General AnestheticsTracy Womble, Ph.DFlorida A&M University, College of Pharmacy and Phamaceutical Sciences
Objectives▪ Historical Perspective▪ Definition of General Anesthetics▪ What is anesthesia▪ Differentiate sleep, amnesia, analgesia, general anesthesia▪ List different stages/depths of GA▪ Classify the agents used for general anesthesia▪ Describe the mechanism of action, pharmacokinetics, therapeutics and adverse effects and drug interactions of different anesthetic drugs
Historical Perspective▪ General anesthesia was absent until the mid-1800’s▪ William Mortonadministered ether to a patient having a neck tumor removed at the Massachusetts General Hospital, Boston, in October 1846. ▪ The discovery of the diethyl etheras general anesthesia was the result of a search for means of eliminating a patient’s pain perception and responses to painful stimuli.▪Ether no longer used in modern practice, yet considered to be the first “ideal” anesthetic(CH3CH2)2O
Sleep, Amnesia, Analgesia, General Anesthetic▪Sleep - a naturally recurring state of mind and body characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings, a decreased ability to react to stimuli. ▪Amnesia - the loss of memories, such as facts, information and experiences.▪Analgesic – a class of drugs that are designed to relieve pain without causing the loss of consciousness.▪General Anesthetic - A drug that brings about a reversible loss of consciousness for the purpose of inducing amnesia, analgesia, skeletal muscle relaxation attenuation of autonomic responses to painful stimuli.
General Anaesthetics (GA)unconsciousnessamnesiaanalgesia▪A drug administered to a patient with the overall aim of ensuring unconsciousness, amnesia and analgesia.
What are General Anesthetics?▪A drug that brings about a reversible loss of consciousness▪generally administered by an anesthesiologist in order to induce or maintain general anesthesia to facilitate surgery. ▪reversible drug-induced loss of consciousness▪depresses the nervous system resulting an induced anesthetic state▪ a lack of awareness ▪ amnesia▪ sedation and reduced anxiety, ▪ skeletal muscle relaxation▪ suppression of undesirable reflexes
General Anesthetics▪ volatile and nonvolatile ▪ general anesthetics are used to induce analgesia, amnesia, loss of consciousness, and skeletal muscle relaxation during surgical procedures▪ usually anesthesia is accomplished by; ▪ preoperative ▪ benzodiazepine (BDZs)▪ Induction anesthesia by an i.v. agent▪ thiopental (pentothal), midazolam (versed), propofol (diprivan) fentanyl (sublimaze)▪ produce rapid and smoother transition into anesthesia compared to inhaled agents▪ maintenance of anesthesia by a combination of inhaled and i.v.