Anesthesia for Orthopedic Surgery

• Anesthesia for Orthopedics surgery, Part 1.

Learning Objectives

• Describe general considerations and goals related to orthopedic surgery.
• Describe specific considerations associated with orthopedic surgery, their anesthetic implications, and management.
• Briefly describe special orthopedic conditions and their anesthetic concerns.

General Considerations

• Perioperative goals divided into pre-op, intraoperative and post operative considerations are important.
• Age-specific orthopedic conditions should be taken into account.
• Medical comorbidities are important to consider.
• Co-existing medications taken by the patient should be reviewed.

Specific Considerations

• Positioning of the patient.
• Bone cement implantation syndrome if applicable.
• Use of pneumatic tourniquets.
• Fat embolism.
• Deep vein thrombosis and thromboembolism.
• Regional anesthesia and anticoagulation.

Pre-Op Considerations

• Age of the patient.
• Co-morbidities.
• Current medications.
• Diagnostic studies.

Pre-Op Considerations: Comorbidities

• Trauma and the need for stabilization.
• Geriatric populations often have conditions like HTN, CAD, CVD, COPD, osteoarthritis, and RA.
• Obesity frequently coexists with HTN, CAD, and DM.

Pre-Op Considerations: Age

• Elderly patients need special attention.
• Elderly patients often have medical conditions like MI, COPD, HTN, CVD, and DM.
• Anticoagulation therapy is a concern.
• Renal dysfunctions should be noted.
• Airway difficulties might exist.
• Osteoporosis.
• Consider congenital deformities in pediatric patients.
• Undiagnosed muscular dystrophies in the pediatric population are a concern.

Pre-Op Considerations: Medications

• Steroids, Opioids, Antihypertensives, NSAIDS and Immunotherapy-Methotrexate are common medications to be aware of.

Pre-Op Considerations: Diagnostic Studies

• Radiologic studies like C-xray and Xray C-spine-AP, lateral views are helpful.
• Cardiac studies like ECG and Echocardiography might be needed.
• Labs to consider: CBC, Platelets, Renal functions and electrolytes and Coagulation studies when anti-coagulation medications or immunotherapy is involved.

Choice of Anesthetic Technique

• Regional anesthesia vs general anesthesia techniques should be considered.
• Many orthopedic surgeries benefit from regional anesthesia (RA) techniques due to localized peripheral sites.

Advantages of RA

• No or minimal airway manipulation.
• Improved postoperative analgesia.
• Decreased incidence of PONV (postoperative nausea and vomiting).
• Less respiratory and cardiac depression.
• Reduced blood loss.
• Decreased risk of DVT/Thromboembolism.

Upper Extremity Surgery

• RA (+/- GA) is common.
• Intravenous Regional Anesthesia (IRVA) may be used.
• IRVA advantage: Simplicity, rapid onset, controllable duration, and rapid return of function.
• IRVA disadvantage: continuous tourniquet use, potential drug toxicity, and lack of postoperative analgesia.
• Brachial Plexus Block is another option.
• Blockade of peripheral nerves, such as radial, median, and ulnar nerve blocks, or digital nerve blocks.

Lower Extremity Surgery

• Lower extremity surgery can often be completely performed under regional anesthesia.

Regional Anesthesia Technique for Lower Extremity

• Hip: can be achieved with Spinal, epidural, lumbar plexus block.
• Knee: can be achieved with Spinal, epidural, 3 in 1 block, femoral sciatic block.
• Lower leg: can be achieved with Spinal, epidural, sciatic block, femoral-sciatic block, sciatic, and saphenous block,.
• Ankle: can be achieved with Spinal, sciatic block.
• Foot: can be achieved with Spinal, sciatic, ankle block, trans metatarsal block.

Post-Operative pain management considerations

• Peripheral nerve blockade with or without a catheter can be utilized.
• Opioids for breakthrough pain/multimodal analgesia.
• NSAIDs and adjuvant analgesic medications.
• Other considerations: ICU/Post op care and Mechanical ventilation if needed.

Intraoperative Goals

• Proper positioning is important to prevent stretch/compression nerve injuries.
• Prevent significant blood loss through proper positioning, intraoperative blood salvage, induced hypotension, and intraoperative hemodilution.

Specific Considerations: Positioning

• Positioning is important for patient safety, preventing nerve injuries, enabling IV access, ET Tube and catheter patency and ensuring surgical approach.
• Common patient positions include supine, lateral, prone and beach chair.

Positioning contd..: Supine

• Patient lies on their back.
• Arms on arm boards, with the arm < 90 degrees.
• Arm is supinated (palm up).
• Elbows should have padding when possible.
• Arms may be tucked.
• Check fingers.
• Check IV lines and SpO2 probe.

Positioning contd..: Lateral

• Body alignment is critical in the lateral postion.
• The neck should be kept in a neutral position.
• Always place an axillary roll.
• Place padding between knees.
• Place padding below the lateral aspect of the dependent leg.
• Position arms parallel to one another.
• Place padding between arms, or place the non-dependent arm on a padded surface.

Positioning Contd..: Prone

• The patient is face down.
• The head should be placed straight forward, ensure that ET tube has placement and patency.
• Check bilateral eyes/ears for pressure points.
• Check that the dependent eye/ear, and ETT placement is appropriate when the head is turned.
• Be aware of potential vascular occlusion.

Positioning Contd..: Prone, Arm Placement

• Tucked, similar to the supine position.
• Abducted.
• Check neck rotation and arm extension to avoid brachial plexus injury.
• Elbows are padded.
• Chest rolls and iliac support may be used. Padding in placed under iliac crests.

Positioning Contd..: Beach Chair

• Arms should be supported.
• Goal: prevent stretching of the brachial plexus.
• Elastic stockings and active leg compression devices - help maintain venous return.

Positioning Contd..: Fracture Chair

• Maintenance of traction on the fractured extremity, allowing manipulation for closed reduction and fixation.
• Improves access to the fracture site for radiography in several planes.
• Position the ipsilateral arm on an arm board or sling without stretching the brachial plexus.
• Genital protection should be implemented.

Bone Cement Implantation Syndrome (BCIS)

• Bone cement typically consists of Methyl methacrylate (MMA), an acrylic bone cement used during arthroplastic procedures.
• BCIS is Characterized by hypoxia, hypotension, or both and/or unexpected loss of consciousness.
• BCIS occurs at the time of cementation, prosthesis insertion, reduction of joint, or occasionally, limb tourniquet deflation during cemented bone surgery.

BCIS Pathophysiology

• Cement interdigitates with bone.
• Hardening of cement and expansion against prosthesis.
• Intramedullary hypertension (>300 mm Hg).
• Embolization of fat, bone marrow, cement and air into venous channels.
• Systemic absorption of residual MMA.
• Vasodilation.
• Release of thromboplastin.
• Platelet aggregation, microthrombus formation.

BCIS Clinical Presentations

• Fever.
• Hypoxia.
• Hypotension.
• Tachycardia.
• Dysrhythmia.
• Mental status change.
• Dyspnea.
• Decreased End tidal CO2.
• Right ventricular failure and cardiac arrest.

BCIS Treatment Strategies

• Increase FiO2 prior to cementing.
• Monitor and maintain hydration.
• Create a vent hole in the distal femur.
• High-pressure lavage of the femoral shaft to remove debris.
• Using cementless prosthesis.

Pneumatic Tourniquet

• Used to create a bloodless field.
• Duration should not exceed 2 hours.
• Prolonged inflation (>2hrs) can leads to transient muscle dysfunction, rhabdomyolysis and nerve injuries.
• Inflation to 100 mmHg above systolic blood pressure.

Pneumatic Tourniquet: Advantage

• Eliminates intraoperative bleeding.
• Improves visualization.

Pneumatic Tourniquet: Disadvantages

• Neurologic effect.
• Muscle change.
• Systemic effects of the tourniquet inflation.
• Systemic effects of the tourniquet release.

DVT/Thromboembolism Risk Factors

• Obesity.
• Age > 60 years.
• Previous PE and DVT.
• Cancer.
• Procedure > 30 mins.
• Use of a tourniquet.
• Lower extremities fracture.
• Immobilization > 4 days.
• Thrombophilia, mainly hereditary, e.g., Factor V Leiden (most common).

DVT/Thromboembolism Treatment

• Prophylactic treatment: Early stabilization of the fracture.
• Supportive treatment: Respiratory care with O2 therapy (with CPAP ventilation - ARDS), Invasive monitoring such as Volume status and Inotropes.
• Vasodilators for Pulmonary HTN and High-dose corticosteroids.

DVT/Thromboembolism Prevention

• Non-pharmacological: Intermittent pneumatic compression, TED stockings, IVC filters: in patients C/I for anticoagulation.
• Pharmacological: Low dose heparin (UF), Warfarin and LMWH.
• Recent alternatives: Fondaparinux and Dabigatran.

DVT/Thromboembolism Treatment

• Anticoagulants OR Thrombolytics?
• Venous thrombi undergo Fibrin thrombi and need anticoagulation for prevention and treatment.
• Severe, possibly fatal PE needs Thrombolytics.
• Warfarin blocks Vit K-dependent coagulation factors II, VII, IX, and X).
• LMWH inactivates thrombin and Factor Xa through an antithrombin (AT)-dependent mechanism.

Regional Anesthesia and Anticoagulation

• Consdierations are important in orthopedic surgeries.
• A plan management of anticoagulants and an anesthetic technique must be in place under anticoagulation.

This lesson covers anesthesia considerations for orthopedic surgery. It includes a discussion of pre-operative, intraoperative, and postoperative goals. Specific considerations such as patient positioning, bone cement implantation syndrome, and the use of pneumatic tourniquets are discussed.