Thursday, December 24, 2015

What is anesthesiology?


The History of Anesthesiology

In a modern hospital, the surgical operating room normally is a very quiet place. The anesthesiologist, surgeon, assisting doctors, and nurses perform their duties with little conversation while the patient sleeps. Family members sit quietly in a nearby waiting room until the operation is over. Before the advent of anesthesiology in the 1840s, however, surgery was a thoroughly gruesome experience. Patients might drink some whiskey to numb their senses, and several strong men were recruited to hold them down. Surgeons cut the flesh with a sharp knife and sawed quickly through the bone while patients screamed in agony. The operating room in the hospital was located as far as possible from other patients awaiting surgery so that they would not hear the cries so plainly.



Many kinds of operations were performed before anesthetics were discovered. Among these were the removal of tumors, the opening of abscesses, amputations, the treatment of head wounds, the removal of kidney stones, and cesarean sections and other surgeries during childbirth. The frightful ordeal of “going under the knife,” however, often caused patients to delay surgery until it was almost too late. Also, for the surgeon it was nerve-racking to work without anesthetics, trying to operate while the patient screamed and struggled.


Sir Humphry Davy (1778–1829) was a distinguished British chemist who studied the intoxicating effect of a gas called nitrous oxide. While suffering from the pain of an erupting wisdom tooth, he sought relief by inhaling some of the gas. In 1800, he published a paper suggesting the use of nitrous oxide to relieve pain during surgery. There was no follow-up on his idea, however, and it was forgotten until after anesthesia had been discovered independently in the United States.


The next episode in the history of anesthesiology was the work of Crawford W. Long (1815–78), a small-town doctor in Georgia. In the early nineteenth century, “ether frolics” had become popular, in which young people at a party would inhale ether vapor to give them a high such as from drinking alcohol. One young man was to have surgery on his neck for a tumor. Long was the town druggist as well as the doctor, so he knew that this fellow had purchased ether and enjoyed its effects. Long suggested that he inhale some ether to ready himself for surgery. On March 30, 1842, the tumor was removed with little pain for the patient. It was the first successful surgery under anesthesia.


Unfortunately, Long did not recognize the great significance of what he had done. He did not report the etherization experiment to his colleagues, and it remained relatively unknown. He used ether a few more times in his own surgical practice, one time while amputating the toe of a young slave. Long finally wrote an article for a medical journal in 1849 telling about his pioneering work, three years after anesthesia had been publicly demonstrated and widely adopted by others.


The story of anesthesiology then moved to Hartford, Connecticut, where a young dentist named Horace Wells (1815–48) played a major role. P. T. Barnum, of show business and circus fame, was advertising an entertaining “GRAND EXHIBITION of the effects produced by inhaling NITROUS OXIDE or LAUGHING GAS!” Wells decided to attend. He was one of the volunteers from the audience and “made a spectacle of himself,” according to his wife.


Another volunteer who had inhaled the gas began to shout and stagger around; finally he ran into a bench, banging his shins against it. The audience laughed, but the observant Wells noticed that the man showed no pain, even though his leg was bleeding. This demonstration gave Wells a sudden insight that a person might have a tooth pulled or even a leg amputated and feel no pain while under the influence of the gas.


Wells became so excited by the idea of eliminating pain that he arranged to have some nitrous oxide gas brought to his office on the next day. Then he had a long talk with a young dentist colleague, John Riggs, about the potential risks of trying it out on a patient. Finally, Wells decided to make himself the first test case, if Riggs would be willing to extract one of his wisdom teeth.


On the morning of December 11, 1844, a bag of nitrous oxide gas was delivered by the man who had been in charge of the previous evening’s exhibition. Wells sat in the dental chair and breathed deeply from the gas bag until he seemed to be asleep. Riggs went to work with his long-handled forceps to loosen and finally pull out the tooth, with no outcry from the patient. After a short time, Wells regained consciousness, spit out some blood, and said that he had felt “no more pain than the prick of a pin.”


After this success, Wells immediately set to work on further experiments. He acquired the apparatus and chemicals to make his own nitrous oxide. Within the next month, he used the gas on more than a dozen patients. Other dentists in Hartford heard about the procedure and started using it. By the middle of January 1845, Wells was confident enough to propose a demonstration to a wider audience.


Wells was able to arrange for a demonstration at Massachusetts General Hospital in Boston. While the audience watched, he anesthetized a volunteer patient with gas and extracted his tooth. Unfortunately, the patient groaned at that moment, causing laughter and scornful comments from the onlookers. Wells was viewed as another quack making grandiose claims without evidence. His demonstration had failed, and he returned to Hartford in discouragement. He later commented that he had probably removed the gas bag too soon, before the patient was fully asleep.


It was another dentist, William T. G. Morton (1819–68), who finally provided a convincing demonstration of anesthesia. Morton tried to obtain some nitrous oxide from a druggist, who did not have any on hand and suggested that ether fumes could be substituted. Morton then used ether on several dental patients, with excellent results. In 1846, he obtained permission for a demonstration at the same hospital where Wells had failed two years earlier. Famous Boston surgeon John Warren and a skeptical audience watched as Morton instructed a patient to breathe the ether. When the patient was fully asleep, Warren removed a tumor from his neck. To everyone’s amazement, there was no outcry of pain during the surgery. After the patient awoke, he said that he felt only a slight scratch on his neck. Warren’s words have been recorded for posterity: “Gentlemen, this is no humbug!” Another doctor said, “What we have seen here today will go around the world.”


The result of this dramatic demonstration of October 16, 1846, spread quickly to other hospitals in the United States and Europe. Several hundred surgeries were performed under anesthesia in the next year. In England, John Snow (1813–58) experimented with a different anesthetic, chloroform, and began to use it for women in childbirth. In 1853, Queen Victoria took chloroform from Snow during the delivery of her eighth child. Acceptance of anesthesia, and the science of anesthesiology, by the medical profession and the general public grew rapidly.




Science and Profession

Nitrous oxide, ether, and chloroform were the big three anesthetics for general surgery and dentistry for nearly a hundred years after their discovery. All three were administered by inhalation, but there were differences in safety, reliability, and side effects for the patient.


Wells, the dentist who had unsuccessfully tried to demonstrate nitrous oxide anesthesia in 1844, came to a tragic end in 1848 because of chloroform. He was testing the gas on himself to find out what an appropriate dosage should be. Unfortunately, he became addicted to the feeling of intoxication that it gave him. While under the influence of a chloroform binge, he accosted a woman on the street and was arrested. He committed suicide while in prison.


Nitrous oxide is a nearly odorless gas that must be mixed with oxygen to prevent asphyxiation. Storing the gases in large, leakproof bags was awkward. By comparison, ether and chloroform were much more convenient to use because they are liquids that can be stored in small bottles. The liquid was dripped onto a cloth and held over the patient’s nose. Ether is hazardous, however, because it is flammable, and it also has a disagreeable odor. Chloroform is not flammable but is more difficult to administer because of the danger of heart stoppage.


Anesthesiology was practiced primarily by dentists, eye doctors, chemists, and all types of surgeons for many years. The Mayo Clinic in Rochester, Minnesota, was one of the first hospitals to recognize the need for specialists to administer anesthesia. In 1904, a nurse from Mayo named Alice Magaw gave a talk on what she had learned from eleven thousand procedures performed under anesthesia. Her concluding comment was that “ether kills slowly, giving plenty of warning, but with chloroform there is not even time to say good-by.” Ether takes more time to induce anesthesia, but Magaw asserted that the patient’s life was in less danger than from chloroform.


A Scottish physician, James Y. Simpson, was one of the early advocates of using chloroform for partial anesthesia during childbirth. The woman could breathe the vapor intermittently for several hours as needed without the disagreeable odor of ether. She would remain conscious, but the anesthetic apparently produced a kind of amnesia so that the pain was not fully remembered. Simpson received much public acclaim for his help to women in labor, including a title of nobility. (One humorist of the day suggested a coat-of-arms for Sir Simpson, showing a newborn baby with the inscription, “Does your mother know you’re out?”)


In the 1920s, several new anesthetic gases were created by chemists working closely with medical doctors. The advantages and drawbacks of each new synthesized compound were tested first on animals, then on human volunteers, and finally during surgery. One of the most successful ones was cyclopropane: it was quick acting and nontoxic and could be mixed with oxygen for prolonged operations. Like other organic gases, however, it was explosive under certain conditions and had to be used with appropriate caution.


A major development in 1928 was the invention of the endotracheal tube by Arthur Guedel. A rubber tube was inserted into the mouth and down the trachea (windpipe) to carry the anesthetic gas and oxygen mixture directly to the lungs. The space around the rubber tube had to be sealed in some way in order to prevent blood or other fluid from going down the windpipe. Guedel’s ingenious idea was to surround the tube with a small balloon. When inflated, it effectively closed off the gap between the tube and the trachea wall. He gave a memorable demonstration at a medical meeting using an anesthetized dog with a breathing tube in its throat. After inflating the seal, the dog was submerged under water for several hours and then revived, showing that no water had entered its lungs.


The first local anesthetic was discovered in 1884 by Carl Koller, a young eye doctor in Vienna. He was a colleague of the famous psychoanalyst
Sigmund Freud, and together they had investigated the psychic effects of cocaine. Koller noticed that his tongue became numb from the drug. He had the sudden insight that a drop of cocaine solution might be usable as an anesthetic for eye surgery. He tried it on a frog’s eye, with much success. Following the tradition of other medical pioneers, he then tried it on himself. The cocaine made his eye numb. Koller published a short article, and the news spread quickly. Within three months, other doctors reported successful local anesthesia, using cocaine for dentistry, obstetrics, and many kinds of general surgery.


Chemists investigated the molecular structure of cocaine and were able to develop synthetic substitutes such as novocaine, which was faster and less toxic. Another improvement was to inject local anesthetic under the skin with a hypodermic needle. With this technique, it was possible to block off pain from a whole region of the body by deadening the nerve fibers. A spinal or epidural block is often used to relieve the pain of childbirth or for various abdominal surgeries.


There is another class of anesthetic drugs called barbiturates, which were originally developed for sleeping pills. Any medication that induces sleep automatically becomes a candidate for use as an anesthetic. The most successful barbiturate anesthetic has been sodium pentothal. It is normally administered by injection into a vein in the arm and puts the patient to sleep in a matter of seconds. When the surgery is over, the needle is withdrawn and consciousness returns, with few aftereffects for most people. The anesthesiologist may use sodium pentothal in combination with an inhaled anesthetic if the surgery is expected to be lengthy.




Diagnostic and Treatment Techniques

There are four categories of anesthesia and the type used depends on the procedure. Local anesthesia, such as novocaine, is used to numb a small area of the body and allows the patient to remain awake and alert during a procedure or minor surgery. With conscious or intravenous sedation, the patient is given a mild sedative and pain medication. The patient is relaxed, pain-free, and awake during the procedure, but may not remember it afterward.


Regional anesthesia is applied near nerve clusters to prevent pain in a larger area of the body, such as a limb. Examples of regional anesthesia include epidural anesthesia, spinal anesthesia, and caudal anesthesia. Epidural anesthesia, often administered during childbirth, is injected near the sac of fluid around the spinal cord. Pain is numbed after ten to twenty minutes. A catheter is inserted to allow pain control during the procedure as needed. Spinal anesthesia usually involves a single shot of medicine into the spinal cord fluid, and allows immediate pain relief. Caudal anesthesia is administered via an injection in the tailbone.


General anesthesia affects the entire body and is used for major surgeries. It renders the patient unconscious, immobile, and numb during the procedure. Patients receiving general anesthesia have no memory of the procedure afterward. General anesthesia is either inhaled as a gas or vapor or administered intravenously.


Suppose that a man is scheduled to have some kind of abdominal surgery, such as the repair of a hernia or hemorrhoids or the removal of the appendix, an intestinal blockage, or a cancerous growth. The anesthesiologist would select a sequence of anesthetics that depends primarily on the expected length of the operation and the physical condition of the patient.


About an hour before surgery , the patient receives a shot of medication to produce relaxation and drowsiness. After he is wheeled into the operating room, the anesthesiologist inserts a needle into a vein in the patient’s arm and injects a barbiturate such as sodium pentothal. This drug puts him to sleep very quickly because it is rapidly distributed through the body, but it is not suitable for maintaining anesthesia.


A muscle-paralyzing agent such is now injected, which allows the anesthesiologist to insert an endotracheal tube into the lungs. The tube delivers the general anesthesia, along with oxygen, as a vapor or gas. The seal around the tube must be inflated to prevent fluids from entering the windpipe. The patient is now in a state of surgical anesthesia.


For a difficult surgery, an additional medication may be injected to paralyze the abdominal muscles completely. In this case, the breathing muscles would also become paralyzed, which means that a mechanical respirator would be needed to inflate and deflate the lungs.


The anesthesiologist monitors the patient’s condition with various instruments, such as a stethoscope, blood pressure and temperature sensors, and an electrocardiograph (EKG or ECG) with a continuous display. A catheter may be inserted into a vein to inject drugs or to give a blood transfusion if necessary. When the surgery is completed, the anesthesiologist is responsible for overseeing procedures undertaken in the recovery room as the patient slowly regains consciousness.




Perspective and Prospects

Many modern surgeries would be impossible without anesthesia. Kidney or other organ transplants, skin grafts for a burn victim, or microsurgery for a severed finger all require that the patient remain still for an extended period of time. Anesthesiologists choose from a variety of local and general anesthetics as the individual situations require.


In the emergency room of a hospital, patients are brought in with injuries from industrial, farm, or car accidents. Gunshot and knife wounds, the ingestion of toxic chemicals, or sports injuries often require immediate action to reduce pain and preserve life. Soldiers who are wounded or burned in battle can be given relief from pain because of the available anesthetics. Beyond operating room patients, another category of people who benefit greatly from anesthesia are those who suffer from chronic pain, including that from arthritis, back pain, asthma, brain damage, cancer, and other serious ailments.


A more recent innovation is electric anesthesia, which employs an electric current. It is widely used for animals and is gaining acceptance for humans. A marine biologist can submerge two electrodes into water and cause nearby fish to become rigid and unable to swim. After being netted and tagged, the fish are released with no harmful aftereffects. Veterinarians can use a commercially available device with two electrodes that attach to the nose and tail of a farm animal. Pulses of electricity are applied, causing the animal to remain immobilized until surgery is completed.


The most common human application of electric anesthesia is in dentistry. The metal drill itself can act as an electrode, sending pulses of electric current into the nerve to deaden the sensation of pain. The discomfort of novocaine injections and the possible aftereffects of the drug are avoided. Another application is to provide relief for people with chronic back pain, using a small, battery-powered unit attached to the person’s waist.


Experiments have been done using electricity for total anesthesia, both on animals and on human volunteers. Electrodes are strapped to the front and back of the head. When an appropriate voltage is applied, the subject falls into deep sleep in a short time. When the electricity is turned off, consciousness is regained almost immediately. In one experiment, two dogs underwent “electrosleep” for thirty days with no apparent ill effects. Long-term studies with more subjects are needed to establish this new technology.




Bibliography


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Gross, Amy, and Dee Ito. “All About Anesthesia: What Are the Choices When It Comes to Childbirth and Surgery?” Parents Magazine 65 (April, 1990): 213–21.



Liou, Louis S. "Spinal and Epidural Anesthesia." MedlinePlus. US Natl. Lib. of Medicine, Natl. Inst. of Health., 7 May 2013. Web. 17 Feb. 2015.



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Palmer, C. M., M. Paech, and R. D’Angelo, eds. Handbook of Obstetric Anesthesia. 6th ed. Oxford, England: Bios Scientific, 2002.



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