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Heitmiller, Eugenie. "How Anesthesia Works." 01 April 2000. HowStuffWorks.com. <http://health.howstuffworks.com/anesthesia.htm> 13 May 2008.
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Inhaled Anesthetics
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Inhaled Anesthetics
Many adults may remember having ether for their anesthetic when they were young. Ether is an inflammable anesthetic that is no longer used in the United States. Today, the commonly used inhaled anesthetics are nitrous oxide (also known as laughing gas), sevoflurane, desflurane, isoflurane and halothane.Why do we have so many different kinds of gases? Because each gas has its own special properties. For example, sevoflurane and halothane are easy to inhale while desflurane is very irritating to inhale and has a shorter duration of action. If you need to breathe yourself to sleep, halothane or sevoflurane would be easiest to inhale. If a very short-acting anesthetic is needed, the anesthesiologist can switch to desflurane after you fall asleep. Nitrous oxide is easy to inhale, but when used alone is not potent enough to be a complete general anesthetic. However, it can be used alone for sedation, or combined with one of the other inhaled anesthetics or injected liquid anesthetics for general anesthesia.
These gases have different effects on other organs as well. For example, halothane may cause the heart rate to slow down and the blood pressure to decrease while desflurane may cause the heart rate to speed up and the blood pressure to increase. How do these inhaled anesthetics reach the brain? When an anesthetic gas is inhaled into the lungs, the blood that travels through the lungs carries the anesthetic gas to central nervous system cells. The rate at which the bloodstream takes up the anesthetic is dependent on many factors including the concentration of the inspired gas, the rate of flow of the gas from the anesthesia machine, the solubility of the gas in blood, the rate and depth of breathing, and the amount of blood the heart pumps each minute in the person breathing the gas.
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.
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Please copy/paste the following text to properly cite this How Stuff Works article:
Heitmiller, Eugenie. "How Anesthesia Works." 01 April 2000. HowStuffWorks.com. <http://health.howstuffworks.com/anesthesia.htm> 13 May 2008.
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