Anesthesia is defined as a temporary state of insensibility or a loss of consciousness. Insensibility can be limited to a region usually by injection of drugs that interfere with the local or regional activity of the nervous tissues (local/regional anesthesia). However, in laboratory practices of anesthetization of animals, general anesthesia is usually preferred. As opposed to local or regional anesthesia, general anesthesia results in loss of consciousness, analgesia, suppression of reflex activity and muscle relaxation. These features of the latter allow researchers and investigators to undertake surgical procedures with precision, without causing any distress to the animals. Often general anesthesia is induced by inhalation or injectable agents or using a combination of these methods.
Anesthesia administration methods and selection of the agent are usually based on the requirements of the procedures or investigation, species, age, and background of the animal being used. Though the use of inhalation agent is a popular method of anesthesia induction, animals can be anesthetized by intravenous, intramuscular, or subcutaneous injections and oral or rectal liquid anesthesia. Although a single anesthesia agent can achieve all the features of general anesthesia, usually a combination of agents is used to create the overall effect. The primary advantage of using a mixture of agents is that the undesirable side effects of anesthetic agents can often be minimized.
Laboratories often utilize anesthesia machines to administer and maintain anesthesia. The system comprises of vaporizers, ventilators, anesthetic breathing circuit, waste gas scavenging system, and pressure gauges. The anesthesia is delivered to the animals from the machine via a face mask, a nasal tube or an endotracheal tube. The system uses compressed gases that are monitored for their flow and pressure rate using flow meters. These gases make their way through the flow meter to a vaporizer where they are transformed into vapors. The vapors then pass on through the breathing system and finally to the subject. Apart from the delivery system, several other instruments are used to ensure adequate airway management and monitoring of the subject throughout the anesthetization process and anesthesia.
Monitoring processes are crucial to ensure the success of the anesthesia procedure. During anesthetization, monitoring of the animal allows detection of ineffective anesthesia and prevention of injury. The monitoring process should be continued post-anesthesia to ensure proper recovery and to discover any issues that may interfere with the investigatory requirements. Appropriate recovery care is also an essential part of the process. This approach improves the quality of the research while also ensuring animal safety and welfare.
Performing appropriate and effective anesthesia procedure is critical for successful experimental design. Anesthesia has profound effects on the animal’s consciousness and sensation. It enables the experimenters to perform surgical and experimental procedures accurately and with minimal distress to the animal. Achieving adequate anesthesia can be a complex process. Hence, it is important that the anesthetic agents are carefully selected, and appropriate measures are adopted to minimize the unwanted side-effects of anesthesia and surgery.