LA Flashcards
1
Q
3 main roles of vasoconstrictors in LA
A
1) prolong length of action and increase depth of action of LA
2) reduce toxicity of LA
3) hemostatic effect
2
Q
absolute contraindications for LA
A
1) severe CVD
- <6 months after MI
- < 6 months after cerebrovascular accident
- < 6 months post coronary artery bypass surgery
- daily episodes of unstable angina
- cardiac dysrhythmias
2) untreated or uncontrolled severe HTN
3) thyrotoxicosis / uncontrolled hyperthyroidism
3
Q
what is the specific receptor theory for LA
A
the LA binds to specific receptor sites located at sodium channels of nervous tissues, blocking entry of Na+, resulting in
- threshold for excitation increasing
- impulse conduction slows
- rate of rise of AP declines
- generation and propagation of AP is inhibited
LA is a membrane stabilising drug so it will decrease rate of depol and prolong repol of excitable membranes
