General anaesthesia(scientifically known as narcosis) is the act of putting a patient to sleep, which induces complete unconsciousness. Its function is to prevent the patient’s awareness during surgery by suppressing reflex activity, which causes surgical interventions to be easier, and ultimately allows comfort to the patient. The development of anaesthetics has a unique and fascinating history.
William Morton, a dentist who was residing in Boston, US, was behind this turning point in surgery. He allows his patient Edward Abbot, who had a tumour in his neck, to inhale diethyl ether. When he was asleep, the surgeon John Warren removed the tumour.
However despite such revolutionary surgery, there was a long period of time before general anaesthesia was fully adopted into surgeries. At the time many surgeries were opposed to anaesthetics as believed they were dangerous or possibly a waste of time and ‘quick surgeons’ did not require them. Before the discovery of anaesthetics, surgeons were required to act with haste and create incisions quickly to reduce the duration of pain for the patient. However this all changed after Queen Victoria had anaesthesia during the birth of her eighth child-Prince Leopald. The anaesthetist responsible was called John Snow. John Snow had already written a book beforehand about ether and chloroform and he had designed a mask which can be used to administer chloroform, which was not permitted to be used in the Queen’s pregnancy. Therefore Snow laid a clean handkerchief on top of her nose and used a pipette to release chloroform drop by drop onto the handkerchief. He released chloroform until she indicated that she felt no pain. He gave 15 drops of chloroform on the handkerchief with every contraction. Snow recorded that ‘Her Majesty expressed a great relief from the application’ and ‘the pains being trifling during the uterine contractions, and whilst between the periods of contraction there was complete ease.’ The Queen described it as ‘soothing and delightful beyond measure’. (LAAR, 2019)After this, anaesthesia grew in popularity all over Europe. However despite its continent wide fame, the Lancet, a prominent medical journal, criticised the use of chloroform in Queen Victoria’s pregnancy. (Anesthesia and Queen Victoria, 2022)
The anaesthetic procedure
It is no surprise that we no longer use ether on a handkerchief as an anaesthetic like John Snow did 200 years ago. Some may assume that a narcotic is sufficient for the pain to be completely repressed, however a narcotic does not prevent increased heartbeat. Therefore analgesics are also given to the patient(usually opium derivatives as they tend to be the most powerful kind). A muscle relaxant is also administered to prevent muscles from tensing during the operation. A ventilator is used and a tracheal tube is inserted via the nose, so it can pass through the trachea. The anaesthetist also checks for more factors such as urine production, oxygen content in the blood, carbon dioxide content in the exhaled air(this is done via a blood pressure band and electrodes placed in the chest and finger) and blood sugar level.
Although many years have passed since William Morton’s discovery , the complete mechanism of anaesthesia is still not fully understood. The anaesthetic state consists of components such as unconsciousness, immobility and analgesia.
There are two types of receptors which are responsible for anaesthetic action: transmitters and ion channels. Cells in the brain communicate via neurotransmitters: neurotransmitters which respond to electrical signals are released into synapse. Based on their function, they can be excitatory neurotransmitters or inhibitory neurotransmitters. Excitatory inhibitors such as glutamate cause depolarisation. Depolarisation is when a gated sodium ion channel opens without warning and allows sodium ions from outside of the membrane to enter the cell. Inhibitory transmitters such as glycine causes postsynaptic activity. The type of neurotransmitter with the most significant role in the functional site of anaesthetics is the GABA A receptors. Activation of GABAA receptors leads to hyper-polarisation of the brain, which reduces the excitability of the neurons. GABAA is the major inhibitor receptor in the CNS. GABA receptor has 5 subunits which merge together to form a chlorine channel. Volatile anaesthetic agents have an agonistic effect (a drug that binds to the receptor, producing a similar response to the intended chemical), however ketamine has an antagonistic effect(unintended effect) on GABA receptors. Glycine receptors are another type of receptor which are located in the CNS, specifically in the spinal cord. When the inhalation anaesthetics bind to glycine receptors in the spinal cord, the inflow of chloride ions is increased so that the painful stimulus is reduced. Another example of receptors are serotonin receptors that lead to membrane depolarisation and cause the excitability of neurons. The activation of serotonin receptors by anaesthetic agents lead to an altered state of consciousness. (Son, 2010)
In conclusion, the discovery of anaesthesia was a significant revolution in surgery as surely it must have been very difficult for a surgeon to operate on a screaming patient with tensing muscles. Before anaesthesia, surgery was only done for those living in excruciating pain who are close to death. Surgeons must have been disturbed by the patients in agony and therefore operations were done very rapidly. The only advantage of this was that a quicker operation reduces the level of infection. Due to this prominent discovery in 1846, many more operations have been performed, as a result of the elimination of one of mankind’s greatest fears-pain.
Bibliography
1. Ph.ucla.edu. 2022. Anesthesia and Queen Victoria. [online] Available at: <https://www.ph.ucla.edu/epi/snow/victoria.html> [Accessed 24 March 2022].
2. Son, Y., 2010. Molecular mechanisms of general anesthesia. Korean Journal of Anesthesiology, 59(1), p.3.
3. Van de Laar, A., 2019. Under the Knife. pp.133-137.
Youth Medical Journal 