Local Anesthesia Chapter 4 - Vasoconstrictors

What are the 4 functions of Vasoconstrictors? [blank_start]Constrict[blank_end] blood vessels at site = decrease dose of LA increase [blank_start]duration[blank_end] of LA = 6 times as long Provides [blank_start]hemostasis[blank_end] at injection site decrease [blank_start]absorption[blank_end] rate of LA = decrease risk of toxicity.

All LA are vasoconstrictors.

All LAs are vasodilators.

The two types of vasoconstrictors used in the US are: [blank_start]Epinephrine[blank_end] [blank_start]Levonordefrin[blank_end]

Epinephrine, levonordfrin, both, neither. [blank_start]Both[blank_end] are absorbed from injection site into bloodstream. [blank_start]Both[blank_end] are unstable in solution.

[blank_start]Sodium Bisulfite[blank_end] is the preservative added for stability. About 10% of asthmatics are allergic.

Epi in LAs have identical structure to the natural hormone.

Epinephrine targets these two groups of receptors located in most tissues: [blank_start]alpha[blank_end] [blank_start]beta[blank_end]

Alpha receptors: [blank_start]vasoconstriction[blank_end]; [blank_start]bronchodilation[blank_end] beta receptors: [blank_start]vasodilation[blank_end]; [blank_start]increase HR[blank_end]; [blank_start]increase force of heart contraction[blank_end].

high levels of epi - [blank_start]alpha[blank_end] receptors override [blank_start]beta[blank_end] receptors = vasoconstriction [blank_start]Low[blank_end] levels of epi - beta receptors override alpha receptors = [blank_start]vasodilation[blank_end].

concentrations of vasoconstrictors in LA solutions are referred to as a ratio of [blank_start]grams[blank_end] of epi per [blank_start]mL[blank_end] of solution.

The highest concentration of epi available in the US is 1:[blank_start]50,000[blank_end] This is only used for [blank_start]hemostasis[blank_end] --> usually via [blank_start]infiltration[blank_end].

Rebound vasodilation occurs after [blank_start]6[blank_end] hours and the [blank_start]beta[blank_end] receptors are prominent.

Rebound vasodilation occurs during the [blank_start]highest[blank_end] concentrations of epi are used

The lowest concentration of epi available in the US is [blank_start]1:200,000[blank_end]. Lower the concentration is [blank_start]ineffective[blank_end] Produces [blank_start]fewer[blank_end] side effects

Levonordefrin is only [blank_start]15[blank_end]% as potent as epi Only available in US as [blank_start]1:20,000[blank_end] concentration in 2% [blank_start]Mepivacaine[blank_end]/[blank_start]carbocaine[blank_end] The 1:20,000 has the same clinical effect as [blank_start]1:100,000[blank_end] epi

Epi affects alpha receptors [blank_start]50[blank_end]% and beta receptors [blank_start]50[blank_end]% Levonordefrin affects the alpha receptors [blank_start]75[blank_end]% and the beta receptors [blank_start]25[blank_end]%.

compared to epinephrine, levonordefrin has the same cardiac affects like increased HR, stroke volume, CO, increased dysrhythmias, and dilating of coronary arteries but to a [blank_start]lesser[blank_end] degree.

Levonordefrin is a great choice of LA with vasoconstrictor because blood sugar increase is to a [blank_start]lesser[blank_end] degree.

[blank_start]Levonordefrin[blank_end] causes potent bronchodilation to a lesser degree and less hemostasis

Both epi and levonordefrin have sodium bisulfite

EPI MRD healthy: [blank_start]0.2[blank_end]mg CV ds: [blank_start]0.04[blank_end]mg Levonordefrin MRD healthy: [blank_start]1.0[blank_end]mg CV ds: [blank_start]0.2[blank_end]mg

OD occurs via [blank_start]intravascular[blank_end] injection administering more than [blank_start]MRD[blank_end] symptoms will occur within [blank_start]60[blank_end] seconds body clears drug within [blank_start]5[blank_end]-[blank_start]10[blank_end] minutes via [blank_start]re-uptake[blank_end]