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How does local anesthetic produce its theraputic effect?
Entry of sodium ions into neurons.
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).
What are early signs of adverse effects?
- CNS stimulation
- - restlessness
- -anxiety followed by:
- CNS depression
- Cardiovascular effects
- - dysrhythmias
What are the therapeutic and pharmacologic classes of lidocaine (Xylocaine)?
- Therapeutic class: Anesthetic (local/topical)
- Pharmacologic class: Sodium channel blocker; amide
How should Lidocaine be administered to treat dysrhythmias?
IV, IM, or SC
Why should Lidocaine not be applied to large skin areas or to broken or abraded areas?
Significant absorption may occur
What are the early symptoms of toxicity?
CNS excitement, irritability confusion
What are serious adverse effects of Lidocaine?
convulsions, respiratory depression, cardiac arrest.
Assess VS especially BP and pulse
If a regional area is blocked, what ahsould the nurese periodically assess for?
Ability to move limbs distal to the block.
If a large regional block was given, what should the nurse assess for?
level of consciousness
Because of epinephrines vasoconstricting effects, never use local ansthetic containing epinephrine for areas of decreased circulation, such as;
Fingertips, toes, earlobes.
What is the goal of general anesthesia?
To provide rapid & complete loss of sedation.
What is balanced anesthesia?
An inhalation anesthesia used in combination with another type of anesthesia , which makes the procedure safer.
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.
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.
Some general anesthetics enhace the sensitivity of the heart to what drugs?
Epinephrine, norepinephrine, dopamine and serotonin
Why is Isoflurane ( Forane) the most commonly used inhalation anesthetic?
because it has less effect on the heart and doesn't damage the liver.
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.
What is the therapeutic and Pharmacologic class of Nitrous Oxide?
- Therapeutic class: General anesthetic
- Pharmacologic class: Inhalation gaseous agent
How does Nitrous Oxide produce analgesia?
Analgesia is caused by supression of pain mechanisms in the CNS
What are the adverse effects of nitrous when used in high doses?
anxiety, excitement and combativeness
What are the contraindications for Nitrous Oxide?
impaired level of consciousness, decpmpression sickness, undiagnosed abdominal pain, bowel obstruction, hypotension, shock, cyanosis, chest trauma, pneumothorax
what are the drug-drug interactions for Nitrous oxide?
Sympathomimetics and phosphodiesterase inhibitors may exacerbate dysrhythmias
What is the treatment for Nitrous oxide overdose?
Metoclopramide may reduce symptoms of nausea and vomiting
What is the therapeutic and pharmacologic class of halothane (Fluothane)?
- Therapeutic class: General anesthetic
- pharmacologic class: inhalation Volatile liquid
-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
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
What are the contraindications of halothane (Fluothane)?
- -History of malignant hyperthermia
- -hepatic function impairment
- -head injury
- -myasthenia gravis
- -pheochromocytoma ( tumor of adrenal gland tissue)
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.
What is the treatment for overdose of halothane (Fluothane)?
There is no overdose treatment. Pts. are treated symptomatically.
What is the therapeutic and pharmacologic class of thiopental(Pentothal)?
- Therapeutic class: general anesthetic
- Pharmacologic class: Intravenous induction agent; short acting barbituate
-Rapidly produces unconsciousness prior to administering inhaled anes.
- Ultra short acting barbituate
-onset 30-60 sesc, dutation 10-30 min
-very low analgesic properties
What are the adverse effects of thiopental (pentothal)/
- - Severe respiratory depression
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.
Drug- Drug interactions with thiopental (Pentothal)
- use with CNS depressants potentiates repiratory & CNS depression.
-Phenothiazines increase risk of hypotension.
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