What is anaesthesia?
What is anaesthesia?
Anaesthesia refers to inducing a state of loss of sensation and/ or loss of awareness in order to allow a surgical procedure to be safely performed without causing pain or distress to the patient. There are many different types of anaesthesia.
For orthopaedic procedures that I perform, I usually use one or a combination of the following:
1. Local anaesthesia
2. General anaesthesia
3. Regional anaesthesia
4. Sedation, with or without anaesthesia
Who performs the anaesthesia?
An anaesthetist does. He/she is a doctor trained in giving anaesthesia. Many patients are under the impression that it is a straightforward and easy role, but the importance of a good anaesthetist cannot be underestimated.
While for most cases the role of the anaesthetist can be considered “easy” for his/her level of training, a good anaesthetist would have had to undergo years of training in order to anticipate potential problems and avoid them in order to make the anaesthesia a walk in the park.
Local anaesthesia involves injecting a pain killer into the area where surgery is to take place, in order to completely numb the area. It is ideal for small procedures where the surgical field is small and not too deep.
Local anaesthesia is often used for procedures such as removing a small lump from the skin or stitching up a laceration.
The medication used (usually lignocaine or something similar) renders the area completely numb so that the procedure can be performed with no discomfort to the patient at all. The patient will continue to have some sensation like vibration and pulling, but there will be absolutely no pain at all. The patient will also be fully awake during the procedure.
The anaesthetic takes effect within a few minutes of injecting it and the procedure can be performed within 5 – 10 minutes of the injection. Patients will find that injection of the local anaesthetic is the most painful part of the procedure. As it is injected, patients will feel slight stinging but that passes after a few seconds.
The numbness will completely wear off after about 1 – 3 hours depending on the type and amount of local anaesthetic medication used. This will give the surgeon a good amount of time to finish the procedure.
Local anaesthesia does not require the expertise of an anaesthetist. It is easily administered by the surgeon.
The same medications (usually lignocaine often in combination with other longer acting anaesthetic drugs) are used in both local and regional anaesthesia.
But the difference between local and regional anaesthesia is that in regional anaesthesia, the anaesthetic injection is administered in the vicinity of a nerve that serves the region of the body being targeted for anaesthesia.
For example, if more extensive surgery is to be performed to fix a forearm fracture, the anaesthetist may choose to perform a regional anaesthesia by targeting and numbing the nerves to the arm (this is also known as a nerve block).
In order to do this, he will need to be familiar with the location of the nerves so that he can effectively and safely block the nerves without causing them any damage. Most anaesthetists trained to do such blocks these days will employ the use of an ultrasound machine in order to locate the nerves and administer the anaesthetic injection close to but certainly not in the nerve.
As administering regional anaesthesia can be painful for the patient, the anaesthetist usually will sedate the patient and give pain-killer medications first.
You might be wondering why not just do a full general anaesthesia instead of a more technically demanding regional anaesthetic? Some patients may have a whole host of medical conditions that increase their risk of general anaesthesia.
Hence for such patients, it may be safer for the patient to have regional anaesthesia maybe together with a light sedation to make them more comfortable.
Another good reason is longer pain relief. An anaesthetist can control the duration of the block. For procedures in which more post-surgical pain may be anticipated, a longer block will make patients much more comfortable after the surgery while the operated area takes some time to get over the surgical trauma.
I find that usually pain after most orthopaedic surgeries start to recede after a day or so. Hence having a block that may last up to 36 hours can be most helpful since nobody wants to be in severe pain after a surgery.
Lastly, it may be important to commence physiotherapy and joint movements as early as possible, after some surgeries. If there is post-surgical pain in that joint, any attempts to move the joint will be very painful, if not downright impossible. With a long block in place, patients will have little to no pain even with movement of the joint.
General Anaesthesia (GA)
General anaesthesia involves administering drugs that will render the patient completely unconscious. The patient will be unable to feel any pain or be aware of anything around him/her at all.
How is GA administered?
The anaesthetist first ensures that all the monitoring devices are in place. These include a heart monitor (ECG), a blood oxygen monitor (pulse oximeter) and often a brain wave monitor. All these monitors are simply placed on the skin surface and are not invasive.
He then inserts a small needle in a vein on the back of the hand or forearm of the patient. Anaesthetic drugs are then given and the patient will drift off to sleep in a few seconds. Most will not be able to even count to 10!
Once the patient is asleep, the priority is to ensure the patient’s airway remains open so that he/she can breathe. This is needed because the potency of the anaesthetic drugs may cause a patient to stop breathing temporarily and the anaesthetist may have to manually ensure air continues to get into the patient’s lungs using either a bag or a machine.
Usually either a silicon airway device is inserted into the mouth and this device seals off the patient’s oesophagus while it keeps the windpipe opening patent (this is known as a laryngeal mask), or a tube inserted into the windpipe held in place by a balloon ring is used.
Once the airway is secured, the various monitors will be hooked up to a machine. The machine will monitor everything from the heart rate, heart wave, blood oxygen level, breathing, brain activity etc.
The monitoring occurs continuously so that if any problem at all occurs, the anaesthetist will be able to react immediately with no lag time.
Will I wake up halfway during the surgery?
No, you will not. The sensationalized cases you might have read about or watched in movies are extremely rare. All the anaesthetists with whom I work use a brain activity monitor which gives a numerical reading constantly.
If brain waves start to increase, an alarm goes off alerting the anaesthetist and he will immediately deepen the anaesthesia. There is a lot of buffer built in so you do not have to worry about waking up before the anaesthetic is deepened.
How long will I take to wake up?
Once the surgery ends, the anaesthetist will stop the anaesthetic drugs and you will wake up in about 10 minutes. You will probably not remember much after waking up though. The anaesthetic drugs make you very forgetful for up to an hour.
Many times, I have spoken to patients and answered their questions 15 minutes after the surgery but the patient had absolutely no recollection the next day!
Will I feel miserable after waking up?
Most patients feel fine when they wake up. Many have told me that was the best sleep they have ever had! Many will feel drowsy and sleepy throughout most of the day but they can simply sleep it off.
Some patients who are more sensitive to the drugs may suffer nausea and vomiting. But that is easily controlled with medications and will pass after a few hours.
Is general anaesthesia dangerous?
No. It is actually very safe. But risks do increase in patients who are in poor health. Certainly, anaesthetic risks are higher in a patient who has had a previous heart attack and stroke, compared to a young healthy patient with no medical issues.
The anaesthetist will definitely assess you prior to administering the anaesthesia to ensure you are safe.
Sedation is often used to make patients woozy and relaxed during a procedure. It helps to calm them and eliminate the anxiety, fear and stress they might otherwise experience. The role of sedation, however, is more than just psychological relaxation though. Sedation is very useful in procedures involving reducing a dislocated joint.
The shoulder and elbow are 2 classic examples. In the case of a dislocated shoulder, trying to reduce it without sedation may not only be difficult but could even be dangerous. Forceful traction may be required to overcome the strong muscle spasm around the shoulder in order to put the joint back in place.
This may result in inadvertent fractures due to the increased amount of force required to achieve the reduction. With sedation and pain relief, the shoulder can usually be reduced gently with little force, making it a much safer procedure.
Finally, sedation is often used to help patient overcome anxiety. Some patients may have claustrophobia which may make it impossible for them to tolerate having an MRI scan done. With sedation, the patient can be not only sufficiently relaxed but even asleep during the MRI which is not only beneficial for the patient’s mental well-being, but also literally improves the scan imaging because the patient will be less inclined to fidget, thus reducing blurring of images due to movement.