General Anesthetics pco 501
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Questions and Answers

What is one of the goals of preanaesthetic medication?

  • Relieve anxiety and apprehension (correct)
  • Increase blood pressure
  • Eliminate the need for anaesthesia
  • Induce sleep immediately

    • Emergence delirium is a common occurrence after anaesthesia.

    True

    Name one drug used for the induction of anesthesia.

    Thiopental

    Preanaesthetic medication can help to decrease _____ and volume of gastric juice.

    <p>acidity</p> Signup and view all the answers

    Match the following phases of anaesthesia with their corresponding drugs:

    <p>Preanesthetic care = Diazepam, Atropine Induction of anesthesia = Thiopental Maintenance of anesthesia = Inhaled anesthetics Postanesthetic care = Metoclopramide</p> Signup and view all the answers

    Which of the following describes general anesthesia?

    <p>It renders the patient unaware of pain during surgical procedures.</p> Signup and view all the answers

    Local anesthesia produces a loss of consciousness and sensation throughout the body.

    <p>False</p> Signup and view all the answers

    Name one common drug used for local anesthesia.

    <p>Lidocaine</p> Signup and view all the answers

    The cardinal features of general anesthesia include loss of sensation, ______, immobilization, and abolition of reflexes.

    <p>unconsciousness</p> Signup and view all the answers

    Match the stages of general anesthesia with their characteristics:

    <p>Analgesia = Patient remains conscious with dream-like state Delirium and excitement = Nausea, vomiting, hyperreactivity Stage of Recovery = Patient gradually comes back to consciousness Stage of Maintenance = Sustaining anesthesia for surgical procedures</p> Signup and view all the answers

    Which statement about inhalation anesthetics is true?

    <p>They induce unconsciousness in patients during surgery.</p> Signup and view all the answers

    Stage 1 of general anesthesia is characterized by unconsciousness and amnesia.

    <p>False</p> Signup and view all the answers

    What is the primary role of an anesthesiologist during surgery?

    <p>To administer anesthetics and monitor the patient's state of anesthesia.</p> Signup and view all the answers

    Which inhalation anesthetic is contraindicated in patients with seizure disorders?

    <p>Enflurane</p> Signup and view all the answers

    Desflurane has a pungent odor and is recommended for pediatric use.

    <p>False</p> Signup and view all the answers

    What is the main advantage of using propofol over thiopentone?

    <p>Lower incidence of postoperative nausea and vomiting</p> Signup and view all the answers

    _________ is a fast-acting intravenous anesthetic that produces unconsciousness within 15-45 seconds.

    <p>Propofol</p> Signup and view all the answers

    Match the anesthetic agents with their characteristics:

    <p>Methoxyflurane = Non irritant, weak analgesic Thiopentone = Ultrashort acting thiobarbiturate Nitrous oxide = Causes diffusion hypoxia Ketamine = Used for inducing general anesthesia</p> Signup and view all the answers

    What is a common side effect of halothane?

    <p>Hepatotoxicity</p> Signup and view all the answers

    Benzodiazepines can produce unconsciousness within minutes.

    <p>False</p> Signup and view all the answers

    Name one mechanism of action for thiopentone.

    <p>Enhances GABA-mediated transmission</p> Signup and view all the answers

    ______ is used as a pre-anesthetic medication and for inducing sedation.

    <p>Benzodiazepines</p> Signup and view all the answers

    Match the following side effects with the respective anesthetics:

    <p>Sevoflurane = Minimal CVS adverse effects Enflurane = CNS stimulation Desflurane = Airway irritation Methoxyflurane = Slow induction and recovery</p> Signup and view all the answers

    Which intravenous anesthetic is known for potential excitatory effects and involuntary movements?

    <p>Propofol</p> Signup and view all the answers

    Nitrous oxide can lead to megaloblastic anemia.

    <p>True</p> Signup and view all the answers

    What effect does thiopentone have on blood pressure immediately after injection?

    <p>It causes a fall in blood pressure due to vasodilation.</p> Signup and view all the answers

    How long does it typically take for a patient to become responsive after administration of diazepam without other anaesthetics?

    <p>1 hour</p> Signup and view all the answers

    Benzodiazepines significantly depress respiration when used with opioids.

    <p>True</p> Signup and view all the answers

    What drug is used to rapidly reverse the anesthetic action of benzodiazepines?

    <p>flumazenil</p> Signup and view all the answers

    Ketamine induces dissociative anesthesia, characterized by sedation, immobility, analgesia, anterograde amnesia, and a strong feeling of __________ from the environment.

    <p>dissociation</p> Signup and view all the answers

    What is the elimination half-life of ketamine?

    <p>2-4 hours</p> Signup and view all the answers

    Fentanyl can be used as an adjunct to spinal anaesthesia.

    <p>True</p> Signup and view all the answers

    Name one common side effect of fentanyl administration.

    <p>respiratory depression</p> Signup and view all the answers

    Which intravenous anesthetic has a risk of causing psychotomimetic effects?

    <p>Ketamine</p> Signup and view all the answers

    Opioid drugs can cause __________, which is marked by reduced respiratory function.

    <p>respiratory depression</p> Signup and view all the answers

    Match the intravenous anesthetics with their main side effects:

    <p>Thiopentone = CVS collapse and respiratory depression Etomidate = Adrenocortical suppression Propofol = Excitation and respiratory depression Ketamine = Psychotomimetic effects</p> Signup and view all the answers

    What is a potential complication of general anesthesia during its use?

    <p>All of the above</p> Signup and view all the answers

    Involuntary movements are stimulated by benzodiazepines.

    <p>False</p> Signup and view all the answers

    What major physiological response does ketamine induce that differs from traditional anesthetics?

    <p>bronchodilation</p> Signup and view all the answers

    The average dose of ketamine for IV administration is __________ mg/kg.

    <p>1.5</p> Signup and view all the answers

    Which stage of surgical anesthesia ends with the loss of corneal and laryngeal reflexes?

    <p>Stage III (Surgical Anesthesia)</p> Signup and view all the answers

    Stage I of surgical anesthesia involves the loss of pain sensation while the patient remains conscious.

    <p>True</p> Signup and view all the answers

    What is the main characteristic of Stage IV anesthesia?

    <p>Medullary/Respiratory Paralysis</p> Signup and view all the answers

    Inhalation anesthetics are primarily halogenated hydrocarbons that end with the suffix '______.'

    <p>flurane</p> Signup and view all the answers

    Match the following inhalation anesthetics with their solubility (Blood: gas partition coefficient):

    <p>Methoxyflurane = Slow Sevoflurane = Rapid Nitrous Oxide = Rapid Halothane = Slow</p> Signup and view all the answers

    Which of the following is a dissociative anesthetic?

    <p>Ketamine</p> Signup and view all the answers

    Nitrous Oxide is considered a potent anesthetic.

    <p>False</p> Signup and view all the answers

    Name one potential adverse effect of Nitrous Oxide.

    <p>Diffusion hypoxia</p> Signup and view all the answers

    Halothane is metabolized to toxic metabolites, which may cause _______ toxicity.

    <p>hepatotoxic</p> Signup and view all the answers

    Match the anesthetic agents with their primary effect:

    <p>Isoflurane = Stable compound with low biotransformation Enflurane = Renal toxicity from fluoride ions Halothane = Cardiac arrhythmias due to vagomimetic action Sevoflurane = Rapid induction and recovery</p> Signup and view all the answers

    What is the induction time characteristic of Sevoflurane?

    <p>Rapid</p> Signup and view all the answers

    All inhalation anesthetics are considered non-inflammable.

    <p>False</p> Signup and view all the answers

    List one contraindication for using Nitrous Oxide.

    <p>Pregnancy</p> Signup and view all the answers

    The rapid elimination of anesthetics occurs primarily during the ______ phase.

    <p>recovery</p> Signup and view all the answers

    Which of the following stages involves pupil dilation and loss of light reflex?

    <p>Stage III</p> Signup and view all the answers

    Enflurane is less potent than Halothane but provides better muscle relaxation.

    <p>True</p> Signup and view all the answers

    Study Notes

    General Anesthetic Agents

    • Definition of Anesthesia: A reversible condition of comfort and inactivity for a patient before, during, and after a surgical procedure, within physiological limits.

    • Types of Anesthesia:

      • General anesthesia: Used for surgical procedures to render the patient unaware of painful stimuli.
      • Local anesthesia: Involves reversible inhibition of nerve impulse generation and propagation to allow for painful procedures like surgery or dentistry.

    General Anesthesia

    • General Anesthetics: Drugs that produce reversible loss of sensation and consciousness, mainly given via inhalation or intravenously.
    • Administration: Usually by an anesthesiologist to induce and maintain anesthesia during surgery.

    Cardinal Features of General Anesthesia

    • Loss of all sensation, especially pain.
    • Sleep (unconsciousness) and amnesia.
    • Immobility and muscle relaxation.
    • Abolition of somatic and autonomic reflexes.

    Stages of General Anesthesia

    • Stage 1 (Analgesia):

      • Loss of pain sensation, patient conscious and conversational.
      • Difficult to maintain for extended periods.
      • Used only for short procedures.

    • Stage 2 (Delirium and Excitement):

      • Loss of consciousness to regular respiration.
      • Patient may shout, struggle, hold breath, increased muscle tone.
      • Irregular respiration, vomiting, micturition, defecation possible.
      • Usually avoided with modern anesthesia techniques.

    • Stage 3 (Surgical Anesthesia):

      • From regular respiration to cessation of spontaneous breathing.
      • Divided into 4 planes based on eye movement, corneal/laryngeal reflexes, and pupil dilation.
        • Plane 1: Roving eyeballs, ending when eyes become fixed.
        • Plane 2: Loss of corneal and laryngeal reflexes.
        • Plane 3: Pupil dilation, loss of light reflex.
        • Plane 4: Intercostal paralysis, shallow abdominal respiration, dilated pupil.

    • Stage 4 (Medullary/Respiratory Paralysis):

      • Cessation of breathing, circulatory failure, and death.
      • Pupils widely dilated, muscles flabby, imperceptible pulse, very low blood pressure.

    Classification of General Anesthetics

    • Inhalation Anesthetics:

      • Gases: Nitrous oxide.
      • Volatile liquids: Ether, Halothane, Enflurane, Isoflurane, Desflurane, Sevoflurane.

    • Intravenous Anesthetics:

      • Inducing agents: Thiopentone, Methohexitone sodium, propofol, etomidate.
      • Benzodiazepines: Diazepam, Lorazepam, Midazolam.
      • Dissociative anesthetic: Ketamine.
      • Neurolept analgesia: Fentanyl.

    Inhalation Anesthetics - Pharmacokinetics

    • Induction: Time from administration to surgical anesthesia.
    • Maintenance: Time patient is anesthetized.
    • Recovery: Time from discontinuation to regaining consciousness.
    • Factors affecting induction/recovery:
      • Inspired anesthetic concentration.
      • Ventilation rate/depth.
      • Blood solubility (Blood: gas partition coefficient).
    • Solubility and speed table (blood: gas partition coefficient):
      • Methoxyflurane: high solubility; slow induction/recovery.
      • Halothane: medium solubility; medium induction/recovery.
      • Enflurane: medium solubility; medium induction/recovery.
      • Isoflurane: medium solubility; medium induction/recovery.
      • Sevoflurane: low solubility; rapid induction/recovery.
      • Desflurane: very low solubility; rapid induction/recovery.
      • Nitrous Oxide: very low solubility; rapid induction/recovery.

    Nitrous Oxide (N₂O)

    • Properties: Colorless, odorless, sweet taste, weak anesthetic, rapid induction/recovery.
    • Uses: Outpatient procedures, balanced anesthesia, neurolept analgesia, delivery.
    • Contraindications: Pregnancy, pernicious anemia, immunosuppression.
    • Adverse Effects: Diffusion hypoxia, nausea/vomiting, B12 inactivation (anemia), bone marrow depression (leukopenia), abortion/congenital anomalies.

    Halothane

    • Properties: Potent anesthetic, slow induction/recovery. Weak analgesic, weak muscle relaxant. Fluorinated volatile liquid.
    • Metabolism: Metabolized to potentially hepatotoxic metabolites (trifluoroethanol).
    • Adverse Effects: Hepatotoxicity (repeated use), malignant hyperthermia, cardiac arrhythmias, CVS depression (hypotension, bradycardia).

    Enflurane

    • Properties: Less potent than halothane, better muscle relaxation and analgesia. Metabolized to fluoride, which can cause renal toxicity.
    • Adverse Effects: Pungent odor, potential CNS stimulation (seizures), can depress myocardial function, sensitization of heart to adrenaline.

    Isoflurane

    • Properties: Similar to enflurane, but slightly more potent, rapid induction/recovery, low biotransformation. No nephrotoxicity or hepatotoxicity. Good analgesic properties.
    • Adverse Effects: Pungent odor

    Intravenous Anesthetics

    • Fast-acting: Thiopentone, propofol, etomidate.
    • Slow-acting: Benzodiazepines(diazepam, lorazepam, midazolam), ketamine, fentanyl.

    Thiopentone

    • Mechanism: Enhances GABA-mediated transmission.
    • Effects: Rapid loss of consciousness, returns quickly due redistribution; poor analgesic, weak muscle relaxant.
    • Adverse Effects: Respiratory depression, hypotension, tachycardia (reflex), laryngospasm, shivering/delirium. Contraindicated in acute intermittent porphyria.

    Propofol

    • Properties: Oily liquid emulsion, used for induction and maintenance. Rapid distribution/elimination.
    • Effects: Rapid loss of consciousness, lacks airway irritancy.
    • Adverse Effects: CVS and respiratory depression, excitatory effects, induction apnea, pain at injection site.

    Benzodiazepines (BZDs)

    • Mechanism: Enhance GABA-mediated transmission.
    • Effects: Sedation, amnesia, and unconsciousness; slower action than propofol, prolonged recovery. Poor analgesic properties.
    • Uses: Induction/maintenance/supplemental anesthesia, conscious sedation.
    • Reversal: Flumazenil.

    Ketamine

    • Mechanism: Blocks NMDA-type glutamate receptors.
    • Effects: Dissociative anesthesia (sedation, immobility, analgesia, amnesia), rapid action.
    • Adverse Effects: Psychotomimetic effects (hallucinations/delirium) during recovery, rapid metabolism, elevated heart rate, cardiac output, blood pressure.

    Opioids (Fentanyl, Alfentanil, Sufentanil, Remifentanil)

    • Properties: Rapid onset and short duration of action, potent analgesics. Neurolept analgesia or anesthesia(with other drugs).
    • Effects: Analgesia, drowsiness, consciousness maintained.
    • Adverse Effects: Respiratory depression, hypotension, nausea/vomiting.

    Complications of General Anesthesia

    • During: respiratory depression/hypercarbia, salivation/respiratory secretions, cardiac arrhythmias/asystole, hypotension, aspiration, laryngospasm/asphyxia, awareness during surgery.
    • After: nausea/vomiting, persisting sedation, pneumonia/atelectasis, organ toxicity, nerve palsies, emergence delirium, cognitive defects.

    Preanesthetic Medications

    • Aims: Reduce anxiety, provide amnesia, enhance analgesia, decrease secretions/vagal stimulation, antiemetic effect, limit gastric acidity, facilitate induction.
    • Examples: Diazepam, lorazepam, chlorpromazine, haloperidol, atropine, morphine/meperidine.

    Modern Balanced General Anesthesia

    • A combination of drugs for different phases.
    • Includes pre-medication, induction, maintenance, and post-anesthesia care.

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    Description

    Test your knowledge on anesthesia, including preanaesthetic medication, drugs used for induction, and the phases of general anesthesia. This quiz covers essential facts and characteristics related to local and general anesthesia. Perfect for medical students or anyone interested in anesthesia practices.

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