Anaesthesia for Orthopaedic Surgery

Orthopaedic surgery in the ever increasing geriatric population carries special risks unlike in the younger age groups.

Surgery is often essential as it is performed to improve quality of life (elective surgery for joint replacement) or in an accident and emergency situation (fractures).

Fortunately most procedures can be performed successfully under neuraxial block and show better outcomes in major hip and knee surgery and femoral neck fractures. Advantages are reduced mortality, DVT, pulmonary embolism, transfusion requirements, pneumonia, and respiratory depression by 33-50%.

PROBLEMS Patient • CVS and RS disease, osteo-arthritis, osteoporosis • DVT (elderly, immobilization, trauma, cardiac failure, limb surgery) • Tendency to hypothermia Anaesthetic • Central regional block in the presence of DVT prophylaxis Surgical • Identify surgery where blood loss may be significant and continue postoperatively.

• Tourniquet application may cause damage to tissues and nerves, and fluid overload. • Tourniquet release causes metabolic acidosis, hypotension and re-perfusion injury. Increased risk if tourniquet time is >lh (upper limb) and >2h (lower limb). Aggravated if fluid loading is inadequate to compensate for the vasodilatation of central blockade.

• Positioning and intra-operative radiography

• Embolization of bone cement, air, platelet, marrow, or fat (in long bone fractures) Cement polymerization releases free methyl-methacrylate monomer and pressurizing causes embolization. Occurs immediately after cementing or I 0 min after prosthesis. Micro-embolization also occurs with fat, air, platelets or marrow due to pressurizing. Fat embolism syndrome (often in young patients) causes a triad of CNS and RS dysfunction and petechial skin rash in the upper body. Prevention : Pre-emptive volume loading and monitor Sp02 for early detection. Signs

: Hypoxia, hypotension, tachypnoea, tachycardia, skin petechiae, mental deterioration.

Treatment : Supportive (02 , fluids, ephedrine steroids). Discontinue Np.