Specific Information: Joint Replacement

The General Role of the Anaesthetist

The role of the anaesthetist for any type of surgery can be examined in three stages, pre-operative, intra-operative and post-operatively.

Prior to any surgery, your anaesthetist determines your health status and ensures that it is optimised. He or she works with you to decide what type of anaesthetic technique would give you the best outcome. A very important part of the pre-operative process is to provide information and allay anxiety.

During surgery, your anaesthetist remains with you while the surgery proceeds, monitors the functions of your heart and lungs, replaces lost fluids. It is your anaesthetist that diagnoses and treats any unexpected events. It is not really an exaggeration when people say, the anaesthetist keeps you alive!

Post-operatively your anaesthetist may be responsible for pain and fluid management and for any complications not of a surgical nature. This responsibility often means being available at any time day or night for up to 2 days post-operatively.

Joint Replacement Surgery

Patients for joint replacement surgery are generally older and have often other medical conditions. Surgery takes 2 hours or longer for a primary (or first time) replacements and up to 4 or 5 hours for a complicated revision. Blood loss can be enough to warrant a blood transfusion. A good pain management strategy is needed to facilitate early mobilisation and rehabilitation. For all these reasons, anaesthesia for joint replacement can be demanding and always needs careful planning.

Preparation for Surgery

As a patient there are several things that you can do in the lead up to surgery to give you a better outcome. Increasing general fitness, eating a healthy diet, loosing weight and stopping smoking have benefits that far outweigh the change in lifestyle that some patients need to adopt. Getting on top of your blood pressure or diabetes may require medication adjustments. Collations of any blood, heart or lung function tests that you may have had are of immense value to your anaesthetist. Some supplements and herbal medications can interact with drugs used during anaesthesia or cause bleeding and are often stopped in the weeks prior to surgery. It is essential that you have a list of all the medicines you are taking and have them checked. Your GP can help you in all these tasks.

Preoperative Assessment and Anaesthetic Technique

The pre-operative task of your anaesthetist is to take your medical history, examine you, order any relevant tests (or review the ones you already have) and to come up with an anaesthetic plan. You, as the patient, have an active role in that process. Numerous studies have tried but have failed to come up with the ideal technique for hip and knee replacement. Each technique has its own risks and benefits. Just as each patient has a unique physiology each patient will react differently to an anaesthetic. As anaesthetists, the best that we can do is to discuss what we regard as the most suitable options for you and for both patient and anaesthetist to agree on the final plan.

Options that your anaesthetist may present you with are:

  • General anaesthesia or sedation
  • Epidural or spinal anaesthesia
  • One or more specific nerve blocks
  • Infiltration of the surgical area with local anaesthetics

Often these choices are combined, such as a general anaesthetic and a spinal, or a general anaesthetic and a nerve block. Combination techniques often avoid using too much of a given drug so as to avoid any potential disadvantages.

There are as many ways to give an anaesthetic as there are anaesthetists to give them. Just as you have chosen your surgeon, your surgeon has chosen the anaesthetist. It is a safe bet that the anaesthetist and surgeon have both been working together to improve outcomes from a surgical and anaesthetic perspective and that the options you are presented with are the best they can offer you. It is your right to make sure that you understand what is being offered by your anaesthetist and why.

Post Operative Care

Post-operatively, the issues that are relevant to joint replacement surgery are pain management, control of nausea, coping with blood loss, avoidance of clots in the legs (DVTs), respiratory complications and the return of normal urinary and bowel function.

The pain management regime in the post operative phase is often determined by the choice of anaesthetic intra-operatively. For example, if a femoral nerve block (which makes the front of the knee numb) is used for a knee replacement it can often be extended for up to 48 hours post-operatively as an infusion. If a spinal anaesthetic is used, morphine can be given by the spinal route to extend analgaesia for 12 to 24 hours post-operatively. A Patient Controlled Analgaesic device or PCA can also be used post-operatively. This is an electrical device that you press to self administer small increments of pain killer as needed without needles. Most hospitals have written information on the pain control methods available. Stronger oral medications for pain relief are available that enable earlier mobilisation without these relatively more invasive techniques.

Up to 30 to 40% of patients having all types of surgery experience nausea and vomiting, hip and knee surgery is no exception. For the first 24 hours it is usually the result of the anaesthetic. Thereafter, it is often due to the type of painkiller used. Your anaesthetist is well aware of this problem and will be doing everything available to counteract it.

Nausea can also be a symptom of blood loss, as can lethargy, dizziness on sitting up or standing, pallor and a rapid heart rate. Bleeding is part of joint replacement surgery and can be extensive enough to require a blood transfusion. Re-infusion systems (where blood collected in the drains post-operatively is given back intravenously to patients) are available. Discuss with your surgeon if pre-donating your own blood is needed. The dizziness on mobilising post-operatively can be alleviated somewhat by getting up in stages. Never attempt to mobilise alone immediately after a replacement always seek your physiotherapist or nurse to assist you until told otherwise.

Hip and knee surgery is associated with a high incidence of DVT. You will be provided with mechanical means of avoiding clots such as stockings or pneumatic compression devices as well as blood thinning drugs. However, simple things such as remembering to regularly move your legs, to do leg exercises while in bed and to mobilise early (despite any discomfort) will speed up your recovery.

Combining leg exercises with deep breathing exercises avoids the other complication that accompanies prolonged bed rest post-operatively namely collapse of the base of the lungs. Simply moving your legs and deep breathing each time you see an ad on the television or turn the page of a book you are reading is frequent enough to help avoid the two main post-op complications, DVTs and lung collapse.

Urinary retention is very common with lower limb orthopaedic surgery especially if spinal anaesthetic has been used. It is very common practice to place a catheter into the bladder while you are anaesthetised and for it to be removed on day 1 or 2 post-op. Constipation often occurs about day 3 post-op and is due to a combination of pain killers and an altered diet habit. There are medicines available that can help and these will be available to you. Mobilisation also helps.