Anaesthesia for hip surgery

By
Dr. Alasdair Dow
MRCP FRCA
Consultant in Anaesthetics / Intensive Care

At the first meeting you have with your hip surgeon, he/she will make an assessment of your fitness for surgery. This will be based on information that your GP has passed on, together with information about your height, weight, blood pressure and associated medical problems. In most circumstances the surgeon will decide that you are fit to proceed to the operation, and you will be admitted in due course to hospital.

A small number of patients may have medical problems that put them at increased risk, and so will be referred by the surgeon to the anaesthetist that they work with.

The anaesthetist is a doctor, like your surgeon, who has undergone training in the assessment and management of patients undergoing all types of surgery. The anaesthetist may ask to meet you in a pre-operative assessment clinic, and you should bring along a list of all the medical therapy that you are receiving.

 At the clinic the anaesthetist will ask you questions about your general health, any operations in the past, and also any problems you might have had with anaesthetics or operations. The anaesthetist will then examine you, and may occasionally request additional tests to assess your suitability for surgery. At the end of the meeting, the anaesthetist will explain whether it is safe to proceed to the hip replacement. This will be the case for the majority of the patients. A small percentage of patients may have to undergo further tests or treatment to reduce any risk of subsequent surgery. These tests will be arranged by the anaesthetist, and will be coordinated through your GP so that he/she is aware of what is happening.

If you are regularly taking aspirin, clopidogrel or warfarin, you will be asked to alter the dose by the surgeon or anaesthetist. This is because these drugs can increase the amount of bleeding during the hip replacement. Usually, you will be asked to stop the drug(s) 5-10 days before the operation, but this will vary according to the reason you are on the drug. Please remember to let the surgeon / anaesthetist know that you are receiving this type of medication as soon as your operation is confirmed.

You will be seen by the anaesthetist on the day before or day of surgery. This is an opportunity for the anaesthetist to reassess your general health, and to also explain the type of anaesthetic that is used. This is a good moment to express any concerns that you have about the anaesthetic, as the anaesthetist will be happy to allay your fears. On the day of operation, you will be starved of food for 6 hours, and liquid for 2-4 hours. It is important that you respect this guidance, as the stomach may become unduly full during an operation. This can lead to potentially dangerous vomiting. You may be prescribed a “pre-med”. This contains one or more tablets that serve to prepare you for theatre. This can include a sedative to relax you, and also a pain killer or anti-sickness drug for after the surgery. The purpose of these drugs is not to put you to sleep, and so you should not be concerned if you are awake when you arrive in the operating theatre.

In the operating theatre, the anaesthetist will begin your anaesthetic by checking that you have agreed to the operation, and that the correct side is to be operated on. The anaesthetist will then perform a local anaesthetic “block”. This will either be a spinal injection, or a regional block. The spinal injection delivers local anaesthetic into your spine, and means that you will have no pain in your hip for 8-12 hours after the operation. It also reduces the amount of bleeding during the operation, and reduces your chance of a DVT or PE (clot in the vein) after the surgery. Thus, it is a very popular technique for patients having a hip replacement. A regional block involves injections of the same local anaesthetic into nerves that run around your hip joint. This will also result in a numb pain-free leg after the operation. Both types of block have a very small risk of damage to the nerves that run to you leg, and the anaesthetist will happily explain these risks to you. However, these techniques are so safe that they are often considered essential for a good hip replacement, and it is felt that the small risk is outweighed by considerable benefit.

These types of block may be inserted before or after you go to sleep. The anaesthetist will discuss this with you, and you may have your own feelings about this matter. The anaesthetist will usually send you off to sleep with in an injection in the arm (“a drip”), although occasionally you may have to breath a gas to go off to sleep. This would only really apply to people who have very poor veins for injection, or are frightened by injections.

When you are asleep the anaesthetist will remain with you at all times, and will watch (monitor) your body to ensure you are safe. You may require a blood transfusion during the operation, but this will only be done if it is essential. The likely rate of blood transfusion is less than 15% of people, and this is due to more modern anaesthetic and surgical techniques that reduce the amount of bleeding during the operation.

At the end of the operation, the anaesthetist will wake you up, and transfer you to the recovery area. You will remain there for 1-2 hours under the care of the anaesthetist and a specially trained recovery nurse. If you have received a local anaesthetic block you should feel no pain. However, you will also notice that you will not b able to move one or both legs. You should not worry about this, as this is a normal effect of the block. This weakness will wear off later in the day, as you start to get feeling back in the leg.

If you have marked pain or sickness after you operation, please let the recovery or ward nurse know. The anaesthetist will have prescribed drugs that can relieve these complaints, and you will benefit from receiving them. It is not good to suffer pain silently, and the anaesthetist will want to know as soon as possible if you are in severe pain, so that he/she can do something about it.

Dr. Alasdair Dow
Dept. of Anaesthetics
RD and E Wonford
Barrack Road
EXETER
EX2 5DW