Preoperative Medical Optimization

Preoperative medical optimisation is the structured process of identifying, quantifying and modifying a patient's medical risk before elective or semi-elective surgery. The aim is to reach the best achievable physiological state rather than to clear every abnormality, to communicate the risk for informed consent, and to plan the right level of perioperative monitoring.

It is a high-yield non-operative topic for the orthopaedic candidate, and it recurs across the MCQ, viva and clinical components because the same principles apply to elective arthroplasty, fracture surgery and revision procedures.

Three questions. Every assessment answers the same three:

• How fit is the patient? ASA grade and functional capacity in METs
• What is the risk of this operation? Cardiac, pulmonary, bleeding and infection risk
• What can be modified before surgery? Glycaemic control, anaemia, smoking, anticoagulation and cardiac medication

Stratify, then optimise. ASA, RCRI and functional capacity together place the patient in a low, intermediate or high-risk band, and the band decides who needs cardiology, CPET or biomarker input. Optimisation then targets the modifiable factors with the strongest evidence (smoking, glycaemic control, anaemia and a clear plan for interrupting and resuming medication) and ends with the postoperative level of care, ward or HDU/ICU.

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ASA physical status. The ASA grade is the first summary of how fit the patient is, and each grade carries a perioperative plan.

The Revised Cardiac Risk Index. The RCRI is the gold standard for cardiac risk. It has six predictors, each scoring one point:

What the score means. The total sets the event rate and the next step.

Functional capacity. 4 METs is the critical threshold: the effort of climbing 2 flights of stairs, walking 4 blocks on level ground or doing heavy housework. Patients who cannot reach 4 METs have significantly increased perioperative cardiac complications and need further evaluation before major surgery. Capacity is read with the score, and age alone does not trigger a stress test.

Who needs stress testing.

• RCRI score 2 or more with 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)

Who does not. Testing is unnecessary with:

• Good functional capacity (above 4 METs), regardless of RCRI
• Low-risk surgery (arthroscopy, minor procedures)
• A stress test within the past year and no change in status
• An asymptomatic ASA 1-2 patient

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ARISCAT. Pulmonary risk is scored with ARISCAT, which awards points for the factors below.

Smoking cessation. The benefit accrues with time off cigarettes:

• 48-72 hours: carbon monoxide levels fall and oxygen-carrying capacity improves
• 4 weeks: mucociliary function improves, sputum volume normalises and postoperative pulmonary complications fall by 20%
• 8 weeks, the optimum: wound complications are significantly reduced, immune function improves and cardiovascular benefits are established

Helping the patient stop. Motivational interviewing is combined with pharmacotherapy (nicotine replacement as patches, gum or lozenges, varenicline or bupropion) and referral to a national smoking-cessation or quitline service.

Perioperatively. Expect increased airway reactivity and use bronchodilators. Target SpO2 above 95%, with aggressive pulmonary toilet and early mobilisation.

Targeted testing. Preoperative investigations are driven by the history, examination and planned surgery, and requested selectively to detect and optimise modifiable disease before anaesthesia. Routine testing in healthy ASA 1-2 patients undergoing low-risk procedures does not improve outcomes and delays surgery, so test on comorbidity and procedure risk rather than age alone. International guidance (NICE, ANZCA, ESA) converges on no routine testing for fit ASA 1-2 patients undergoing minor surgery.

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Preoperative anaemia. Treating anaemia before surgery reduces transfusion requirements and improves outcomes. The work-up starts 4-6 weeks before surgery.

1. Identify: screen high-risk patients (age over 65, known CKD, inflammatory arthritis, previous transfusion) with FBC, iron studies (ferritin, transferrin saturation), B12 and folate.
2. Find the cause: iron deficiency (ferritin under 30 or TSAT under 20%), chronic disease (high ferritin, low TSAT), B12 or folate deficiency (macrocytic anaemia), or CKD (low EPO production).
3. Treat for at least 4 weeks: oral iron 200mg elemental iron daily, or IV iron (Ferinject 1000mg) if oral iron is not tolerated or time is critical; IM hydroxocobalamin for B12 deficiency; EPO if CKD and Hb under 100.
4. Recheck 1 week before: expect an Hb rise of 10-20 g/L with 4 weeks of treatment and document it. Plan transfusion if Hb is still under threshold and surgery cannot be delayed.

Day-of-surgery medication is sorted into three groups: stop it, continue it, or never start it for the operation.

Warfarin. Thrombotic risk decides whether the interruption is bridged. A mechanical heart valve, atrial fibrillation with CHADS2 greater than 4, or VTE within 3 months is high risk and is bridged with LMWH.

1. 5 days before: stop warfarin, check the INR and assess thrombotic risk.
2. Day before surgery: confirm INR under 1.5. If it is still elevated, consider vitamin K 1-2 mg orally. If bridging, the last LMWH dose is 24 hours before surgery.
3. Day of surgery: an INR under 1.5 is needed for neuraxial anaesthesia. Proceed, and document that haemostasis is achieved.
4. 12-24 hours after: resume warfarin the evening of surgery or the next morning if haemostasis is good. Restart LMWH bridging 24 hours postoperatively if thrombotic risk is high.

Antiplatelets. Aspirin is usually continued, especially with a coronary stent under 12 months old or a recent MI, and neurosurgery is the exception. In a stented patient, any change to dual therapy needs cardiology.

Antiplatelet management is individualised to stent type, timing and thrombotic risk.

DOACs. These are simpler than warfarin: offset is predictable from the half-life and no bridging is required. They are restarted 24-48 hours after surgery once haemostasis is secure.

Insulin. Reduce long-acting basal insulin (glargine, detemir) by 20-25% and hold short-acting bolus insulin, in type 1 and insulin-treated type 2 diabetes alike. In type 1 diabetes, give 5% dextrose with an insulin sliding scale if the patient will be nil by mouth for more than 6 hours, check blood glucose hourly intraoperatively and 2-hourly postoperatively, and target 6-10 mmol/L perioperatively.

Oral agents in type 2 diabetes.

• Metformin: hold on the day of surgery (lactic acidosis risk)
• Sulfonylureas: hold on the day of surgery (hypoglycaemia risk)
• SGLT2 inhibitors: hold 3 days before (DKA risk)
• GLP-1 agonists: hold on the day of surgery
• DPP-4 inhibitors: can continue

The metformin hold is the traditional teaching, and the Controversies section sets out how weak its evidence is.

Cardiovascular drugs. Established cardiac medication is mostly continued, and nothing new is started for the operation.

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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, and orthopaedic surgery, especially arthroplasty and hip-fracture surgery, is among the highest-risk.

Risk assessment. A structured tool (the Caprini score, or the NICE VTE risk-assessment tool) is weighed against the bleeding risk. Higher VTE risk and lower bleeding risk push towards pharmacological prophylaxis; the reverse favours mechanical methods alone.

Duration after arthroplasty. Prophylaxis is extended, roughly 28 to 35 days after total hip replacement and about 10 to 14 days after total knee replacement, and it is also standard for hip-fracture surgery.

Choice of agent. This is debated. LMWH and the DOACs are effective, and aspirin has gained favour after arthroplasty, with large trials suggesting broad equivalence for many patients; efficacy is balanced against wound-bleeding risk. The highest-risk joints get mechanical and pharmacological prophylaxis combined, with the first pharmacological dose timed to balance VTE prevention against postoperative bleeding.

The way the patient is prepared for surgery and recovered from it also changes outcomes. Fasting, prehabilitation and the ERAS bundle are frequently examined.

Fasting: the 2-4-6 rule. Before anaesthesia:

• Clear fluids up to 2 hours
• 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.

Carbohydrate loading. A clear carbohydrate drink up to about 2 hours preoperatively reduces insulin resistance and improves patient well-being, and it is a core ERAS element.

Prehabilitation. Structured preoperative exercise, nutritional and psychological optimisation builds functional reserve before surgery, and is particularly valuable in the frail or low-METs patient.

Enhanced Recovery After Surgery. ERAS is a multimodal bundle of minimal fasting and carbohydrate loading, opioid-sparing multimodal and regional analgesia, normothermia, early feeding, early mobilisation, and minimising drains and catheters. It reduces length of stay and complications across elective orthopaedics.

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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

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

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.