Anesthetic Management of an IHD Patient Posted for Total Knee Replacement (TKR)

Introduction

I. PREOPERATIVE ASSESSMENT AND OPTIMIZATION

A. Cardiac Risk Stratification

1. High-risk surgery (intrathoracic, intraabdominal, suprainguinal vascular)
2. Ischemic heart disease (history of MI, angina, positive stress test)
3. Congestive heart failure
4. Cerebrovascular disease (TIA/stroke)
5. Insulin-dependent diabetes mellitus
6. Serum creatinine >2.0 mg/dL

• Poor/unknown (<4 METs): Cannot walk 4 blocks or climb 2 flights of stairs - proceed to noninvasive testing if it would change management.
• Moderate-Good (≥4 METs): Proceed to surgery.
• This is particularly problematic in TKR patients due to limited mobility from knee disease - the pre-existing orthopedic condition often masks poor cardiorespiratory reserve.

B. Investigations

C. Medication Management

• Continue if the patient is already on chronic beta-blocker therapy (abrupt withdrawal is dangerous - causes rebound tachycardia and hypertension).
• Initiate in high-risk patients (≥3 RCRI factors or intermediate/high-risk ischemia on stress testing), ideally days-to-weeks before surgery to assess tolerability.
• Never initiate on the day of surgery (POISE trial showed high-dose acute initiation increased stroke and mortality despite reducing MI) - Harrison's, p. 3951.

• Continue all statin therapy perioperatively - reduces perioperative cardiac events.
• Initiation is reasonable in statin-naïve patients undergoing elevated-risk procedures.

• Aspirin: Continue unless bleeding risk outweighs cardiac benefit (risk-benefit decision with surgeon).
• DAPT (if patient has a coronary stent):
  • Bare Metal Stent (BMS): Delay elective surgery ≥1 month; ideally 6 months.
  • Drug-Eluting Stent (DES): Delay elective surgery ≥6 months; ideally 12 months after ACS.
  • If surgery cannot be delayed and DAPT must be stopped: maintain aspirin, restart P2Y12 inhibitor ASAP postoperatively.
  • Premature discontinuation risks stent thrombosis - Harrison's, p. 3950.

• Generally continue; if held preoperatively (due to hypotension risk), restart as soon as clinically feasible postoperatively.

• Discontinue 3-4 days before surgery to prevent euglycemic diabetic ketoacidosis from perioperative fasting - Harrison's, p. 3950.

II. INTRAOPERATIVE MANAGEMENT

A. Choice of Anesthesia

• Avoids the hemodynamic stress of laryngoscopy and intubation
• Provides excellent surgical anesthesia and postoperative analgesia
• Reduces systemic opioid requirements
• Meta-analyses show lower rates of pneumonia and respiratory failure with neuroaxial vs. general anesthesia
• However: no significant difference in cardiac events between neuroaxial and general anesthesia has been demonstrated - Harrison's, p. 3951

• Causes sympathetic block → hypotension → compensate with cautious IV fluids and vasopressors (phenylephrine, ephedrine)
• Bradycardia may occur - have atropine ready
• Level of block: T12-L1 adequate for TKR

• All inhaled agents cause dose-dependent vasodilation, myocardial depression, and decreased cardiac output - use cautiously
• Avoid tachycardia (HR <80 bpm target to reduce myocardial oxygen demand)
• TIVA (propofol-based) may be preferable in LV dysfunction
• Careful titration of induction agents (reduced doses in compromised patients)

• Allows intraoperative spinal anesthesia plus postoperative epidural analgesia
• Caution: epidural hematoma risk if systemic anticoagulation used for VTE prophylaxis

• Femoral nerve block / Adductor canal block as part of multimodal analgesia - reduces opioid use

B. Intraoperative Monitoring

• Continuous ECG (5-lead preferred, with ST-segment analysis in leads II and V5)
• Pulse oximetry
• NIBP (5-minute intervals minimum)
• Capnography (if GA)
• Temperature monitoring
• Urine output

• Invasive arterial line (IBP) - continuous BP monitoring, arterial blood sampling
• Central venous catheter - if poor IV access, major fluid shifts expected
• Pulmonary artery catheter / TEE - only in severely compromised LV function

C. Hemodynamic Goals

• Treat hypotension promptly: IV fluids, vasopressors (phenylephrine if sinus rhythm, ephedrine if bradycardic)
• Treat hypertension: deepen anesthesia, opioids, nitroglycerin infusion
• Avoid anemia (TKR involves significant blood loss - use tourniquet judiciously, cell saver, tranexamic acid)
• Tourniquet inflation causes sudden afterload increase and BP spike - monitor closely; deflation causes sudden BP drop and reperfusion arrhythmias

D. Special Considerations in TKR

• Cement implantation (bone cement implantation syndrome - BCIS): Polymethylmethacrylate cement can cause hypotension, hypoxia, arrhythmias, and even cardiac arrest due to fat/marrow/cement embolism to pulmonary circulation. More dangerous in IHD patients with poor cardiac reserve. Have resuscitation drugs ready.
• Tourniquet pain/hypertension: Intraoperative tourniquet use causes progressive hypertension - ensure adequate analgesia/anesthesia depth.
• VTE: TKR carries very high DVT/PE risk - mechanical and pharmacological prophylaxis essential.

III. POSTOPERATIVE MANAGEMENT

A. Recovery and Monitoring

• ICU/HDU admission for high-risk IHD patients (RCRI ≥3, EF <40%, recent MI)
• Continue continuous ECG monitoring for 24-48 hours
• Serial high-sensitivity troponins for 48-72 hours postoperatively in high-risk patients - to detect Perioperative Myocardial Injury (PMI)

B. Analgesia

• Multimodal analgesia: paracetamol + NSAIDs (caution with NSAIDs in IHD - COX-2 inhibitors increase cardiovascular events) + opioids (titrated) + regional blocks (adductor canal block)
• Epidural analgesia (if CSE placed): Provides superior pain control; maintain for >24 hours
• Avoid pain-induced tachycardia and hypertension - both increase myocardial oxygen demand

C. VTE Prophylaxis

• Mechanical: Graduated compression stockings + pneumatic compression devices - start immediately
• Pharmacological: LMWH (enoxaparin 40 mg OD or 30 mg BD) or fondaparinux, or direct oral anticoagulants (rivaroxaban 10 mg OD preferred in some guidelines)
• Balance VTE prophylaxis with risk of epidural hematoma if epidural catheter is in place (follow ASRA neuraxial-anticoagulation guidelines for timing)
• Aspirin is NOT recommended as the sole agent for VTE prophylaxis - Harrison's, p. 3953

D. Resumption of Cardiac Medications

• Restart all cardiac medications as soon as oral intake resumes
• ACE inhibitors/ARBs: restart when hemodynamically stable
• Antiplatelet agents: restart as per the bleeding/stent risk balance
• Beta-blockers: do NOT miss doses - rebound can precipitate MI

E. Watch for Postoperative Complications

• Myocardial Infarction (highest risk in first 6 weeks post TKR based on MI incidence data - Miller's Anesthesia, p. 9148)
• Acute Heart Failure
• Arrhythmias (AF incidence ~3% after noncardiac surgery)
• Pulmonary Embolism
• Acute kidney injury

IV. SUMMARY TABLE

Key References

• Harrison's Principles of Internal Medicine 22E (2025), Chapter 492: Perioperative Medical Care - Cardiac Risk Assessment
• Miller's Anesthesia 10E, Chapter 60: Orthopedic Anesthesia - Cardiac Risk in TKR
• Sabiston Textbook of Surgery: Cardiac-Specific Preoperative Evaluation
• ACC/AHA 2014 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery
• 2022 ESC Guidelines on Cardiovascular Assessment for Noncardiac Surgery

Anesthetic Management of an IHD Patient Posted for Total Hip Replacement (THR)

Introduction

I. PREOPERATIVE ASSESSMENT AND OPTIMIZATION

A. Surgical Risk Classification

• Greater blood loss (500-1500 mL for primary THR vs. 500-1000 mL for TKR)
• Lateral decubitus positioning with significant hemodynamic implications
• Higher incidence of fat embolism syndrome (FES) due to femoral canal reaming
• Bone cement implantation syndrome (BCIS) in cemented prostheses
• No intraoperative tourniquet (unlike TKR) - therefore more continuous blood loss

B. Cardiac Risk Stratification (RCRI)

C. Functional Capacity Assessment

• Expressed in METs (Metabolic Equivalents)
• THR patients often have limited mobility from hip disease/pain, making functional capacity assessment difficult - similar to TKR
• Pharmacologic stress testing (dobutamine stress echocardiography or nuclear perfusion imaging) is indicated in patients with poor or unknown functional capacity where results will change management
• Myocardial infarction peaks in the first 6 weeks post-THR based on nationwide cohort data - Miller's Anesthesia 10E, p. 9148

D. Investigations

E. Medication Management

II. INTRAOPERATIVE MANAGEMENT

A. Patient Positioning - Key Difference from TKR

1. Lateral decubitus position (most common - posterior approach): The patient lies on the non-operative side with the operative hip uppermost.
   • Anesthetic implications: ventilation-perfusion mismatch (dependent lung receives more perfusion, non-dependent lung is better ventilated)
   • Axillary roll must be placed to protect the brachial plexus and axillary artery
   • Head and cervical spine kept strictly neutral
   • If spinal/epidural: can be placed in lateral or sitting position before positioning
   • If GA: airway must be secured before final lateral positioning
2. Supine/Anterior approach (increasingly popular - tissue-sparing, faster recovery, no axillary roll needed): Patient lies supine on a specialized hip table (e.g., Mizuho OSI Hana table) - Barash Clinical Anesthesia 9E, p. 4378

B. Choice of Anesthesia

• Large database studies show neuraxial anesthesia for THA is associated with:
  • Lower 30-day mortality
  • Decreased thromboembolic events
  • Less blood loss and lower transfusion requirements
  • Shorter length of stay
  • Lower in-hospital complications
• Barash Clinical Anesthesia 9E, p. 4377

• Hypovolemic patients (preoperative IV fluid preloading advised)
• Patients on chronic ACE inhibitors/ARBs
• Patients with IHD (hypotension = reduced coronary perfusion pressure = ischemia)
• A preload fluid bolus before spinal block is recommended; have vasopressors (phenylephrine, ephedrine) ready - Barash Clinical Anesthesia 9E, p. 4379

C. Intraoperative Monitoring

• Continuous 5-lead ECG with ST-segment monitoring (leads II + V5)
• SpO2
• NIBP every 3 minutes (more frequent during cement insertion)
• Capnography (if GA or sedation)
• Temperature

• Invasive arterial line (IBP): Mandatory for continuous BP monitoring especially during:
  • Induction of anesthesia
  • Cement insertion (BCIS risk - sudden catastrophic hypotension)
  • Joint reduction
• Central venous catheter: For CVP monitoring and vasoactive drug infusion
• TEE or PAC: Reserved for severely compromised LV function (EF <30%) or pulmonary hypertension

D. Hemodynamic Goals

E. Blood Conservation - Specific to THR

• Tranexamic Acid (TXA): IV 10-15 mg/kg before incision, then 1 mg/kg/hr during surgery; or topical 1-3 g; significantly reduces blood loss and transfusion requirements in THA/TKA. Safe even in IHD patients - a retrospective study of 765,011 patients showed TXA in those with MI, stroke, AF, and renal disease was not associated with increased complications - Miller's Anesthesia 10E, p. 9198
• Cell salvage (autologous transfusion)
• Deliberate hypotension (MAP 55-65 mmHg) during neuraxial anesthesia reduces blood loss - but use with extreme caution in IHD patients (may precipitate ischemia)
• Maintain normothermia to preserve coagulation

F. Surgery-Specific Intraoperative Hazards in IHD Patients

1. Bone Cement Implantation Syndrome (BCIS)

• Mechanism: Pressurization of cement into the femoral medullary canal forces bone marrow debris, fat globules, air, and methyl methacrylate monomer into the venous circulation → pulmonary embolization → acute right heart strain → cardiovascular collapse
• Clinical features: Sudden profound hypotension, hypoxia, bronchoconstriction, arrhythmias, increased pulmonary vascular resistance (PVR), right ventricular failure, and potentially cardiac arrest
• Risk factors specific to IHD patients: Pre-existing poor LV function, pulmonary hypertension, right ventricular dysfunction, long-stem prosthesis, first-time femoral canal instrumentation, pathological fractures, large cement volume - Miller's Anesthesia 10E, p. 9200
• Prevention: Pulsatile lavage of medullary canal; distal venting holes in the femur before cement; consider uncemented/cementless prosthesis in very high-risk IHD patients
• Management of BCIS:
  • Immediately increase FiO2 to 1.0
  • Vigorous IV fluid resuscitation
  • Vasopressors: Epinephrine is the drug of choice (inotropic + vasopressor effect, offloads the right ventricle)
  • Norepinephrine / vasopressin for refractory hypotension
  • If cardiac arrest: CPR per ACLS protocol
  • Inform surgeon immediately

2. Fat Embolism Syndrome (FES)

• Occurs during femoral canal reaming - intramedullary pressure forces fat and marrow debris into circulation
• Subclinical form in nearly all THR patients; clinical FES in up to 30%
• In IHD patients with patent foramen ovale (PFO): paradoxical fat embolism to coronary and cerebral circulation can cause acute MI or stroke
• Clinical triad: Hypoxemia + neurological changes + petechial rash (conjunctival/axillary/neck)
• Intraoperatively: presents as cardiovascular collapse during or after reaming
• Management: Supportive (O2, ventilation, fluids); no proven role for steroids, heparin, or dextran; mortality up to 20% - Miller's Anesthesia 10E, p. 9199

3. Joint Reduction

• Reduction of the new prosthetic hip joint causes a sudden vasovagal reflex → severe bradycardia and hypotension
• In IHD patients: can precipitate acute myocardial ischemia
• Have atropine (0.6 mg IV) drawn and ready

III. POSTOPERATIVE MANAGEMENT

A. Recovery and Monitoring

• ICU/HDU admission for high-risk IHD patients (RCRI ≥3, EF <40%, recent MI, perioperative instability)
• Continuous ECG monitoring for minimum 24-48 hours
• Serial high-sensitivity troponins (hsTnI/hsTnT) at 24 and 48 hours post-surgery - to detect Perioperative Myocardial Injury (PMI)

• 30-day mortality: up to 9%
• 1-year mortality: up to 22%
• Miller's Anesthesia 10E, p. 9148-9149

B. Postoperative Analgesia

• Epidural analgesia (if CSE placed): 0.1-0.125% bupivacaine ± fentanyl; continue >24 hours; most effective pain control; but risk of epidural hematoma with anticoagulation - follow ASRA timing guidelines
• Peripheral nerve blocks:
  • Lumbar plexus (psoas compartment) block - most effective for hip surgery; covers femoral, obturator, and lateral femoral cutaneous nerves; avoid in anticoagulated patients
  • Fascia iliaca block - easier, safer alternative; widely used
  • PENG block (Pericapsular Nerve Group block) - motor-sparing, targets articular branches of the hip capsule
  • FNB (femoral nerve block) - useful but causes quadriceps weakness, increasing fall risk
• Periarticular injection by surgeon: local anesthetic ± epinephrine ± ketorolac ± steroid cocktail; does not outperform peripheral nerve blocks but is a useful adjunct
• Systemic: Paracetamol + celecoxib (NSAIDs with caution in IHD - COX-2 inhibitors increase CV risk) + low-dose opioids (titrated)

C. VTE Prophylaxis

• Graduated compression stockings (thigh-high)
• Intermittent pneumatic compression (IPC) devices - start immediately in recovery

• LMWH (enoxaparin 40 mg OD or 30 mg BD SC) - start 12 hours postoperatively
• Fondaparinux 2.5 mg OD SC
• Direct oral anticoagulants (DOACs): Rivaroxaban 10 mg OD - favored in many guidelines for THA/TKR (shown superior to enoxaparin with similar bleeding risk)
• Duration: Continue for 35 days post-THR (longer than TKR's 14 days)

D. Resumption of Cardiac Medications

• Restart all IHD medications (beta-blockers, statins, aspirin, ACE inhibitors) as soon as oral intake is established
• Beta-blocker: Do not miss a single dose - rebound tachycardia can precipitate MI
• Statin: Restart immediately - perioperative statin continuation reduces MACE
• Antiplatelet / DAPT: Restart per the balance of bleeding risk (wound) vs. stent thrombosis risk - discuss with cardiologist

E. Watch for Postoperative Complications

IV. KEY DIFFERENCES: THR vs. TKR in IHD Patient

V. SUMMARY

1. Preoperative: RCRI scoring, cardiac workup, medication optimization (especially DAPT/stent timing), anemia correction, informed consent for transfusion
2. Intraoperative: Neuraxial anesthesia preferred, invasive arterial monitoring, anticipate and prepare for BCIS and FES, strict hemodynamic targets, TXA for blood conservation, consider cementless prosthesis in very high-risk patients
3. Postoperative: ICU/HDU monitoring, serial troponins, multimodal analgesia (avoid COX-2 inhibitors), ASRA-compliant VTE prophylaxis for 35 days, early restart of cardiac medications

• Barash, Cullen & Stoelting's Clinical Anesthesia 9E, Chapter 51: Orthopedic Anesthesia
• Miller's Anesthesia 10E, Chapter 60: Orthopedic Anesthesia - BCIS, FES, TXA
• Harrison's Principles of Internal Medicine 22E, Chapter 492: Perioperative Cardiac Risk Assessment