, functional capacity, the medication interruption/resumption plan and patient-specific consent. The commonest sources of litigation worldwide are failure to identify a high-risk patient, anticoagulation/antiplatelet errors around surgery, and proceeding despite a clearly modifiable risk factor.
PREOPERATIVE MEDICAL OPTIMIZATION
Clinical 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