Article - Lipid Emulsion in Treatment of LAST Flashcards
Best method for avoiding LA toxicity
Prevention
What most frequently causes LA toxicity?
Accidental IV injection during performance of a peripheral nerve block
What determines toxic effects of LA?
Drug used
Amount administered
At therapeutic levels, LAs can help achieve _______ and ______ blockade
Sensory and motor
What limits high plasma concentrations from systemic absorption of LA drugs?
Establishing and adhering to a maximum acceptable safe dose for that particular drug
What is unusual about bupivicaine?
What is the significance of this?
It exhibits high potency at cardiac sodium channels
Results in cardiac toxicity before CNS toxicity
Pharmacodynamic feature of bupivicaine
Highly lipophilic
Which LA has been a major culprit in morbidity and mortality?
Bupivicaine
What drugs have shown to be effective in pretreatment and prevention of LA induced seizures in animals?
Benzodiazepines
What is Cm?
Minimum concentration of LAs needed to block nerve conduction
What causes variations in Cm?
What type of nerve fiber is to be blocked
Which type of neuron fiber (motor or sensory) requires higher concentration to block?
Motor neuron fibers require approximately double the concentration needed to block sensory neuron fibers
Addition of what agent can shorten onset and increase depth of blockade? Explain how this works.
Sodium bicarb
Addition of a base increases solubility percentage of LA in the lipid, thus making more drug available to traverse across several cellular compartments. This also explains why nerve blockade from LAs injected into acidic tissues is much less profound
What affects absorption of LA
- Injection site
- Drug dosage
- Drug properties
- Drug tissue binding
- Vasoconstriction
- Blood flow
Why was epinephrine historically added to LAs
To prolong duration of action
