Unit III: The Nervous System

1. Unit III: The Nervous System Chapter 19: Drugs for Local and General Anesthesia

2. Local Anesthetics Sodium Channel Blockers Classifications: Esters Cocaine procaine (Novocain) Benzocaine (Solarcaine) Amides lidocaine Local anesthetics block sodium movement into the cell----- inhibits firing of the neuron Non-selective� inhibits both sensory and motor impulses---- sensation and muscle activity temporarily diminishes Effects must last long enough to complete procedure Epinephrine added to constrict vessels and keep agent there longer--- extends duration of drug action If area has localized infection or abscess, tissue environment will be acidic and effectiveness of agent will be decreased---- will add sodium hydroxide to neutralize environment procaine (Novocain) was popular for dental procedures until the 1960s Amides produce fewer side effects and usually have a longer duration of action lidocaine (Xylocaine) most commonly used amide for short surgical procedures Local anesthetics block sodium movement into the cell----- inhibits firing of the neuron Non-selective� inhibits both sensory and motor impulses---- sensation and muscle activity temporarily diminishes Effects must last long enough to complete procedure Epinephrine added to constrict vessels and keep agent there longer--- extends duration of drug action If area has localized infection or abscess, tissue environment will be acidic and effectiveness of agent will be decreased---- will add sodium hydroxide to neutralize environment procaine (Novocain) was popular for dental procedures until the 1960s Amides produce fewer side effects and usually have a longer duration of action lidocaine (Xylocaine) most commonly used amide for short surgical procedures

3. Local Anesthetics: Adverse Effects Uncommon Allergy rare Early signs: Restlessness or anxiety Later signs: Drowsiness and unresponsiveness, hypotension dysrhythmia Early signs are related to CNS stimulation Late signs are related to CNS depression CNS and Cardiovascular signs not expected unless: Rapid absorption Accidental injection into blood vesselEarly signs are related to CNS stimulation Late signs are related to CNS depression CNS and Cardiovascular signs not expected unless: Rapid absorption Accidental injection into blood vessel

4. Local Anesthetic: Nursing Considerations Carefully monitor client condition Provide education as it relates to prescribed drug treatment Physician usually administers Nurse Prepares area Monitors pain and comfort levels Assesses skin integrity at site Skin is checked are non-intact areas: broken skin, infection, burns, and woundsSkin is checked are non-intact areas: broken skin, infection, burns, and wounds

5. Local Anesthetic: Nursing Considerations Monitor for adverse reactions Assess VS during procedure If an oral local anesthetic preparation (lidocaine viscous) is administered, what must the nurse monitor for? What type of procedure would indicate use of an oral local anesthetic preparation? Monitor for cardiac palpitations, difficulty breathing or difficulty swallowing, and signs of CNS stimulation (excitation): restlessness and anxiety Report VS changes immediately Presence of a rash would indicate local reaction Post oral local anesthetic monitor for return of gag reflex before allowing fluid or food Oral anesthetic preparation used for any procedure which calls for anesthetizing the throat, e.g., EGDMonitor for cardiac palpitations, difficulty breathing or difficulty swallowing, and signs of CNS stimulation (excitation): restlessness and anxiety Report VS changes immediately Presence of a rash would indicate local reaction Post oral local anesthetic monitor for return of gag reflex before allowing fluid or food Oral anesthetic preparation used for any procedure which calls for anesthetizing the throat, e.g., EGD

6. Local Anesthesia: Contraindications Hypersensitiviy Sepsis and blood dyscrasias Untreated sinus bradycardia Severe A-V, S-A, and intraventricular heart block in absence of a pacemaker Use cautiously over large body areas Do not use on eyes Avoid use over large body areas to avoid systemic effects Avoid use over large body areas to avoid systemic effects

7. General Anesthesia Goal: provide rapid and complete loss of sensation General anesthetic agents depress most nervous activity in the brain

8. Balanced Anesthesia Use of combined drugs to achieve: Rapid induction of unconsciousness Muscle relaxation Maintenance of deep anesthesia (stage 3) What is the benefit of balanced anesthesia? Benefit: Allows lower dose of inhalation anesthesia which results in a safer procedure Benefit: Allows lower dose of inhalation anesthesia which results in a safer procedure

9. General Anesthetics Drugs that rapidly produce unconsciousness and total analgesia Route: IV or Inhalation Adjunct drugs supplement effects Adjunct drugs may be given before, during or after surgical procedure to supplement the effects of the anesthetic agent When giving pre-op sedatives/hypnotics to elderly patients monitor closely for confusion or excitement and initiate measures to prevent injury or fall First IV agents will be given, act within seconds Then once patient is unconscious, inhaled agents will be given to maintain anesthesia Inhaled agents are gases (nitrous oxide) or volitile liquids--- prevent flow of sodium into neurons Exact mechanism not known, likely that GABA receptors are activated Not same mechanism of action as local anestheticsAdjunct drugs may be given before, during or after surgical procedure to supplement the effects of the anesthetic agent When giving pre-op sedatives/hypnotics to elderly patients monitor closely for confusion or excitement and initiate measures to prevent injury or fall First IV agents will be given, act within seconds Then once patient is unconscious, inhaled agents will be given to maintain anesthesia Inhaled agents are gases (nitrous oxide) or volitile liquids--- prevent flow of sodium into neurons Exact mechanism not known, likely that GABA receptors are activated Not same mechanism of action as local anesthetics

10. Inhaled General Anesthetics Gas: Nitrous oxide Prototype (p. 251) Often in conjuction with other general anesthetics Use cautiously in myasthenia gravis, Increased intracranial pressure Volatile liquids Halothane (prototype, p. 252), enflurane, isoflurane Liquid at room temperature Converted into vapor and inhaled to produce effect Excreted almost entirely by lungs through exhalation Nitrous Oxide is only gas routinely used Used in dental procedures, brief obstetrical procedures, and brief surgical procedures In myasthenia gravis can cause respiratory depression and prolonged hypnosis In increased ICP the hypnotic effect is prolonged or potentiated halothane (Fluothane) is most potent volatile liquid; can be hepatotoxic� no halothane if has had drug in previous 14-21 days; Contraindicated in decreased hepatic function and pregnancy (Category D) Use cautiously in cardiac conditions (esp. bradycardia and dysrhythmias)--- causes hypotension and sensitizes myocardium to catecholamines Some general anesthetics enhance sensitivity of the heart to epinephrine, norephinephrine, dopamine and seratonin isoflurane (Forane) becoming most widely used inhalation anesthetic--- less effect on heart and does not damage liver. Nitrous Oxide is only gas routinely used Used in dental procedures, brief obstetrical procedures, and brief surgical procedures In myasthenia gravis can cause respiratory depression and prolonged hypnosis In increased ICP the hypnotic effect is prolonged or potentiated halothane (Fluothane) is most potent volatile liquid; can be hepatotoxic� no halothane if has had drug in previous 14-21 days; Contraindicated in decreased hepatic function and pregnancy (Category D) Use cautiously in cardiac conditions (esp. bradycardia and dysrhythmias)--- causes hypotension and sensitizes myocardium to catecholamines Some general anesthetics enhance sensitivity of the heart to epinephrine, norephinephrine, dopamine and seratonin isoflurane (Forane) becoming most widely used inhalation anesthetic--- less effect on heart and does not damage liver.

11. Inhaled General Anesthetics:Nursing Considerations Carefully monitor client condition Provide education as it relates to the prescribed drug treatment General anesthesia� primarily for lengthy surgeries Benefits must outweigh risks to fetus for pregnant patients Pre-op: Baseline VS and labs Assessments Pre-op assessments include: Health history Level of knowledge about procedure Presence of anxiety Alcohol or CNS depressant use within previous 24 hours--- potentiates the effects of the anesthetic agentsPre-op assessments include: Health history Level of knowledge about procedure Presence of anxiety Alcohol or CNS depressant use within previous 24 hours--- potentiates the effects of the anesthetic agents

12. Inhaled General Anesthetics:Nursing Considerations Immediate post-op Monitor for side effects What side effects would you anticipate? What population(s) is/are more susceptible to side effects? Side effects: Nausea and vomiting, CNS depression, respiratory depression or difficulty, change in VS, complications related to the procedure (bleeding or impending shock) Children usually more sensitive than adults. Elderly more affected by anesthesia (esp. effects of barbiturates and general anesthetics) due to changes in drug metabolism that accompany aging.Side effects: Nausea and vomiting, CNS depression, respiratory depression or difficulty, change in VS, complications related to the procedure (bleeding or impending shock) Children usually more sensitive than adults. Elderly more affected by anesthesia (esp. effects of barbiturates and general anesthetics) due to changes in drug metabolism that accompany aging.

13. Case Study Miss N, 86-year-old, has just returned to the floor following a colon resection. The anesthetic agents used were a combination of an IV agent and a volatile liquid. As you complete her post-op check you determine her VS are within normal range although she is very drowsy and her respiratory rate is 14 and somewhat shallow. What will you do? Stimulate her and encourage deep breathing to facilitate excretion of the inhaled general anesthesia via her lungs. Stimulate her and encourage deep breathing to facilitate excretion of the inhaled general anesthesia via her lungs.

14. Client Education R/T General Anesthetic Drugs Stop meds, herbals, dietary supplements 24 hours prior to surgery No alcohol 24 hours prior No food or fluids after anesthesia until ordered Deep breathe postoperatively Follow direction of health care provider regarding medication doses Alcohol potentiates effect of general anesthesia No food or fluids to minimize or prevent nausea, prevent aspiration if vomits Deep breathe to excrete inhaled agents Follow direction of health care provider regarding medication doses Alcohol potentiates effect of general anesthesia No food or fluids to minimize or prevent nausea, prevent aspiration if vomits Deep breathe to excrete inhaled agents

15. Intravenous Anesthetics Supplement to general anesthesia What are the benefits to concurrent administration of IV and inhaled agents? IV agents� sometimes administered along, most often administered with an inhaled general agent Used to decrease anxiety and fear related to use of mask Benefits: Allows dose of inhaled agent to be reduced Lowers potential for serious side effects Provides greater analgesia and muscle relaxation than could be provided by inhaled anesthetic aloneIV agents� sometimes administered along, most often administered with an inhaled general agent Used to decrease anxiety and fear related to use of mask Benefits: Allows dose of inhaled agent to be reduced Lowers potential for serious side effects Provides greater analgesia and muscle relaxation than could be provided by inhaled anesthetic alone

16. Intravenous Anesthetics: Nursing Considerations Carefully monitor client condition Provide education as it relates to the prescribed drug treatment Thorough assessment Administer pre-meds Post-operatively monitor for s/s of CNS depression Use thiopental (Pentothal) cautiously if neuro hx Contraindicated: drug sensitivity Use cautiously: CVD, respiratory disorders Assessment: Medical history must be assessed prior to selection of anesthetic or combination by MDA or CRNA--- nurse can assist in gathering data Assess suitability of IV Pre-meds: Antianxiety agents, sedatives, analgesics (opioids), anticholinergics Neurological disorders: Seizures, Increased ICP, mxyedema, and others CNS signs: VS changes, hallucinations, confusion, excitability Respiratory difficulties, shivering and trembling, n/v, headache, somnolence Assessment: Medical history must be assessed prior to selection of anesthetic or combination by MDA or CRNA--- nurse can assist in gathering data Assess suitability of IV Pre-meds: Antianxiety agents, sedatives, analgesics (opioids), anticholinergics Neurological disorders: Seizures, Increased ICP, mxyedema, and others CNS signs: VS changes, hallucinations, confusion, excitability Respiratory difficulties, shivering and trembling, n/v, headache, somnolence

17. Non-anesthetic Drugs Compliment the effects of general anesthetics Treat anticipated side effects During surgery� neuromuscular blockers Depolarizing: succinylcholine (prototype, p. 257) Nondepolarizing Post-operative- analgesics, antiemetics, parasympthomimetics Adjuncts to anesthesia; can be given before, during or after surgery Neuromuscular blocking agents cause skeletal muscle to totally relax Succinylcholine binds to acetylcholine receptors at neuromuscular junction resulting in skeletal muscle relaxation Nondepolarizing: cause muscle paralysis by competing with acetylcholine for cholinergic receptors at neuromuscular junctions. Once attached to receptor, nonpolarizing blocker prevents muscle contraction.Adjuncts to anesthesia; can be given before, during or after surgery Neuromuscular blocking agents cause skeletal muscle to totally relax Succinylcholine binds to acetylcholine receptors at neuromuscular junction resulting in skeletal muscle relaxation Nondepolarizing: cause muscle paralysis by competing with acetylcholine for cholinergic receptors at neuromuscular junctions. Once attached to receptor, nonpolarizing blocker prevents muscle contraction.

18. Non-anesthetic Drugs: Nursing Considerations Carefully monitor client condition Provide education as it relates to the prescribed drug treatment Assess physical status before use Monitor for adverse effects Do not use in children under 2 Physical assessment should include: VS, reflexes, muscle tone and response, pupil size and reactivity, ECG, lung sounds, bowel sounds, affect and LOC Monitor for: HTN, tachycardia, prolonged apnea, bronchospasm, respiratory depression, paralysis, and hypersensitivity If history is positive for hepatic or renal dysfunction, neuromuscular disease, fractures, myasthenia gravis, malignant hypertermia, glaucoma, or penetrating eye injury, the use of succinylcholine is contraindicated. Physical assessment should include: VS, reflexes, muscle tone and response, pupil size and reactivity, ECG, lung sounds, bowel sounds, affect and LOC Monitor for: HTN, tachycardia, prolonged apnea, bronchospasm, respiratory depression, paralysis, and hypersensitivity If history is positive for hepatic or renal dysfunction, neuromuscular disease, fractures, myasthenia gravis, malignant hypertermia, glaucoma, or penetrating eye injury, the use of succinylcholine is contraindicated.