Anaesthesia for Joint Replacement Surgery – An Update

Dr PrabakarDharmeswaran, MBBS, DA, FCARCSI
Consultant Anaesthetist& Trauma Lead
New Cross Hospital
Royal Wolverhampton Hospitals NHS Trust
Wolverhampton - WV10 0QP
West Midlands, UK

Introduction
This lecture provides updated guidance on anaesthesia for primary and repeat revision joint replacement surgery. Patient profile would typically include senior citizens with multiple co-morbidities.Younger people with severe osteoporosis, rheumatoid arthritis or obesity may also present for joint replacement.

Assessment of co-morbidities
A thorough preoperative anaesthetic assessment is essential for safe planning and execution of anaesthesia.
Estimation of cardiopulmonary reserve is critical supplemented with routineECG, oxygen saturation in air, arterial blood gases and lung function tests.Regional blockade would mandate a thorough examination & assessment of spine and musculoskeletal system.
Preoperative preparation

After optimisation of co-morbidities, cross-matched blood availability, deep vein thrombosis (DVT) prophylaxis, antibiotic prophylaxis (usually cephalosporin or aminoglycoside) and a large bore IV access are a bare minimum.

Anaesthetic technique

Choices of anesthesia include central neuraxial blocks (CNB), peripheral nerve blocks (PNB), general anesthesia (GA) or a combination of any two.

General anaesthesia
Airway management is either with Endo-Tracheal Tube (ETT) or Laryngeal Mask Airway (LMA). If there is no risk of aspiration, spontaneous ventilation with a LMA is usually appropriate. Anaesthesia can be maintained with either inhalational or intravenous technique. Blood loss can be reduced by modest hypotension in carefully selected patients, using volatile agents or propofol infusion.

Regional anaesthesia
Spinal or epidural is preferable for reduced blood loss andreduced incidence of DVT and pulmonary embolus in hip and knee arthroplasty. Regional techniques offerperioperative hypotension and less postoperative cognitive dysfunction. Addition of neuraxial opiates is an option, which however, brings in the need for respiratory monitoring.Conscious sedation is often desirable because of the duration of the operation, intraoperativenoise and patient request.

Peripheral nerve block techniques
For hip replacement, recommended supplement would be the use of a 3-in-1 (femoral/obturator/lateral cutaneousnerve of thigh) block. Lumbar plexus block is an alternative technique as this also blocks the sciatic nerve, which has a component supplying the hip. For knee replacement, a 3-in-1 block either alone or combined with a sciatic nerve block can be effective.

Postoperative management

Oxygen and simple analgesics are the mainstay.Epidural analgesia is an excellent optionin providing quality analgesia; however early mobilization can be difficult.
Strict fluid balance monitoring is essentialto detect blood loss postoperatively.

Revision arthroplasty

The specific challenges are prolonged surgery and high blood loss and hence invasive blood pressure and central venous pressure monitoring should be considered. A urinary catheter should be inserted to monitor hourly urine output.

A combination of general anaesthesiawith lumbar epidural catheter is preferable to a single shot spinal considering the fact that the length of the operation may outlast its effect. An epidural helps in minimisingintraoperative blood loss and improving operating conditions, as well as reducing the risk of DVT.Fluid warmers, hot air blowers, humidification systems and patient hats can be used to prevent intraoperative hypothermia, which can contribute significantly tocoagulopathy and perioperative blood loss. Maintaining normovolaemia throughout surgery is crucial. The haemoglobin concentration should be assessed often, either from blood gases or by using a haemocue device.

The lecture discusses foreseen potential intraoperative problems and solutions in detail.