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39 Cards in this Set
- Front
- Back
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Define regional anesthesia |
Because local anaesthetics are introduced into a specific region |
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Define conduction anesthesia |
Local anesthesia impairs conduction along a nerve or a group of nerves |
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List two subtypes of regional anesthesia |
Spinal anesthesia Epidural anesthesia Nerve blocks |
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Describe the presumed mechanism of action of the local anaesthetics by explaining the role of membrane ion channels |
Check page 171 |
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Polarization |
Cell membranes that possess electrical potential |
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Polarization |
Cell membranes that possess electrical potential |
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Depolarization |
Is the loss and reversal of membrane polarization brought about by the rapid opening of voltage-gated Na+ channels |
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Polarization |
Cell membranes that possess electrical potential |
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Depolarization |
Is the loss and reversal of membrane polarization brought about by the rapid opening of voltage-gated Na+ channels |
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Repolarization |
Is the recovery step whereby the resting membrane potential is restored through the opening of voltage-gated K+ channels and the closing of Na+ channels |
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Three types of nerve fibers affected by local anesthetic |
Group A, B and C. Classified based on axon diameter, myelination and conduction velocity |
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Nerve fiber - group A Myelinated? Axon diameter? Conduction velocity? Location? |
Least sensitive Myelinated - yes Diameter - large Velocity - 100 (rapid) Location - somatic nerve fibers |
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Nerve fiber - group B Myelinated? Axon diameter? Conduction velocity? Location? |
Myelinated - yes Diameter - medium Velocity - 10 (intermediate) Location - preganglionic autonomic fibers ( autonomic paralysis) |
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Nerve fiber - group B Myelinated? Axon diameter? Conduction velocity? Location? |
Myelinated - yes Diameter - medium Velocity - 10 (intermediate) Location - preganglionic autonomic fibers ( autonomic paralysis) |
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Nerve fiber - group C Myelinated? Axon diameter? Conduction velocity? Location? |
Most sensitive Myelinated - no Diameter - small Velocity - 1 (slow) Location - sympathetic postganglionic fibers |
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Nerve fiber - group B Myelinated? Axon diameter? Conduction velocity? Location? |
Myelinated - yes Diameter - medium Velocity - 10 (intermediate) Location - preganglionic autonomic fibers ( autonomic paralysis) |
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Nerve fiber - group C Myelinated? Axon diameter? Conduction velocity? Location? |
Most sensitive Myelinated - no Diameter - small Velocity - 1 (slow) Location - sympathetic postganglionic fibers |
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Loss of nerve function due to local anesthetic action |
Small diameter, unmyelinated fibers are affected first, followed by larger-diameter myelinated fibers. Nerve function is lost in this order: Autonomic, cold, warmth, pain, touch, pressure, vibration, proprioception, motor |
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Surgical anesthesia |
Produced when a clients perception of and reaction to pain is blocked |
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Surgical anesthesia |
Produced when a clients perception of and reaction to pain is blocked |
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Local anesthesia |
Produce local or regional blockade of sensory impulses without loss of consciousness |
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General anesthesia |
Unconscious state and seen in oral surgery. Administered through inhalational or parenteral route. |
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Properties of an ideal local anesthetics |
1. Potent local (action produced at low dose) 2. Adequate tissue penetration 3. Rapid onset of action with a useful duration of action 4. No systemic reactions 5. Satisfactory rates of metabolism and excretion 6. Low cost and adequate stability
No current local carries all these properties |
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Ionization of the drug and pH |
Free form base Lipid soluble (Nonionized) More absorption across lipid rich cell membranes Has phospholipids, glycolipids and cholesterol
Salt form Water soluble (Ionized) Less absorption across lipid rich cell membranes |
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Explain why a vasoconstrictor drug is usually included with a local anesthetic |
In order to maximize the local effect at a depot site and minimize systemic effects. Drugs such as epinephrine limit the spread of the local anesthetic into general circulation by constricting arterioles in the vicinity of the injection site |
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Ester containing durations of actions |
Procaine is metabolized to an intermediate compound, PABA. This may cause allergic reactions others have an atypical plasma cholinesterase. This faulty enzyme system results in prolonged duration of action and a risk for toxicity |
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Amide containing duration of action |
Lidocaine, metabolized by the hepatic mixed function oxidase system. The slower the rate of metabolism results in longer duration of metabolism ( 3 times longer that procaine) |
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Describe toxicity of the local anesthetics |
May lead to tissue injury such as hematoma if an artery or vein is accidentally nicked. Involves CNS and CVS |
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Pharmacologic activity of tetracaine (ester) + trade name |
Conduction anesthesia
Pontocaine |
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Pharmacologic activity of chloroprocaine (ester) + trade name |
Conduction anesthesia
Nesacaine |
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Toxicity CNS |
CNS stimulation cause by depression of inhibitory pathways in the brain may result in restlessness, tremors, or convulsions. CNS depression may lead to respiratory depression, cardiovascular depression or coma |
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Pharmacologic activity of lidocaine (amide) + trade name |
Topical, conduction, intravenous
Xylocaine |
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Pharmacologic activity of bupivacaine (amide) + trade name |
conduction anesthesia
Sensorcaine |
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Pharmacologic activity of dibucaine (amide) + trade name |
Topical, conduction
Nupercaine |
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Pharmacologic activity of etidocaine (amide) + trade name |
Conduction anesthesia
Duranest |
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Pharmacologic activity of mepivacaine (amide) + trade name |
Conduction anesthesia
Carbocaine |
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Pharmacologic activity of procaine (ester) + trade name |
Conduction anesthesia
Nivocaine |
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Pharmacologic activity of cocaine (ester) |
Topical anesthesia |
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Pharmacologic activity of benzocaine (ester) + trade name |
Topical anesthesia
Solarcaine |
