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42 Cards in this Set
- Front
- Back
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What are general anesthetics? |
- A heterogeneous group of potent CNS depressants - Reversible loss of consciousness and insensibility to painful stimuli - Balanced anesthesia = combination of drugs to minimize adverse effects |
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What are the Stages of Anesthesia? |
- Stage I: Analgesia - Stage II: Delirium or Excitement - Stage III: Surgical Anesthesia - Stage IV: Medullary/Respiratory Paralysis |
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What happens in Stage I: Analgesia?
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- Reduced pain sensation
- Pt. is conscious & responsive to commands - Reflexes present, normal respiration |
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What happens in Stage II: Delirium or Excitement? |
- Unconsciousness with involuntary movement/excitement - Irregular respiration, ^ muscle tone, sympathetic stimulation (tachycardia, mydriasis, hypertension) - Emesis and incontinence may occur |
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What happens in Stage III: Surgical Anesthesia? |
- Resumes regular respiration, muscle relaxation, normal heart & pulse rates |
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What happens in Stage IV: Medullary/Respiration Paralysis? |
- Pupils dilated, blood pressure falls, respiration stops |
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What are the Levels of Anesthesia using Flagg's Approach? What do they consist of? |
- Induction * Includes all preparation and pre-op meds - Maintenance * Begins when Pt. is at the depth of anesthesia needed for the procedure, continues until procedure completion - Recovery * Starts when surgical procedure is complete and continues until Pt. is fully responsive
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What are the adverse reactions/hazards of general anesthetics? |
- Cardiovascular collapse, cardiac arrest - Arrhythmia - Hypertension (Stage II); hypotension - Depressed respiration; respiratory arrest - Explosions w/ inhaled gases |
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What are the two catagories of general anesthetics? Which one cannot be removed through respiration? |
- Inhalation Anesthetics - Intravenous Anesthetics: can not be removed through respiration |
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What are the types of Inhalation Anesthetics?
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- Inhalation gases
* Nitrous oxide - Inhalation volatile liquids * Ether (no longer in use) * Halogenated hydrocarbons: enflurane and isoflurane most popular |
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What are the types of Intravenous Anesthetics? |
- Barbiturates: thiopental - Dissociative: ketamine - Neuroleptanalgesic: fentanyl
* Cannot be removed through respiration * |
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What do Inhalation Anesthetics come from? What do they do? |
- Vaporized from liquid form and inhaled to produce general anesthesia - Inhaled Gas
- Depress spontaneous and evoked activity of neurons - Influence GABAA receptor - chloride channel |
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What are the 7 examples of Inhaled Anesthetics?
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- Nitrous oxide
- Halothane (Halogenated hydrocarbon) - Isoflurane (Halogenated ether) - Enflurane - Sevoflurane - Methoxyflurane - Desflurane * Helpful Hint: Bottom 5 end in "flurane" * |
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What is Nitrous oxide? What is its blood solubility, potency, and combination ability? What Stage(s) does does it produce? |
- Colorless, odorless gas
- Least solubility in blood - Low potency: unsatisfactory as a single agent general anesthetic * Used alone to reduce anxiety - Can be used in combination with other general anesthetics * Intention of the nitrous oxide is to relax and slightly sedate the Pt.
- Produces Stage I: Analgesia level of anesthesia |
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What is the MOA, speed of onset action, use and metabolism of Nitrous oxide? |
- MOA * Not truly known. Potentiation of neurotransmitter GABA; stimulation of endorphin release (reduces pain); stimulation of noradrenergic receptors in brainstem; stimulatory neurotransmitter NMDA receptor antagonist; etc. - Rapid onset of action - Used to achieve a lightly sedated and relaxed Pt. - Not metabolized in the body - save to use even w/ poor liver function |
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What are the advantages of Nitrous oxide? |
- Rapid onset of action - Elevates pain threshold - Pleasant induction - Titratable (adjustable) - Rabid and complete recovery - Virtually no adverse effects - Therapeutic for medically compromised Pts. - Suitable for all ages |
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What are 5 of the things to remember about Nitous oxide safety? (Always, Hypoxia, Scavenging, Patient, Nitrous) |
- Always administered in combination with oxygen ("Fail Safe" on flow meter) - Hypoxia is caused by administration of 100% nitrous oxide (nitrous binds to hemoglobin, kicks oxygen off) -Scavenging: Double Mask by Porter; removes exhaled gas - Nitrous indicators available - should not leave room to know which room has leak |
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What are 4 additional things to remember about Nitrous oxide safety? (Nausea, Nausea, Higher, Diffusion) |
- Nausea and vomiting in adults is associated with adjusting the nitrous dose - Nausea and vomiting in children is associated with children eating 1 hr prior to procedure - Higher resistance to nitrous in pts. who are alcoholics, drug addicts, chronic cigarette smokers - Diffusion Hypoxia * Avoid by administering 100% oxygen to pt for at least 5 min after termination of nitrous oxide sedation. |
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What are the last 6 things to remember about Nitrous oxide safety? (Nitrous, Potential, Don't, Heavey, Reduces, Associated) |
- Nitrous badges: chronic exposure defined as 8 hrs of 50ppm - Potential for abuse - Don't leave operatory when pt. is on nitrous - constantly monitor pt. - Heavy gas difficult to remove: fans, open windows - Reduces fertility with chronic exposure - Associated with miscarriages with chronic exposure during pregnancy |
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What are contraindications for Nitrous oxide? |
- Upper respiratory infection - COPD (Chronic Obstructive Pulmonary Disease) - Pregnancy - Communication barrier (may misunderstand Dr's actions) - Contagious disease such as hepatitis if tubing cannot be completely sterilized - Epilepsy - Emotional instability - Previous negative experience w/ nitrous |
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What are the other general anesthetics besides Nitrous oxide? |
- Halogenated hydrocarbons - Barbiturates - Propofol - Ketamine |
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What do halogenated hydrocarbons contain? What are their potency and tissue solubility? What is their boiling point? Which ones does this include? |
- Contain flourine, chlorine, and bromine
- Potent with limited solubility in tissues
- Very low boiling points - evaporate easily at room temp *Halothane *Enflurane *Isoflurane *Desflurane *Sevoflurane
* Helpful Hint - All the "flurane"s except Methoxyflurane * |
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Halothane
What is the flammability/volatility, induction/recovery rate, MAC, bronchial irritability, muscle relaxant ability, heart rate/vasodilation effect, myocardial effect, and hepatic effect of Halothane? |
- Nonflammable and nonexplosive
- relatively rapid induction and recovery - MAC: 0.77; OR 0.29 when in combo w/ 70% N2O - Not irritating to bronchial mucous membrane * Good choice for ashmatics - Incomplete muscle relaxation - Depresses heart rate, increases peripheral vasodilation - Sensitizes myocardium to Epi and NE which can lead to arrhythmias - Can lead to post anesthetic hepatitis |
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What is the induction/recovery rate, MAC, respiration effect, muscle relaxant ability, CV/BP effect, motor activity effect, and metabolic ability / hepatic effect of Enflurane? |
- Rapid induction and recovery - MAC: 0.57 in combo w/ N2O - Depresses respiration - use assisted ventilation - Still requires additional muscle relaxants - CV and BP depression, but less sensitivity to Epi than w/ Halothane - Alters electroencephalographic activity leading to more motor activity - Lower amounts of metabolites, no hepatotoxicity |
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What is the induction/recovery rate, MAC, BP effect, metabolic ability / hepatic effect, myocardial effect, and respiratory effect of Isoflurane? |
- Rapid induction and recovery - MAC: 0.5 in combo with 70% N2O - Reduced BP - Limited amounts metabolized, low if any liver toxicity - Limited sensitization of myocardium to Epi - Respiratory acidosis w/ deeper anesthesia |
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What is the blood/gas partition coefficiency of Desflurane and Sevoflurane? What is the volatility, respiratory effect, and speed of Desflurane? What is the chemical stability and renal effect of Sevoflurane? |
- Lower blood/gas partition coefficient * More rapid onset and shorter duration
Desflurane - Low volatility, requires a special vaporizer - causes cough and laryngospasm, can not use for induction - Not faster than older agents
Sevoflurane - Chemically unstable, potential for renal toxicity due to release of fluoride when metabolized |
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What is the duration of action, use, lipid solubility, anesthetic ability of Ultrashort Acting Barbiturates? What are some examples of Ultrashort Acting Barbiturates? |
- Duration of action: 5-20 min (IV administration) - Used for induction of general anesthesia due to rapid onset (about 30 sec) - Highest lipid solubility, accumulates in fat leading to prolonged recovery with repeated dosses - Not good as sole anesthetic for short procedures because there is NO ANALGESIA if using doses that allow for spontaneous respiration
- Examples: thiopental, methohexital |
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What are complications and overdosage effects of Ultrashort Acting Barbiturates? |
- Complications: * Extravascular injection-necrosis or sloughing * intraaterial injection can lead to ischemia due to arteriospasm * Laryngospasm and pronchiospasm - Overdosage is respiratory failure
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What are contraindications for Ultrashort Acting Barbiturates? |
- Absence of good veins for injection - Status asthmaticus (multiple asthma attacks w/o pause) - Porphyrias (hereditary blood condition) - Known hypersensitivity |
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What is Propofol? What is its onset, use, Vaso / BP effects, and analgesic effects? |
- General anesthetic
- Rapid onset ( about 30 sec) - Used for induction and maintenance of anesthesia - Vasodilator leading to large decreases in BP - NO analgesic effects * Must provide suplemental pain relief |
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What is Ketamine? What is its analgesic effect, administration method(s)/Onset, Blood flow/Cardiac output/Salivation effects, and mental/perceptive effects? What is its contraindications? |
- Dissociative anesthetic, causes amnesia
- Analgesia without loss of conciousness - can be administered IV or IM * Onset 1-2 min by either route - Causes increase in cerebral blood flow and increases cardiac output. Excessive salivation so pretreat w/ antropine - Can cause hallucinations and delirium during recovery * Reduce audio and visual stimulation
- Contraindications include cerebrovascular disease, hypertension and hypersensitivity |
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What is the MOA of Barbiturates? |
- MOA: Binds to components of the GABA receptor present in neuronal membranes in the CNS. The GABA receptor is a transmembrane chloride ion channel composed of 5 protein subunits. Binding to the receptor by barbiturates causes hyperpolarization of the neuron to suppress nerve function. |
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What are the Barbiturate Classifications? |
- Long Acting (8-12 hrs) - Intermediate Acting (6-8 hrs) - Short Acting (4-6 hrs) - Ultrashort Acting (1-2 hrs) - for surgery so after IV has stopped delivering medication, Pt. has shorter recovery. |
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What is the duration of action, lipid solubility, and use of Long Acting Barbiturates? What are some examples of Long Acting Barbiturates and what they are for? |
- Duration of action: 6-10 hrs - Least lipid soluble - Used for daytime sedation and anticonfulsant
- Examples: * Phenobarbital, primidone (antiseizure) * Mephobarbital (sleep, anxiety) |
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What is the duration of action, use, and use regularity of Intermediate Acting Barbiturates? What are some examples of Intermediate Acting Barbiturates? |
- Duration of action 3-6 hrs - Used to treat insomnia - Not used very often
- Examples: * Amobarbital, butabarbital (not commonly used today) |
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What is the duration of action, use, lipid solubility, use regularity and drawbacks of Short Acting Barbiturates? What are some examples of Short Acting Barbiturates? |
- Duration of action: 1-3 hrs - Used to treat insomnia - Increased lipid solubility - Rarely used anymore. Replaced by benzodiazepine hypnotics such as valium due to safety - Addition and tolerance
- Examples: * secobarbital, pentobarbital |
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What is the duration of action relation, method of entery, metabolic organ, potential interactions, and analgesic action of Barbiturates? |
- duration of action related to lipid solubility (the more lipid soluble - can act on CNS more easily) - Medication has to cross blood brain barrier to have its action - Metabolized by the liver (decrease dose for cirrhosis) - potential interactions by long term use. Liver increases enzymes for metabolism (upregulation) - NO analgesic action, agitation may result if analgesic is not also given |
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What is the MOA of Benzodiazepines? What is its action similar to? What has its therapeutic use replaced? |
- MOA: Bind to GABA receptor causing CNS depression (3 types omega 1-2); enhance the action of GABA; action on CNS depends on which GABA receptor subunit drug binds to and where the receptor is located (limbic, cortical, thalamic, hypothalamous).
- Similar action as barbiturates, but safer (less respiratory depression
- Therapeutic use has replaced barbiturates. |
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What are benzodiazepines clinically used for? What do they account for? |
- Anti-Anxiety - Sedative/hypnotic - Skeletal Muscle Relaxant - valium - Anticonvulsant - Treatment of alcohol withdrawal
- Accounts for 10 of the "Top 200" |
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What are Benzodiazepines uses in dentistry? What can Pt. not do while taking these? How is an overdose treated? |
- Pre-Medication - Anti-Anxiety : Diazepam (Valium) - Conscious Sedation * IV Lorazepam, Midazolam, Diazepam * Oral Triazolam (Halcion) - conscious sedation * Muscle relaxation; amnesia
-Pt. cannot drive while taking benzodiazepines
- Overdose: treated w/ flumazenil (Mazicon) |
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What is/are the side effect(s) of Benzodiazepines? When should they be avoided? What do they interact with and what this cause? |
-Drowsiness
-Avoid in pregnancy * Most are pregnancy category D or X
- Interactions with other drugs (enhanced sedation): * Nitrous oxide * Pain medications * Muscle relaxants |
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What is Chloral hydrate? What is its respiratory/CV effect, mucosal tissue effects and possible causation(s)? How is it administered and why? What is it used for, its adverse effects, and what replaced it? |
- Inexpensive, sedative-hypnotic w/ rapid onset (20-30 min)
- No pronounced respiratory or cardiovascular depression -Very irritating to mucosal tissue, may cause aspiration
- Usually given in syrup form, unflavorable taste and odor * Administer with food or milk
- Used for pre-op sedation of children * gastrointestinal adverse effects, vasodialation, and hypotension seen with chloral hydrate. *benzodiazepines are now more preferred |
