Risk Stratification | Cardiovascular Assessment | Medication Management | Functional Capacity
- 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
- “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
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.
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.
STOP: warfarin 5 days, clopidogrel 5-7 days, DOACs 24-48h. CONTINUE: aspirin (unless neurosurgery), beta-blockers, statins, ACE inhibitors. START: nothing new perioperatively.
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.
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
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.
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
- Definition
- Healthy patient
- Examples
- No organic, physiologic, biochemical abnormality
- Perioperative Management
- Routine perioperative care
- Definition
- Mild systemic disease
- Examples
- Well-controlled HTN, BMI 30-40, social smoker
- Perioperative Management
- Standard care with monitoring
- Definition
- Severe systemic disease
- Examples
- Poorly controlled DM, COPD, BMI greater than 40, active smoker
- Perioperative Management
- Preoperative optimization, HDU consideration
- Definition
- Life-threatening disease
- Examples
- Recent MI under 3 months, sepsis, ESRF
- Perioperative Management
- ICU planning, intensivist involvement
Laboratory and Investigation Optimization
Preoperative Testing Guidelines
Targeted preoperative investigations are driven by the history, examination and planned surgery rather than ordered routinely. The common cardiorespiratory tests below are requested selectively to detect and optimise modifiable disease before anaesthesia.
- ASA 1-2 Under 40
- Not routine
- ASA 1-2 Over 40
- If significant blood loss expected
- ASA 3-4 Any Age
- Always
- ASA 1-2 Under 40
- Not routine
- ASA 1-2 Over 40
- If on ACE-I, diuretics, diabetes
- ASA 3-4 Any Age
- Always
- ASA 1-2 Under 40
- Not routine
- ASA 1-2 Over 40
- If diabetic or obese
- ASA 3-4 Any Age
- Always
- ASA 1-2 Under 40
- Only if bleeding history
- ASA 1-2 Over 40
- If on anticoagulation
- ASA 3-4 Any Age
- If liver disease or anticoagulated
- ASA 1-2 Under 40
- Not routine
- ASA 1-2 Over 40
- Over 45 or cardiac history
- ASA 3-4 Any Age
- Always
- ASA 1-2 Under 40
- Not routine
- ASA 1-2 Over 40
- If cardiopulmonary symptoms
- ASA 3-4 Any Age
- If moderate-severe lung/cardiac disease
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.
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
- 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
- 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 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 Action
- CONTINUE
- Rationale
- Withdrawal causes rebound tachycardia and ischemia. Continue at same dose.
- Perioperative Action
- DO NOT START
- Rationale
- POISE trial: increased stroke and mortality. Only continue if already established.
- Perioperative Action
- CONTINUE (controversial)
- Rationale
- May cause intraoperative hypotension. Some hold on day of surgery. No consensus.
- Perioperative Action
- CONTINUE
- Rationale
- Anti-inflammatory effect. Reduced perioperative MI. Give night before surgery.
- Perioperative Action
- HOLD on day of surgery
- Rationale
- Risk of hypovolemia and electrolyte disturbance.
Venous Thromboembolism (VTE) Prophylaxis
Stopping and restarting therapeutic anticoagulation is only half of perioperative haematology; every surgical patient also needs a VTE risk assessment and a prophylaxis plan for the operation itself - orthopaedic surgery, especially arthroplasty and hip-fracture surgery, is among the highest-risk.
Risk assessment: combine a structured tool (the Caprini score, or the NICE VTE risk-assessment tool) with the bleeding risk. Higher VTE risk and lower bleeding risk push toward pharmacological prophylaxis; the reverse favours mechanical methods alone.
- Examples
- Early mobilisation, graduated compression stockings, intermittent pneumatic compression
- Role
- Used in most patients; the sole method when bleeding risk is high
- Examples
- LMWH, fondaparinux, DOAC (rivaroxaban/apixaban/dabigatran), aspirin, warfarin
- Role
- Added for moderate-to-high VTE risk once bleeding risk is acceptable
Arthroplasty / hip-fracture specifics:
- Extended duration: roughly 28 to 35 days after total hip replacement and about 10 to 14 days after total knee replacement; prophylaxis is also standard for hip-fracture surgery.
- Agent choice is debated: LMWH and the DOACs are effective, and aspirin has gained favour after arthroplasty (large trials suggest broad equivalence for many patients) - balance efficacy against wound-bleeding risk.
- Combine mechanical and pharmacological prophylaxis for the highest-risk joints, and time the first pharmacological dose to balance VTE prevention against post-operative bleeding.
Every patient gets a VTE risk assessment (Caprini / NICE tool) weighed against bleeding risk. Orthopaedic arthroplasty is high-risk and needs extended pharmacological prophylaxis - about 28 to 35 days for hip and 10 to 14 days for knee replacement - plus mechanical methods, with the agent (LMWH, DOAC or aspirin) chosen by balancing thrombotic against bleeding risk. Do not confuse this with the separate task of managing the patient's pre-existing therapeutic anticoagulation.
Fasting, Prehabilitation and Enhanced Recovery (ERAS)
Optimisation is not only about disease - the way the patient is prepared and recovered changes outcomes, and three high-yield areas (fasting, prehabilitation and the ERAS bundle) are frequently examined.
- Clear fluids up to 2 hours before anaesthesia.
- Breast milk up to 4 hours.
- A light meal, non-clear fluids or formula up to 6 hours.
- Prolonged fasting is harmful (dehydration, insulin resistance, patient discomfort) and should be avoided.
a clear carbohydrate drink up to about 2 hours pre-operatively reduces insulin resistance and improves patient well-being, and is a core ERAS element.
structured preoperative exercise, nutritional and psychological optimisation to build functional reserve before surgery - particularly valuable in the frail or low-METs patient.
a multimodal bundle - minimal fasting and carbohydrate loading, opioid-sparing multimodal and regional analgesia, normothermia, early feeding, early mobilisation, and minimising drains and catheters - that reduces length of stay and complications across elective orthopaedics.
Quote the fasting rule precisely: clear fluids 2 hours, breast milk 4 hours, light meal or formula 6 hours - and avoid prolonged fasting. Add carbohydrate loading, prehabilitation and the ERAS bundle (multimodal opioid-sparing analgesia, regional anaesthesia, early feeding and mobilisation) as the modern, evidence-based wrap-around to medical optimisation.
Clinical Relevance - Respiratory Optimization
ARISCAT Score for Pulmonary Risk
- Points
- 3 points
- Clinical Significance
- Decreased respiratory reserve
- Points
- 16 points
- Clinical Significance
- High risk group
- Points
- 8 points
- Clinical Significance
- Baseline hypoxemia
- Points
- 17 points
- Clinical Significance
- Active inflammation
- Points
- 11 points
- Clinical Significance
- Impaired oxygen delivery
- Points
- 15 points
- Clinical Significance
- 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.
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.
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
- Cardiac Risk Tool
- RCRI + stepwise algorithm, biomarkers (BNP/troponin)
- Perioperative Beta-Blocker
- Continue if established; do not start de novo
- Distinctive Emphasis
- Functional capacity and METs central to the algorithm
- Cardiac Risk Tool
- RCRI / NSQIP + NT-proBNP, troponin surveillance
- Perioperative Beta-Blocker
- May start only with careful titration days ahead
- Distinctive Emphasis
- Strong push for biomarker-guided risk and PMCM clinics
- Cardiac Risk Tool
- Selective testing by ASA grade and surgical severity
- Perioperative Beta-Blocker
- Continue established therapy
- Distinctive Emphasis
- Routine testing minimised; perioperative medicine pathways
- Cardiac Risk Tool
- RCRI plus mandatory NT-proBNP/BNP screening
- Perioperative Beta-Blocker
- Avoid initiation; continue chronic therapy
- Distinctive Emphasis
- Postoperative troponin surveillance strongly recommended
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
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.
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.
Controversies & Areas of Uncertainty
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.
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.
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.
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.
Memory Aids
HI DISCRCRI - 6 Predictors
Hook:Each predictor scores 1 point: 0-1 = low risk, 2 = intermediate, 3+ = high risk warranting cardiology input.
STOP-GO-NODay-of-Surgery Medications
Hook:STOP - GO - NO new starts: a quick framework for the common viva on which drugs to stop, continue or avoid initiating.
MCQ Practice Points
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.
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.
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.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“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?”
“62-year-old female, HbA1c 9.8%, listed for revision TKA in 2 weeks. Previous wound infections. Patient keen to proceed. Your plan?”
“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?”
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
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