- Pages: 4
- Word count: 879
- Category: Patient
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Anesthetics are used to block pain or other sensations from a patient as they undergo a surgery. This helps the patient go through procedures with little or no distress as they would feel otherwise. In this paper I will discuss the types of anesthesia, how each works, and give a little background on anesthetics.
There are four broad categories of anesthesia: general anesthesia, regional anesthesia, local anesthesia, and sedation. General anesthesia is issued for the reversible loss of consciousness and effects the brain cells. Regional anesthesia effects a large bundle of nerves on a particular area of the body, which results in losing sensation to that area without affecting your level of consciousness. Local anesthesia is similar to regional anesthesia in that it is used for the reversible loss of sensation in part of the body. Sedation can be given in many ways. A common example of an anesthetic gas used for sedation is nitrous oxide or “laughing gas”.
Anesthetics have been in use since prehistory. Back then, however, they used only simple herbs such as opium and hemp. These were either burned or their smoke was inhaled. In Asia, it was also popular to administer anesthetics by way of acupuncture.
The modern use of anesthesia began when the anesthetic qualities of nitrous oxide were discovered by the British chemist Sir Humphry Davy during the 1800’s. This gas was used in 1844 for painless tooth extraction by American dentist Horace Wells. In 1842 in Georgia, Dr. Crawford Williamson Long was the first to use anesthesia during an operation. He used ether to aid his wife during childbirth. Five years later, in 1847, Sir James Simpson discovered the anesthetic use of chloroform.
General anesthetics produce an unconscious state in which the person is: unaware of what is happening, pain-free, immobile, and free from any memory of the period of time during which he or she is anesthetized. Scientists are not completely sure how general anesthetics work at a cellular level, but it is speculated that general anesthetics affect the spinal cord, which results in immobility. It has an effect on the brain-stem reticular activating system, which results in a patient’s unconsciousness. It also effects the cerebral cortex, which is seen as changes in electrical activity on an electroencephalogram. A common exapmle of general anesthesia is Nitrous Oxide.
Unlike general anesthesia, regional anesthesia does not make the person unconscious, it simply isolates one region of the body. It does so by blocking a set of nerves that are responsible for the sensation of that area, whether it is the arm, leg, etc. One example of this is spinal anesthesia, which is often used on women during childbirth. Spinal anesthesia can be used for surgery on the legs or lower abdomen (below the bellybutton). Epidural anesthesia is similar to spinal anesthesia in that a patient loses sensation in the legs and lower abdomen, but the anesthetic is injected into a space outside the spinal canal called the epidural space.
A local anesthetic numbs the area to which it is applied. When damage is done to tissues in the body, nerve cells are stimulated to send the message of pain to our brains. These messages are carried by small electrical currents through adjacent nerve cells. The currents are carried by ions. In order for these currents to flow, the nerve cells must take up ions, such as sodium ions. Local anesthetics work by blocking the channels the sodium ions use to get into the cell. This cuts off any current and therefore any message of pain.
The effect of a local anesthetic wears off as the anesthetic diffuses throughout your body. One of the first local anesthetics used was cocaine. However, because of its addictive nature, scientists looked for alternative anesthetics. Many of the local anesthetics used today, such as Novocain, are chemically similar to cocaine but not addictive.
Sedation is the use of medications to make a patient drowsy. This is used to make a patient more comfortable. It does not result in complete unconsciousness, but can result in amnesia and the patient may “fall asleep” for a period of time. Liquid sedating drugs are usually given by injection, but some can also be given by mouth. Ketamine and Versed are examples of sedating drugs that can be given by injection or by mouth.
An important property of anesthetics is reversibility. When the surgery is over, the anesthesiologist wants to shut off the anesthetic and have the patient wake up from the anesthetic-induced sleep. Once the anesthetic gas is turned off, the blood stream brings the gas back to the lungs where it is eliminated. The more soluble the gas is in blood, the longer it takes to eliminate. Nitrous oxide and desflurane are the shortest-acting anesthetic gases because they are the least soluble in blood.
Each medication has its own effects, side effects, duration of action, etc. Often, multiple types of medication are combined to achieve the desired results in a given situation. The amount of anesthesia that a patient needs is determined by multiple factors and the individual patient’s needs. A knowledge of the potency of each medication helps determine how much of each drug to give to the patient.