Getting ready for joint replacement: your anaesthetic assessment and health check

In short: expect a pre-anaesthetic assessment, in person or by telehealth. Bring a full list of your medicines and tell the anaesthetist about your health, past anaesthetics and allergies. Ask early whether your iron levels have been checked, mention sleep apnoea (and bring your CPAP machine), stop smoking as soon as you can, and follow your hospital's fasting and medicine instructions exactly.

Why getting ready matters

Hip and knee replacements are often done in older people, and ANZCA notes that many have other conditions, such as high blood pressure or heart problems, which may or may not have been diagnosed. Finding them before the operation gives time to treat them. The Australian Society of Anaesthetists (ASA) says further tests or a specialist opinion are sometimes needed, which can delay surgery but may improve your condition before it.

The pre-anaesthetic assessment

Your anaesthetist will review your medical history before the operation, in person or by telehealth. Be ready to talk about:

• your general health and fitness, and what you can manage day to day
• heart and lung conditions, including asthma, bronchitis or sleep apnoea
• any recent cough, cold or fever
• previous operations and anaesthetics, and any problems you or your blood relatives have had with an anaesthetic
• allergies, or reactions you have had to medicines
• every medicine you take, including ones bought without a prescription
• anything else that might affect your anaesthetic.

If something changes between the assessment and the operation, such as a new diagnosis or a new medicine, let the hospital or your anaesthetist know. Before you go into theatre, your anaesthetist will usually talk with you again and answer any last questions.

Your medicines

The ASA notes that most medicines can be continued up to the day of surgery, but blood thinners and diabetes medicines need specific instructions. Do not stop or change a medicine unless your surgeon, anaesthetist or prescribing doctor has told you to.

• Blood thinners. These affect both bleeding and clot prevention. Ask early, because the plan may involve the doctor who prescribes them.
• Diabetes medicines. Fasting changes what you need on the day, so you should be given specific instructions.
• Weekly or daily GLP-1 injections for diabetes or weight management. ANZCA’s current advice is to tell your treating team as early as possible; you may be asked to follow a clear-fluid diet beforehand.
• Hormone medicines, including contraceptive pills and hormone therapy. Some make blood clots more likely, so mention them.

Dr Aly’s main website has a fuller guide to medicines before an anaesthetic.

Anaemia and iron

Anaemia means a low level of red blood cells or haemoglobin, often caused by low iron. The National Blood Authority says around one in five people having planned surgery have anaemia, and that it is linked to slower recovery and a higher chance of needing a blood transfusion.

It is worth asking early whether your blood count and iron levels have been checked. The National Blood Authority’s approach, called patient blood management, starts with your GP: a full blood count and iron studies, then treatment to build up your own iron and haemoglobin before surgery if they are low. The earlier this is checked, the more time there is to act on the result before your operation date.

Sleep apnoea

Sleep and anaesthesia both relax the muscles of the throat and reduce the drive to breathe. The Sleep Health Foundation explains that people with obstructive sleep apnoea are more likely to have their airway block under sedation or anaesthesia, and are less able to wake themselves when it does.

• Tell your anaesthetist if you have sleep apnoea, or think you might.
• If you use a CPAP machine, bring it and your mask to hospital, and know your pressure settings and mask type.
• Your anaesthetist may change the anaesthetic plan, arrange closer monitoring after the operation, or ask you to use your CPAP while you are drowsy.

Smoking

ANZCA notes that people who smoke have a higher risk of breathing, heart and wound complications after surgery. Stopping helps at any point, and the benefits build over time:

• After about a day, carbon monoxide and nicotine levels fall, which is likely to help oxygen reach your tissues.
• After about three weeks, wound healing improves.
• After six to eight weeks, lung function improves.
• After about six months, the immune system has largely recovered.

Your GP or Quitline (13 7848) can help. Dr Aly’s main website covers smoking and vaping before an anaesthetic in more detail.

Fitness, weight and keeping warm

healthdirect suggests that regular exercise can help you prepare for an operation and recover from it, and that a healthy weight lowers the risk of complications. Check with your GP, surgeon or physiotherapist before starting a new exercise program, especially if a painful joint limits what you can do.

Hospitals can be cooler than home, and staying warm matters around an operation. Pack warm clothes or a dressing gown.

Fasting

You will be told when to stop eating and drinking. Fasting rules differ between hospitals and depend on your health and your medicines, so follow the written instructions from your hospital or anaesthetist exactly. ANZCA’s patient page explains why fasting matters, and Dr Aly’s main website has a guide to fasting before anaesthesia.

Planning for going home

• Length of stay. The ASA says people generally stay in hospital for one to five days after a hip or knee replacement. Confirm the plan with your surgeon.
• Getting home. Arrange for someone to collect you. ANZCA advises against driving for at least 24 hours after an anaesthetic, and you should not drive while taking opioid pain medicine. Your surgeon will tell you when you can drive again after the operation itself.
• Help at home. Ask your surgeon or physiotherapist what equipment and help you will need, and organise it before the operation.
• Your discharge plan. You should leave with a written plan covering your medicines, any clot prevention and follow-up appointments.

What to take to your assessment

In an emergency, call 000. This information is general and does not replace advice from your treating practitioner.