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How does local anesthetic produce its theraputic effect?
Entry of sodium ions into neurons.
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Why is sodium hydroxide sometimes added to local anesthetic?
To increase effectiveness in regions that have extensive local infection or abscess. (Bacteria acidify an infected site & local anesthetic are less effective in this environment. Adding alkaline substances such as sodium hydroxide or sodium bicarbonate neutralizes the region).
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What are early signs of adverse effects?
- CNS stimulation
- - restlessness
- -anxiety followed by:
- CNS depression
- -drowsiness
- -unresponsiveness
- Cardiovascular effects
- -hypotension
- - dysrhythmias
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What are the therapeutic and pharmacologic classes of lidocaine (Xylocaine)?
- Therapeutic class: Anesthetic (local/topical)
- Pharmacologic class: Sodium channel blocker; amide
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How should Lidocaine be administered to treat dysrhythmias?
IV, IM, or SC
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Why should Lidocaine not be applied to large skin areas or to broken or abraded areas?
Significant absorption may occur
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What are the early symptoms of toxicity?
CNS excitement, irritability confusion
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What are serious adverse effects of Lidocaine?
convulsions, respiratory depression, cardiac arrest.
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Assess VS especially BP and pulse
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If a regional area is blocked, what ahsould the nurese periodically assess for?
Ability to move limbs distal to the block.
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If a large regional block was given, what should the nurse assess for?
level of consciousness
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Because of epinephrines vasoconstricting effects, never use local ansthetic containing epinephrine for areas of decreased circulation, such as;
Fingertips, toes, earlobes.
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What is the goal of general anesthesia?
To provide rapid & complete loss of sedation.
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What is balanced anesthesia?
An inhalation anesthesia used in combination with another type of anesthesia , which makes the procedure safer.
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What are the stages of general anesthesia?
- Stage1: Loss of pain :loss of general sensation but may be awake
- Stage 2:Excitement and hyperactivity: pt. may be delirious and try to resist treatment. Heartrate and breathing may become irregular & BP can increase.
- Stage 3: Surgical anes. : Skeletal muscles relax & delirium stabilizes. Cardiovascular & breathing activities stabilize. Surgery begins and ends here.
- Stage 4: paralysis of the medulla region in brain.(responsible for controlling respiratory & cardioactivity). this stage is usually avoided. Death could result if heart or breathing stops.
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How do inhaled anesthetics (gases or volatile liquids) produce their effect?
By preventing flow of sodium into neurons in the CNS, thus delaying nerve impulses and producing a dramatic reduction in neural activity. It is likely that GABA receptors are activated.
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Some general anesthetics enhace the sensitivity of the heart to what drugs?
Epinephrine, norepinephrine, dopamine and serotonin
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Why is Isoflurane ( Forane) the most commonly used inhalation anesthetic?
because it has less effect on the heart and doesn't damage the liver.
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What is neuroleptanalgesia and what is an example of a drug combo that produces it?
A state where the patient is conscious, but insensitive to pain & unconnected with surroundings. Fentanyl(Sublimaze) combined with droperidol (Inapsine) produce this effect. This combo is marketed as Innovar.
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What is the therapeutic and Pharmacologic class of Nitrous Oxide?
- Therapeutic class: General anesthetic
- Pharmacologic class: Inhalation gaseous agent
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How does Nitrous Oxide produce analgesia?
Analgesia is caused by supression of pain mechanisms in the CNS
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What are the adverse effects of nitrous when used in high doses?
anxiety, excitement and combativeness
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What are the contraindications for Nitrous Oxide?
impaired level of consciousness, decpmpression sickness, undiagnosed abdominal pain, bowel obstruction, hypotension, shock, cyanosis, chest trauma, pneumothorax
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what are the drug-drug interactions for Nitrous oxide?
Sympathomimetics and phosphodiesterase inhibitors may exacerbate dysrhythmias
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What is the treatment for Nitrous oxide overdose?
Metoclopramide may reduce symptoms of nausea and vomiting
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What is the therapeutic and pharmacologic class of halothane (Fluothane)?
- Therapeutic class: General anesthetic
- pharmacologic class: inhalation Volatile liquid
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-Halothane (Fluothane) produces potent level of surgical anesthesia that is rapid onset.
-Does not produce as much muscle relaxation or analgesia.
-Primarily used with other muscle relaxants & analgesics. ( sometimes combined with N2O)
- Duration varies among age group
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What are the adverse effects of halothane (Fluothane)?
- -Sensitizes heart muscle to epinephrine; ttherefore dysrhythmias are a concern
- - lowers BP & respiration rate
- -Overcomes reflex mechanisms that normally keep contents of stomach from entering lungs (possibility of aspiration)
- -Use of this drug has declined because of hepatoxicity
- -Malignant hyperthermia (rare but fatal).
- - Dilates cerebral vasculature and may increase intracranial pressure
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What are the contraindications of halothane (Fluothane)?
- -History of malignant hyperthermia
- -hepatic function impairment
- -dysrhythmias
- -head injury
- -myasthenia gravis
- -pheochromocytoma ( tumor of adrenal gland tissue)
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What are the drug-drug interactions with halothane (Fluothane)?
- -When combined with antihypertensives, excessive hypotension results
- -Potentiates action of non-depolarizing neuromuscular blocking agents
- -When taken with Levodopa, levels of dopamine in the CNS is increased. (Should be discontinued 6-8 hrs before halothane).
- -If taken with polymoxins lincomycin or aminoglycosides, muscle weakness, respiratory depression, or apnea may occur.
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What is the treatment for overdose of halothane (Fluothane)?
There is no overdose treatment. Pts. are treated symptomatically.
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What is the therapeutic and pharmacologic class of thiopental(Pentothal)?
- Therapeutic class: general anesthetic
- Pharmacologic class: Intravenous induction agent; short acting barbituate
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Thiopental (Pentothal)
-Rapidly produces unconsciousness prior to administering inhaled anes.
- Ultra short acting barbituate
-onset 30-60 sesc, dutation 10-30 min
-very low analgesic properties
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What are the adverse effects of thiopental (pentothal)/
- - Severe respiratory depression
- -hallucination
- -Confusion
- -Excitability
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Contraindications of thiiopental (Pentothal):
- - Pts. with cardiovascular disease ( can depress the myocardium and cause dysrhythmias).
- -Demyelination and CNS lesions in those with porphyria which causes pain, weakness and paralysis.
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Drug- Drug interactions with thiopental (Pentothal)
- use with CNS depressants potentiates repiratory & CNS depression.
-Phenothiazines increase risk of hypotension.
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What is the treatment of overdose for thiopental (Pentothal)?
Due to very short half life, overdose is managed by discontinuing drug, assisting with ventilation until respirations are normal
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