How Anesthesia Works?
Anesthesia is one of the luxuries our ancestors couldn’t get in the earlier centuries, when their doctors had to open up their body and perform complex surgeries. If it weren’t for these body-numbing elixirs, our generation patients would pretty much be experiencing the movie ‘Saw’ for real.
Anesthesia can be local or general depending on the process one is subjected to and the corresponding medical history. General anesthetics causes complete knockouts where as local anesthetics acts as a numbing agent regionally. Centuries back, doctors used opium to alleviate the pain temporarily. Alcohol was also preferred, but these drugs did not completely obstruct the flow of pain. The Japanese were the first to perform surgery back in 1804, using the mixture of potent herbs as anesthetic. Later in 1846, the first surgery was performed under general anesthesia at Massachusetts General Hospital, which was nothing more than a flask of sulfuric ether, which was held close to the patient’s face until they reached the state of unconsciousness.
General anesthetics are intended to induce the inability to feel pain, loss of memory, inhibition any movement of motor reflexes and unconsciousness obviously.
The general anesthetics affect the spinal cord, which causes immobility and the reticular activating system (RAS) that makes one unconscious. When the general anesthetic is induced into a patient, they start to feel its effects slowly. This leads to muscle twitching and causes irregular heart rates. By this time, the patients enter into a gentle slumber, thus unconscious. And because of this, the muscles relax and the heart rate and breathing comes to normal. This represents that the patient is completely anesthetized and is good to go for operating.
These are also termed as Volatile or Inhalational anesthetics as the anesthetic agents are administered by breathing which are the mixtures of nitrous oxide (The one called as the laughing gas… :D ) and other derivatives of ether such as Isoflurane, Sevoflurane and desflurane.
The local anesthetics block the transmission of the pain response to the neuropathic pain processing centers in CNS (Central Nervous System) by targeting a specific ion channel that produces the neurotransmitter. This is achieved when the anesthetics bind to a specific sodium channel present in the cell membranes of the nerve cells. It inhibits the function of the sodium channel. Due to the inhibited sodium channel, the action potential is blocked and so, the pain conduction is stopped too.
Of course, these occur in the area where the local anesthetic is injected. When local anesthetics like Novocain is administered, in case of root canal surgery it numbs the nerves in your mouth.
The drug can be given as a shot, a spray, or an ointment. These last for a short period and is often used for smaller regions in a body such as mouth or a hand or a foot.
These are at times misunderstood with local anesthesia. This is injected near a cluster of nerves blocking transmission to pain centers. But unlike local anesthesia, the scope of regional anesthesia is extended to an entire arm or leg when the regional anesthetics are injected. In case of epidurals, lidocaine, fentanyl or clonidine are given as pain relief resulting in a loss of sensation from the waist down resulting in a relatively painless childbirth.
Despite the fact that the anesthetics play a vital role in any surgical operations or more, the fact is that the scientists do not know the exact molecular mechanisms that cause the effect it currently produces. The present best theory suggests that the general anesthetic agents dissolve the fat present in brain cells thereby changing their activity. However, the times of brutal yet necessary surgeries are gone as the anesthetics continue to evolve into lifesaving necessity—enabling doctors to perform safer surgeries.
This post was first published on November 25, 2014.