Anesthesia is the controllable and reversible loss of consciousness induced by chemical intoxication of the central nervous system. The goal of anesthetic administration is to prevent the perception of painful stimuli without undue depression of physiological functions.
Characteristic features of the anesthetic state include lowered sensitivity to outside stimuli (including pain), relaxation, and diminished motor response.
In general, the safest anesthetics are inhalants if used with the proper delivery and scavenging systems. The most commonly used, currently available inhalant anesthetics are isoflurane and sevoflurane. Sevoflurane and isoflurane both have applications in animal research due to their rapid onset and offset with minimal side effects.
Isoflurane and sevoflurane are the currently recommended inhalant anesthetics. Both of these agents require a precision vaporizer for delivery to the animal. Induction in mice or rats with these agents must be conducted in an induction chamber, where concentration is restricted to 5 percent. These are very rapid-acting inhalant anesthetics, and death can result if the animal is not observed closely or the concentration is too high.
An advantage of these agents is that they are not metabolized and therefore have little or no toxic effects. Also, they are relatively insoluble in blood, and therefore are “blown-off” quickly, providing a quick recovery. While very similar, isoflurane and sevoflurane have slightly different effects and mechanisms of action, even though the anesthetic result is nearly identical.
Anesthesia Administration Systems
For safety, waste gas scavenging systems are required when using these agents. Precision vaporizers provide precise, controlled levels of anesthesia administered to the patient, providing a margin of safety to the animal. Using gas anesthetics at full concentration out of the bottle quickly results in overdosing the animal, and can kill very quickly.
Precision vaporizers are part of an anesthesia machine and serve to mix oxygen with the anesthetic in a precisely-controlled concentration. Animal researchers who routinely incorporate surgery or the use of anesthetics in their animal experiments should consider purchasing an anesthesia machine.
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