The word anaesthesia is coined from two Greek words: “an” meaning “without” and “aesthesis” meaning “sensation”, so it’s no surprise that relieving pain and suffering is central to the practice of anaesthesia.
Anaesthesia involves applying a wide range of techniques ranging from sedation, analgesia, general anaesthesia, regional anaesthesia, local anaesthesia or a combination thereof to achieve the necessary conditions for performing the required operation in the safest way possible for the patient’s condition.
Despite an increase in the complexity of surgical operations, modern anaesthesia is relatively safe due to high standards of training that emphasise quality and safety.
In addition, there have been improvements in drugs and equipment. Increased support for research to improve anaesthesia has resulted in Australia and New Zealand having one of the best patient safety records in the world.
Types of Anaesthesia
Local Anaesthesia
Local anaesthesia involves injecting local anaesthetic into the tissues near the surgical site. Local anaesthesia may be used alone or in combination with sedation, regional or general anaesthesia. This depends on the size of the surgery and the time it will take, and the preferences of the patient. Local anaesthesia is usually used for minor surgery, such as toenail repair, skin lesion or a cut to remove something. It may not be used if the patient has an infection as infected tissue may render local anaesthesia less effective.
Regional anaesthesia
Regional anaesthesia involves injecting anaesthetic around major nerve bundles supplying body areas, such as the thigh, ankle, forearm, hand, shoulder or abdomen. Regional anaesthesia is an umbrella term which includes techniques such as nerve blocks, spinal and epidural anaesthetics. Spinal and epidural anaesthetics can be highly effective modes of anaesthesia and pain relief for surgery, in addition to their commonly perceived use in labour and obstetric surgery.
Regional anaesthesia is sometimes performed using a nerve-locating device such as a nerve stimulator, or using ultrasound, to accurately locate the nerves. Once anaesthetic is injected, patients may experience numbness and tingling and it may become difficult or impossible to move that part of the body.
Your anaesthetist will advise on whether the addition of sedation or general anaesthesia is required or recommended in addition to your regional anaesthetic. The primary consideration is always safety, but personal preferences are also taken into account.
The duration of effect of the regional anaesthesia depends on which anaesthetic combination is used, the region into which it is injected and whether it is maintained by continual doses or repeated injections. Numbness can last several hours but may last several days. Generally, the “heaviness” wears off within a few hours but the numbness and tingling can persist for much longer.
As the anaesthetic effect wears off, numbness will diminish and the surgical pain may return, in which case your doctor will prescribe pain relief. In this situation, it’s advisable to start taking pain relief prior to the regional anaesthetic fully wearing off, so that by the time it has worn off you will have sufficient pain relief on board.
Sedation
Conscious sedation (colloquially known as “twilight”) reduces the patient’s level of consciousness but allows them to respond to verbal commands or light touch so that a specialist can perform a procedure. A variety of medications and techniques are used for procedural sedation and/or pain relief. Common medications include benzodiazepines, such as midazolam, which act on the brain and the nervous system to cause sedation, and opioids, such as fentanyl, which decrease the patient’s perception of pain to provide pain relief. These medications may be administered orally but are usually administered into a vein.
Deeper levels of sedation, where patients may lose consciousness and respond only to painful touch, may be associated with the patient having difficulty breathing normally and their heart function may be affected. The anaesthetist is trained to manage these situations.
It is never a case of “just sedation”, as increasingly deeper levels of sedation can cross the fine line into general anaesthesia very easily, along with all the complexities that come with it. It often requires more skill and experience to perform this type of sedation, and therefore it is important that it is performed only by a qualified anaesthetist in a facility with the equipment and staff to support it.
General anaesthesia
General anaesthesia involves putting a patient into a medication-induced state of carefully controlled unconsciousness. When the anaesthetic is deep enough, the patient will not respond to pain. It also includes changes in breathing and circulation. During a general anaesthetic, the anaesthetist is constantly monitoring the patient to manage the airway, blood circulation and general responses.
Other procedures
Often there are additional procedures that need to be performed in order to provide a safe anaesthetic. For example, these may include:
• Arterial cannulation: This involves inserting a cannula into one of your arteries (usually in the wrist but not always) to closely monitor the blood pressure in your arterial system and address any changes in a timely manner, to ensure adequate perfusion of your vital organs. It also allows sampling of arterial blood to check your blood counts and other parameters of how your body systems are functioning throughout the operation. Where possible, I will try to do this after you are asleep.
• Central venous cannulation: This involves inserting a cannula into a large vein close to the heart (usually in the neck but not always) to closely monitor the pressure in your venous system and address any changes in a timely manner. It also allows me to deliver medications to support your circulatory system which would otherwise be too strong to deliver through an ordinary intravenous cannula. Where possible, I will try to do this after you are asleep.
• Blood transfusion: If your blood count is low or anticipated to fall during or after the operation, it may be necessary to give you blood during the surgery. Sometimes we can recycle your own blood by using a special filter, but sometimes you will require donor blood from the blood bank.
Considering your specific medical conditions and the operation you are having, if these procedures are anticipated they will be discussed during the preoperative consultation. However, in some situations where the necessity for these procedures arise during the surgery, it may be necessary to just proceed.
Analgesia
Depending on the type of surgery you are having and your medical conditions, an analgesic plan will be tailored for you.
Analgesia starts while you are still having your surgery. You may be given intravenous analgesics, or have local anaesthetic injections while you are asleep, or there may be a plan to extend the duration of any regional anaesthetic technique into the postoperative period. The aim is to manage a smooth transition from an anaesthetised state to an awake state. In the anaesthetised state, there are clues that your body gives the anaesthetist as to your level of discomfort, so pain relief is delivered throughout the operation and finetuned towards the end. However, pain is a subjective personal experience which means that only the patient can truly gauge their level of pain, and so true finetuning of pain relief can only occur upon waking up.
Postoperative pain relief may range from nil or minimal, to requiring a complex combination of oral, intravenous and or local/regional anaesthetic infusions. There are other forms of pain relief such as patches, dissolving wafers under the tongue, intramuscular, just to name a few.
Once you have returned to the ward after surgery, it is important to communicate your pain relief needs with the nurse looking after you. Some pain relief is delivered on a schedule, while others require that you request it when needed which means you won’t get any if you don’t ask. Most forms of pain relief take time to reach the desired level of effect, as it has to be absorbed into your bloodstream first, which takes time. The aim is to not allow the pain to reach excruciating levels in the first place before addressing it. However, if your pain relief is inadequate despite reaching the maximum prescribed doses, you must inform the nurse, as the anaesthetist may need to increase or change your analgesic regimen earlier rather than later. Rarely, a surgical complication can cause disproportionate levels of pain for what’s expected with the surgery performed, and this needs to be excluded at the earliest opportunity.
Analgesia for having a baby
This is quite a big topic, fortunately the Australian and New Zealand College of Anaesthetists has a section on their website covering a wide range of topics including the various options for labour pain relief:
Please take the time to read through the website. If you have any questions please feel free to ask me when I see you.
Anaesthesia for having a baby
Caesarean sections may either be planned ahead of time, or performed in an emergency situation. Planned caesarean sections are often done under a spinal anaesthetic, it is generally safer for both mum and baby, and a more pleasant experience overall. For emergency caesarean sections, sometimes it is safe and there is time to perform a spinal anaesthetic, but sometimes the urgency will require an immediate general anaesthetic. If you happen to have a labour epidural which has been working effectively, it can often be used (with a stronger anaesthetic) for the surgery.
Sometimes surgery is required for reasons other than caesarean sections. This can include situations such as surgeon-assisted delivery in theatre, or repairing tears, or removing retained parts of the placenta, etc. Usually a spinal or general anaesthetic is used for these situations, but a labour epidural which has been working effectively can often be more than adequate for this.
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