Perioperative Guidelines & Complex Comorbidity Review

Patient: Margaret R. Donnelly — Right TKA (Cemented), 11 Jun 2026 | ASA III

⚠️ This is a research summary for a synthetic mock patient and is for demonstration purposes only. Not for real clinical use.

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Summary of Active Risks

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1. Glycaemic Management (T2DM, HbA1c 7.9%)

• HbA1c of 7.9% (63 mmol/mol) is below the critical threshold of 8% (64 mmol/mol) at which surgery delay is formally recommended, but is above the 7% level associated with increased wound complications. Ideally, glycaemic optimisation should have been attempted prior to listing. If there is still time before 11 Jun, referral to endocrinology or the primary care physician for optimisation is best practice.
• The textbook recommendation is explicit: "Referral of surgical patient to primary care physician or endocrinologist for glycemic optimization if preoperative HbA1c greater than 8%." At 7.9%, this sits in a grey zone -- the surgical team should document risk acknowledgement. (Current Surgical Therapy 14e)
• SGLT2 inhibitors (if she is on one -- confirm her medication list includes no empagliflozin, dapagliflozin, etc.): the FDA recommended stopping these agents before surgery due to risk of euglycaemic DKA. Stop at least 3 days pre-operatively for short-acting agents. (Current Surgical Therapy 14e)
• Metformin: hold on the day of surgery given her CKD (eGFR 58) and the risk of lactic acidosis with the perioperative fasting/fluid shift.
• GLP-1 receptor agonists (semaglutide, liraglutide, dulaglutide): A 2025-2026 meta-analysis of 346,899 patients found GLP-1RA use is associated with reduced periprosthetic joint infection and lower 90-day complications after TKA/THA. However, GLP-1RAs delay gastric emptying and raise aspiration risk -- the current consensus is to withhold weekly GLP-1RA formulations for at least 1 week before surgery, and daily formulations on the day of surgery [PMID: 41072556; PMID: 40617546].

• Blood glucose < 180 mg/dL (10 mmol/L) in theatre; < 150 mg/dL (8.3 mmol/L) in recovery/ICU
• Hourly glucose monitoring intraoperatively at minimum (Current Surgical Therapy 14e)
• Insulin is the only agent indicated intra-operatively (IV or SC). If fasting, basal insulin dose should be reduced by one-half to two-thirds the night before or morning of surgery.
• New ERAS carbohydrate loading (clear carbohydrate drinks up to 2 hours pre-op) may prevent catabolic hypoglycaemia in diabetic patients.

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2. Obstructive Sleep Apnoea (OSA) & Airway

• Bring her own CPAP machine to hospital. CPAP should be used immediately post-operatively in the PACU and on the ward. Pre-operative initiation of CPAP has been shown to reduce postoperative cardiac complications (ASA guideline evidence). (Morgan and Mikhail's Clinical Anesthesiology 7e)
• Airway assessment: Mallampati II with good mouth opening and full neck extension is reassuring, but all OSA patients must be treated as potential difficult airway -- both intubation and ventilation may be harder. Difficult airway trolley/video laryngoscopy must be immediately available.

• Regional/neuraxial anaesthesia is strongly preferred for TKA in OSA patients. Spinal (intrathecal) anaesthesia avoids airway manipulation entirely, reduces systemic opioid exposure, and decreases PONV risk. If sedation is required, keep depth minimal.
• Propofol TIVA (total intravenous anaesthesia) reduces opioid-induced nausea and vomiting if GA is needed.
• Neuromuscular blockade increases risk of postoperative respiratory failure in OSA -- ensure full reversal (sugammadex preferred over neostigmine in this patient given her CKD, as neostigmine/atropine dosing is less predictable). (Morgan and Mikhail's Clinical Anesthesiology 7e)

• Do not discharge to an unmonitored setting until the patient is no longer at risk for perioperative respiratory depression.
• Opioids substantially raise the risk of apnoea events -- opioid-sparing multimodal analgesia is mandatory (see Section 5).
• Consider continuous pulse oximetry monitoring for at least the first night post-op, ideally telemetry-linked.
• Avoid residual sedation, hypnotics, or benzodiazepines post-operatively.
• Sleep disturbance pre-operatively is also independently associated with worse acute postoperative pain control (systematic review 2025, PMID: 39504912) -- this patient's pre-op sleep disruption from pain may compound her post-op opioid requirements; plan multimodal strategies proactively.

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3. Chronic Kidney Disease (Stage 3a, eGFR 58)

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4. Anaemia Optimisation (Pre-operative Hb 11.4 g/dL)

• Check serum ferritin and iron studies to determine if iron stores are still depleted. If ferritin is low or transferrin saturation is <20%, IV iron infusion (ferric carboxymaltose or iron sucrose) is the recommended treatment for pre-operative iron deficiency anaemia, as oral iron takes weeks to raise Hb. IV iron can raise Hb by 1-2 g/dL within 2-3 weeks when given early enough.
• 2023 meta-analysis confirmed intraoperative or postoperative IV iron supplementation accelerates haemoglobin recovery after TKA (PMID: 37904349).
• Consider EPO (erythropoietin) stimulating agents if ferritin is adequate but anaemia persists -- this is typically only used in specific blood management programmes.

• Tranexamic acid (TXA) is the single most important intervention. Multiple high-quality meta-analyses confirm TXA significantly reduces blood loss and transfusion requirement in TKA (Campbell's Operative Orthopaedics 15e, Miller's Anesthesia 10e).
  • IV TXA: 1g IV 5 mins before tourniquet inflation, and a second dose of 1g IV at tourniquet release is a standard protocol.
  • Topical TXA (intra-articular injection before wound closure, 2-3g in 50-100 mL saline) is non-inferior to IV TXA for blood loss and avoids any systemic thromboembolic concern (though the absolute VTE risk difference with IV TXA has not been clinically demonstrated -- both are safe in TKA) [PMID: 40763214].
  • Combined IV + topical TXA may give the best blood conservation. A 2023 meta-analysis found combined dexamethasone + TXA further reduces blood loss and pain [PMID: 37329454].
  • No specific contraindication to TXA in CKD 3a or controlled hypertension. Use standard protocol.
• Tourniquet use: standard for cemented TKA but associated with haematoma risk post-deflation -- TXA is most critical at this moment.

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5. Analgesia: Opioid-Sparing Multimodal Strategy

1. Spinal anaesthesia with intrathecal bupivacaine (avoids GA/opioids entirely for the surgical period) -- preferred mode in this patient. Intrathecal morphine (50-100 mcg) provides excellent post-op analgesia with careful respiratory monitoring.
2. Adductor canal block (ACB) -- the current gold standard regional block for TKA. Provides quadriceps-sparing analgesia superior to femoral nerve block for mobilisation. A 2025 meta-analysis compared femoral triangle block vs ACB with comparable analgesic outcomes [PMID: 40269716]. ACB + periarticular local infiltration analgesia (LIA) with liposomal bupivacaine or standard bupivacaine/epinephrine/ketorolac mix is now standard practice. Note: omit ketorolac from the LIA mixture in this patient given CKD -- substitute with additional bupivacaine or ropivacaine concentration.
3. Regular paracetamol (acetaminophen) 1g QDS -- safe, well tolerated, effective.
4. COX-2 inhibitor (celecoxib) -- generally safe in CKD 3a at short courses but use with caution. Celecoxib has renal-sparing advantages over non-selective NSAIDs but still carries risk in CKD. A short 3-5 day post-op course may be acceptable -- team decision.
5. Gabapentinoid (gabapentin 100-200 mg BD -- dose reduced for CKD) as an adjunct. Reduces central sensitisation and opioid requirements. Monitor for excessive sedation in OSA patient.
6. Dexamethasone 8 mg IV at induction -- dual benefit: reduces PONV AND reduces post-op pain/inflammation (see below). Note the transient glucose rise (~2-3 mmol/L for 4-6 hours) -- plan for hourly glucose check post-induction.
7. Weak opioids (tramadol, oxycodone 5-10 mg IR PRN) -- as rescue only. Avoid regular opioid prescribing. If opioids are needed post-operatively, ensure SpO2 monitoring and CPAP availability.

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6. PONV Prophylaxis (High-Risk)

• At very high risk = 3-4 antiemetics from different classes + TIVA if GA is used.
• Recommended combination:
  • Dexamethasone 8-10 mg IV at induction (Class 1 -- also analgesic benefit)
  • Ondansetron 4 mg IV at end of surgery (5-HT3 antagonist -- she failed this before, consider switching to palonosetron 0.75 mg IV which has longer duration of action and may be more effective in ondansetron failures)
  • Aprepitant 40 mg PO, 1-3 hours pre-op (NK1 antagonist -- different mechanism; standard in high-risk PONV patients)
  • Scopolamine transdermal patch (1-3 hours pre-op) as a fourth agent if very high risk
  • Propofol TIVA if general anaesthesia is used (reduces PONV vs volatile agents)
• If spinal anaesthesia is used (preferred), the PONV risk is substantially reduced but still manage with at least 2 prophylactic agents given her history.

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7. VTE Prophylaxis

• DOACs (direct oral anticoagulants) are first-line: rivaroxaban 10 mg OD or apixaban 2.5 mg BD (both have non-inferior efficacy to enoxaparin with lower bleeding risk in meta-analyses). Duration: 10-14 days minimum after TKA; many guidelines (NICE, ACCP) recommend 28-35 days for knee replacement.
• Enoxaparin 40 mg SC OD is the alternative if DOACs are not tolerated or contraindicated. At eGFR 58, enoxaparin is safe at standard dosing.
• CKD consideration: Rivaroxaban is renally cleared (~33%); at eGFR 58, standard dosing is acceptable but avoid if eGFR <15. Apixaban is less renally dependent (~27% renal excretion) and may be slightly preferred in CKD patients. Both are acceptable at this eGFR.
• Mechanical prophylaxis (TED stockings + pneumatic compression devices) should be used from admission and continued until fully mobile.
• Timing of chemical prophylaxis: typically start 6-12 hours post-op once haemostasis is confirmed. With TXA used intra-operatively, early anticoagulation is appropriate.

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8. Hypothyroidism

• TSH 2.1 mU/L is normal and she is on stable thyroxine replacement -- this is well controlled and low risk.
• Continue levothyroxine on the morning of surgery with a sip of water. Do not omit.
• Symptomatic hypothyroidism (which she does not have) would require delaying elective surgery. Asymptomatic treated hypothyroidism carries no significant perioperative risk. (Sabiston Textbook of Surgery)
• Hypothyroidism can affect myocardial conduction and electrolyte regulation if poorly controlled -- irrelevant here given her normal TSH and ECG.

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9. Hypertension

• BP 138/84 on admission is mild and acceptable for surgery.
• Continue antihypertensives (except: hold ACE inhibitors/ARBs on the morning of surgery to prevent induction hypotension; restart post-op when oral intake resumed).
• Beta-blockers (if prescribed): do not stop perioperatively -- abrupt cessation risks rebound hypertension/tachycardia.
• No evidence of end-organ damage beyond the CKD (which is multifactorial). No echo indicated based on the pre-op assessment.

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10. ERAS (Enhanced Recovery After Surgery) Protocol

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11. Edge Cases & Special Flags

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Key References (Recent PubMed Evidence)

1. OSA management -- confirm CPAP arrives with the patient; plan spinal anaesthesia + opioid-sparing multimodal analgesia; continuous SpO2 monitoring post-op. This is the biggest acute safety risk.
2. Glycaemic control -- her HbA1c of 7.9% is in the borderline zone. Confirm her oral agents (stop SGLT2i if prescribed, hold metformin day-of, hold any GLP-1RA if applicable). Target glucose <10 mmol/L intraoperatively with hourly monitoring. Plan for dexamethasone-induced glucose spike.
3. Blood conservation -- pre-op IV iron if time allows (she is at Hb 11.4 with known iron deficiency history). TXA IV + topical at surgery. No crossmatch currently ordered -- re-evaluate if Hb drops further before June 11.
4. PONV prevention -- she failed ondansetron before. Use a 3-4 agent protocol: dexamethasone at induction + palonosetron at end + aprepitant pre-op + scopolamine patch. Spinal anaesthesia reduces baseline PONV risk considerably.
5. CKD drug avoidance -- no NSAIDs (no ketorolac, no ibuprofen, no diclofenac intraoperatively or post-operatively). Dose-reduce gabapentinoids. Monitor creatinine 24-48 hours post-op.