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Anesthesia |
Anesthesia, (literally: without sensations) is drug-induced mental state created to make any kind of painful or distressful therapeutic or diagnostic procedure possible.
General anesthesia today, including intravenous induction, iv. analgesia and inhaled or intravenous maintenance, is truly ‘state of the art’. Going to sleep for the duration of the surgical procedure unaware and experiencing no sensation, is today accepted as the norm for both patients and healthcare providers.
During anesthesia, highly-trained and dedicated anesthesia personnel monitor the drug delivery, basic vital signs and the surgical intervention throughout the procedure.
The combination of safe and efficacious drugs, good monitoring equipment and drug delivery devices and, not least, highly-trained and dedicated personnel, has made general anesthesia overwhelmingly safe. |
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One may argue whether it was the first use of ether in 1846 or the first use of nitrous oxide in 1844 that defines the birth of modern anesthesia. In either case, general anesthesia today is a basic and natural part of the general management of surgical patients. Although physiologically anesthesia is very far from being the same as sleep, it is still often referred to as narcosis or a period of sleep.
A number of drugs are available today, primarily registered and indicated, for anesthesia. The barbiturates introduced during the first half of the last century represent an important step in the evolution of general anesthesia. By injecting these agents intravenously a rapid induction of anesthesia was achieved. Some years later the first halogenated, inhaled anesthetic was introduced, halothane. This was another major milestone in the history of modern anesthesia. A non-explosive highly potent vapor with a most acceptable clinical profile became available. In concentrations of about 1 vol.% a majority of patients experienced an acceptable level of anesthesia for general surgery.
Halothane was followed by a series of other halogenated inhaled anesthetics; penthrane, enflurane, isoflurane and, during the last decade, desflurane and sevoflurane. All these vapors are highly efficacious and safe. The potency for these drugs varies, however, to some extent. In order to describe their clinical potency the MAC-concept was created by Professor Ed Eger II in the mid-sixties. MAC, minimal alveolar concentration is more or less exactly the same as the ED50 for intravenous drugs. It describes the gas concentration needed to create anesthesia, with no movement or other signs of insufficient anesthesia, in 50 % of a population.
During the second half of the last century a number of potent and safe analgesics were also introduced. One of the first was fentanyl, a highly potent opioid to be used intravenously during anesthesia. A family of other semi-synthetic and synthetic opioids for intra- as well as postoperative use also followed.
Along with these anesthetic drugs came an increasing knowledge of basic physiology and the pathophysiology associated with trauma/stress. These all mark important milestones in the fast evolution of modern, safe and effective anesthesia. |
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