Anaesthesia

The term anaesthesia comes from the Greek words ‘an’ and ‘aisthesis’, meaning ‘without feeling’. This lack of feeling (especially pain) can be referred to as local, applying to a certain specific area of the body, or general, applying to the whole body with the patient put to sleep. For general anaesthesia, specialists use three main groups of anaesthetic agents: hypnotics, analgesics and muscle relaxants.

Hypnotic agents, also known as induction agents put the patient into a deep sleep. Years ago, large doses of hypnotics were necessary to achieve the deep level of sleep and muscle relaxation required for painless surgery. Today smaller doses are used as other more efficient drugs have been developed to relieve pain and relax the muscles. This helps patients to recover more quickly after surgery.

Analgesics are used to reduce pain during and after surgery, and are necessary both for the patient’s comfort and safety.

Many patients also receive muscle relaxants (medicines which relax the muscles to the point where the muscles can no longer move, known as neuromuscular blockade). This is necessary when patients need to be kept completely still during major or delicate surgery, or to facilitate surgery in the abdomen. Patients given a muscle relaxant cannot breathe alone and require artificial assistance to help them breath usually via a breathing machine known as a ventilator. This muscle block may be allowed to “wear off” or medicine that reverse muscle block may be given.