Flashcards in Regional Anesthesia Test 1 Deck (71)
What is the definition of a drugs pKA?
It is the ph level of the drug?
What is the significance of a drugs pKA in relation to absorption?
The closer the drugs pKa is to the bodies pH, the quicker onset it will have, the only exception is Chloroprocaine due to its concentration
Which regional anesthetic has the quickest onset of action and why?
Chloroprocaine; its concentration
In local anesthesia agents, lipid solubility directly correlates with what?
In local anesthesia agents, protein binding directly correlates to what?
What three other factors also impact local anesthesia duration of action?
1. lipid solubility
3. tissue blood flow
In local anesthesia agents, speed of onset directly correlates to what?
In local anesthesia agents, onset of action indirectly correlates to what?
How does blood flow affect the absorption of local anesthetics?
Tissue sites with greater blood flow exhibit increased absorption of local anesthetics
What is the pneumonic for tissue sites from most vascular to least? Most blood flow to the least?
In Time I Can Please Everyone But Sally & Shelby
List the tissues sites in order from most vascular to least as related to absorption of local anesthetic agents and onset of action.
7. Brachial Plexus
8. Subarachnoid, Sciatic, Femoral
If the plasma concentration of local anesthesia becomes significantly elevated what can happen?
it can lead to toxicity of the CV and the CN systems
What is the most common cause of Local Anesthetic Systemic Toxicity(LAST)?
the inadvertent intravascular injection and administration of an excessive dose of local anesthetic.
What substance sequester any lipid binding drug in cases of LAST?
What are clinical signs of increased plasma concentrations of local anesthetics @ 5 mcg/ml?
Lightheadedness, tinnitus, circumoral and tongue numbness
What are clinical signs of increased plasma concentrations of local anesthetics @ 10 mcg/ml?
Muscular twitching and visual disturbances
What are clinical signs of increased plasma concentrations of local anesthetics @ 15 mcg/ml?
convulsions and unconsciousness
What are clinical signs of increased plasma concentrations of local anesthetics @ 20 mcg/ml?
unconsciousness and coma
What are clinical signs of increased plasma concentrations of local anesthetics @ 25 mcg/ml?
Respiratory arrest and CVS depression
What drug should you pretreat with 5-10 minutes before administering local anesthetics? And why?
Pretreat with benzodiazepine such as versed, versed elevates the seizure threshold in case they become toxic
What patient habitus is particularly at risk for LAST?
patients with poor muscle mass as there is not protein to bind too
How long does it take from of the time of injection can LAST occur?
5 - 25 minutes
What should you do frequently while injecting the local anesthetics?
What is the 4 most important treatments of LAST?
1. airway management
2. seizure suppression
4. 20% Lipid emulsion injection
At what dose should lipid emulsion be given for LAST?
1.5 ml/kg initial bolus, followed by 0.25 ml/kg/min for 30 - 60 minutes
Bolus could be repeated 1 -2 times for persistent systole
Infusion rate could be increased if the BP declines
What is meant by Lidocaine(2345678)?
234 g/mol Molecular Weight
56 % Protein bound
Is it ionized or unionized local anesthetic that renders the nerve insensate?
On what structure in the nerve does neuromuscular blockade occur
What is the name of the node in which the nerve blockade jumps from and how many nodes to achieve blockade??
Node of Ranvier; 2-3 nerves to achieve blockade