Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
|
List the local anesthestics that are Amides
|
Bupivicaine
Dibucaine Etidocaine Lidocaine Mepivicaine Ropivicaine L-Bupivicaine(isomer of bupivicaine) |
|
|
What is the chmical structure of local anesthetics?
|
they are amides or esters
all have Lipophilic Hydrophilic ends separated by a connecting hydrocarbon chain |
|
|
What part of the local anesthetics chemical structure plays a major role in determineing their pharmacokinetics (lipid solubility, etc.)
|
the # of Carbons on the the molecule
|
|
|
List the local anesthetics that are Esters
|
Chloroprocaine
Cocaine Procaine Tetracaine |
|
|
What is the mechanisms of action of local anesthetics?
|
1. Diffusion of basic drug through the nerrver sheath
2. Binding of cationic form to membrane receptor site Both of these cause failure to achieve thrshold by blocking sodium channels and conduction blockade |
|
|
Sensitivity of nerve fiber to blockade of local anesthetics is determine by what 3 things?
|
Axonal diameter
Degree of myelination Anatomic an dphysical factors (how much tissue it has to pnetrate) |
|
|
What is Differential Blockade?
|
it is the order of blockade occurence
usually progreeses in following order: Sympathetic block: peripheral vasodilation and increased skin temp Sensoty: Loss of pain and temperature Loss of proprioception Loss of toucn and pressure sensation Motor: paralysis |
|
|
whcih type of nerve fiber requires blockade of 3 adjacent nodal regions to have conduction blocked?
|
Type A fibers
|
|
|
What are the 3 protective layers that surround nerve fibers
|
Endoneurium: surround the axon
Perinurium: connective tissue surrounding groupings of nerve fibers Epineurium: dense connective tissue that encases entire peripheral nerve |
|
|
What state does the Na channel have to be in for local anesthetic to bind to it?
|
Inactivated-Closed state
when the anesthetic binds to it, this prevents channel activation and depolarization |
|
|
will local anesthetics with lower pKa have fsater or slower onset of action?
|
Faster
B/c they are basic drugs , so will have larger nonionized fraction at physiologic pH BH+ -- B + H+ |
|
|
Which has faster onset: lidocaine or Bupivicaine?
|
Lidocaine
Pka 7.9 (closer to physiologic pH) |
|
|
What does sodium bicarbonate do when added to local anesthetic solution?
|
1. Decreses pain with injections
2. speed onset of action by shifting the reaction to the right (more nonionized form) |
|
|
What is main factor in absortion of local anesthetics?
|
Site of injection and vasularity
IV> Tracheal> Interrcostal> Caudal> Paracervical> Epicural> Brachial Plexus> Sciatic > Subcutaneous |
|
|
Why would you use vasoconstrictors be used with local anesthetics?
|
decrease absorption (keep local anesthetic where you put is) -- increased neuronal uptake and this enhances quality of the block
Prolong duration of action limit toxic effects *these effects are more pronounces with shorter-acting local anesthetics |
|
|
What are the contraindications for adding Epinephrine to local anesthetic solution?
|
Unstable Angina Pectoris
Cardiac Dysrhythmias Histoyr of HTN Uteroplacental Insufficiency Peripheral nerve block anesthesia in areas that may lack collateral blood flow (digits, penis) Intravenous regional anesthesia |
|
|
what factors are thought to be cause of Cauda Equina Syndrome?
|
1. Lidocaine 5%
2. Small bore catherters used for continuous spinal anesthesia (bllod pooling) 3. Positioning: lithotomy |
|
|
When person has allergy to Local anesthetic, what is their allergy most likely to?
|
most likely to PABA(metabolite of Esters), but want to avoid both esters and amides b/c amides contain a preservative that is a relative to PABA (methylparaben)
|
