How does Anesthesia Work?

After surgery, you may recall counting backward from ten. But before you could reach five, you would wake up and realize the surgery was already finished.

You may think you were asleep, but you weren't. During surgery, you were under anesthesia, which is a complex process. You were unconscious and unable to move or form memories. The goal is to ensure you don't feel any pain. Without blocking all these processes simultaneously, surgeries would be too traumatic to perform.

Anesthesia is a powerful tool used by medical professionals to provide pain relief during surgical procedures. It has enabled surgeons to perform complex operations safely and quickly without causing unnecessary suffering to the patient. Yet despite its importance, relatively little is known about how anesthesia affects the human body. Anesthesia has a number of effects on the human body, It numbs the area of the body being operated on, helping to reduce the risk of infection and other complications that could arise from surgery. 

Ancient medical texts mention anesthetics with opium poppy, mandrake fruit, and alcohol. Nowadays, anesthesiologists use a combination of regional, inhalational, and intravenous agents for surgeries. Regional anesthesia blocks pain signals from a specific body part to the brain. Pain and other messages travel as electrical impulses through the nervous system. Regional anesthetics create an electrical barricade by binding to proteins in neurons' cell membranes, preventing the entry of positively charged particles.

Cocaine is one compound that can do this. Its painkilling effects were discovered accidentally when an ophthalmology intern tasted it. Cocaine is still used occasionally as an anesthetic. Regional anesthetics, which have a similar chemical structure, also work in a similar way. However, for major surgeries where unconsciousness is needed, anesthetics that act on the entire nervous system, including the brain, are preferred. Inhalational anesthetics fulfill this requirement.

Diethyl ether was the first commonly used anesthesia in Western medicine. It was initially known as a recreational drug, but doctors soon discovered that it caused patients to overlook their injuries. In the 1840s, ether was used to sedate patients during dental procedures and surgeries. Nitrous oxide gained popularity in the following decades and is still used today, although ether derivatives like sevoflurane are more commonly used. Inhalational anesthesia is typically combined with intravenous anesthesia, which was developed in the 1870s.

Common intravenous agents include sedatives like propofol, which induce unconsciousness, and opioids like fentanyl, which reduce pain. These general anesthetics affect electrical signals in the nervous system. The brain's electrical signals are normally chaotic as different parts communicate with each other, keeping you awake and aware. However, when someone is anesthetized, these signals become calmer and more organized, indicating a lack of communication between different brain regions. There is still much to learn about the exact mechanism behind this. Some common anesthetics bind to the GABA-A receptor in the brain's neurons.

They hold the gateway open, allowing negatively charged particles to enter the cell. The negative charge builds up and creates a blockage, preventing the neuron from sending electrical signals. The nervous system has many of these gated channels, controlling movement, memory, and consciousness. Most anesthetics likely affect more than one channel and not just the nervous system. Anesthetics can also impact the heart, lungs, and other vital organs. Similar to early anesthetics, which contained poisonous substances like hemlock and aconite, modern drugs can have severe side effects.

An anesthesiologist mixes drugs, monitors vital signs, and adjusts the mixture as needed. Anesthesia is complicated, but it allowed for the development of new surgical techniques. Surgeons can safely perform C-sections, reopen blocked arteries, and replace damaged organs. New anesthesia techniques are developed each year to ensure more patients survive the surgery.