Anesthesia In the “old days” the following were used for anesthesia. Alcohol Drugs Ice for numbing Blow to the head Strangulation

Anesthesia Now, anesthesia is designed to focus on specific systems, such as Nervous system • Skeletal system Respiratory system • GI system Endocrine system • Hepatic system Cardiovascular system

Anesthesia Goals of Balanced Anesthesia Amnesia (Loss of memory) Adequate Muscle Relaxation Adequate Ventilation Pain Control

Types of Anesthesia Preansthetics agents General (inhaled: desflurane, halothane, isoflurane, Nitrous oxide, sevoflurane, enflurane; IV: barbiturate, benzodiazepines, ketamine, opoids, propofol, etomidate) Local ( Bupivacaine, Lidocaine, Procaine, Tetracaine)

General Anesthesia Preanesthetic Medications (antiemetics, muscle relaxants, Anticholinergics, antihistamines, Benzodazepines, Opioids) Control sedation Reduce postoperative pain Provide amnesia Decrease anxiety

Discussion What are some of the indicators used to access general anesthesia? Answer: Blood pressure, hypervolemia, oxygen level, pulse, respiratory rate, tissue perfusion, urinary output

General Anesthesia Malignant Hyperthermia Side effect of anesthesia Fever of 110°F or more Life threatening Treatment: dantrolene (Dantrium)

Drug List Inhalant Anesthetics desflurane (Suprane) enflurane (Ethrane) halothane isoflurane (Forane) nitrous oxide

Inhalant Anesthesia Side Effects Causes reduction in blood pressure May cause nausea and vomiting

nitrous oxide Causes analgesia only; no amnesia or relaxation May be given alone or may be given with more powerful anesthetics to hasten the uptake of the other agent (s) Commonly used for dental procedures Rapidly eliminated

desflurane (Suprane) Has rapid onset and recovery Often used in ambulatory surgery

Intravenous General Anesthesia Often dispensed by IV drip Very lipid soluble

Injectable Anesthetics Drug List Injectable Anesthetics etomidate (Amidate) fentanyl (Duragesic, Sublimaze) fentanyl-droperidol ketamine (Ketalar) morphine propofol (Diprivan) sufentanil (Sufenta)

Injectable Anesthetics Drug List Injectable Anesthetics Barbituates methohexital (Brevital) thiopental (Pentothal) Benzodiazepines diazepam (Valium) lorazepam (Ativan) midazolam (Versed)

propofol (Diprivan) Used for maintenance of anesthesia, sedation, or treatment of agitation Has antiemetic properties Drowsiness Respiratory depression Motor restlessness Increased blood pressure

fentanyl Dosage Forms IV patch lozenge for children Used extensively for open-heart surgery due to lack of cardiac depression

Benzodiazepines Used for induction, short procedures, and dental procedures Useful in controlling and preventing seizures induced by local anesthetics midozolam (Versed) fastest onset of action greatest potency most rapid elimination

Antagonist Agents Antagonist agents reverse benzodiazepine and narcotic overdose.

Drug List Antagonist Agents flumazenil (Romazicon) nalmefene (Revex) naloxone (Narcan)

Neuromuscular Blocking Agents Causes immediate skeletal muscle relaxation. Short Duration Intermediate Duration Extended Duration Used to facilitate endotracheal intubation. Allows for easier insertion of endotracheal tube. Keeps airway open.

Neuromuscular Blocking Agents Drug List Neuromuscular Blocking Agents atracurium (Tracrium) cisatracurium (Nimbex) mivacurium (Mivacron) pancuronium rocuronium (Zemuron) succinylcholine (Quelicin) vecuronium (Norcuron)

succinylcholine (Quelicin) Often called “sux.” Only depolarizing agent. All others work as competitive antagonists to ACh receptors. Persistent depolarization at motor endplate. Causes sustained, brief period of flaccid skeletal muscle paralysis.

Reversal of Neuromuscular Blocking Agents Increases the action of acetylcholine by inhibiting acetylcholinesterase Used for reversal of nonpolarizing agents

Anticholinesterase Agents Drug List Anticholinesterase Agents edrophonium (Enlon) neostigmine (Prostigmin) pyridostigmine (Mestinon)

Local Anesthesia Relieves pain without altering alertness or mental function.

Local Anesthesia Variety of Dosage Forms Topical Superficial injection (infiltration) Nerve block IV Spinal

Under what conditions would a local anesthetic be used over a general anesthetic? Answer: It is chosen when a well-defined area of the body is targeted.

Discussion Ester Amides Local anesthetics are classified by their chemistry into two classes. Ester Amides

Local Anesthesia Esters Short acting Metabolized in the plasma and tissue fluids Excreted in urine

Local Anesthesia Amides Longer acting Metabolized by liver enzymes Excreted in urine

Drug List Local Anesthesia Esters benzocaine (Americaine) chloroprocaine (Nesacaine) dyclonine (Cēpacol Maximum Strength) procaine (Novocain) tetracaine (Cēpacol Viractin, Pontocaine)

Drug List Local Anesthesia Amides bupivacaine (Marcaine) levobupivacaine (Chirocaine) lidocaine (L-M-X, Solarcaine, Xylocaine) lidocaine-epinephrine (Xylocaine w/ Epinephrine) lidocaine-prilocaine (EMLA) mepivacaine (Carbocaine)

What functions are lost with local anesthetics? Answer Pain perception Temperature Touch sensation Skeletal muscle tone