Chapter 19 Drugs for Local and General Anesthesia Slide 18 Media Directory Lidocaine Animation Upper Saddle River, New Jersey 07458 All rights reserved. Topical (Surface) Anesthesia Creams, sprays, suppositories Drops and lozenges Applied to mucous membranes Safe, unless absorbed in the systemic system Infiltration (Field-Block) Anesthesia Direct injection into tissue immediate to surgical site Blocks specific nerves near site Nerve-Block Anesthesia Spinal Anesthesia Direct injection into tissues that may be distant from surgical site Affects nerve bundles supplying surgical area Used to block sensation in a limb or large area of face Injected into CSF Affects large, regional areas such as lower abdomen and legs 1
Epidural Anesthesia Esters Injected into epidural space of spinal canal Used most often in labor and delivery Contain an ester chemical linkage Incidence of allergic reaction is low Method of metabolism is plasma esterases Amides Contain amide chemical linkage Incidence of allergic reaction is very low Method of metabolism is hepatic enzymes Longer duration of action than esters Work by stopping axonal conduction Block sodium channels Stop conduction Epinephrine Sodium Hydroxide Constricts blood vessels Increases duration of anesthetic Alkaline agent Increases effectiveness of anesthetic Used in areas of infection that may be acidic (from bacteria) 2
General Anesthetics Inhalation Anesthesia Block flow of sodium into neurons Delays nerve impulses and reduces neural activity Produces unconsciousness Produces lack of responsiveness to painful stimuli Gases Nitrous oxide Volatile liquids Intravenous Anesthetics Stages of General Anesthesia Act within a few seconds Used alone or in combination with inhalation agents: balanced anesthesia Stage I: Loss of pain Stage II: Excitement and hyperactivity Stage III: Surgical anesthesia Stage IV: Paralysis of the medulla Lidocaine Animation Prototype drug: lidocaine (Xylocaine) Mechanism of action: to stop axonal conduction by blocking sodium channels Primary use: for brief medical or dental procedures Click here to view an animation on the topic of lidocaine. Back to Directory 3
(continued) Esters Adverse effects uncommon: may include CNS stimulation with early adverse effects CNS depression with later adverse effects Rash; allergies to sulfites used as preservative Prototype drug: procaine (Novocain) The mechanism of action and primary use is as stated above with the amides Amides have largely replaced the esters General Anesthetic: Inhalation Agents Either gases or volatile liquids Prototype drug: nitrous oxide Mechanism of action: prevent flow of sodium into CNS; reduce neural activity General Anesthetic: Inhalation Agents Primary use: with IV agents to maintain loss of consciousness; used alone for dental procedures Adverse effects: nausea and vomiting, CNS depression, respiratory difficulty, vital-sign changes General Anesthetic: Intravenous Agents Barbiturate and barbiturate-like agents, opioids, benzodiazepines Prototype drug: thiopental sodium (Penthonal) Used in combination with inhalation agents Fewer side effects Produce unconsciousness quickly and amnesia General Anesthetic: Intravenous Agents (continued) Some used for conscious sedation Adverse effects: allergic reactions, dysrhythmias, respiratory depression CNS depression, shivering, headache Nausea and vomiting, vital-sign changes During postoperative period: hallucinations, confusion, excitability may occur 4
Adjuncts to Anesthesia Medications given to Complement effects of general anesthesia Treat anticipated side effects of anesthesia May be given prior to, during, or after surgery Amides and esters Stop axonal conduction Block sodium channels Causes rapid loss of sensation in limited part of body Amides Esters Lidocaine (Xylocaine) Articaine (Septodont) Bupivacaine (Marcaine) Benzocaine (Solarcaine) Procaine (Novocain) Chloroprocaine (Nesacaine) General Anesthetics: Inhalation Gaseous Agent Gaseous agents; volatile liquids Prevent flow of sodium into neurons in CNS Delays nerve impulses Produces reduction in neural activity Usually combined with IV agents Nitrous oxide 5
Halothane (Fluothane) Enflurane (Ethrane) Isoflurane (Forane) Volatile Liquids General Anesthetics: Intravenous Barbiturate and barbiturate-like agents Opioids, benzodiazepines Used in combination with inhalation agents Administered first Rapidly induce unconsciousness Barbiturate and Barbiturate- Like Agents Induce unconsciousness Thiopental sodium (Penthonal) Methohexital sodium (Brevital) Benzodiazepines Induce unconsciousness and amnesia Diazepam (Valium) Lorazepam (Ativan) Midazolam hydrochloride (Versed) Opioids Fentanyl citrate (Sublimaze) Given with antipsychotic agent to produce neurolept analgesia General Anesthesia Assessment Ascertain allergies to anesthetics Obtain complete health and drug history Assess for system disorders 6
Obtain baseline vitals and labs Assess client knowledge and anxiety Assess skin Nursing Diagnoses Risk for aspiration Risk for injury Deficient knowledge related to drug use Nursing Diagnoses for General Anesthetics Anxiety related to surgical procedure Impaired gas exchange Nausea Disturbed sensory perception Ineffective breathing pattern Decreased cardiac output Planning Goals No pain No side effects No adverse reaction Adequate anesthesia Implementation Monitor cardio/respiratory side effects Monitor length of anesthetic effectiveness Provide client safety Monitor vital signs Monitor recovery from anesthesia General Anesthesia Evaluation Effectiveness of drug therapy Goals met Expected outcomes met 7
Administration of Selected Table 19.1 Administration of Table 19.2 Selected Stages of General Anesthesia Inhaled General Anesthetics Table 19.3 Stages of General Anesthesia Table 19.4 Inhaled General Anesthetics Intravenous Anesthetics Adjuncts to Anesthesia Table 19.5 Intravenous Anesthetics Table 19.6 Adjuncts to Anesthesia 8