All About Anaesthesia…

The literal translation of anaesthesia is ‘loss of sensation‘.


Anaesthetics are the medications used that cause anaesthesia which are used during tests and surgical procedures. Anaesthetics block the signals that pass along your nerves to your brain; after the anaesthetic has worn off, the nerve signals will be able to reach your brain and your feelings will return.

Types of Anaesthesia

There are a number of different types of anaesthetic and only general anaesthetic makes you unconscious.

  • Regional anaesthetic:-¬†used for larger/deeper operations where nerves are more difficult to reach (this is commonly used for Caesarean sections). Only ever conducted in an environment where a team is able to easily provide general anaesthesia if necessary.
  • Epidural anaesthetic:- a type of local anaesthetic usually used to numb the lower half of the body. A needle is used to locate an area of the spine known as the ‘epidural space’ and can numb areas such as the thoracic area (chest), abdomen, pelvic area and legs
  • Spinal anaesthetic:- type of regional anaesthetic that is used to numb the nerves of your spine so that surgery can be performed in this area.
  • Sedation:- sometimes used for minor procedures- a sedative relaxes you physically and mentally.
  • Local anaesthetic:- used to induce the absence of sensation in part of the body ( local insensitivity to pain). Anaesthetics sometimes combine both local and general anaesthesia techniques.
  • General anaesthetic:- a drug that has the ability to induce a reversible loss of consciousness. These are given to a patient in order to facilitate surgery so that they don’t feel any pain

There are a number of theories about how general anaesthetics work, however, the precise mechanisms remain unknown.

Side Effects

Anaesthetics consist of a number of medications that can cause side effects in some people.
These are some of the side effects of general or regional anaesthetics:

  • Nausea or vomiting (1 in 3 people feel sick after an operation)
  • Sore throat
  • Aches and pains
  • Dizziness
  • Blurred vision
  • Headache
  • Itchiness
  • Bruising and soreness

These side effects do not last very long and can be treated with further medication if necessary.


Anaesthesia has become much safer over the years and advances have meant that serious problems are uncommon.
However, there are always potential complications:

  • Permanent nerve damage (cause numbness or paralysis)
  • Anaphylaxis (serious allergic reaction)
  • Death (approx. 5 deaths for every million anaesthetics given in the UK).

History of Anaesthesia

Thankfully, anaesthetics have been developed and so now they are used commonly under safe situations. However, it has not always been like this.
The concept of anaesthesia has been around since they have been performing surgery.

Early anaesthetics such as soporifics (which dull the senses and induce sleep) and narcotics (including opium, mandrake, jimson weed, marijuana, alcohol and belladonna) were all used as substitutes of today’s drugs. Although all of these can provide some pain relief, sedation or amnesia, there were no guarantees.
In mid 1840s, opium and alcohol were the only two substances used regularly as anaesthesia in industrial countries. There were many negative side effects to using these:

  • Patients could easily become addicted
  • The doses needed to provide the amount of pain relief/ sedation could easily result in death.
  • Surgery usually resulted in the tortured screams of patients because the anaesthesia wasn’t good enough.

1845– Dr Horace Wells was the first person to use nitrous oxide to pull teeth out

Dr Horace Wells

Dr Horace Wells

1846– Dr William Morton removed a tumour for the jaw of a patient. He used a sponge soaked in ether and the patient claimed he had no memory of the surgery or any pain.

Dr William Morton

Dr William Morton

Chloroform was first used as an anaesthetic in the mid 1840s by Dr James Simpson. It is highly toxic and so ether was used instead in the early 1900s.
Using a sponge made it hard to control the dosage and therefore, nitrous oxide is now used as an inhalable gas. Anaesthesiologists administer the drugs via machines that measure the specific amount necessary for each individual patient.

Because the drugs interfere with breathing, patients are often intubated- a plastic/ rubber tube is inserted in the trachea to keep the airway open- and then, during surgery, the patient is kept on a mechanical ventilator.


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